title: Athens

text: Athens was awarded the 2004 Summer Olympics on 5 September 1997 in Lausanne, Switzerland, after having lost a previous bid to host the 1996 Summer Olympics, to Atlanta, United States. It was to be the second time Athens would host the games, following the inaugural event of 1896. After an unsuccessful bid in 1990, the 1997 bid was radically improved, including an appeal to Greece's Olympic history. In the last round of voting, Athens defeated Rome with 66 votes to 41. Prior to this round, the cities of Buenos Aires, Stockholm and Cape Town had been eliminated from competition, having received fewer votes.


title: Athens

text: During the first three years of preparations, the International Olympic Committee had expressed concern over the speed of construction progress for some of the new Olympic venues. In 2000, the Organising Committee's president was replaced by Gianna Angelopoulos-Daskalaki, who was the president of the original Bidding Committee in 1997. From that point forward, preparations continued at a highly accelerated, almost frenzied pace.


title: Athens

text: Although the heavy cost was criticized, estimated at $1.5 billion, Athens was transformed into a more functional city that enjoys modern technology both in transportation and in modern urban development. The games welcomed over 10,000 athletes from all 202 countries.


title: Athens

text: The 2004 Games were judged a success, as both security and organization worked well, and only a few visitors reported minor problems mainly concerning accommodation issues. The 2004 Olympic Games were described as "unforgettable, dream games", by IOC President Jacques Rogge for their return to the birthplace of the Olympics, and for meeting the challenges of holding the Olympic Games. The only observable problem was a somewhat sparse attendance of some early events. Eventually, however, a total of more than 3.5 million tickets were sold, which was higher than any other Olympics with the exception of Sydney (more than 5 million tickets were sold there in 2000).


title: Athens

text: In 2008, it was reported that most of the Olympic venues had fallen into disrepair: according to those reports, 21 of the 22 facilities built for the games had either been left abandoned or are in a state of dereliction, with several squatter camps having sprung up around certain facilities, and a number of venues afflicted by vandalism, graffiti or strewn with rubbish. These claims were disputed and are likely to be inaccurate, as most of the facilities used for the Athens Olympics are either in use or in the process of being converted for post-Olympics use. The Greek Government has created a corporation, Olympic Properties SA, which is overseeing the post-Olympics management, development and conversion of these facilities, some of which will be sold off (or have already been sold off) to the private sector, while other facilities are still in use just as during the Olympics, or have been converted for commercial use or modified for other sports. Concerts and theatrical shows, such as those by the troupe Cirque du Soleil, have recently been held in the complex.


title: The Vanguard Group

text: The Vanguard Group, Inc. is an American registered investment advisor based in Malvern, Pennsylvania, with about $7 trillion in global assets under management, as of January 13, 2021. It is the largest provider of mutual funds and the second-largest provider of exchange-traded funds (ETFs) in the world after BlackRock's iShares. In addition to mutual funds and ETFs, Vanguard offers brokerage services, educational account services, financial planning, asset management, and trust services. Several mutual funds managed by Vanguard are ranked at the top of the list of US mutual funds by assets under management. Along with BlackRock and State Street, Vanguard is considered to be one of the Big Three index fund managers that dominate corporate America.


title: The Vanguard Group

text: Founder and former chairman John C. Bogle is credited with the creation of the first index fund available to individual investors and was a proponent and major enabler of low-cost investing by individuals, though Rex Sinquefield has also been credited with the first index fund open to the public a few years before Bogle.


title: The Vanguard Group

text: Vanguard is owned by the funds managed by the company and is therefore owned by its customers. Vanguard offers two classes of most of its funds: "investor shares" and "admiral shares". Admiral shares have slightly lower expense ratios but require a higher minimum investment, often between $3,000 and $100,000 per fund. Vanguard's corporate headquarters is in Malvern, a suburb of Philadelphia. It has satellite offices in Charlotte, North Carolina, Dallas, Texas, Washington D.C. and Scottsdale, Arizona. The company also has offices in Canada, Australia, Asia, and Europe.


title: The Vanguard Group

text: In 1951, for his undergraduate thesis at Princeton University, John C. Bogle conducted a study in which he found that most mutual funds did not earn more money compared to broad stock market indexes. Even if the stocks in the funds beat the benchmark index, management fees reduced the returns to investors below the returns of the benchmark.


title: The Vanguard Group

text: Immediately after graduating from Princeton University in 1951, Bogle was hired by Wellington Management Company. In 1966, he forged a merger with a fund management group based in Boston. He became president in 1967 and CEO in 1970. However, the merger ended badly and Bogle was therefore fired in 1974. Bogle has said about being fired: "The great thing about that mistake, which was shameful and inexcusable and a reflection of immaturity and confidence beyond what the facts justified, was that I learned a lot. And if I had not been fired then, there would not have been a Vanguard."


title: The Vanguard Group

text: Bogle arranged to start a new fund division at Wellington. He named it Vanguard, after Horatio Nelson's flagship at the Battle of the Nile, . Bogle chose this name after a dealer in antique prints left him a book about Great Britain's naval achievements that featured HMS "Vanguard". Wellington executives initially resisted the name, but narrowly approved it after Bogle mentioned that Vanguard funds would be listed alphabetically next to Wellington Funds.


title: The Vanguard Group

text: The Wellington executives prohibited the fund from engaging in advisory or fund management services. Bogle saw this as an opportunity to start a passive fund tied to the performance of the S&P 500, which was established in 1957. Bogle was also inspired by Paul Samuelson, an economist who later won the Nobel Memorial Prize in Economic Sciences, who wrote in an August 1976 column in "Newsweek" that retail investors needed an opportunity to invest in stock market indexes such as the S&P 500.


title: The Vanguard Group

text: In 1976, after getting approval from the board of directors of Wellington, Bogle established the First


title: The Vanguard Group

text: Index Investment Trust (now called the Vanguard 500 Index Fund). This was one of the earliest passive investing index funds, preceded a few years earlier by a handful of others (e.g., Jeremy Grantham's "Batterymarch Financial Management" in Boston, and index funds managed by Rex Sinquefield at American National Bank in Chicago, and John "Mac" McQuown at Wells Fargo's San Francisco office).


title: The Vanguard Group

text: Bogle's S&P 500 index raised $11 million in its initial public offering, compared to expectations of raising $150 million. The banks that managed the public offering suggested that Bogle cancel the fund due to the weak reception, but Bogle refused. At this time, Vanguard had only three employees: Bogle and two analysts. Asset growth in the first years was slow, partially because the fund did not pay commissions to brokers who sold it, which was unusual at the time. Within a year, the fund had only grown to $17 million in assets, but one of the Wellington Funds that Vanguard was administering had to be merged in with another fund, and Bogle convinced Wellington to merge it in with the Index fund. This brought assets up to almost $100 million.


title: The Vanguard Group

text: Growth in assets accelerated after the beginning of a bull market in 1982, and the indexing model became more popular at other companies. These copy funds were not successful since they typically charged higher fees, which defeated the purpose of index funds. In December 1986, Vanguard launched its second mutual fund, a bond index fund called the Total Bond Fund, which was the first bond index fund ever offered to individual investors. One earlier criticism of the first Index fund was that it was only an index of the S&P 500. In December 1987, Vanguard launched its third fund, the Vanguard Extended Market Index Fund, an index fund of the entire stock market, excluding the S&P 500. Over the next five years, other funds were launched, including a small-cap index fund, an international stock index fund, and a total stock market index fund. During the 1990s, more funds were offered, and several Vanguard funds, including the S&P 500 index fund and the total stock market fund, became among the largest funds in the world, and Vanguard became the largest mutual fund company in the world. Noted investor John Neff retired as manager of Vanguard's Windsor Fund in 1995, after a 30-year career in which his fund beat returns of the S&P 500 index by an average of 300 basis points per year.


title: The Vanguard Group

text: In March of 2021, Vanguard joined over 70 asset managers, aiming to have companies within their portfolios to achieve net-zero emissions by 2050, a goal that parallels the Paris Agreement. Climate and Indigenous advocates felt optimistic about this development, but stressed the issue that Vanguard must also stop investing in companies that engage in deforestation, fossil fuel extraction, and environmental degradation. In line with their sustainability efforts, Vanguard has put out a number statements aimed at tackling climate change within their portfolios and the world at large. Despite these statements, the company still continues to have companies within their investor portfolios, such as ENAP Sipetrol, CPNC, and Petroamazonas, all of which contribute to fossil fuel production and the furtherance of climate change. When it comes to the issue of Indigenous rights, the Vanguard has released a statement titled “Social Risks and Right of Indigenous Peoples” which lists a series of questions for companies on the topic. However Vanguard frames these questions in the aims of protecting Indeigenous culture without any concrete policy to safeguard Indigenous rights and ensure that the internationally recognized right of Free, Prior, and Informed Consent is present in discussions with Indigenous communities.


title: The Vanguard Group

text: In terms of financial involvement, today, Vanguard holds at least $86 billion in coal, making them the world’s number-one investor in the industry. Additionally, according to Amazon Watch, the company holds $2.6 billion in debt and $9.6 billion in equities for oil companies currently working within the Amazon rainforest.


title: The Vanguard Group

text: Bogle retired from Vanguard as chairman in 1999 when he reached the company's mandatory retirement age of 70 and he was succeeded by John J. ("Jack") Brennan. In February 2008, F. William McNabb III became President and in August 2008, he became CEO. Both of Bogle's successors expanded Vanguard's offerings beyond the index mutual funds that Bogle preferred, in particular into exchange traded funds (ETFs) and actively managed funds. Some of Vanguard's actively-managed funds predate Bogle's retirement however (their healthcare stock fund began in 1984). Bogle had been skeptical of ETFs as they trade mid-day like single stocks while mutual funds trade on a single price at day's end. He believed buy and hold investors could make good use of ETFs tracking broad indices, but thought ETFs had potentially higher fees due to the bid ask spread, could be too narrowly specialized, and worried anything that "could" be traded mid-day "would" be traded mid-day, potentially reducing investor returns.


title: The Vanguard Group

text: In July 2017, it was announced that McNabb would be replaced as chief executive officer by chief investment officer Mortimer J. Buckley, effective January 1, 2018. McNabb remains at the company as chairman.


title: The Vanguard Group

text: In 2020, Vanguard rolled out a digital adviser and began building up an investment team in China. In October 2020, Vanguard returned about $21 billion in managed assets to government clients in China due to concerns about legal compliance, staffing and profitability.


