Chapter 8 – WiMAX Implementation

Publisher Summary This chapter focuses on the schemes from current and future IEEE 802.16 specifications. It describes the schemes existing in current IEEE 802.16e specifications and discusses briefly the solutions proposed for IEEE 802.16m. It provides the benefits of UL-MIMO together with a new method, namely, tile-switched diversity (TSD), which benefits from transmit diversity without any channel knowledge at the transmitter side. UL-MIMO techniques are introduced in the standards to provide additional gains on the uplink link budget compared to single transmit antenna schemes. In addition to the STC based on Alamouti scheme, the current WiMAX specifications include CDD as the transparent UL transmission technique. Although this technique does not require specific detection mechanism at the base station, it suffers from performance loss in specific channels like near line of side ones. In this contribution, this chapter presents an alternative transparent transmission technique, which has similar performance to CDD in channel conditions where CDD is thought to perform well and does not suffer from performance loss as CDD in specific channel conditions. Moreover, it studies the effect of second transmit antenna in the front-end design and shows that it possible to realize second transmission path in mobile stations with a small cost increase.