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Standards are very important in telecommunications, and wireless is no exception. Wireless technologies have the dubious distinction of lots of standards, most of which are incompatible and conflicting. There exist standards that are U.S. (FCC), European (CEPT/ETSI), international (ITU-R) and, of course, Japanese. There are formal standards and de facto standards. Ultimately, the standards wars will yield winners and losers, but not in the immediate future.
Regulation is extremely important in the wireless world, because there exists significant potential for interference between transmissions. In order to avoid this problem, radio must be managed along several dimensions, including frequency allocation and power levels. Regulatory Authorities and standards bodies of significance include the ITU-R, IEEE, ETSI, and FCC. The ITU-R originally was known as the CCIR (Consultative Committee on International Radio); a branch of the ITU it sets international standards. The IEEE (Institute of Electrical and Electronics Engineers) is in the process of developing standards for Wireless LANs, through the 802.11 Working Group. ETSI (European Telecommunications Standards Institute) sets standards within the EC (European Commission) countries of Western Europe. The RACE program, which is directed at the promotion of Integrated Broadband Communications addresses wireless in its R1043 recommendation document. The Federal Communications Commission (FCC) has been responsible for regulation of the wireless, as well as the wired, world in the United States since 1934. On a periodic basis, the various national regulatory authorities meet to sort out national and international spectrum allocation issues at WARC (World Administrative Radio Conferences), which is sponsored by the ITU-R.
Frequency Allocation
Frequency Allocation or Spectrum Management, involves the designation of certain frequencies in the electromagnetic spectrum in support of certain applications. Examples include AM and FM broadcast radio, UHF and VHF broadcast TV, Trunk Mobile Radio (TMR), cellular radio and microwave radio. This requirement is essential in order to avoid interference among various applications using the same, or overlapping, frequency ranges. In limiting each application to a specific range of frequencies, the manufacturers, carriers, and end users of such systems can better be monitored and controlled.
Power Levels
The power levels various transmitters must be regulated, as stronger signals propagate farther. Clearly, the end result of transmitting at too high a power level is that of interference with distant systems using the same, or overlapping frequency ranges.
Before dealing with technology and applications specifics, we should pause to address the advantages and disadvantages of wireless, at least in a general way. The deployment and management of networks without wires offers clear benefits, but also suffers from severe limitations.
Deployment of wireless networks certainly can offer advantages of reduced cost of installation and reconfiguration. Tremendous costs can be saved by eliminating requirements to secure terrestrial right-of-way, dig trenches and plant poles, place conduits and hang crossarms, splice cables, place repeaters, and so on. For that matter, wired networks may not even be a viable option in rocky or soggy terrain. Additionally, wireless offers greatly improved speed of deployment and reconfiguration. Wireless networks also offer great portability; in other words, the antennae quite easily can be disassembled and reassembled at another location, whereas wired networks must be either abandoned or removed and sold as scrap metal. Finally, wireless networks can even offer the great advantage of mobility, as is the case with cordless telephony, cellular radio, and packet radio data networks.
Wireless also suffers from certain limitations, the most significant of which is that of spectrum availabilityradio is a finite resource. The laws of physics and Mother Nature (not to mention Table 3.1), state that radio operates between 3 kHz and 30 GHz. While that may seem like a lot of spectrum, there also are a lot of applications and users competing for it. This limited radio spectrum is divided into even more limited spectrum allocated in support of each application (e.g, microwave and cellular radio). Within each slice of allocated spectrum there clearly exists only so much bandwidth. Regardless of how cleverly we design compression algorithms to maximize its use, there still is only so much bandwidth available. As was discussed in connection with microwave and satellite radio (Chapter 3), error performance and security are always issues with airwave transmission.
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