Praise for Fundamentals of WiMAX

30 Chapter 1 • Introduction to Broadband Wirelessacross the communication link is not tampered with. This is usually achieved through the use ofencryption.From the service provider’s perspective, an important security consideration is preventingunauthorized use of the network services. This is usually done using strong authentication andaccess control methods. Authentication and access control can be implemented at various levelsof the network: the physical layer, the network layer, and the service layer. The service provider’sneed to prevent fraud should be balanced against the inconvenience that it may imposeon the user.Besides privacy and fraud, other security concerns include denial-of-service attacks in whichmalignant users attempt to degrade network performance, session hijacking, and virus insertion.Chapter 7 presents a more detailed discussion of the various security issues and solutions.1.7.7 Supporting IP in WirelessThe Internet Protocol (IP) has become the networking protocol of choice for modern communicationsystems. Internet-based protocols are now beginning to be used to support not only databut also voice, video, and multimedia. Voice over IP is quickly emerging as a formidable competitorto traditional circuit-switched voice and appears likely to displace it over time. Videoover IP and IPTV are also emerging as potential rivals to traditional cable TV. Because more andmore applications will migrate to IP, IP-based protocols and architecture must be considered forbroadband wireless systems.A number of arguments favor the use of IP-based protocols and architecture for broadbandwireless. First, IP-based systems tend to be cheaper because of the economies of scale theyenjoy from widespread adoption in wired communication systems. Adopting an IP architecturecan make it easier to develop new services and applications rapidly. The large IP applicationdevelopment community can be leveraged. An IP-based architecture for broadband wireless willenable easier support for such applications as IP multicast and anycast. An IP-based architecturemakes it easy to integrate broadband wireless systems with other access technologies andthereby enable converged services.IP-based protocols are simple and flexible but not very efficient or robust. These deficiencieswere not such a huge concern as IP evolved largely in the wired communications space,where transmission media, such as fiber-optic channels, offered abundant bandwidth and veryhigh reliability. In wireless systems, however, introducing IP poses several challenges: (1) makingIP-based protocols more bandwidth efficient, (2) adapting them to deliver the required QoS(delay, jitter, throughput, etc.) when operating in bandwidth-limited and unreliable media, and(3) adapting them to handle terminals that move and change their point of attachment to the network.Some of these issues and solutions are also presented in Chapter 7.