Multi-Carrier and Spread Spectrum Systems: From OFDM and MC ...

238 ApplicationsTable 5-15 Uplink LTE spectrum efficiency per cell in ascenario with 1732 m inter-site distance [4]Spectrum efficiency Spectrum efficiency(bit/s/Hz/cell) (relative to UTRA)Requirement 0.316 2–3 × UTRA1 × 2SIMO 0.681 2.2 × UTRA1 × 4SIMO 1.038 3.3 × UTRAstandard specifications covering the carrier frequencies between 10 and 66 GHz for LOSapplications. Later in 2003 they re-scoped the goal to cover carrier frequencies below11 GHz as well, enabling support of NLOS reception with OFDM technology. From thattime the WiMAX forum made rapid progress. The forum is a large nonprofit organizationand currently made of more than 350 broadband wireless access (BWA) systemmanufacturers, components suppliers (silicon, RF, antenna), and operators.Furthermore, there has been a close collaboration between the European ETSI BroadbandRadio Access Network (BRAN) standardization body and the WiMAX forum. Thiscollaboration has resulted in full harmonization between ETSI and IEEE and is reflected inthe interoperability standards below 11 GHz: PHY- (ETSI TS 102 177) and MAC- (ETSITS 102 178) protocol specifications. In addition, the activities of the conformance testing,used in the WiMAX forum certification process, are being done in close co-operationbetween the ETSI BRAN and WiMAX forum.As illustrated in Figure 5-18, originally the WiMAX forum had the goal to cover thefollowing applications [33]:• broadband wireless access (BWA) for the last miles of residential properties wherexDSL has no coverage;• BWA for small and medium sized enterprises (SME)/business; and• Wi-Fi backhauling, interconnecting the Wi-Fi base stations,and in later steps to support nomadic and future mobility applications.WiMAX follows an evolutionary strategy. WiMAX has the intention to cover firstthe last mile applications (residential and business) [28] where at the present time noxDSL services are available at these geographical places. For this application the IEEE802.16d 256-OFDM mode will be used. Later on the support of nomadic applicationswithout roaming/handover for dense spots networks is foreseen. Here the utilization of theso-called scalable-OFDMA (S-OFDMA) mode with antenna diversity is envisaged. Mobilitywith handover possibility is planned as migration strategy, where the IEEE 802.16eS-OFDMA mode, together with antenna diversity, will play an important role. The mainservices to be covered are: Voice over IP (VoIP), video conferencing, web./internet access,file transfer, interactive gaming, etc.