title: Wi-Fi

text: Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio waves. These are the most widely used computer networks in the world, used globally in home and small office networks to link desktop and laptop computers, tablet computers, smartphones, smart TVs, printers, and smart speakers together and to a wireless router to connect them to the Internet, and in wireless access points in public places like coffee shops, hotels, libraries and airports to provide visitors with Internet access for their mobile devices.


title: Wi-Fi

text: "Wi-Fi" is a trademark of the non-profit Wi-Fi Alliance, which restricts the use of the term "Wi-Fi Certified" to products that successfully complete interoperability certification testing. the Wi-Fi Alliance consisted of more than 800 companies from around the world. over 3.05 billion Wi-Fi enabled devices are shipped globally each year.


title: Wi-Fi

text: Wi-Fi uses multiple parts of the IEEE 802 protocol family and is designed to interwork seamlessly with its wired sibling, Ethernet. Compatible devices can network through wireless access points to each other as well as to wired devices and the Internet. The different versions of Wi-Fi are specified by various IEEE 802.11 protocol standards, with the different radio technologies determining radio bands, and the maximum ranges, and speeds that may be achieved. Wi-Fi most commonly uses the UHF and SHF radio bands; these bands are subdivided into multiple channels. Channels can be shared between networks but, within range, only one transmitter can transmit on a channel at a time.


title: Wi-Fi

text: Wi-Fi's radio bands have relatively high absorption and work best for line-of-sight use. Many common obstructions such as walls, pillars, home appliances, etc. may greatly reduce range, but this also helps minimize interference between different networks in crowded environments. An access point range of about indoors while some access points claim up to a range outdoors. Hotspot coverage can be as small as a single room with walls that block radio waves, or as large as many square kilometres using many overlapping access points with roaming permitted between them. Over time the speed and spectral efficiency of Wi-Fi have increased. some versions of Wi-Fi, running on suitable hardware at close range, can achieve speeds of 9.6 Gbit/s (gigabit per second).


title: Wi-Fi

text: A 1985 ruling by the U.S. Federal Communications Commission released parts of the ISM bands for unlicensed use for communications. These frequency bands include the same 2.4 GHz bands used by equipment such as microwave ovens, and are thus subject to interference.


title: Wi-Fi

text: A prototype test bed for a wireless local area network (WLAN) was developed in 1992 by researchers from the Radiophysics Division of the CSIRO (Commonwealth Scientific and Industrial Research Organisation) in Australia.


title: Wi-Fi

text: About the same time in The Netherlands in 1991, the NCR Corporation with AT&T Corporation invented the precursor to 802.11, intended for use in cashier systems, under the name WaveLAN. NCR's Vic Hayes, who held the chair of IEEE 802.11 for 10 years, along with Bell Labs engineer Bruce Tuch, approached the Institute of Electrical and Electronics Engineers (IEEE) to create a standard and were involved in designing the initial 802.11b and 802.11a standards within the IEEE. They have both been subsequently inducted into the Wi-Fi NOW Hall of Fame.


title: Wi-Fi

text: The first version of the 802.11 protocol was released in 1997, and provided up to 2 Mbit/s link speeds. This was updated in 1999 with 802.11b to permit 11 Mbit/s link speeds.


title: Wi-Fi

text: In 1999, the Wi-Fi Alliance formed as a trade association to hold the Wi-Fi trademark under which most IEEE 802.11 products are sold.


title: Wi-Fi

text: The major commercial breakthrough came with Apple Inc. adopting Wi-Fi for their iBook series of laptops in 1999. It was the first mass consumer product to offer Wi-Fi network connectivity, which was then branded by Apple as AirPort. This was in collaboration with the same group that helped create the standard: Vic Hayes, Bruce Tuch, Cees Links, Rich McGinn, and others from Lucent.


title: Wi-Fi

text: Wi-Fi uses a large number of patents held by many different organizations. Australia claims Wi-Fi is an Australian invention. This claim is controversial. Nevertheless, in April 2009, 14 technology companies agreed to pay the Australian CSIRO $1 billion for infringements on CSIRO patents. CSIRO won a further $220 million settlement for Wi-Fi patent infringements in 2012, with global firms in the United States required to pay CSIRO licensing rights estimated at an additional $1 billion in royalties. In 2016, the CSIRO's WLAN prototype test bed was chosen as Australia's contribution to the exhibition "A History of the World in 100 Objects" held in the National Museum of Australia.


title: Wi-Fi

text: The name "Wi-Fi", commercially used at least as early as August 1999, was coined by the brand-consulting firm Interbrand. The Wi-Fi Alliance had hired Interbrand to create a name that was "a little catchier than 'IEEE 802.11b Direct Sequence'." According to Phil Belanger, a founding member of the Wi-Fi Alliance, the term "Wi-Fi" was chosen from a list of ten names that Interbrand proposed.


title: Wi-Fi

text: The Wi-Fi Alliance used the advertising slogan "The Standard for Wireless Fidelity" for a short time after the brand name was created, and the Wi-Fi Alliance was also called the "Wireless Fidelity Alliance Inc" in some publications. The name is often written as "WiFi", "Wifi", or "wifi", but these are not approved by the Wi-Fi Alliance. IEEE is a separate, but related, organization and their website has stated "WiFi is a short name for Wireless Fidelity".


title: Wi-Fi

text: Interbrand also created the Wi-Fi logo. The yin-yang Wi-Fi logo indicates the certification of a product for interoperability.


title: Wi-Fi

text: Other technologies intended for fixed points, including Motorola Canopy, are usually called "fixed wireless". Alternative wireless technologies include Zigbee, Z-Wave, Bluetooth and mobile phone standards, such as 2G, 3G, 4G, 5G and LTE.


title: Wi-Fi

text: To connect to a Wi-Fi LAN, a computer must be equipped with a wireless network interface controller. The combination of a computer and an interface controller is called a "station". Stations are identified by one or more MAC addresses.


title: Wi-Fi

text: Wi-Fi nodes often operate in infrastructure mode in which all communications go through a base station. "Ad hoc mode" refers to devices communicating directly with each other, without communicating with an access point.


title: Wi-Fi

text: A service set is the set of all the devices associated with a particular Wi-Fi network. Devices in a service set need not be on the same wavebands or channels. A service set can be local, independent, extended, mesh, or a combination.


title: Wi-Fi

text: Each service set has an associated identifier, a 32-byte service set identifier (SSID), which identifies the network. The SSID is configured within the devices that are part of the network.


title: Wi-Fi

text: A basic service set (BSS) is a group of stations that share the same wireless channel, SSID, and other settings that have wirelessly connected, usually to the same access point. Each BSS is identified by a MAC address called the "BSSID".


title: Wi-Fi

text: The IEEE does not test equipment for compliance with their standards. The non-profit Wi-Fi Alliance was formed in 1999 to fill this voidto establish and enforce standards for interoperability and backward compatibility, and to promote wireless local-area-network technology. , the Wi-Fi Alliance includes more than 800 companies. It includes 3Com (now owned by Hewlett Packard Enterprise), Aironet (now owned by Cisco), Harris Semiconductor (now owned by Intersil), Lucent (now owned by Nokia), Nokia and Symbol Technologies (now owned by Zebra Technologies). The Wi-Fi Alliance enforces the use of the Wi-Fi brand to technologies based on the IEEE 802.11 standards from the IEEE. This includes wireless local area network (WLAN) connections, a device to device connectivity (such as Wi-Fi Peer to Peer aka Wi-Fi Direct), Personal area network (PAN), local area network (LAN), and even some limited wide area network (WAN) connections. Manufacturers with membership in the Wi-Fi Alliance, whose products pass the certification process, gain the right to mark those products with the Wi-Fi logo.


title: Wi-Fi

text: Specifically, the certification process requires conformance to the IEEE 802.11 radio standards, the WPA and WPA2 security standards, and the EAP authentication standard. Certification may optionally include tests of IEEE 802.11 draft standards, interaction with cellular-phone technology in converged devices, and features relating to security set-up, multimedia, and power-saving.


title: Wi-Fi

text: Not every Wi-Fi device is submitted for certification. The lack of Wi-Fi certification does not necessarily imply that a device is incompatible with other Wi-Fi devices. The Wi-Fi Alliance may or may not sanction derivative terms, such as Super Wi-Fi, coined by the US Federal Communications Commission (FCC) to describe proposed networking in the UHF TV band in the US.


title: Wi-Fi

text: Equipment frequently supports multiple versions of Wi-Fi. To communicate, devices must use a common Wi-Fi version. The versions differ between the radio wavebands they operate on, the radio bandwidth they occupy, the maximum data rates they can support and other details. Some versions permit the use of multiple antennas, which permits greater speeds as well as reduced interference.


title: Wi-Fi

text: Historically, the equipment has simply listed the versions of Wi-Fi using the name of the IEEE standard that it supports. In 2018, the Wi-Fi Alliance introduced simplified Wi-Fi generational numbering to indicate equipment that supports Wi-Fi 4 (802.11n), Wi-Fi 5 (802.11ac) and Wi-Fi 6 (802.11ax). These generations have a high degree of backward compatibility with previous versions. The alliance has stated that the generational level 4, 5, or 6 can be indicated in the user interface when connected, along with the signal strength.


title: Wi-Fi

text: The list of most important versions of Wi-Fi is: 802.11a, 802.11b, 802.11g, 802.11n (Wi-Fi 4), 802.11h, 802.11i, 802.11-2007, 802.11-2012, 802.11ac (Wi-Fi 5), 802.11ad, 802.11af, 802.11-2016, 802.11ah, 802.11ai, 802.11aj, 802.11aq, 802.11ax (Wi-Fi 6), 802.11ay.


title: Wi-Fi

text: Wi-Fi technology may be used to provide local network and Internet access to devices that are within Wi-Fi range of one or more routers that are connected to the Internet. The coverage of one or more interconnected access points ("hotspots") can extend from an area as small as a few rooms to as large as many square kilometres (miles). Coverage in the larger area may require a group of access points with overlapping coverage. For example, public outdoor Wi-Fi technology has been used successfully in wireless mesh networks in London. An international example is Fon.


title: Wi-Fi

text: Wi-Fi provides services in private homes, businesses, as well as in public spaces. Wi-Fi hotspots may be set up either free-of-charge or commercially, often using a captive portal webpage for access. Organizations, enthusiasts, authorities and businesses, such as airports, hotels, and restaurants, often provide free or paid-use hotspots to attract customers, to provide services to promote business in selected areas. Routers often incorporate a digital subscriber line modem or a cable modem and a Wi-Fi access point, are frequently set up in homes and other buildings, to provide Internet access and internetworking for the structure.


