A combined LLC/MAC traffic analysis of the radio interface in TDMA-based third generation mobile systems

Abstract

SIP, DG, V. Valcannuta 250, I -00166 Rome, Italy (work carried aut when the puthot was w i h Fondazione Ugo Bordoni)Absrrucr -PRMA is a TDM-based multiple access protocol for third generation mobile radio systems capable of accommodating synchFonous and asynchmnous traffic and enabling efficient specaum usage. However, a traffic performance analysis of the protocol has been only carried out for speech traffic. This paper extends the analysis to a vaffic mixture comprising speech and data applications. The paper also considers error detectionhecovery functonalities as exercised at the Data Link layer. I. INTRODUCITONAmong the objectives set for third generation mobile radio systems are high capacity and integration with ISDNB-ISDN, [l], [2]. These objectives reflect, i.a.. in demanding design of the radio subsystem and in particular of the radio interface. One key element in the architecture of the radio interface is the multiple access technique because of its impact on the traffic handling capacity. Two major techniques, TDMA, [31, and CDMA, [41, [SI, are currently considered to have the potential for achieving the high capacity needed in third generation systems. A TDM-based multiple access protocol, PRMA (packet Reservation Multiple Access) has been proposed in [6], [7]. The protocol has the attractive property of enabling flexible and efficient specvum usage. Also, the protocol has the potential for coping with the service requirements of a range of traffic and application types.However, a traffic performance analysis of the protocol has been only carried out for speech traffic. This paper extends the analysis to a rraffic m i x m comprising speech and data applications. Since data information has to be transpotted transparently, the paper also considers LLC (Logical Link Control) error detectiordrecovery functionalities as exercised at the Data Link layer and prompted by access collision on the medium. The recovery mechanism is of the Go-back-n type and is based on a dynamic window flow conml algorithm, [8], which has proven effective in a variety of traffic situations. 11. LLC & MAC FUNCTION MODELLING The model described in the following relates to user information flowing from the mobile stations to the base station. Each mobile is involved in only one session, either speech or data. The base only delivers acknowledgement signals to the mobiles in case of data