摘要：To utilize residual redundancy to reduce the error induced by fading channels and decrease the complexity of the field model to describe the probability structure for residual redundancy, a simplified statistical model for residual redundancy and a low complexity joint source-channel decoding（JSCD） algorithm are proposed. The complicated residual redundancy in wavelet compressed images is decomposed into several independent 1-D probability check equations composed of Markov chains and it is regarded as a natural channel code with a structure similar to the low density parity check （LDPC） code. A parallel sum-product （SP） and iterative JSCD algorithm is proposed. Simulation results show that the proposed JSCD algorithm can make full use of residual redundancy in different directions to correct errors and improve the peak signal noise ratio （PSNR） of the reconstructed image and reduce the complexity and delay of JSCD. The performance of JSCD is more robust than the traditional separated encoding system with arithmetic coding in the same data rate.

摘要：因为车辆节点的移动方向与速度大小均存在差异,节点间通信链路的持续时间短暂,通信质量难以满足车载自组织网络(VANET)中传递消息的要求。利用成簇算法来提高通信链路的稳定性是解决上述问题的有效途径,但目前成簇算法的设计主要针对高速公路环境,没有考虑车辆节点方向、速度变化频繁的城市环境。在经典成簇算法的基础上提出了一种更加稳定且可靠的VANET成簇算法。该算法针对城市环境对成簇算法的多个稳定性条件进行改进,同时考虑信道质量对通信服务质量的影响。最后利用SUMO仿真平台模拟真实的城市交通环境,并通过NS-2仿真平台验证该算法的各项指标。仿真结果表明,对比LID算法和MOBIC算法,提出的算法具有更高的稳定性和可靠性,且端到端的数据传输时延更低。