title: Wi-Fi

text: Similarly, battery-powered routers may include a cellular Internet radio modem and a Wi-Fi access point. When subscribed to a cellular data carrier, they allow nearby Wi-Fi stations to access the Internet over 2G, 3G, or 4G networks using the tethering technique. Many smartphones have a built-in capability of this sort, including those based on Android, BlackBerry, Bada, iOS, Windows Phone, and Symbian, though carriers often disable the feature, or charge a separate fee to enable it, especially for customers with unlimited data plans. "Internet packs" provide standalone facilities of this type as well, without the use of a smartphone; examples include the MiFi- and WiBro-branded devices. Some laptops that have a cellular modem card can also act as mobile Internet Wi-Fi access points.


title: Wi-Fi

text: Many traditional university campuses in the developed world provide at least partial Wi-Fi coverage. Carnegie Mellon University built the first campus-wide wireless Internet network, called Wireless Andrew, at its Pittsburgh campus in 1993 before Wi-Fi branding originated. By February 1997, the CMU Wi-Fi zone was fully operational. Many universities collaborate in providing Wi-Fi access to students and staff through the Eduroam international authentication infrastructure.


title: Wi-Fi

text: In the early 2000s, many cities around the world announced plans to construct citywide Wi-Fi networks. There are many successful examples; in 2004, Mysore (Mysuru) became India's first Wi-Fi-enabled city. A company called WiFiyNet has set up hotspots in Mysore, covering the whole city and a few nearby villages.


title: Wi-Fi

text: In 2005, St. Cloud, Florida and Sunnyvale, California, became the first cities in the United States to offer citywide free Wi-Fi (from MetroFi). Minneapolis has generated $1.2 million in profit annually for its provider.


title: Wi-Fi

text: In May 2010, the then London mayor Boris Johnson pledged to have London-wide Wi-Fi by 2012. Several boroughs including Westminster and Islington already had extensive outdoor Wi-Fi coverage at that point.


title: Wi-Fi

text: New York City announced a city-wide campaign to convert old phone booths into digitized "kiosks" in 2014. The project, titled LinkNYC, has created a network of kiosks which serve as public Wi-Fi hotspots, high-definition screens and landlines. Installation of the screens began in late 2015. The city government plans to implement more than seven thousand kiosks over time, eventually making LinkNYC the largest and fastest public, government-operated Wi-Fi network in the world. The UK has planned a similar project across major cities of the country, with the project's first implementation in the Camden borough of London.


title: Wi-Fi

text: Officials in South Korea's capital Seoul are moving to provide free Internet access at more than 10,000 locations around the city, including outdoor public spaces, major streets, and densely populated residential areas. Seoul will grant leases to KT, LG Telecom, and SK Telecom. The companies will invest $44 million in the project, which was to be completed in 2015.


title: Wi-Fi

text: Wi-Fi stations communicate by sending each other data packets: blocks of data individually sent and delivered over radio. As with all radio, this is done by the modulation and demodulation of carrier waves. Different versions of Wi-Fi use different techniques, 802.11b uses DSSS on a single carrier, whereas 802.11a, Wi-Fi 4, 5 and 6 use multiple carriers on slightly different frequencies within the channel (OFDM).


title: Wi-Fi

text: As with other IEEE 802 LANs, stations come programmed with a globally unique 48-bit MAC address (often printed on the equipment) so that each Wi-Fi station has a unique address. The MAC addresses are used to specify both the destination and the source of each data packet. Wi-Fi establishes link-level connections, which can be defined using both the destination and source addresses. On the reception of a transmission, the receiver uses the destination address to determine whether the transmission is relevant to the station or should be ignored. A network interface normally does not accept packets addressed to other Wi-Fi stations.


title: Wi-Fi

text: Channels are used half duplex and can be time-shared by multiple networks. When communication happens on the same channel, any information sent by one computer is locally received by all, even if that information is intended for just one destination. The network interface card interrupts the CPU only when applicable packets are received: the card ignores information not addressed to it. The use of the same channel also means that the data bandwidth is shared, such that, for example, available data bandwidth to each device is halved when two stations are actively transmitting.


title: Wi-Fi

text: A scheme known as carrier sense multiple access with collision avoidance (CSMA/CA) governs the way stations share channels. With CSMA/CA stations attempt to avoid collisions by beginning transmission only after the channel is sensed to be "idle", but then transmit their packet data in its entirety. However, for geometric reasons, it cannot completely prevent collisions. A collision happens when a station receives multiple signals on a channel at the same time. This corrupts the transmitted data and can require stations to re-transmit. The lost data and re-transmission reduces throughput, in some cases severely.


title: Wi-Fi

text: The 802.11 standard provides several distinct radio frequency ranges for use in Wi-Fi communications: 900 MHz, 2.4 GHz, 3.6 GHz, 4.9 GHz, 5 GHz, 5.9 GHz and 60 GHz bands. Each range is divided into a multitude of channels. In the standards, channels are numbered at 5 MHz spacing within a band (except in the 60 GHz band, where they are 2.16 GHz apart), and the number refers to the centre frequency of the channel. Although channels are numbered at 5 MHz spacing, transmitters generally occupy at least 20 MHz, and standards allow for channels to be bonded together to form wider channels for higher throughput.


title: Wi-Fi

text: Countries apply their own regulations to the allowable channels, allowed users and maximum power levels within these frequency ranges. 802.11b/g/n can use the 2.4 GHz band, operating in the United States under FCC Part 15 Rules and Regulations. In this frequency band equipment may occasionally suffer interference from microwave ovens, cordless telephones, USB 3.0 hubs, and Bluetooth devices.


title: Wi-Fi

text: Spectrum assignments and operational limitations are not consistent worldwide: Australia and Europe allow for an additional two channels (12, 13) beyond the 11 permitted in the United States for the 2.4 GHz band, while Japan has three more (12–14). In the US and other countries, 802.11a and 802.11g devices may be operated without a licence, as allowed in Part 15 of the FCC Rules and Regulations.


title: Wi-Fi

text: 802.11a/h/j/n/ac/ax can use the 5 GHz U-NII band, which, for much of the world, offers at least 23 non-overlapping 20 MHz channels rather than the 2.4 GHz frequency band, where the channels are only 5 MHz wide. In general, lower frequencies have longer range but have less capacity. The 5 GHz bands are absorbed to a greater degree by common building materials than the 2.4 GHz bands and usually give a shorter range.


title: Wi-Fi

text: As 802.11 specifications evolved to support higher throughput, the protocols have become much more efficient in their use of bandwidth. Additionally, they have gained the ability to aggregate (or 'bond') channels together to gain still more throughput where the bandwidth is available. 802.11n allows for double radio spectrum/bandwidth (40 MHz- 8 channels) compared to 802.11a or 802.11g (20 MHz). 802.11n can also be set to limit itself to 20 MHz bandwidth to prevent interference in dense communities. In the 5 GHz band, 20 MHz, 40 MHz, 80 MHz, and 160 MHz bandwidth signals are permitted with some restrictions, giving much faster connections.


title: Wi-Fi

text: Wi-Fi is part of the IEEE 802 protocol family. The data is organized into 802.11 frames that are very similar to Ethernet frames at the data link layer, but with extra address fields. MAC addresses are used as network addresses for routing over the LAN.


title: Wi-Fi

text: Wi-Fi's MAC and physical layer (PHY) specifications are defined by IEEE 802.11 for modulating and receiving one or more carrier waves to transmit the data in the infrared, and 2.4, 3.6, 5, 6, or 60 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee (IEEE 802). The base version of the standard was released in 1997 and has had many subsequent amendments. The standard and amendments provide the basis for wireless network products using the Wi-Fi brand. While each amendment is officially revoked when it is incorporated in the latest version of the standard, the corporate world tends to market to the revisions because they concisely denote capabilities of their products. As a result, in the market place, each revision tends to become its own standard.


title: Wi-Fi

text: In addition to 802.11 the IEEE 802 protocol family has specific provisions for Wi-Fi. These are required because Ethernet's cable-based media are not usually shared, whereas with wireless all transmissions are received by all stations within the range that employ that radio channel. While Ethernet has essentially negligible error rates, wireless communication media are subject to significant interference. Therefore, the accurate transmission is not guaranteed so delivery is, therefore, a best-effort delivery mechanism. Because of this, for Wi-Fi, the Logical Link Control (LLC) specified by IEEE 802.2 employs Wi-Fi's media access control (MAC) protocols to manage retries without relying on higher levels of the protocol stack.


title: Wi-Fi

text: For internetworking purposes, Wi-Fi is usually layered as a link layer (equivalent to the physical and data link layers of the OSI model) below the internet layer of the Internet Protocol. This means that nodes have an associated internet address and, with suitable connectivity, this allows full Internet access.


title: Wi-Fi

text: In infrastructure mode, which is the most common mode used, all communications go through a base station. For communications within the network, this introduces an extra use of the airwaves but has the advantage that any two stations that can communicate with the base station can also communicate through the base station, which enormously simplifies the protocols.


title: Wi-Fi

text: Wi-Fi also allows communications directly from one computer to another without an access point intermediary. This is called "ad hoc" Wi-Fi transmission. Different types of ad hoc networks exist. In the simplest case network nodes must talk directly to each other. In more complex protocols nodes may forward packets, and nodes keep track of how to reach other nodes, even if they move around.


title: Wi-Fi

text: Ad hoc mode was first described by Chai Keong Toh in his 1996 patent of wireless ad hoc routing, implemented on Lucent WaveLAN 802.11a wireless on IBM ThinkPads over a size nodes scenario spanning a region of over a mile. The success was recorded in "Mobile Computing" magazine (1999) and later published formally in "IEEE Transactions on Wireless Communications", 2002 and "ACM SIGMETRICS Performance Evaluation Review", 2001.


title: Wi-Fi

text: This wireless ad hoc network mode has proven popular with multiplayer handheld game consoles, such as the Nintendo DS, PlayStation Portable, digital cameras, and other consumer electronics devices. Some devices can also share their Internet connection using ad hoc, becoming hotspots or "virtual routers".


title: Wi-Fi

text: Similarly, the Wi-Fi Alliance promotes the specification Wi-Fi Direct for file transfers and media sharing through a new discovery- and security-methodology. Wi-Fi Direct launched in October 2010.


