Role of MAC/RLC in achieving higher data rates and QoS in third generation (3G) UMTS system

This paper highlights the key requirements of IMT-2000. The main characteristic of the proposed 3G solution is to satisfy the IMT-2000 requirements. A layered structure based on the Open System Interconnection (OSI) model is discussed to provide multimedia services. The functions of a flexible and efficient MAC/RLC (medium access control/radio link control) sublayer are identified. The paper is concluded by presenting the proposed implementations of the MAC/RLC sublayer in the 3G UMTS system. The MAC protocol has to resolve contention between mobiles accessing the same physical resources and also has to manage the packet access procedure. Since 3G systems will offer services to mobiles having varying QoS requirements, the MAC will need to be capable of managing the access demands of different users and different service classes. This can be achieved by using reservation and priority schemes. Delay sensitive services can use a capacity reservation scheme to guarantee quality of service. Priority schemes can be used to prioritize the requests from different services.