【作者】 杨婷婷；

【导师】 张淑芳；

【作者基本信息】 大连海事大学 ， 通信与信息系统， 2010， 博士

【摘要】 协作(Cooperative)分集技术是近几年发展十分迅猛的通信技术,它是基于中继传输原理,通过用户之间的协作传输实现空间分集增益。可有效对抗无线衰落、提高通信的可靠性,是未来无线通信领域广泛采用的重要传输技术之一。UWB(Ultra-WideBand,超宽带)通信技术以其巨大的带宽资源、高速率、低功耗等独特优势成为无线个域网领域的研究热点。然而如何在发射功率受限的情况下有效提高系统性能是超宽带系统设计中面临的挑战。UWB设备在无线个域网中多出现在家庭及办公室环境中,通常只有很少的设备处于同时工作的状态,使得在UWB系统中引入协作分集技术成为一种非常好的解决方案。本论文首先综述了国内外协作通信技术、超宽带技术的研究热点及进展。研究了再生和非再生协作无线通信系统的性能,并重点对多用户协作超宽带系统的资源优化分配算法展开深入的研究和探讨。具体研究工作包括以下两方面：一方面是关于协作无线通信系统性能分析的研究工作,主要包括：在Rayleigh衰落环境和基于DF再生中继并行协作框架下,研究了多点再生协作通信系统性能。针对最大比合并(MRC)接收与选择合并(SC)接收处理技术,采用平均分配功率(EPA)方法和近似最优功率分配(A-OPA)方法给出了多点再生协作通信系统误符号率SER的渐近表达式和功率分配。在Rayleigh衰落环境和基于AF非再生中继并行协作框架下,研究了多点非再生协作通信系统性能。基于一种有效的数值计算方法——调和平均数方法推导其累计分布函数CDF、概率密度函数PDF、中断概率函数OP和误符号率SER近似表达式。这些数学表达式对于性能分析及研究参数对系统性能的影响都具有一定的实用价值。另一方面是关于协作超宽带系统资源优化分配算法的研究工作,主要包括：针对非再生协作多频带超宽带系统,在推导其误符号率SER表达式的基础上,分别在发送功率最小化和覆盖范围最大化的优化目标下,提出了关于子频带、功率及中继位置的资源优化分配算法,该算法将拉格朗日乘子法及求解一元三次方程的方法应用到数学推导中。仿真结果证明该算法可使系统总功率消耗有效减少,误符号率性能和覆盖范围显著改善。针对分簇多频带超宽带系统,引入协作分集技术,提出改进的TFC模型,基于凸优化理论提出了簇分配算法和二维功率分配递归算法。为降低算法复杂度,进一步提出了以用户对簇的相对需求度为判断的快速跨层资源优化分配算法。该算法可在满足用户服务质量QOS的前提下最大化系统容量。将博弈论引入到协作超宽带系统的资源优化分配算法中,提出了基于合作博弈论的纳什议价解方法,以最大化系统净效用为目标、以用户QOS需求作为公平性指标的协作伙伴选择算法和自适应功率分配算法。仿真中与最大化系统速率(max-rate)和最大化最小用户速率(max-min)公平性算法比较,证明该算法在系统速率和用户QoS公平性两方面有很好的折衷。将机会中继方式引入到协作超宽带系统中,提出一个新的系统“机会中继协作超宽带系统”,推导其误符号率SER的精确数学表达式。提出以用户公平性基础上最大化系统容量为优化目标的分三步走的资源优化分配算法,包括子频带分配算法、中继节点选择算法、功率优化分配算法。该算法可分布式解决协作伙伴选择问题,并在满足用户QoS需求的同时提高系统容量。更多还原

【Abstract】 Cooperative technology is a communication technology developing rapidly in recent years. It can get diversity gain through cooperation between users, which bases on relay transmission principle. It serves to confront the decadence of wireless channel and enhance the reliability of communication. It is likely that cooperative communication technology will become one of the most promising transmission technologies for future wireless communication field.UWB (Ultra-WideBand) wirless communication technology becomes a research hot spot of WPAN (Wireless Personal Area Network) for its unique advangtages as enormous bandwidth, high-speed rate, low power and so on. However a challenge in the design of UWB system is how to effectively improve the performance in limited transmitter power level. Furthermore, UWB devices are usually used at home and office in WPAN, and only a few of them are in the active mode simultaneously. Therefore the employ of cooperative diversty in UWB systems is a good solution.The thesis begins with a summary of the research hot spots and advances of domestic and international cooperative communication technology and UWB technology. Investigations are made on the performance of regenerative and non-regenerative cooperative communication systems. The thesis focuses on the study of resource allocation algorithms for multiuser cooperative UWB systems. Detailed contents are listed as:On one hand, researches of cooperative wireless commnunication performance include:Investigation is made upon the performance of parallel multi-node cooperative communication systems with regenerative relaying over flat Rayleigh fading channels. As to the Maximal-ratio Combining (MRC) and Selection Combining (SC) diversity reception techniques, asymptotic SER (Symbol Error Rate) expressions are proposed according to EPA (Equal Power Allocation) algorithm and A-OPA (Asymptotic-Optimal Power Allocation) algorithm.Investigation is made upon the performance of parallel multi-node cooperative communication systems with non-regenerative relaying over flat Rayleigh fading channels. Applying an effective calculate means——harmonic mean to derive the closed-form cumulative distribution function (CDF), probability density function(PDF), outage probability (OP),moment generating function (MGF) expressions and approximate expression of symbol error rate (SER). These mathematic expressions have practical values for performance analysis and discussion the effects of selecting different parameters.On the other hand, researches on resource optimum allocation algorithm of cooperative UWB system include:As to the non-regenerative cooperative MB-OFDM (Multiband OFDM) UWB system, on the basis of deducing the closed-form formulation and upper limit of SER (Signal Error Ratio), with the optimizing purpose of minimizing overall transmitted power and maximizing coverage respectively, we propose optimum resource allocation algorithms about sub-band, power and relay location. These algorithms are derived by applying Lagrange multiplier method and solution of unitary cubic equation method. Simulation results show that these algorithms can efficiently reduce the total output of the system and significantly improve the SER performance and coverage.As to the cluster MB-OFDM UWB system, we introduce cooperative diversity to it, and improve the TFC (Time-Frequency Coded) model. The cluster allocation algorithm and planar recursion power allocation algorithm are proposed based on convex optimal theory. To reduce the complexity of algorithm, a quick cross-layer allocation algorithm judged by the relative requirement of cluster is further introduced. This algorithm can maximize the system capacity under the premise of satisfying users’QoS requirement.A novel relay partner selection algorithm and adaptive power allocation algorithm are proposed adopting Nash bargaining solution (NBS) method combing the game theory with the resource allocation algorithm of cooperative UWB system. The algorithms aim at maximizing the payoffs of system and regard the QoS requirements of users as the fairness index. Simulation results show that the proposed algorithm can provide a good trade-off in both overall system rate and fairness compared with the maximizing system rate algorithm and the max-min farness algorithm.A novel system named "OR cooperative UWB" is proposed by bringing OR (Opportunistic Relaying) to UWB system. Particularly, exact and closed-form symbol error rate (SER) expression is derived. In order to maximize the capacity on the basis of fairness between users, we propose resource allocation algorithm which includes three steps:sub-band allocation algorithm, relaying allocation algorithm and power allocation algorithm. The algorithm serves to distributely solve the problem of relay partner selecting and increase the system capacity while satisfying the users’QoS requirement.更多还原