title: Wi-Fi

text: Another mode of direct communication over Wi-Fi is Tunneled Direct-Link Setup (TDLS), which enables two devices on the same Wi-Fi network to communicate directly, instead of via the access point.


title: Wi-Fi

text: An Extended Service Set may be formed by deploying multiple access points that are configured with the same SSID and security settings. Wi-Fi client devices typically connect to the access point that can provide the strongest signal within that service set.


title: Wi-Fi

text: Increasing the number of Wi-Fi access points for a network provides redundancy, better range, support for fast roaming, and increased overall network-capacity by using more channels or by defining smaller cells. Except for the smallest implementations (such as home or small office networks), Wi-Fi implementations have moved toward "thin" access points, with more of the network intelligence housed in a centralized network appliance, relegating individual access points to the role of "dumb" transceivers. Outdoor applications may use mesh topologies.


title: Wi-Fi

text: Wi-Fi operational range depends on factors such as the frequency band, radio power output, receiver sensitivity, antenna gain, and antenna type as well as the modulation technique. Also, the propagation characteristics of the signals can have a big impact.


title: Wi-Fi

text: Compared to cell phones and similar technology, Wi-Fi transmitters are low-power devices. In general, the maximum amount of power that a Wi-Fi device can transmit is limited by local regulations, such as FCC Part 15 in the US. Equivalent isotropically radiated power (EIRP) in the European Union is limited to 20 dBm (100 mW).


title: Wi-Fi

text: To reach requirements for wireless LAN applications, Wi-Fi has higher power consumption compared to some other standards designed to support wireless personal area network (PAN) applications. For example, Bluetooth provides a much shorter propagation range between 1 and 100 metres (1 and 100 yards) and so in general has a lower power consumption. Other low-power technologies such as ZigBee have fairly long range, but much lower data rate. The high power consumption of Wi-Fi makes battery life in some mobile devices a concern.


title: Wi-Fi

text: An access point compliant with either 802.11b or 802.11g, using the stock omnidirectional antenna might have a range of . The same radio with an external semi parabolic antenna (15 dB gain) with a similarly equipped receiver at the far end might have a range over 20 miles.


title: Wi-Fi

text: Higher gain rating (dBi) indicates further deviation (generally toward the horizontal) from a theoretical, perfect isotropic radiator, and therefore the antenna can project or accept a usable signal further in particular directions, as compared to a similar output power on a more isotropic antenna. For example, an 8 dBi antenna used with a 100 mW driver has a similar horizontal range to a 6 dBi antenna being driven at 500 mW. Note that this assumes that radiation in the vertical is lost; this may not be the case in some situations, especially in large buildings or within a waveguide. In the above example, a directional waveguide could cause the low-power 6 dBi antenna to project much further in a single direction than the 8 dBi antenna, which is not in a waveguide, even if they are both driven at 100 mW.


title: Wi-Fi

text: On wireless routers with detachable antennas, it is possible to improve range by fitting upgraded antennas that provide a higher gain in particular directions. Outdoor ranges can be improved to many kilometres (miles) through the use of high gain directional antennas at the router and remote device(s).


title: Wi-Fi

text: Wi-Fi 4 and higher standards allow devices to have multiple antennas on transmitters and receivers. Multiple antennas enable the equipment to exploit multipath propagation on the same frequency bands giving much higher speeds and longer range.


title: Wi-Fi

text: The Wi-Fi 5 standard uses the 5 GHz band exclusively, and is capable of multi-station WLAN throughput of at least 1 gigabit per second, and a single station throughput of at least 500 Mbit/s. As of the first quarter of 2016, The Wi-Fi Alliance certifies devices compliant with the 802.11ac standard as "Wi-Fi CERTIFIED ac". This standard uses several signal processing techniques such as multi-user MIMO and 4X4 Spatial Multiplexing streams, and wide channel bandwidth (160 MHz) to achieve its gigabit throughput. According to a study by IHS Technology, 70% of all access point sales revenue in the first quarter of 2016 came from 802.11ac devices.


title: Wi-Fi

text: With Wi-Fi signals line-of-sight usually works best, but signals can transmit, absorb, reflect, refract, diffract and up and down fade through and around structures, both man-made and natural. Wi-Fi signals are very strongly affected by metallic structures (including rebar in concrete, low-e coatings in glazing) and water (such as found in vegetation.)


title: Wi-Fi

text: Due to the complex nature of radio propagation at typical Wi-Fi frequencies, particularly around trees and buildings, algorithms can only approximately predict Wi-Fi signal strength for any given area in relation to a transmitter. This effect does not apply equally to long-range Wi-Fi, since longer links typically operate from towers that transmit above the surrounding foliage.


title: Wi-Fi

text: Mobile use of Wi-Fi over wider ranges is limited, for instance, to uses such as in an automobile moving from one hotspot to another. Other wireless technologies are more suitable for communicating with moving vehicles.


title: Wi-Fi

text: Distance records (using non-standard devices) include in June 2007, held by Ermanno Pietrosemoli and EsLaRed of Venezuela, transferring about 3 MB of data between the mountain-tops of El Águila and Platillon. The Swedish Space Agency transferred data , using 6 watt amplifiers to reach an overhead stratospheric balloon.


title: Wi-Fi

text: Wi-Fi connections can be blocked or the Internet speed lowered by having other devices in the same area. Wi-Fi protocols are designed to share the wavebands reasonably fairly, and this often works with little to no disruption. To minimize collisions with Wi-Fi and non-Wi-Fi devices, Wi-Fi employs Carrier-sense multiple access with collision avoidance (CSMA/CA), where transmitters listen before transmitting and delay transmission of packets if they detect that other devices are active on the channel, or if noise is detected from adjacent channels or non-Wi-Fi sources. Nevertheless, Wi-Fi networks are still susceptible to the hidden node and exposed node problem.


title: Wi-Fi

text: A standard speed Wi-Fi signal occupies five channels in the 2.4 GHz band. Interference can be caused by overlapping channels. Any two channel numbers that differ by five or more, such as 2 and 7, do not overlap (no adjacent-channel interference). The oft-repeated adage that channels 1, 6, and 11 are the "only" non-overlapping channels is, therefore, not accurate. Channels 1, 6, and 11 are the only "group of three" non-overlapping channels in North America. However, whether the overlap is significant depends on physical spacing. Channels that are four apart interfere a negligible amountmuch less than reusing channels (which causes co-channel interference)if transmitters are at least a few metres apart. In Europe and Japan where channel 13 is available, using Channels 1, 5, 9, and 13 for 802.11g and 802.11n is viable and recommended.


title: Wi-Fi

text: However, many 2.4 GHz 802.11b and 802.11g access-points default to the same channel on initial startup, contributing to congestion on certain channels. Wi-Fi pollution, or an excessive number of access points in the area, can prevent access and interfere with other devices' use of other access points as well as with decreased signal-to-noise ratio (SNR) between access points. These issues can become a problem in high-density areas, such as large apartment complexes or office buildings with many Wi-Fi access points.


title: Wi-Fi

text: Other devices use the 2.4 GHz band: microwave ovens, ISM band devices, security cameras, ZigBee devices, Bluetooth devices, video senders, cordless phones, baby monitors, and, in some countries, amateur radio, all of which can cause significant additional interference. It is also an issue when municipalities or other large entities (such as universities) seek to provide large area coverage. On some 5 GHz bands interference from radar systems can occur in some places. For base stations that support those bands they employ Dynamic Frequency Selection which listens for radar, and if it is found, it will not permit a network on that band.


title: Wi-Fi

text: These bands can be used by low power transmitters without a licence, and with few restrictions. However, while unintended interference is common, users that have been found to cause deliberate interference (particularly for attempting to locally monopolize these bands for commercial purposes) have been issued large fines.


title: Wi-Fi

text: Various layer-2 variants of IEEE 802.11 have different characteristics. Across all flavours of 802.11, maximum achievable throughputs are either given based on measurements under ideal conditions or in the layer-2 data rates. This, however, does not apply to typical deployments in which data are transferred between two endpoints of which at least one is typically connected to a wired infrastructure, and the other is connected to an infrastructure via a wireless link.


title: Wi-Fi

text: This means that typically data frames pass an 802.11 (WLAN) medium and are being converted to 802.3 (Ethernet) or vice versa.


title: Wi-Fi

text: Due to the difference in the frame (header) lengths of these two media, the packet size of an application determines the speed of the data transfer. This means that an application that uses small packets (e.g. VoIP) creates a data flow with high overhead traffic (low goodput).


title: Wi-Fi

text: Other factors that contribute to the overall application data rate are the speed with which the application transmits the packets (i.e. the data rate) and the energy with which the wireless signal is received. The latter is determined by distance and by the configured output power of the communicating devices.


title: Wi-Fi

text: The same references apply to the attached throughput graphs, which show measurements of UDP throughput measurements. Each represents an average throughput of 25 measurements (the error bars are there, but barely visible due to the small variation), is with specific packet size (small or large), and with a specific data rate (10 kbit/s – 100 Mbit/s). Markers for traffic profiles of common applications are included as well. This text and measurements do not cover packet errors but information about this can be found at the above references. The table below shows the maximum achievable (application-specific) UDP throughput in the same scenarios (same references again) with various WLAN (802.11) flavours. The measurement hosts have been 25 metres (yards) apart from each other; loss is again ignored.


title: Wi-Fi

text: Wi-Fi allows wireless deployment of local area networks (LANs). Also, spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs. However, building walls of certain materials, such as stone with high metal content, can block Wi-Fi signals.


title: Wi-Fi

text: A Wi-Fi device is a short-range wireless device. Wi-Fi devices are fabricated on RF CMOS integrated circuit (RF circuit) chips.


title: Wi-Fi

text: Since the early 2000s, manufacturers are building wireless network adapters into most laptops. The price of chipsets for Wi-Fi continues to drop, making it an economical networking option included in ever more devices.


title: Wi-Fi

text: Different competitive brands of access points and client network-interfaces can inter-operate at a basic level of service. Products designated as "Wi-Fi Certified" by the Wi-Fi Alliance are backward compatible. Unlike mobile phones, any standard Wi-Fi device works anywhere in the world.


title: Wi-Fi

text: A wireless access point (WAP) connects a group of wireless devices to an adjacent wired LAN. An access point resembles a network hub, relaying data between connected wireless devices in addition to a (usually) single connected wired device, most often an Ethernet hub or switch, allowing wireless devices to communicate with other wired devices.


