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

240 Applications• System Profiles• Conformance Testing802.16c802.16• Original air Interface for 10–66 GHz• LOS only, Backhauling802.16a• Amendment for below 11 GHz• Target NLOS applications: “last mile”broadband residential & SME access• Amendment for unlicensed band802.16b802.16f(MIBs for 802.16d)802.16d(802.16-2004)• 802.16 Revision, merge all,address all Errata• Introduce “portability”802.16gManagement plan process &interfaces (mobility)802.16e• Extension for mobility in licensedbands from 2-6 GHz• Roaming for mobile & portable802.16i(MIBs for 802.16e)WiMAX Profiles• WiMAX profiles for certification• Interoperability/ConformanceFigure 5-19 WiMAX and IEEE 802.16specify and release in addition the roaming (handover) and network management specificationsand the management information base (MIB) (IEEE 802.16f/g/i).In parallel with the IEEE 802.16x and ETSI BRAN standardization activities, WiMAXhas specified the conformance test specifications based on a predefined set of profiles (seeSection 5.3.6) agreed among all forum members. The definition of these profiles enabledthe system vendors and the silicon suppliers to start to develop the WiMAX products.The first chips based on IEEE 802.16d (supporting only fixed applications) were ready in2005. Based on these components, since 2005 several field trials and WiMAX installationshave been started.In Table 5-16 a summary of the related IEEE 802.16x specification and its applications[23, 24] is given. Note that the main focus of the WiMAX forum is the so-calledbelow 11 GHz carrier frequencies (2–11 GHz). As we see here, to increase capacityand coverage, besides the OFDM/OFDMA technology, additional implementation optionssuch as adaptive antenna system (AAS), space time coding (STC), point to point mesh,and automatic repeat request (ARQ) are also part of these specifications.Hence, the main technical features of WiMAX air interface specifications (MAC &PHY) versus existing networks can be summarized as follows [33]:• Multi-carrier transmission, OFDM and OFDMA– Robust against multi-path fading– Power optimization in terminal station due to the use of OFDMA