Worldwide interoperability for microwave access (WiMAX) has been envisioned by the WiMAX forum as a single worldwide adopted standard for high-speed wireless metropolitan area networking. The term WiMAX denotes wireless metropolitan area network (WMAN) technology based on IEEE 802.16 specifications. In this chapter, we provide an overview of the salient features and most important specifications of legacy and next-generation WMANs.

Fixed WiMAX

The initial IEEE 802.16 WiMAX standard was established in the frequency band 10–66 GHz, providing up to 75 Mb/s line-of-sight (LOS) connections for both point-to-multipoint and mesh modes. Table 7.1 summarizes the IEEE 802.16 WiMAX standard family.

PHY layer

IEEE 802.16a provides non-LOS connections in the frequency band of 2–11 GHz (licensed and unlicensed). The WiMAX physical (PHY) layer supports the following four different modulation schemes: WirelessMAN-SC (single carrier), WirelessMAN-SCa (single carrier access), WirelessMAN-OFDM (orthogonal frequency division multiplexing), and WirelessMAN-OFDMA (orthogonal frequency division multiple access). WhileWirelessMAN-SC has been designed for the frequency band 10–66 GHz, the other modulation schemes can be used for the frequency band 2–11 GHz. Additionally, the WiMAX PHY layer transfers bidirectional data by means of time division duplex (TDD) or frequency division duplex (FDD).

MAC layer

IEEE 802.16 is a connection-oriented standard, i.e., prior to transmitting data between subscriber stations (SSs) and base station (BS) connections must be established.