title: Wi-Fi

text: Wireless adapters allow devices to connect to a wireless network. These adapters connect to devices using various external or internal interconnects such as PCI, miniPCI, USB, ExpressCard, Cardbus, and PC Card. As of 2010, most newer laptop computers come equipped with built-in internal adapters.


title: Wi-Fi

text: Wireless routers integrate a Wireless Access Point, Ethernet switch, and internal router firmware application that provides IP routing, NAT, and DNS forwarding through an integrated WAN-interface. A wireless router allows wired and wireless Ethernet LAN devices to connect to a (usually) single WAN device such as a cable modem, DSL modem, or optical modem. A wireless router allows all three devices, mainly the access point and router, to be configured through one central utility. This utility is usually an integrated web server that is accessible to wired and wireless LAN clients and often optionally to WAN clients. This utility may also be an application that is run on a computer, as is the case with as Apple's AirPort, which is managed with the AirPort Utility on macOS and iOS.


title: Wi-Fi

text: Wireless network bridges can act to connect two networks to form a single network at the over Wi-Fi. The main standard is the wireless distribution system (WDS).


title: Wi-Fi

text: Wireless bridging can connect a wired network to a wireless network. A bridge differs from an access point: an access point typically connects wireless devices to one wired network. Two wireless bridge devices may be used to connect two wired networks over a wireless link, useful in situations where a wired connection may be unavailable, such as between two separate homes or for devices that have no wireless networking capability (but have wired networking capability), such as consumer entertainment devices; alternatively, a wireless bridge can be used to enable a device that supports a wired connection to operate at a wireless networking standard that is faster than supported by the wireless network connectivity feature (external dongle or inbuilt) supported by the device (e.g., enabling Wireless-N speeds (up to the maximum supported speed on the wired Ethernet port on both the bridge and connected devices including the wireless access point) for a device that only supports Wireless-G).


title: Wi-Fi

text: A dual-band wireless bridge can also be used to enable 5 GHz wireless network operation on a device that only supports 2.4 GHz wireless and has a wired Ethernet port.


title: Wi-Fi

text: Wireless range-extenders or wireless repeaters can extend the range of an existing wireless network. Strategically placed range-extenders can elongate a signal area or allow for the signal area to reach around barriers such as those pertaining in L-shaped corridors. Wireless devices connected through repeaters suffer from an increased latency for each hop, and there may be a reduction in the maximum available data throughput. Besides, the effect of additional users using a network employing wireless range-extenders is to consume the available bandwidth faster than would be the case whereby a single user migrates around a network employing extenders. For this reason, wireless range-extenders work best in networks supporting low traffic throughput requirements, such as for cases whereby a single user with a Wi-Fi-equipped tablet migrates around the combined extended and non-extended portions of the total connected network. Also, a wireless device connected to any of the repeaters in the chain has data throughput limited by the "weakest link" in the chain between the connection origin and connection end. Networks using wireless extenders are more prone to degradation from interference from neighbouring access points that border portions of the extended network and that happen to occupy the same channel as the extended network.


title: Wi-Fi

text: The security standard, Wi-Fi Protected Setup, allows embedded devices with a limited graphical user interface to connect to the Internet with ease. Wi-Fi Protected Setup has 2 configurations: The Push Button configuration and the PIN configuration. These embedded devices are also called The Internet of Things and are low-power, battery-operated embedded systems. Several Wi-Fi manufacturers design chips and modules for embedded Wi-Fi, such as GainSpan.


title: Wi-Fi

text: Increasingly in the last few years (particularly ), embedded Wi-Fi modules have become available that incorporate a real-time operating system and provide a simple means of wirelessly enabling any device that can communicate via a serial port. This allows the design of simple monitoring devices. An example is a portable ECG device monitoring a patient at home. This Wi-Fi-enabled device can communicate via the Internet.


title: Wi-Fi

text: These Wi-Fi modules are designed by OEMs so that implementers need only minimal Wi-Fi knowledge to provide Wi-Fi connectivity for their products.


title: Wi-Fi

text: In June 2014, Texas Instruments introduced the first ARM Cortex-M4 microcontroller with an onboard dedicated Wi-Fi MCU, the SimpleLink CC3200. It makes embedded systems with Wi-Fi connectivity possible to build as single-chip devices, which reduces their cost and minimum size, making it more practical to build wireless-networked controllers into inexpensive ordinary objects.


title: Wi-Fi

text: The main issue with wireless network security is its simplified access to the network compared to traditional wired networks such as Ethernet. With wired networking, one must either gain access to a building (physically connecting into the internal network), or break through an external firewall. To access Wi-Fi, one must merely be within the range of the Wi-Fi network. Most business networks protect sensitive data and systems by attempting to disallow external access. Enabling wireless connectivity reduces security if the network uses inadequate or no encryption.


title: Wi-Fi

text: An attacker who has gained access to a Wi-Fi network router can initiate a DNS spoofing attack against any other user of the network by forging a response before the queried DNS server has a chance to reply.


title: Wi-Fi

text: A common measure to deter unauthorized users involves hiding the access point's name by disabling the SSID broadcast. While effective against the casual user, it is ineffective as a security method because the SSID is broadcast in the clear in response to a client SSID query. Another method is to only allow computers with known MAC addresses to join the network, but determined eavesdroppers may be able to join the network by spoofing an authorized address.


title: Wi-Fi

text: Wired Equivalent Privacy (WEP) encryption was designed to protect against casual snooping but it is no longer considered secure. Tools such as AirSnort or Aircrack-ng can quickly recover WEP encryption keys. Because of WEP's weakness the Wi-Fi Alliance approved Wi-Fi Protected Access (WPA) which uses TKIP. WPA was specifically designed to work with older equipment usually through a firmware upgrade. Though more secure than WEP, WPA has known vulnerabilities.


title: Wi-Fi

text: The more secure WPA2 using Advanced Encryption Standard was introduced in 2004 and is supported by most new Wi-Fi devices. WPA2 is fully compatible with WPA. In 2017, a flaw in the WPA2 protocol was discovered, allowing a key replay attack, known as KRACK.


title: Wi-Fi

text: A flaw in a feature added to Wi-Fi in 2007, called Wi-Fi Protected Setup (WPS), let WPA and WPA2 security be bypassed, and effectively broken in many situations. The only remedy as of late 2011 was to turn off Wi-Fi Protected Setup, which is not always possible.


title: Wi-Fi

text: Virtual Private Networks can be used to improve the confidentiality of data carried through Wi-Fi networks, especially public Wi-Fi networks.


title: Wi-Fi

text: A URI using the WIFI scheme can specify the SSID, encryption type, password/passphrase, and if the SSID is hidden or not, so users can follow links from QR codes, for instance, to join networks without having to manually enter the data. A MECARD-like format is supported by Android and iOS 11+.


title: Wi-Fi

text: The older wireless encryption-standard, Wired Equivalent Privacy (WEP), has been shown easily breakable even when correctly configured. Wi-Fi Protected Access (WPA and WPA2) encryption, which became available in devices in 2003, aimed to solve this problem. Wi-Fi access points typically default to an encryption-free ("open") mode. Novice users benefit from a zero-configuration device that works out-of-the-box, but this default does not enable any wireless security, providing open wireless access to a LAN. To turn security on requires the user to configure the device, usually via a software graphical user interface (GUI). On unencrypted Wi-Fi networks connecting devices can monitor and record data (including personal information). Such networks can only be secured by using other means of protection, such as a VPN or secure Hypertext Transfer Protocol over Transport Layer Security (HTTPS).


title: Wi-Fi

text: Wi-Fi Protected Access encryption (WPA2) is considered secure, provided a strong passphrase is used. In 2018, WPA3 was announced as a replacement for WPA2, increasing security; it rolled out on June 26.


title: Wi-Fi

text: Piggybacking refers to access to a wireless Internet connection by bringing one's computer within the range of another's wireless connection, and using that service without the subscriber's explicit permission or knowledge.


title: Wi-Fi

text: During the early popular adoption of 802.11, providing open access points for anyone within range to use was encouraged to cultivate wireless community networks, particularly since people on average use only a fraction of their downstream bandwidth at any given time.


title: Wi-Fi

text: Recreational logging and mapping of other people's access points have become known as wardriving. Indeed, many access points are intentionally installed without security turned on so that they can be used as a free service. Providing access to one's Internet connection in this fashion may breach the Terms of Service or contract with the ISP. These activities do not result in sanctions in most jurisdictions; however, legislation and case law differ considerably across the world. A proposal to leave graffiti describing available services was called warchalking.


title: Wi-Fi

text: Piggybacking often occurs unintentionally – a technically unfamiliar user might not change the default "unsecured" settings to their access point and operating systems can be configured to connect automatically to any available wireless network. A user who happens to start up a laptop in the vicinity of an access point may find the computer has joined the network without any visible indication. Moreover, a user intending to join one network may instead end up on another one if the latter has a stronger signal. In combination with automatic discovery of other network resources (see DHCP and Zeroconf) this could lead wireless users to send sensitive data to the wrong middle-man when seeking a destination (see man-in-the-middle attack). For example, a user could inadvertently use an unsecured network to log into a website, thereby making the login credentials available to anyone listening, if the website uses an insecure protocol such as plain HTTP without TLS.


title: Wi-Fi

text: On an unsecured access point, an unauthorized user can obtain security information (factory preset passphrase and/or Wi-Fi Protected Setup PIN) from a label on a wireless access point and use this information (or connect by the Wi-Fi Protected Setup pushbutton method) to commit unauthorized and/or unlawful activities.


title: Wi-Fi

text: Wireless internet access has become much more embedded in society. It has thus changed how the society functions in many ways.


title: Wi-Fi

text: Over half the world does not have access to the internet, prominently rural areas in developing nations. Technology that has been implemented in more developed nations is often costly and low energy efficient. This has led to developing nations using more low-tech networks, frequently implementing renewable power sources that can solely be maintained through solar power, creating a network that is resistant to disruptions such as power outages. For instance, in 2007 a 450 km (280 mile) network between Cabo Pantoja and Iquitos in Peru was erected in which all equipment is powered only by solar panels. These long-range Wi-Fi networks have two main uses: offer internet access to populations in isolated villages, and to provide healthcare to isolated communities. In the case of the aforementioned example, it connects the central hospital in Iquitos to 15 medical outposts which are intended for remote diagnosis.


