Praise for Fundamentals of WiMAX

1.7 Technical Challenges for Broadband Wireless 231.7 Technical Challenges for Broadband WirelessSo far, we have discussed the history, applications, and business challenges of broadband wireless.We now address the technical challenges of developing and deploying a successful broadbandwireless system. The discussion presented in this section sets the stage for the rest of thebook, especially Part II, where the technical foundations of WiMAX are discussed in detail.To gain widespread success, broadband wireless systems must deliver multimegabit per secondthroughput to end users, with robust QoS to support a variety of services, such as voice,data, and multimedia. Given the remarkable success of the Internet and the large variety ofemerging IP-based applications, it is critical that broadband wireless systems be built to supportthese IP-based applications and services efficiently. Fixed broadband systems must, ideally,deliver these services to indoor locations, using subscriber stations that can be easily selfinstalledby the enduser. Mobile broadband systems must deliver broadband applications to laptopsand handheld devices while moving at high speeds. Customers now demand that all this bedone without sacrificing quality, reliability, or security. For WiMAX to be successful, it mustdeliver significantly better performance than current alternatives, such as 3G and Wi-Fi. This isindeed a high bar.Meeting these stringent service requirements while being saddled with a number of constraintsimposed by wireless make the system design of broadband wireless a formidable technicalchallenge. Some of the key technical design challenges are• Developing reliable transmission and reception schemes to push broadband data through ahostile wireless channel• Achieving high spectral efficiency and coverage in order to deliver broadband services to alarge number of users, using limited available spectrum• Supporting and efficiently multiplexing services with a variety of QoS (throughput, delay,etc.) requirements• Supporting mobility through seamless handover and roaming• Achieving low power consumption to support handheld battery-operated devices• Providing robust security• Adapting IP-based protocols and architecture for the wireless environment to achievelower cost and convergence with wired networksAs is often the case in engineering, solutions that effectively overcome one challenge mayaggravate another. Design trade-offs have to be made to find the right balance among competingrequirements—for example, coverage and capacity. Advances in computing power, hardwareminiaturization, and signal-processing algorithms, however, enable increasingly favorable tradeoffs,albeit within the fundamental bounds imposed by laws of physics and information theory.Despite these advances, researchers continue to be challenged as wireless consumers demandeven greater performance.