Broadband Wireless Multimedia Networks

CHAPTER 3

IEEE 802.16 STANDARD

The 802.16 Working Group (WG) was formed in August 1998. The overarching goal of the WG was to specify a wireless metropolitan area network (WMAN) air interface for fixed and mobile broadband wireless access. Three physical layers (PHYs) were considered, namely:

• Single carrier (SC)
• Orthogonal frequency division multiplexing (OFDM)
• Orthogonal frequency division multiple access (OFDMA).

802.16 defines the standard interface between the core medium access control (MAC) sublayer and any convergence sublayer (CS). The interface allows multiple encapsulated payloads, such as IP, Ethernet, and even legacy ATM. Like many wireless standards, the data rates are scalable and can be lowered if a longer operating range is desired. Like 802.11, the 802.16 standard is available for free download [1]. Unlike 802.11, where data packets are transmitted asynchronously in the forward and reverse directions, 802.16 may allow two-way simultaneous (full-duplex) communication. The IEEE 802.16 standard originally adopted a reservation-based time division multiple access (TDMA) mechanism, which precludes the occurrence of collisions when a reservation request is successfully received by the base station (BS). Subsequently, an OFDMA interface with subchannelization was specified for channel access. This channel access method allows the possibility of a frequency reuse of 1, which leads to more flexible deployment since it removes the need to perform frequency planning. In this ...