Abstract: A space-time block coded orthogonal frequency division multiple access (STBC-OFDMA) scheme based on combination of user grouping (UG) and frequency reuse (FR) is proposed for WiMAX uplink transmission where each user employs an STBC scheme. First, a direction-of-arrival (DOA)-based intra-cell UG model is combined with the idea of inter-cell FR so as to produce a UGFR-STBC-OFDMA uplink access scheme which satisfies with both UG constraints and the inter-cell FR planning. Furthermore, a Capons beamforming-based receiver with a smart antenna array is proposed for directional reception of signals coming from different user groups as well as multiple access interference (MAI) suppression at the base station. Both theoretical analysis and simulation results show that the proposed uplink access scheme not only achieves a well-behaved tradeoff in ideal average spectral efficiency, bit error rate (BER) and computational complexity, but also suppresses inter-cell interferences without power control, compared with some conventional schemes for uplink transmission.

Key words: user grouping, frequency reuse, STBC, OFDMA, uplink transmission, smart antenna array

摘要： 针对 WiMAX 系统中各用户端采用空时分组编码( STBC) 的正交频分多址(OFDMA) 上行链路, 提出一种基于用户分组( UG) 和频率复用( FR) 相结合的UGFR-STBC-OFDMA 上行传输技术。首先, 将基于波达方向( DOA) 的小区内用户分组模型与小区间频率复用思想相结合, 设计出一种可同时满足小区内分组约束条件和小区间频率复用规划的UGFR-STBC-OFDMA 上行接入方案; 其次, 设计了基于 Capon 波束形成技术的智能天线接收方案以实现基站对分组信号的方向性接收和对多址接入干扰(MAI) 的抑制。理论分析和仿真结果均表明:相对于几种传统的上行传输技术, UGFR-STBC-OFDMA 技术实现了理想平均频谱利用率、误比特率和计算复杂度的良好折中, 同时在无须功率控制条件下依然能够部分抑制上行传输时相邻小区间的干扰。

关键词: 频率复用, 空时分组编码, 正交频分多址, 上行传输, 智能天线, 用户分组