【作者】 李建军；

【导师】 曹志刚； 樊平毅；

【作者基本信息】 清华大学 ， 通信与信息系统， 2002， 博士

【摘要】 下一代移动通信系统需要实现宽带传输，并能支持多种业务。为了在保证不同用户服务质量的基础上，提高无线系统对有限资源的利用率，需要对系统的各种资源进行优化分配。而在无线环境下，信道质量差且不稳定，这样系统在进行资源分配时，如何克服恶劣无线信道的影响来保证各种用户的传输质量就成了一个比较棘手的问题。本文对主要的系统资源，即信道、功率和传输速率的分配优化问题进行了深入的研究，主要包括： 首先，在分析无线信道传输特性的基础上，提出了一种基于多载波DS-CDMA的支持宽带多业务接入的系统模型。在该模型的基础上，我们研究了多载波 DS-CDMA前向链路中的子信道优化分配问题。根据最大信号干扰加噪声比原理，分析得出了随机特征码条件下最优的子信道分配策略，并提出了一种类似于灌水原理的子信道分配算法，该算法能在保证各个用户传输质量的前提下，使系统的整体性能接近最优。信道分配完成以后，用户需要知道各自的分配结果以便进行数据接收。为此我们提出了盲最大似然子信道检测算法，该算法在实际中是切实可行的，并能使系统的效率有很大提高。其次，提出了在双天线发送分集中对不同天线的发送功率进行优化分配的技术方案，并分析了信道估计误差对其性能的影响，理论分析和仿真结果表明：在Alamouti双天线发送分集中采用自适应优化功率分配，不仅提高了系统的性能，还可以提高其对信道估计误差的鲁棒性。最后，提出了在宽带多速率DS-CDMA系统中采用GPS辅助功率控制的自适应速率分配方案。该方案能在保证信道传输质量的前提下实现数据业务的多速率传输。并对功率控制误差不敏感。本文的研究结果表明：在未来无线宽带多业务的通信系统中，通过采用我们提出的资源优化分配方案，可以使系统性能有很大的改善，同时也扩大了系统的容量和增强了系统的可靠性。更多还原

【Abstract】 The next-generation mobile communication systems are expected to provide wideband transmission for mobiles and support multiple services. In order to make the most of the wireless resources to guarantee the quality of service, optimal resource allocations are needed. Due to the fading and time varing characteristics of the wireless channel, it is very troublesome to guarantee the transmission quality in wireless resource allocation. In this dissertation, we investigate in depth the optimal allocation of the various system resources including subchannel, power and transmission rate.First, a multicarrier DS-CDMA system model for wideband access is proposed, according to the characteristic of wireless channels, the subchannel allocation is investigated in forward links of the multicarrier DS-CDMA system. Based on the criterion of maximizing the total average signal to interference plus noise ratio (SINR), the optimal subchannel allocation strategy is obtained in theory when random signature sequences are used. For its implementation, an iterative algorithm is proposed, which is similar to the water filling principle. By using the proposed algorithm, we obtain significant improvement on the performance of the system, and the transmission quality can be guaranteed. On the other hand, the information about the allocation result is required at the mobile for data receiving. In order to make the mobile know its subchannel allocation result, a blind maximum-likelihood subchannel detection algorithm is proposed, which can improve the system efficiency and has been proved to be feasible in practice. Secondly, we present a new transmit diversity scheme with adaptive power allocation in which two antennas are employed at the transmitter, and the effect of the channel estimation error on its performance is also analyzed. Theoretical analysis and simulation results indicate that the new scheme has a considerable performance gain and is robust to the estimate bias of channel fading parameters.<WP=6>Finally, to support multiple services, an adaptive rate allocation scheme associated with GPS aided power control is proposed for the data traffic through fading channels in the DS-CDMA system. The performances of the system over different channels are investigated. It has been shown that the proposed scheme can support multiple rate transmission and is very robust to the offset of the power control.In a word, the resource allocation algorithms proposed in this dissertation are very helpful in the improvements of the performance, capacity and stability of the system.更多还原