title: Wi-Fi

text: Access to Wi-Fi in public spaces such as cafes or parks allows people, in particular freelancers, to work remotely. While the accessibility of Wi-Fi is the strongest factor when choosing a place to work (75% of people would choose a place that provides Wi-Fi over one that does not), other factors influence the choice of specific hotspots. These vary from the accessibility of other resources, like books, the location of the workplace, and the social aspect of meeting other people in the same place. Moreover, the increase of people working from public places results in more customers for local businesses thus providing an economic stimulus to the area.


title: Wi-Fi

text: Additionally, in the same study it has been noted that wireless connection provides more freedom of movement while working. Both when working at home or from the office it allows the displacement between different rooms or areas. In some offices (notably Cisco offices in New York) the employees do not have assigned desks but can work from any office connecting their laptop to Wi-Fi hotspot.


title: Wi-Fi

text: The internet has become an integral part of living. 81.9% of American households have internet access. Additionally, 89% of American households with broadband connect via wireless technologies. 72.9% of American households have Wi-Fi.


title: Wi-Fi

text: Wi-Fi networks have also affected how the interior of homes and hotels are arranged. For instance, architects have described that their clients no longer wanted only one room as their home office, but would like to work near the fireplace or have the possibility to work in different rooms. This contradicts architect's pre-existing ideas of the use of rooms that they designed. Additionally, some hotels have noted that guests prefer to stay in certain rooms since they receive a stronger Wi-Fi signal.


title: Wi-Fi

text: The World Health Organization (WHO) says, "no health effects are expected from exposure to RF fields from base stations and wireless networks", but notes that they promote research into effects from other RF sources. (a category used when "a causal association is considered credible, but when chance, bias or confounding cannot be ruled out with reasonable confidence"), this classification was based on risks associated with wireless phone use rather than Wi-Fi networks.


title: Wi-Fi

text: The United Kingdom's Health Protection Agency reported in 2007 that exposure to Wi-Fi for a year results in the "same amount of radiation from a 20-minute mobile phone call".


title: Wi-Fi

text: A review of studies involving 725 people who claimed electromagnetic hypersensitivity, "...suggests that 'electromagnetic hypersensitivity' is unrelated to the presence of an EMF, although more research into this phenomenon is required."


title: Fibromyalgia

text: Fibromyalgia (FM) is a medical condition defined by the presence of chronic widespread pain, fatigue, waking unrefreshed, cognitive symptoms, lower abdominal pain or cramps, and depression. Other symptoms include insomnia and a general hypersensitivity.


title: Fibromyalgia

text: The cause of fibromyalgia is unknown, but is believed to involve a combination of genetic and environmental factors. Environmental factors may include psychological stress, trauma, and certain infections. The pain appears to result from processes in the central nervous system and the condition is referred to as a "central sensitization syndrome".


title: Fibromyalgia

text: The treatment of fibromyalgia is symptomatic and multidisciplinary. The European Alliance of Associations for Rheumatology strongly recommends aerobic and strengthening exercise. Weak recommendations are given to mindfulness, psychotherapy, acupuncture, hydrotherapy, and meditative exercise such as qigong, yoga, and tai chi. The use of medication in the treatment of fibromyalgia is debated, although antidepressants can improve quality of life. The medications duloxetine, milnacipran, or pregabalin have been approved by the US Food and Drug Administration (FDA) for the management of fibromyalgia. Other common helpful medications include serotonin-noradrenaline reuptake inhibitors (SNRI), non-steroidal anti-inflammatory drugs (NSAIDs), and muscle relaxants. Q10 coenzyme and vitamin D supplements may reduce pain and improve quality of life. While fibromyalgia is persistent in nearly all patients, it does not result in death or tissue damage.


title: Fibromyalgia

text: Fibromyalgia is estimated to affect 2–4% of the population. Women are affected about twice as often as men. Rates appear similar in different areas of the world and among different cultures. Fibromyalgia was first defined in 1990, with updated criteria in 2011, 2016, and 2019. The term "fibromyalgia" is from New Latin "fibro-", meaning "fibrous tissues", Greek μυο- "myo-", "muscle", and Greek άλγος "algos", "pain"; thus, the term literally means "muscle and fibrous connective tissue pain".


title: Fibromyalgia

text: Fibromyalgia is classed as a disorder of pain processing due to abnormalities in how pain signals are processed in the central nervous system. The International Classification of Diseases (ICD-11) includes fibromyalgia in the category of "Chronic widespread pain", code MG30.01.


title: Fibromyalgia

text: The defining symptoms of fibromyalgia are chronic widespread pain, fatigue, and sleep disturbance. Other symptoms may include heightened pain in response to tactile pressure (allodynia), cognitive problems, musculoskeletal stiffness, environmental sensitivity, hypervigilance, sexual dysfunction, and visual symptoms.


title: Fibromyalgia

text: Fibromyalgia is predominantly a chronic pain disorder. According to the NHS, widespread pain is one major symptom, which could feel like: an ache, a burning sensation, or a sharp, stabbing pain.


title: Fibromyalgia

text: Fatigue is one of the defining symptoms of fibromyalgia. Patients may experience physical or mental fatigue. Physical fatigue can be demonstrated by a feeling of exhaustion after exercise or by a limitation in daily activities.


title: Fibromyalgia

text: Sleep problems are a core symptom in fibromyalgia. These include a difficulty to fall asleep or stay asleep, awakening while sleeping and waking up feeling unrefreshed. A meta-analysis compared objective and subjective sleep metrics in people with fibromyalgia and healthy people. Individuals with fibromyalgia had lower sleep quality and efficiency, as well as longer wake time after sleep start, shorter sleep duration, lighter sleep, and greater trouble initiating sleep when objectively assessed, and more difficulty initiating sleep when subjectively assessed. Sleep problems may contribute to pain by decreased release of IGF-1 and human growth hormone, leading to decreased tissue repair. Improving sleep quality can help people with fibromyalgia minimize pain.


title: Fibromyalgia

text: Many people with fibromyalgia experience cognitive problems (known as "fibrofog" or "brainfog"). One study found that approximately 50% of fibromyalgia patients had subjective cognitive dysfunction and that it was associated with higher levels of pain and other fibromyalgia symptoms. The American Pain Society recognizes these problems as a major feature of fibromyalgia, characterized by trouble concentrating, forgetfulness and disorganized or slow thinking. About 75% of fibromyalgia patients report significant problems with concentration, memory, and multitasking. A 2018 meta-analysis found that the largest differences between fibromyalgia patients and healthy subjects were for inhibitory control, memory, and processing speed. It is hypothesized that the increased pain compromises attention systems, resulting in cognitive problems.


title: Fibromyalgia

text: In addition to a hypersensitivity to pain, patients with fibromyalgia show hypersensitivity to other stimuli, such as bright lights, loud noises, perfumes and cold. A review article found that they have a lower cold pain threshold. Other studies documented an acoustic hypersensitivity.


title: Fibromyalgia

text: Fibromyalgia as a stand-alone diagnosis is uncommon, as most fibromyalgia patients often have other chronic overlapping pain problems or mental disorders. Fibromyalgia is associated with mental health issues like anxiety, posttraumatic stress disorder, bipolar disorder, and depression. Patients with fibromyalgia are five times more likely to have major depression than the general population.


title: Fibromyalgia

text: Fibromyalgia and numerous chronic pain conditions frequently coexist. These include chronic tension headaches, myofascial pain syndrome, and temporomandibular disorders. Multiple sclerosis, post-polio syndrome, neuropathic pain, and Parkinson's disease are four neurological disorders that have been linked to pain or fibromyalgia. Fibromyalgia largely overlaps with chronic fatigue syndrome and may share the same pathogenetic mechanisms.


title: Fibromyalgia

text: Comorbid fibromyalgia has been reported to occur in 20–30% of individuals with rheumatic diseases. It has been reported in people with noninflammatory musculoskeletal diseases.


title: Fibromyalgia

text: The prevalence of fibromyalgia in gastrointestinal disease has been described mostly for celiac disease and irritable bowel syndrome (IBS). Fibromyalgia has also been linked with obesity. Other conditions that are associated with fibromyalgia include an overactive bladder.


title: Fibromyalgia

text: The cause of fibromyalgia is unknown. However, several risk factors, genetic and environmental, have been identified.


title: Fibromyalgia

text: Genetics play a major role in fibromyalgia, and may explain up to 50% of the disease susceptibility. Fibromyalgia is potentially associated with polymorphisms of genes in the serotoninergic, dopaminergic and catecholaminergic systems. Several genes have been suggested as candidates for susceptibility to fibromyalgia. These include SLC6A4, TRPV2, MYT1L, NRXN3, and the 5-HT2A receptor 102T/C polymorphism. The heritability of fibromyalgia is estimated to be higher in patients younger than 50.


title: Fibromyalgia

text: Neuropathic pain and major depressive disorder often co-occur with fibromyalgia – the reason for this comorbidity appears to be due to shared genetic abnormalities, which leads to impairments in monoaminergic, glutamatergic, neurotrophic, opioid and proinflammatory cytokine signaling. In these vulnerable individuals, psychological stress or illness can cause abnormalities in inflammatory and stress pathways that regulate mood and pain. Eventually, a sensitization and kindling effect occurs in certain neurons leading to the establishment of fibromyalgia and sometimes a mood disorder.


title: Fibromyalgia

text: Stress may be an important precipitating factor in the development of fibromyalgia. A 2021 meta-analysis found psychological trauma to be strongly associated with fibromyalgia. People who suffered abuse in their lifetime were three times more likely to have fibromyalgia, people who suffered medical trauma or other stressors in their lifetime were about twice as likely.


title: Fibromyalgia

text: Some authors have proposed that, because exposure to stressful conditions can alter the function of the hypothalamic-pituitary-adrenal (HPA) axis, the development of fibromyalgia may stem from stress-induced disruption of the HPA axis.


title: Fibromyalgia

text: Although some have suggested that fibromyalgia patients are more likely to have specific personality traits, when depression is statistically controlled for, it appears that their personality is no different than that of people in the general population.


title: Fibromyalgia

text: Other risk markers for fibromyalgia include premature birth, female sex, cognitive influences, primary pain disorders, multiregional pain, infectious illness, hypermobility of joints, iron deficiency and small-fiber polyneuropathy. Metal-induced allergic inflammation has also been linked with fibromyalgia, especially in response to nickel but also inorganic mercury, cadmium, and lead.


title: Fibromyalgia

text: As of 2022, the pathophysiology of fibromyalgia has not yet been elucidated and several theories have been suggested.


