IEEE 802.16作为全球微波接入互操作系统技术标准,虽然定义了5类信流(分别是UGS,rtPS,ertPS,nrtPS和BE),并将服务质量支持机制引入媒体接入控制层,却没有规定相应的调度算法.为有效保证各种多媒体通信的服务质量,提出了一种基于正交频分多址接入技术和自适应调制编码机制的二级调度方案.该调度方案采用跨层设计思想,适用于PMP Wi MAX网络下行链路中.一级调度器按照QoS优先级顺序调度位于不同类型缓存器的队头分组,从而满足rtPS业务的最大时延限定和nrtPS业务的最小速率要求;完成一级调度后,为满足用户速率公平性,二级调度器根据自适应调制编码信息及用户状态信息调度位于不同用户缓存器的队头分组.仿真结果表明该方案能够有效保证各种多媒体通信服务满足QoS要求并兼顾用户速率公平,同时也可获得较高的Wi MAX系统吞吐量.
A novel BLAST transceiver named turbo-like BLAST(TLBLAST) for MIMO communications is proposed,which combines the characteristics of HBLAST and VBLAST with the structure of turbo encoder. The high data rate transmission can be implemented and in each transmitted antenna,different encode schemes can be used to supply different protection levels. The system performance is improved effectively through serially concatenating a soft input soft output(SISO) detector and decoder by iterative process with comparable complexity of VBLAST. Simulation results show that the performance of TLBLAST is better than HBLAST and VBLAST in Rayleigh flat fading channels.
