Research On Some Issues Of QoS Support Cross-layer Optimization In Wireless Networks

Wireless communication is one of most active areas in modern communication researches,whose QoS (Quality of Service) support is very important for wireless communication systemsdesign, especially for applications such as streaming video etc., which require strict QoS assurance.QoS is concerned with metrics for data transmiting quailty in networks. The third-generation (3G)and the fourth-generation (4G) wireless communication systems support diverse quality of service(QoS) traffics. Time varying wireless channel conditions, traffic flow random arrival and complexnetworks strcture make QoS guarantee a complex and important issue in modern wirelesscommunication networks.This dissertation, with Markovian process theory, queuing theory, optimization andonline-learning theory, studied some key technologies for wireless networks QoS support, includingmathematical models and algorithms for the burstiness of wireless channel service process, MarkovModeling for wireless channel, layered QoS metrics vertical mapping, cross layer QoS optimization,and node fairness assurance in multi-hop wireless networks. The feasibility and effectiveness of theproposed models are analyzed and verified via simulation. The main contributions of thisdissertation include following five points.1) First time modeling adaptive modulation and coding (AMC) Rayleigh wireless channelservice process. With queuing theory, this work analyzes the relation between wireless channelservice process and wireless link traffic flow, link queue and AMC adopted in physical layer;models the AMC wireless channel service process. With the peakedness function in discrete timefor process bustiness, the author analyzes the bursiness of wireless channel service process, and therelation between the burstiness of wireless channel service process and service rate of receiver inwireless channel, system expected packet error rate, and signal-noise rate of channel with numericalexamples.2) Based on the burstiness of wireless channel service process, this work proposes anequivalent burstiness characteristic AMC wireless channel modeling method, and with numericalanalyses, validates the effectiveness and superiority of the proposed modeling method bycomparing with existing models.3) For the issue of vertical QoS mapping in wireless networks, based on the virtual bufferconception, a unified layered QoS vertical mapping model between protocol layers is proposeed, and the feasibility and effectiveness of the proposed model is preliminary validated by queuinganalysis and numerical examples.4) For the issue of unpredictability of traffic flow and wireless channel in wirelss networks, anonline-learning based cross-layer QoS optimization framework and its realization algorithm areproposed.5) A new Mesh Routers (MRs) fairness metric in Wireless Mesh Networks (WMNs) is proposed,which, according to weighted max-min fairness optimization, measures MR fairness in WMNs withthe consistent level of weighted redundant throughput of route and relaying MRs. Also, a nodethroughput and relaying MRs fairness optimization framework is proposed to analyze, together withnumerical examples, the trade-off between node throughput and MRs fairness.