title: Fibromyalgia

text: Chronic pain can be divided into three categories. Nociceptive pain is pain caused by inflammation or damage to tissues. Neuropathic pain is pain caused by nerve damage. Nociplastic pain (or central sensitization) is less understood and is the common explanation of the pain experienced in fibromyalgia. Because the three forms of pain can overlap, fibromyalgia patients may experience nociceptive (e.g., rheumatic illnesses) and neuropathic (e.g., small fiber neuropathy) pain, in addition to nociplastic pain.


title: Fibromyalgia

text: Fibromyalgia can be viewed as a condition of nociplastic pain. Nociplastic pain is caused by an altered function of pain-related sensory pathways in the periphery and the central nervous system, resulting in hypersensitivity.


title: Fibromyalgia

text: Nociplastic pain is commonly referred to as "Nociplastic pain syndrome" because it is coupled with other symptoms. These include fatigue, sleep disturbance, cognitive disturbance, hypersensitivity to environmental stimuli, anxiety, and depression. Nociplastic pain is caused by either (1) increased processing of pain stimuli or (2) decreased suppression of pain stimuli at several levels in the nervous system, or both.


title: Fibromyalgia

text: An alternative hypothesis to nociplastic pain views fibromyalgia as a stress-related dysautonomia with neuropathic pain features. This view highlights the role of autonomic and peripheral nociceptive nervous systems in the generation of widespread pain, fatigue, and insomnia. The description of small fiber neuropathy in a subgroup of fibromyalgia patients supports the disease neuropathic-autonomic underpinning. However, others claim that small fiber neuropathy occurs only in small groups of those with fibromyalgia.


title: Fibromyalgia

text: Some suggest that fibromyalgia is caused or maintained by a decreased vagal tone, which is indicated by low levels of heart rate variability, signaling a heightened sympathetic response. Accordingly, several studies show that clinical improvement is associated with an increase in heart rate variability. Some examples of interventions that increase the heart rate variability and vagal tone are meditation, yoga, mindfulness and exercise.


title: Fibromyalgia

text: Some neurochemical abnormalities that occur in fibromyalgia also regulate mood, sleep, and energy, thus explaining why mood, sleep, and fatigue problems are commonly co-morbid with fibromyalgia. Serotonin is the most widely studied neurotransmitter in fibromyalgia. It is hypothesized that an imbalance in the serotoninergic system may lead to the development of fibromyalgia. There is also some data that suggests altered dopaminergic and noradrenergic signaling in fibromyalgia. Supporting the monoamine related theories is the efficacy of monoaminergic antidepressants in fibromyalgia.


title: Fibromyalgia

text: Neuroimaging studies have observed decreased grey matter of the default mode network in people with fibromyalgia. These deficits are associated with pain processing.


title: Fibromyalgia

text: Studies on the neuroendocrine system and HPA axis in fibromyalgia have been inconsistent. One study found fibromyalgia patients exhibited higher plasma cortisol, more extreme peaks and troughs, and higher rates of dexamethasone non-suppression. However, other studies have only found correlations between a higher cortisol awakening response and pain, and not any other abnormalities in cortisol. Increased baseline ACTH and increase in response to stress have been observed, hypothesized to be a result of decreased negative feedback.


title: Fibromyalgia

text: Inflammation has been suggested to have a role in the pathogenesis of fibromyalgia. People with fibromyalgia tend to have higher levels of inflammatory cytokines IL-6, and IL-8. There are also increased levels of the pro-inflammatory cytokines IL-1 receptor antagonist. Increased levels of pro-inflammatory cytokines may increase sensitivity to pain, and contribute to mood problems. Anti-inflammatory interleukins such as IL-10 have also been associated with fibromyalgia.


title: Fibromyalgia

text: A repeated observation shows that autoimmunity triggers such as traumas and infections are among the most frequent events preceding the onset of fibromyalgia. Neurogenic inflammation has been proposed as a contributing factor to fibromyalgia.


title: Fibromyalgia

text: Gut bacteria may play a role in fibromyalgia. People with fibromyalgia are more likely to show dysbiosis, a decrease in microbiota diversity. There is a bidirectional interplay between the gut and the nervous system. Therefore, the gut can affect the nervous system, but the nervous system can also affect the gut. Neurological effects mediated via the autonomic nervous system as well as the hypothalamic pituitary adrenal axis are directed to intestinal functional effector cells, which in turn are under the influence of the gut microbiota.


title: Fibromyalgia

text: The gut-brain axis, which connects the gut microbiome to the brain via the enteric nervous system, is another area of research. Fibromyalgia patients have less varied gut flora and altered serum metabolome levels of glutamate and serine, implying abnormalities in neurotransmitter metabolism.


title: Fibromyalgia

text: There is no single pathological feature, laboratory finding, or biomarker that can diagnose fibromyalgia and there is debate over what should be considered diagnostic criteria and whether an objective diagnosis is possible. In most cases, people with fibromyalgia symptoms may have laboratory test results that appear normal and many of their symptoms may mimic those of other rheumatic conditions such as arthritis or osteoporosis. The specific diagnostic criteria for fibromyalgia have evolved over time.


title: Fibromyalgia

text: The first widely accepted set of classification criteria for research purposes was elaborated in 1990 by the Multicenter Criteria Committee of the American College of Rheumatology. These criteria, which are known informally as "the ACR 1990", defined fibromyalgia according to the presence of the following criteria:


title: Fibromyalgia

text: The ACR criteria for the classification of patients were originally established as inclusion criteria for research purposes and were not intended for clinical diagnosis but have later become the "de facto" diagnostic criteria in the clinical setting. A controversial study was done by a legal team looking to prove their client's disability based primarily on tender points and their widespread presence in non-litigious communities prompted the lead author of the ACR criteria to question now the useful validity of tender points in diagnosis. Use of control points has been used to cast doubt on whether a person has fibromyalgia, and to claim the person is malingering.


title: Fibromyalgia

text: In 2010, the American College of Rheumatology approved provisional revised diagnostic criteria for fibromyalgia that eliminated the 1990 criteria's reliance on tender point testing. The revised criteria used a widespread pain index (WPI) and symptom severity scale (SSS) in place of tender point testing under the 1990 criteria. The WPI counts up to 19 general body areas in which the person has experienced pain in the preceding week. The SSS rates the severity of the person's fatigue, unrefreshed waking, cognitive symptoms, and general somatic symptoms, each on a scale from 0 to 3, for a composite score ranging from 0 to 12. The revised criteria for diagnosis were:


title: Fibromyalgia

text: In 2016, the provisional criteria of the American College of Rheumatology from 2010 were revised. The new diagnosis required all of the following criteria:


title: Fibromyalgia

text: In 2019, the American Pain Society in collaboration with the U.S. Food and Drug Administration developed a new diagnostic system using two dimensions. The first dimension included core diagnostic criteria and the second included common features. In accordance to the 2016 diagnosis guidelines, the presence of another medical condition or pain disorder does not rule out the diagnosis of fibromyalgia. Nonetheless, other conditions should be ruled out as the main explaining reason for the patient's symptoms. The core diagnostic criteria are:


title: Fibromyalgia

text: Common features found in fibromyalgia patients can assist the diagnosis process. These are tenderness (sensitivity to light pressure), dyscognition (difficulty to think), musculoskeletal stiffness, and environmental sensitivity or hypervigilance.


title: Fibromyalgia

text: Some research has suggested using a multidimensional approach taking into consideration somatic symptoms, psychological factors, psychosocial stressors and subjective belief regarding fibromyalgia. These symptoms can be assessed by several self-report questionnaires.


title: Fibromyalgia

text: The Fibromyalgia Impact Questionnaire (FIQ) and the Revised Fibromyalgia Impact Questionnaire (FIQR) assess three domains: function, overall impact and symptoms. It is considered a useful measure of disease impact.


title: Fibromyalgia

text: Other measures include the "Hospital Anxiety and Depression Scale," "Multiple Ability Self-Report Questionnaire", "Multidimensional Fatigue Inventory, and" "Medical Outcomes Study Sleep Scale."


title: Fibromyalgia

text: As of 2009, as many as two out of every three people who are told that they have fibromyalgia by a rheumatologist may have some other medical condition instead. Fibromyalgia could be misdiagnosed in cases of early undiagnosed rheumatic diseases such as preclinical rheumatoid arthritis, early stages of inflammatory spondyloarthritis, polymyalgia rheumatica, myofascial pain syndromes and hypermobility syndrome. Neurological diseases with an important pain component include multiple sclerosis, Parkinson's disease and peripheral neuropathy. Other medical illnesses that should be ruled out are endocrine disease or metabolic disorder (hypothyroidism, hyperparathyroidism, acromegaly, vitamin D deficiency), gastro-intestinal disease (celiac and non-celiac gluten sensitivity), infectious diseases (Lyme disease, hepatitis C and immunodeficiency disease) and the early stages of a malignancy such as multiple myeloma, metastatic cancer and leukemia/lymphoma. Other systemic, inflammatory, endocrine, rheumatic, infectious, and neurologic disorders may cause fibromyalgia-like symptoms, such as systemic lupus erythematosus, Sjögren syndrome, ankylosing spondylitis, Ehlers-Danlos syndromes, psoriatic-related polyenthesitis, a nerve compression syndrome (such as carpal tunnel syndrome), and myasthenia gravis. In addition, several medications can also evoke pain (statins, aromatose inhibitors, biophosphonates, and opioids).


title: Fibromyalgia

text: The differential diagnosis is made during the evaluation on the basis of the person's medical history, physical examination, and laboratory investigations. The patient's history can provide some hints to a fibromyalgia diagnosis. A family history of early chronic pain, a childhood history of pain, an emergence of broad pain following physical and/or psychosocial stress, a general hypersensitivity to touch, smell, noise, taste, hypervigilance, and various somatic symptoms (gastrointestinal, urology, gynecology, neurology), are all examples of these signals


title: Fibromyalgia

text: Extensive laboratory tests are usually unnecessary in the differential diagnosis of fibromyalgia. Common tests that are conducted include complete blood count, comprehensive metabolic panel, erythrocyte sedimentation rate, C-reactive protein, and thyroid function test.


title: Fibromyalgia

text: As with many other medically unexplained syndromes, there is no universally accepted treatment or cure for fibromyalgia, and treatment typically consists of symptom management and improving patient quality of life. A personalized, multidisciplinary approach to treatment that includes both non-pharmacologic and pharmacologic therapy and begins with effective patient education is most beneficial. Developments in the understanding of the pathophysiology of the disorder have led to improvements in treatment, which include prescription medication, behavioral intervention, and exercise.


