| Broadband Wireless Access technologies have recently received vast attentions in communication technology market, and become significant components in next generation communication technologies. In the area of mobile wireless broadband, IEEE 802.16e standard family serves as the official standard. It appears worthwhile to study the physical layers.This paper focuses on the OFDMA physical layers of IEEE 802.16e.Firstly, the IEEE 802.16 standards, the relationship between WIMAX and 802.16 standards and the evolution process of 802.16 are introduced. The structure and the OFDMA physical layer of 802.16e are also generally presented.Secondly, based on OFDM and OFDMA principles, the scheme of OFDMA physical layer is discussed in detail, including symbol description, frame structure and subcarriers allocation. In symbol description, time domain description, frequency domain description, primitive parameters, derived parameters and transmitted signal are given. In subcarriers allocation, downlink FUSC, downlink PUSC and uplink PUSC are described.Thirdly, system structure from transmitter to receiver of OFDMA physical layer simulation platform, the design principle of the main module and interfaces of software designing are described which focus on channel coding - CC, BTC, LDPC, CTC, and the system performance under different modulation, different coding and CTC, LDPC decoding with different number of iterations. At the same time, the performances of these channel coding are compared.Fourthly, space-time coding technology application in IEEE 802.16e is studied. The scheme of Alamouti and V-BLAST application and the improvement on software simulation platform interface design using STC are given. Also the results of system performances are listed.Lastly, the system performances of synchronization are evaluated. Through theoretical analysis and the actual system simulation, the effects of timing and frequency synchronization errors on the performance are given. |
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