A Simple RLC/MAC Protocol Architecture for a Wireless IP Network

Abstract

This paper presents a simple RLC/MAC protocol architecture for a wireless IP (Internet Protocol) network. In order to support IP-based multimedia services in a wireless network, two different approaches can be used. One approach is to transmit end-to-end IP packets in a multi-hop network, such as a cellular mobile telephone network. In this case IP packets can be transmitted on high data rate air interfaces using a suitable IP header compression technique. Another possibility is to transmit non-IP packets from a UE to a BTS using standard 2G/3G air interfaces. IP packets can be generated at a BTS by encapsulating received MAC packets on an uplink. On a downlink, an IP packet received from a RAN is fragmented at a BTS for further transmission using a standard air interface. This paper first reviews the end-to-end IP packet transmission strategy based on IP header compression techniques. Next a simple RLC/MAC protocol architecture for a wireless IP network is proposed. The proposed protocol architecture is suitable for generating IP packets at a BTS by encapsulating MAC packets. IP packet encapsulation delay at a BTS is minimized by using a reservation-based MAC protocol. The MAC protocol uses class-based reservation and priority queuing techniques to satisfy QoS needs of different classes of traffic. The RLC protocol is mapped onto the MAC protocol to minimize signaling overhead. The proposed RLC/MAC layer is simple, flexible, and generates minimum signaling load to maintain high QoS for multimedia traffic. Performance of the RLC/MAC protocol is analyzed using a simulation model.