宽带卫星通信系统多址接入与带宽分配策略研究

发布时间：2018-06-07 14:01

本文选题：宽带卫星通信 + 多址接入　；参考：《重庆大学》2014年硕士论文

【摘要】：宽带卫星网络作为地面网络的补充和延伸，是未来空天地一体化网络系统的重要组成部分。然而卫星通信的带宽是有限的，如何在有限资源下提高信道利用率并满足用户业务服务质量是多址接入与带宽分配策略研究的关键问题。目前一些传统的多址接入与带宽分配策略能够对连续数据流业务和语音业务实现较高信道利用率和较低端到端时延，但是针对具有较强突发性多媒体业务和多样化业务需求，这些技术已不能胜任。本文系统研究了已有多址接入与带宽分配策略，在基于带宽按需分配的宽带卫星网络下提出了一种改进的信道接入协议CFDAMA-FP，，并同时改进了其中的带宽分配算法，旨在提高信道利用率和业务服务质量，适应业务突发特性。本文主要工作有：（1）基于混合按需/自由分配的多址接入协议CFDAMA采用自由分配时隙有效降低了平均传输时延，但随着信道负载增大，自由分配时隙减少而预约次数增多造成网络性能下降。针对这个问题，提出具有快速反应机制的多址接入协议。该协议改进随机接入算法，降低了接入碰撞概率；然后，继承基于突发目标的接入思想，采用在得到资源分配后周期发送带宽需求更新信息的方式，代替反复申请资源的预约方式，能有效降低平均接入时延；最后，本文建立了接入端到端时延计算模型，证明了该协议能够减少接入时延和平均传输时延；（2）在带宽按需分配策略中，带宽申请到分配的时延过长造成资源浪费，传统分配方式采用预测业务策略来合理利用这段时延，但是由于业务高突发性，预测值和实际业务很难达到一致，本文提出基于预约的带宽请求分配算法。首先，采用基于最大Lyapunov指数的混沌时间序列信源预测算法，该算法对高突发性信源具有较好预测性；然后，利用实际分配结果反馈控制预约申请，优化带宽分配结果，有效维持了用户队列稳定性，降低了业务时延抖动；最后，为了满足不同等级业务性能需要，将业务要求作为优先级排序分配依据，提高了业务性能和用户接入公平性；最后，通过对CFDAMA-FP进行建模实现和对比仿真，结果表明在具有高突发特性的Pareto ON-OFF信源模型下，CFDAMA-FP能够在高突发信源和用户数目较大的条件下提供比CFDAMA-PA和CFDAMA-PB更优的平均端到端时延/吞吐量性能和更好的用户接入公平性能。
[Abstract]:As a supplement and extension of terrestrial network, broadband satellite network is an important part of future integrated space and earth network system. However, the bandwidth of satellite communication is limited. How to improve the channel utilization and satisfy the quality of service (QoS) is the key problem in the research of multiple access and bandwidth allocation strategy. At present, some traditional multiple access and bandwidth allocation strategies can achieve higher channel utilization and lower end-to-end delay for continuous data flow services and voice services, but for the demand of strong burst multimedia services and diversified services, some traditional multiple access and bandwidth allocation strategies can achieve higher channel utilization and lower end-to-end delay for continuous data flow services and voice services. These techniques are no longer up to the mark. In this paper, the existing multiple access and bandwidth allocation strategies are systematically studied. An improved channel access protocol, CFDAMA-FPFP, is proposed for broadband satellite networks based on bandwidth allocation on demand, and the bandwidth allocation algorithm is also improved. The purpose of this paper is to improve channel utilization and quality of service (QoS) and adapt to service burst characteristics. The main work of this paper is as follows: 1) CFDAMA, a hybrid on-demand / free allocation multiple access protocol, effectively reduces the average transmission delay by free allocation of time slots. However, with the increase of channel load, the number of free allocated slots decreases and the number of reservations increases, which results in network performance degradation. To solve this problem, a fast response multiple access protocol is proposed. The protocol improves the random access algorithm and reduces the access collision probability. Then, it inherits the access idea based on the burst target and transmits the bandwidth requirement update information in the period after the resource allocation. Instead of the reservation mode of repeatedly requesting resources, the average access delay can be reduced effectively. Finally, the end-to-end delay calculation model is established, which proves that the protocol can reduce the access delay and average transmission delay. 2) in the bandwidth allocation strategy, the delay of bandwidth allocation is too long, which results in waste of resources. The traditional allocation method uses the predictive service strategy to make use of the delay reasonably, but because of the high traffic burst, the traditional allocation method uses the predictive service strategy to make use of the delay reasonably. It is difficult to match the predicted value with the actual traffic. In this paper, a bandwidth request allocation algorithm based on reservation is proposed. First of all, chaotic time series source prediction algorithm based on maximum Lyapunov exponent is adopted, which has good predictability for high burst source, and then the bandwidth allocation result is optimized by feedback control of reservation application based on actual allocation result. It can effectively maintain the stability of the user queue and reduce the delay jitter. Finally, in order to meet the performance needs of different traffic levels, the traffic requirements are taken as the priority allocation basis, which improves the service performance and user access fairness. Finally, through modeling and simulation of CFDAMA-FP, The results show that CFDAMA-FP can provide better average end-to-end delay / throughput performance and better fair access performance than CFDAMA-PA and CFDAMA-PB in the case of high burst source and large number of users under the Pareto ON-OFF source model with high burst characteristics.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN927.2

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