Researches On Cross-Layer Wireless Resource Management

In the mobile communication systems centring on users,the level of users' satisfaction to the quality of service(QoS)of systems is one of the most important criterions to scaling system performance.This thesis are engaged in cross-layer wireless resource management algorithm research in the OFDM systems,jointing the dynamic character in the media access control sublayer as well as time-frequency dispersion character in the physical layer,considering the improvement of users' satisfaction to the system.Firstly,this thesis introduces the OFDM technique,traffics model and moduling methods,as well as multiuser multi-traffics OFDM downlink.Then,this thesis introduces the resource management schemes in wireless communication systems, including scheduling schemes in multi-carrier systems,adaptive subcarrier-bit-power allocation schemes,as well as cross-layer wireless resource management schemes.The characters of multi-media traffic,such as high rate and low delay,bring great challenge to the design of packet-based mobile communication systems.Since dropping a packet is less desirable than delaying a packet,this thesis introduces a cross-layer resource allocation scheme for this type of traffics.According to the relationship between the head-of-line delay and the maximum tolerable packet delay, users' packets are classified into two priorities:high priority and low priority.Through the policy of allocating resources to packets with high priority firstly,and to packets with low priority secondly,which is combined with adaptive subcarrier-power allocation,the scheme can improve system power efficiency,decrease average packet delay and enhance users' satisfying level.In the mobile communication systems,fairness among users have come under more and more attention.Focusing on the actuality of fairness disunity,this thesis introduces a new fairness criterion based on cross-layer design,that is the QoS satisfaction fairness criterion.Unlike the existed throughput fairness criterion suitable for non-real-time traffic and the existed delay fairness criterion tailored for real-time traffic,the proposed QoS satisfaction criterion handles heterogeneous traffics in an unified fashion.With the new fairness criterion,this thesis develeops a cross-layer adaptive resource allocation algorithm.Simulation resultes show that the scheme can not only satisfy the QoS requirements of heterogeneous types of traffics in OFDM systems,but also guarantee users' QoS satisfaction fairnessFoucsing on the actuality that cross-layer wireless resource management schemes mainly improve system performance through the design of utility functions,this thesis introduces a framework which can utilize sufficiently the characters of two dimensions (the time domain and the frequency domain)in OFDM systems.Resource management schemes either designed for single carrier systems or for multi-carrier systmes,as well as,either designed for real-time traffics or for non-real-time traffics, can be utilized efficiently in the OFDM systems based on the proposed framework, which can have either heterogeneous types of traffics or single type of traffics. Through configuring different values of parameters for different types of traffics,the algorithm can achieve diverse levels of tradeoff between system utility and traffic QoS satisfaction,guarantee the fairness among different types of traffics as well as the QoS requirements of users'.