From the initial analog systems, such as those defined by the standards AMPS (Advanced Mobile Phone System) and NMT (Nordic Mobile Telephone), the cellular telephone industry has had an enormous development in the world in the past decades. In the past years, the development has been almost exclusively focused on standards for digital solutions for cellular radio network systems, such as D-AMPS (e.g., as specified in EIA/TIA-IS-54-B and IS-136) and GSM (Global System for Mobile Communications), generally referred to as the second generation of mobile communications systems.
Currently, the cellular technology is entering the 3rd generation, also denoted 3G. WCDMA (Wideband Code Division Multiple Access) is by far the most widely adopted 3G air-interface technology in the new IMT-2000 frequency bands. Standardized by 3GPP (Third Generation Partnership Project) and ITU (international Telecommunication Union), WCDMA has gained broad acceptance within the wireless communication industry. By 2005, there is expected to be close to 100 WCDMA networks in operation globally.
From the outset, WCDMA was designed to provide cost-efficient capacity for both modern mobile multimedia applications and traditional mobile voice services. One of the key benefits of the technology is efficient, flexible support for radio bearers, in which network capacity can be freely allocated between voice and data within the same carrier. WCDMA also supports both multiple simultaneous services and multimedia services comprising multiple components with different service quality requirements in terms of throughput, transfer delay, and bit error rate.
In WCDMA, user data is spread over a bandwidth of circa 5 MHz. The wide bandwidth supports high user data rates and also provides performance benefits due to frequency diversity. However, the exact data transmission speed that will be available for the system users is not easily predictable. The actual capacity in the mobile networks is affected by a number of factors, such as weather conditions, how many users currently communicate through a common base station, and, most importantly, the cell density and the radio traffic channel density. In the terminology for WCDMA, a radio base station is referred to as a Node B.
A general object is to reduce the installation/operation/maintenance cost of base stations when designing/building/operating a cellular radio network.
While large macro radio base stations provide both high capacity and coverage over wide areas, a Pico Node B is designed to enhance the capacity and serves an additional number of (indoor) users within a relatively small coverage area in comparison with the coverage of a macro cell. Thus, Pico Nodes B are normally used in 3G systems as auxiliary base stations to decrease the traffic load for macro base stations on geographically restricted areas, often referred to as a hot spot areas. A Pico Node B can also be used to cover white spots where macro base stations do not provide satisfactory radio coverage. A Pico Node B may also be used to increase the capacity in local indoor hot spots and offices, and thereby improve the overall quality in the UMTS radio network by offloading the existing macro-based network.
Conventional fire and burglar alarms normally communicates with a central alarm station through the telephone network. A general problem is that telephone connection jacks are not always accessible where these alarms are desirable.