LLC-MAC analysis of general packet radio service in GSM
Cristian Demetrescu · Bell Labs Technical Journal · 2002
General Packet Radio Service (GPRS) is one of the major services currently standardized by the European Telecommunications Standards Institute (ETSI) for Global System for Mobile Communications (GSM) Phase 2+. GPRS has been introduced to support bursty packet-switched traffic such as e-mail, World Wide Web traffic, and telemetry. This paper presents a unified analytical model of two GPRS protocols, namely, logical link control (LLC) and radio link control/medium access control (RLC/MAC). The interaction between selective automatic repeat-request (ARQ) schemes at the two layers is investigated. In order to save scarce radio resources, we calculate a finite optimal number of RLC/MAC retransmissions per LLC frame as a function of the number of radio link errors and the LLC frame size. A novel channel-dependent ARQ mechanism is introduced at the LLC layer. Finally, throughput and delay performances of the two ARQ stacks are presented.