title: Fibromyalgia

text: A number of associations have published guidelines for the diagnosis and management of fibromyalgia. The European League Against Rheumatism (EULAR; 2017) recommends a multidisciplinary approach, allowing a quick diagnosis and patient education. The recommended initial management should be non-pharmacological, later pharmacological treatment can be added. The European League Against Rheumatism gave the strongest recommendation for aerobic and strengthening exercise. Weak recommendations were given to a number of treatments, based on their outcomes. Qigong, yoga, and tai chi were weakly recommended for improving sleep and quality of life. Mindfulness was weakly recommended for improving pain and quality of life. Acupuncture and hydrotherapy were weakly recommended for improving pain. A weak recommendation was also given to psychotherapy. It was more suitable for patients with mood disorders or unhelpful coping strategies. Chiropractic was strongly recommended against, due to safety concerns. Some medications were weakly recommended for severe pain (duloxetine, pregabalin, tramadol) or sleep disturbance (amitriptyline, cyclobenzaprine, pregabalin). Others were not recommended due to a lack of efficacy (nonsteroidal anti-inflammatory drugs, monoamine oxidase inhibitors and selective serotonin reuptake inhibitors). Growth hormone, sodium oxybate, opioids and steroids were strongly recommended against due to lack of efficacy and side effects.


title: Fibromyalgia

text: The guidelines published by the Association of the Scientific Medical Societies in Germany inform patients that self-management strategies are an important component in managing the disease. The Canadian Pain Society also published guidelines for the diagnosis and management of fibromyalgia.


title: Fibromyalgia

text: Exercise is the only fibromyalgia treatment which has been given a strong recommendation by the European Alliance of Associations for Rheumatology (EULAR). There is strong evidence indicating that exercise improves fitness, sleep and quality of life and may reduce pain and fatigue for people with fibromyalgia. Exercise has an added benefit in that it does not cause any serious adverse effects.


title: Fibromyalgia

text: Exercise may diminish fibromyalgia symptoms through a number of hypothesized biological mechanisms. Exercise may improve pain modulation through serotoninergic pathways. It may reduce pain by altering the hypothalamic-pituitary-adrenal axis and reducing cortisol levels. It also has anti-inflammatory effects that may improve fibromyalgia symptoms. Aerobic exercise can improve muscle metabolism and pain through mitochondrial pathways.


title: Fibromyalgia

text: When comparing different exercise programs, aerobic exercise is capable of modulating the autonomic nervous function of fibromyalgia patients, whereas resistance exercise does not show such effects. A 2022 meta-analysis found that aerobic training showed a high effect size while strength interventions showed moderate effects. Meditative exercise seems preferable for improving sleep, with no differences between resistance, flexibility and aquatic exercise in their favorable effects on fatigue.


title: Fibromyalgia

text: Despite its benefits, exercise is a challenge for patients with fibromyalgia, due to the chronic fatigue and pain they experience. They perceive it as more effortful than healthy adults. Exercise may intimidate them, in fear that they will be asked to do more than they are capable of. They may also feel that those who recommend or deliver exercise interventions do not fully understand the possible negative impact of exercise on fatigue and pain. This is especially true for non-personalized exercise programs. Adherence is higher when the exercise program is recommended by doctors or supervised by nurses. A recommended approach to a graded exercise program begins with small, frequent exercise periods and builds up from there. In order to reduce pain, it is recommended to use an exercise program of 13 to 24 weeks, with each session lasting 30 to 60 minutes.


title: Fibromyalgia

text: Aerobic exercise for fibromyalgia patients is the most investigated type of exercise. It includes activities such as walking, jogging, spinning, cycling, dancing and exercising in water. A 2017 cochrane summary concluded that aerobic exercise probably improves quality of life, slightly decreases pain and improves physical function and makes no difference in fatigue and stiffness. A 2019 meta-analysis showed that exercising aerobically can reduce autonomic dysfunction and increase heart rate variability. This happens when patients exercise at least twice a week, for 45–60 minutes at about 60%-80% of the maximum heart rate. Aerobic exercise also decreases anxiety and depression and improves the quality of life.


title: Fibromyalgia

text: Combinations of different exercises such as flexibility and aerobic training may improve stiffness. However, the evidence is of low-quality. It is not clear if flexibility training alone compared to aerobic training is effective at reducing symptoms or has any adverse effects.


title: Fibromyalgia

text: In resistance exercise, participants apply a load to their body using weights, elastic band, body weight or other measures.


title: Fibromyalgia

text: Two meta-analyses on fibromyalgia have shown that resistance training can reduce anxiety and depression and one found that it improves quality of life.


title: Fibromyalgia

text: The dosage of resistance exercise for women with fibromyalgia was studied in a 2022 meta-analysis. Effective dosages were found when exercising twice a week, for at least eight weeks. Symptom improvement was found for even low dosages such as 1–2 sets of 4–20 repetitions. Most studies use moderate exercise intensity of 40% to 85% one-repetition maximum. This level of intensity was effective in reducing pain. Some treatment regimes increase the intensity over time (from 40% to 80%), whereas others increase it when the participant is able to perform 12 repetitions. High-intensity exercises may cause lower treatment adherence.


title: Fibromyalgia

text: A 2021 meta-analysis found that meditative exercise programs (tai chi, yoga, qigong) were superior to other forms of exercise (aerobic, flexibility, resistance) in improving sleep quality. Other meta-analyses also found positive effects of tai chi for sleep, fibromyalgia symptoms, and pain, fatigue, depression and quality of life. These tai chi interventions frequently included 1-hour sessions practiced 1-3 times a week for 12 weeks. Meditative exercises, as a whole, may achieve desired outcomes through biological mechanisms such as antioxidation, anti-inflammation, reduction in sympathetic activity and modulation of glucocorticoid receptor sensitivity.


title: Fibromyalgia

text: Several reviews and meta-analyses suggest that aquatic training can improve symptoms and wellness in people with fibromyalgia.


title: Fibromyalgia

text: Limited evidence suggests vibration training in combination with exercise may improve pain, fatigue, and stiffness.


title: Fibromyalgia

text: A few countries have published guidelines for the management and treatment of fibromyalgia. As of 2018, all of them emphasize that medications are not required. However, medications, though imperfect, continue to be a component of treatment strategy for fibromyalgia patients. The German guidelines outlined parameters for drug therapy termination and recommended considering drug holidays after six months.


title: Fibromyalgia

text: Health Canada and the US Food and Drug Administration (FDA) have approved pregabalin and duloxetine for the management of fibromyalgia. The FDA also approved milnacipran, but the European Medicines Agency refused marketing authority.<ref name="Doc. Ref.: EMA/814249/2009"></ref>


title: Fibromyalgia

text: Antidepressants are one of the common drugs for fibromyalgia. A 2021 meta-analysis concluded that antidepressants can improve the quality of life for fibromyalgia patients in the medium-term. As of 2018, the only tricyclic antidepressant (TCA) that has sufficient evidence is amitriptyline.


title: Fibromyalgia

text: For most people with fibromyalgia, the potential benefits of treatment with the serotonin and noradrenaline reuptake inhibitors (SNRI) duloxetine and milnacipran and the TCAs, such as amitriptyline, are outweighed by significant adverse effects (more adverse effects than benefits), however, a small number of people may experience relief from symptoms with these medications. In addition, while amitriptyline has been used as a first line treatment, the quality of evidence to support this use and comparison between different medications is poor. Very weak evidence indicates that a very small number of people may benefit from treatment with the tetracyclic antidepressant mirtazapine, however, for most, the potential benefits are not great and the risk of adverse effects and potential harm outweighs any potential for benefit.


title: Fibromyalgia

text: The length of time that antidepressant medications take to be effective at reducing symptoms can vary. Any potential benefits from the antidepressant amitriptyline may take up to three months to take effect and it may take between three and six months for duloxetine, milnacipran, and pregabalin to be effective at improving symptoms. Some medications have the potential to cause withdrawal symptoms when stopping so gradual discontinuation may be warranted particularly for antidepressants and pregabalin.


title: Fibromyalgia

text: There is tentative evidence that the benefits and harms of selective serotonin reuptake inhibitors (SSRIs) appear to be similar. SSRIs may be used to treat depression in people diagnosed with fibromyalgia.


title: Fibromyalgia

text: Tentative evidence suggests that monoamine oxidase inhibitors (MAOIs) such as pirlindole and moclobemide are moderately effective for reducing pain. Very low-quality evidence suggests pirlindole as more effective at treating pain than moclobemide. Side effects of MAOIs may include nausea and vomiting.


title: Fibromyalgia

text: Central nervous system depressants include drug categories such as sedatives, tranquilizers, and hypnotics. A 2021 meta-analysis concluded that such drugs can improve the quality of life for fibromyalgia patients in the medium-term.


title: Fibromyalgia

text: The anti-convulsant medications gabapentin and pregabalin may be used to reduce pain. There is tentative evidence that gabapentin may be of benefit for pain in about 18% of people with fibromyalgia. It is not possible to predict who will benefit, and a short trial may be recommended to test the effectiveness of this type of medication. Approximately 6/10 people who take gabapentin to treat pain related to fibromyalgia experience unpleasant side effects such as dizziness, abnormal walking, or swelling from fluid accumulation. Pregabalin demonstrates a benefit in about 9% of people. Pregabalin reduced time off work by 0.2 days per week.


title: Fibromyalgia

text: Cannabinoids may have some benefits for people with fibromyalgia. However, as of 2022, the data on the topic is still limited. Cannabinoids may also have adverse effects and may negatively interact with common rheumatological drugs.


title: Fibromyalgia

text: The use of opioids is controversial. As of 2015, no opioid is approved for use in this condition by the FDA. A 2016 Cochrane review concluded that there is no good evidence to support or refute the suggestion that oxycodone, alone or in combination with naloxone, reduces pain in fibromyalgia. The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) in 2014 stated that there was a lack of evidence for opioids for most people. The Association of the Scientific Medical Societies in Germany in 2012 made no recommendation either for or against the use of weak opioids because of the limited amount of scientific research addressing their use in the treatment of FM. They strongly advise against using strong opioids. The Canadian Pain Society in 2012 said that opioids, starting with a weak opioid like tramadol, can be tried but only for people with moderate to severe pain that is not well-controlled by non-opioid painkillers. They discourage the use of strong opioids and only recommend using them while they continue to provide improved pain and functioning. Healthcare providers should monitor people on opioids for ongoing effectiveness, side effects, and possible unwanted drug behaviors.