Research On The Resource Optimization Allocation Algorithms Of Cooperative UWB Systems

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.