Research On The QoS Mechanism In B3G System

With the rapid growing up of the mobile communication technology and the continuous consummating of the core network equipment and terminal equipment, mobile communication network is gradually evolving from voice related single-service system into multi-service system which can support high speed multimedia services. In order to provide people using wireless-network the similar services used on the wired-network, such as high quality voice, packet-switch services, real-time video and so on. A new generation of cellular mobile communication system (B3G system) is emerging as the times require.However, services in the multi-service system are much different from each other, and need different requirement of the Quality of Service (QoS). A multi-service system should be able to support different QoS requirement, because a multimedia communication between users may include voice, video, data transmitting with different QoS requirement.Therefore, how to guarantee the QoS of each service in the multi-service system becomes a key problem in the B3G system. According to the problem raised above, a QoS control mechanism on the wireless data-link layer which is suitable for B3G system is proposed. As a part of the QoS control mechanism, the cross-layer technology of combining ARQ (Auto-Repeat-reQuest) with modulation and coding is also researched.The main researchs in the dissertation are listed below:1) Proposed the architecture of data-link layer QoS control mechanism based on the DiffServ which can satisfy all kinds of QoS requirement.2) Base on the architecture proposed above, the dissertation gave a detail design of flow control and packet schedule and did some simulations to prove it.3) According to the different characteristic of each RLC entity, improvements and necessary simulations of the performance after improvement have been done.4) Combining ARQ with modulation and coding to improve the system performance such as delay, packet loss, and throughput.The result of simulations proves that the QoS control mechanism is effective to guarantee the different QoS requirement of all the services. And the cross-layer technology of combining ARQ with modulation and coding can effectively improve the performance of real-time video services.