Studyies On QoS Guarantee Technologies In Wireless Networks

Recently,with the fast development of the communication technologies,wireless communication has been one of the most important communication modes.The next generation wireless network is an integrated one with multiple typical broadband fixed and wireless access technologies such as WLAN,WPAN,WMAN,2G,3G and 4G mobile systems etc.On the other hand,more and more applications will be emerge in wireless networks.Especially, multimedia service will be an important application which need wireless network has enough bandwidth,small delay and jitter,low packet loss and so on.However,due to mobility,fluctuant wireless link and limited bandwidth,it poses many difficulties to provide QoS guarantee for multimedia in wireless networks.Provision of QoS guaranteed multimedia service in wireless networks has been one of hot topics.Therefore,it is very important to study mechanisms and algorithms for QoS guarantee in wireless networks.In this thesis,we focus on the research of QoS guarantee schemes for multimedia services in wireless networks.Our research mainly includes the QoS guarantee scheme at MAC layer in WPAN,the multipath routing in mobile Ad hoc networks and the Adaptive Multi-rate(AMR)in GSM/WCDMA networks.The main contributions of this thesis are as follows. 1)A novel QoS guaranteed power-efficient management scheme for IEEE 802.15.3 HR-WPAN,coined Hierarchical MAC Scheduling Scheme(HMSS)is proposed.By classifying traffics into layers with different priorities,HMSS schedules the traffic layer with high priority preferentially.The order of intra-layer traffics is scheduled to minimize the wakeup times.In addition,a sharing common DEV scheme(SCDS)is proposed to reduce the number of the patches caused by classifying traffics.HMSS can not only guarantee the QoS of multimedia services,but also minimize the power consumption of energy-sensitive DEVs.2)An analytical framework for the optimal partitioning of traffics with different priorities in mobile Ad hoc networks is proposed. Specifically,each path is modeled as a multiple-node M/M/1 tandem network,and the scheduling rule of each queue is non-preemptive. The arrival traffics with different priorities are distributed on multiple paths.Making use of the proposed framework,we obtain the optimal splitting probability to minimize the end-to-end path delay.Moreover, the obtained minimal end-to-end path delay is much less than that of the equally splitting scheme.We guarantee less delay for the traffic with higher priority,facilitating the delivery of real-time services in mobile Ad hoc networks.3)A packet scheduling framework is proposed to study the effect of scheduling strategy on the resequencing delay.Specifically,each path is modeled as a multiple-node M/M/1 tandem network,and the end-to-end path delay follows the normal distribution.Two scheduling schemes are studied,uniform round scheduling(URS)and non-uniform round scheduling(NURS).Analytical results show that the URS scheme outperforms the NURS one,and by increasing the round length,URS scheme can further reduce the resequencing delay in mobile ad hoc networks.4)In this thesis,by compressing the AMR frame,a new defined lower bit rate AMR mode with 3.95 kbps is proposed to guarantee the voice quality when the channel condition is so worse that the voice quality is unacceptable even using the lowest rate mode(4.75 kbps). The proposed mode is completely compatible with the specified AMR codec in standard.Moreover,this mode can be adopted in WCDMA networks.This new mode can increase the capacity and coverage gain.