Scheduling and handoff algorithms for QoS in next generation wireless communication systems

Abstract

The next generation wireless communication systems will support high data rate with various services such as VoIP, Video stream, wireless internet, and so on in limited radio resource environment. Recently, a wireless internet service, Wireless Broadband (WiBro) supporting high data rate and various services was commercialized in Korea. Therefore, several systems coexist such as CDMA, WiBro, and WLAN. To increase system efficiency, a subscriber can be supported by not only from a single system but also from various systems, which should guarantee QoS of subscribers regarding all services. We propose two different methods for QoS: scheduling and handoff. First, a scheduling scheme should guarantees QoS of services offered. Many scheduling schemes such as Round Robin (RR), Proportional Fair (PF), Max C/I, and so on for 2G or 3G systems exist. However, these scheduling schemes cannot be applied to WiBro system because those scheduling schemes are suitable to support a single service. We consider multi-traffic scheduling with requirements on maximum delay time and data rate of each service. To guarantee QoS of real time (RT) and nonreal time (NRT) service, we propose scheduling scheme without high complexity. Simulation results show that QoS of RT and NRT service is guaranteed by proposed scheme. Next, to guarantee a subscriber``s service, heterogeneous systems should support vertical handoff. The criterion for handoff decision in homogeneous system considered in regency systems is received signal strength (RSS). However, in heterogeneous systems, the criterion of handoff decision should consider more important factor such as bandwidth, service type, and data rate in addition to RSS. In this thesis, we propose a vertical handoff decision scheme considering system characteristics and service type. Simulation results show that the proposed scheme increases the throughput and decreases handoff rate and connection time to receive periodic system information messa...