ABSTRACT
Mobile WiMAX is not the same as IEEE 802.16e-2005, rather it is a subset of the IEEE STD 802.16 standard features and functionalities [9,10]. Both IEEE 802.16-2004 and IEEE 802.16e-2005 have multiple physical-layer options: single-carrier-based Wireless-MAN-SC and WirelessMAN-SCa, an orthogonal frequency division multiple (OFDM)-based WirelessMANOFDM, and an orthogonal frequency division multiple access (OFDMA)-based Wireless-OFDMA [1,2]. However, mobile WiMAX based on IEEE 802.16e-2005 currently supports only OFDMA. IEEE 802.16-2004 and IEEE 802.16e-2005 support both time division duplexing (TDD) and frequency division duplexing (FDD), as well as a half-duplex FDD, while the current mobile WiMAX system profile Release 1.0 [6,7] supports only TDD [6,11]. TDD holds its advantages: (1) flexibility in choosing uplink-to-downlink data rate ratios, (2) ability to exploit channel reciprocity, (3) ability to implement in a nonpaired spectrum, and (4) less complex transceiver design. WiMAX products may simultaneously support both fixed WiMAX and mobile WiMAX through duo-mode base stations (BS) or mobile stations (MS).∗ It is worth mentioning that future mobile WiMAX system
“AU8824_C022.tex” — 597[#3]
profile Release 1.5 may further support both FDD and half-duplex FDD [12,13], and all required fixes and minor enhancements to support Release 1.5 are included in IEEE 802.16 REV2, which is a unified specification document embracing the IEEE 802.16-2004 as well as IEEE 802.16e/f/g amendments and related corrigenda [12].
