Cost Effective Coverage Extension in IEEE802.16j Based Mobile WiMAX Systems

Recently, there have been numerous standardization activities for making the IEEE802.16e system highly effective in supporting mobile users based on orthogonal frequency division multiple access (OFDMA) with Time Division Duplex (TDD) mode in (IEEE Standard 802.16e-2005, 2005) and (WiMAX Forum). Standardization activities of the IEEE802.16e system were completed in 2005, and currently enhancements of the IEEE802.16e standard are under discussion. One such enhancement effort is cell coverage extension and link throughput enhancement which was studied in IEEE802.16j TG in (IEEE802.16j-2008, 2008). In order to achieve these goals, the IEEE802.16j TG introduces mobile multi-hop relay technology to the IEEE802.16e system. The other enhancement effort is being discussed in IEEE802.16m TG. The IEEE802.16m system, called the gigabit WiMAX, makinly aims to enhance system throughput up to 1Gbps. Besides, this system aims to support legacy IEEE802.16 standards including the IEEE802.16j, and to interworking with other wireless systems such as 3GPP LTE and IMT-advanced system in (WiMAX Forum) and (Lee et al., 2006).