On The Research Of QoS Techniques In IEEE802.16 System

With the development of wireless communication, the contents of multimedia applications are expected to be enriched. As a competitive technology of the next generation of wireless network, Wireless Metropolitan Area Network (WMAN) has taken the problem of providing QoS guarantees to different applications into consideration. IEEE802.16 standard specifies QoS signaling mechanisms such as bandwidth request/allocation and scheduling service types. However, the standard leaves some important issues such as admission control, QoS parameter mapping, traffic conditioning and packet scheduling, undefined. These problems are expected to be resolved by the developers.In this thesis, the protocol structure and signaling framework of IEEE802.16 are analysed and an efficient architecture is proposed to support QoS in IEEE802.16 standard. At the SS side, a Traffic Conditioner Module is proposed to keep the traffic conform to the negotiated rate. At the BS side, an Admission Control Module is added to make admission decision and a Packet Scheduling Module is proposed to schedule packet transmission. To support all types of services defined in the standard, the proposed packet scheduler uses a combined scheduling algorithm with priority discipline. This scheduling algorithm has a hierarchical structure. The overall bandwidth is shared among different service types according to their priority level, the bandwidth allocated to each service type is allocated to each connection according to some discipline. A scheduling algorithm named Weighted Fair Scheduling is proposed to share bandwidth among rtPS connections as well as nrtPS connections. The WFS is a practical realization of the fluid GPS in IEEE802.16 QoS architecture. It inherits some advantages of GPS, such as fairness and delay bound guarantees. A prioritized multicast polling scheme is proposed to provide differentiated contention access opportunities to connections with different priority. This can ensure the connection with higher priority experience lower request access delay as specified in the standard.An OPNET simulation platform is developed, and the performance of the key algorithms proposed in this thesis is evaluated.The IEEE802.16a standard defines a 2,048-carrier OFDMA physical layer. A packet scheduling scheme applicable to IEEE 802.16a OFDMA PHY standard is proposed. By making use of multi-user diversity characteristic, taking QoS requirements and packet arrival process into consideration, this scheme can provide QoS guarantees as well as improve bandwidth efficiency. Performance of this proposed scheme is evaluated via OPNET simulation.