Designing efficient frameworks for link layer QoS provisioning in wireless data networks

The rapid advancement in wireless communications and availability of powerful wireless devices are the main driving forces behind the emerging third generation (3G) wireless data networking technologies. One of the important challenges in the development of future communication networks is to improve the quality of communication. In this regard, this thesis addresses a host of issues and challenges from a link layer perspective pertaining to quality-of-service (QoS) provisioning for supporting multimedia services over the wireless network, particularly CDMA systems. With an integrated traffic model comprising both voice and data, system performance with respect to various QoS parameters like delay, channel utilization and blocking probability have been studied and a performance metric is proposed. This performance metric is optimized to design the expiration timer for channel retention which takes advantage of the bursty nature of multimedia traffic in allocating, de-allocating and re-allocating the traffic channels. A fast retransmission mechanism has been proposed for the 3G systems to deal with the recovery of dropped or corrupted packets. The proposed mechanism is integrated at the medium access control (MAC) layer and works hand-in-hand with the existing radio link protocols (RLP) to support TCP applications with strict delay requirements. The concept of differentiated services is also proposed for the wireless domain and a utility function is defined to optimize the revenue from the standpoint of a service provider. The aggregate QoS is achieved by controlling the power vector which can be represented by a point in the QoS space. Vector quantization is used to characterize the QoS space which helps in preventing the system from going into a situation that would reduce the utility.