1. Field of the Invention
The present invention relates to powerline communications and in particular, powerline communication devices, and systems of use therefore.
2. Description of the Related Art
With the growing need for the exchange of digital content (e.g. MP3 audio, MPEG4 video and digital photographs) there is a widely recognized need to improve digital communication systems. Powerline communication (PLC) is a technology that encodes data in a signal and transmits the signal on existing electricity powerlines in a band of frequencies that are not used for supplying electricity. Accordingly, PLC leverages the ubiquity of existing electricity networks to provide extensive network coverage. Furthermore, since PLC enables data to be accessed from conventional power-outlets, no new wiring needs to be installed in a building (or different parts of a building). Accordingly, PLC offers the additional advantage of reduced installation costs.
Referring to FIG. 1, a household 100 typically has a distributed mains wiring system (not shown) consisting of one or more ring mains, several stubs and some distribution back to a junction box 112. In other constructs the distributed mains wiring system has a breaker box with circuits routed there from in a star configuration. For the sake of example, the household 100 has four rooms 104, 106, 108, and 120. Each room 104, 106, 108, and 120 may have a different number of outlets and other mains connections. For example, room 104 may have only one connection 122, room 106 may have two connections 124, 126, room 108 may have three connections 128, 130, 132 and room 120 may have six connections 134, 136, 138, 140, 142, 144.
Accordingly, there are a variety of distances and paths between different power outlets in the household 100. In particular, the outlets most closely located to each other are those on multi-plug strips, and the outlets furthest away from each other are those on the ends of stubs of different ring mains (e.g. power outlets in the garden shed and the attic). Communication between these furthest outlets typically passes through the junction box 112. Nonetheless, the majority of outlets associated with a particular application (e.g. Home Cinema) are normally located relatively close together.
Because the channel capacity of a powerline and connectors attenuates according to, amongst other features, the frequency of a transmitted signal, current generation PLC systems have been developed to transmit signals at relatively low frequencies (i.e. below 30 MHz) and thereby obtain suitable transmission distances. However, the use of such low transmission frequencies limits the maximum data throughput obtainable by PLC systems. Only recently have powerline systems extended beyond 30 MHz, which causes problems due to regulations that require lower injected power above 30 MHz. This requirement places additional demands on the dynamic range of transceivers servicing PLC communications in these higher frequency ranges.
The processes of receiving analog signals and injecting modulated signals are treated differently by different PLC communication standards. A number of powerline communication standards have been defined. These include the Homeplug 1.0/1.1 standards, the Homeplug AV standard, the CEPCA standard, the Digital Home Standard, IEEE 1901, and ITU-T G.9960. Current PLC approaches often include some analog conditioning to the signal-path (e.g., low-pass filtering for anti-aliasing or smoothing, or AC coupling to remove the low-frequency [<<1 KHz] high voltage content of the electricity mains). However, because differing PLC communication standards support differing communication bands, differing modulations, channel bandwidths, etc., PLC devices typically service only a single PLC communication standard. In common with most communication systems, one of the main problems with prior art PLC systems is obtaining high throughput and wide coverage at reasonable implementation cost, whilst maintaining compatibility with existing technologies. There is, therefore, a need for improved PLC systems that overcome the above and other problems.
Communications within the household 100 or within other premises may also be serviced by a Wireless Local Area Network (WLAN), a cellular network, millimeter wave communications, e.g., 60 GHz, Wireless Personal Area Network (WPAN), Cable Modem Network, Local Area Network (LAN), and other communication techniques. Each of these communication types has its respective benefits and shortcomings. None of these communication types is typically able to provide a full coverage solution within the household 100 (or other premises). The shortcoming of all wired technologies is the lack of mobility thereof. Shortcomings of all wireless technologies are coverage holes, which are typical, interference from other wireless devices, including competing wireless devices, Radar, etc., and bandwidth limitations.