TY - JOUR
T1 - Dynamic spreading gain control in multiservice CDMA networks
AU - Oh, Seong Jun
AU - Wasserman, Kimberly M.
N1 - Funding Information:
Manuscript received January 1997; revised January 1999. This work was supported in part by the United States Army Research Office under Grants DAAH04-96-1-0177 and DAAH04-96-1-0377. This work was presented in part at the INFORMS Telecom Conference, Boca Raton, FL, 1998, and the IEEE International Conference on Communication (ICC’98), Atlanta, GA, 1998.
PY - 1999/5
Y1 - 1999/5
N2 - In this paper, we consider a direct-sequence code division multiple access (DS-CDMA) network consisting of a single radio access point and a collection of wireless terminals. The network offers two classes of service: class-1 (real-time) and class-2 (reliable). We are interested in studying the effect of dynamic spreading gain control (SGC) on the dynamics of multiple access interference (MAI), spectral efficiency, and the quality of service (QoS) experienced by each service class. We first consider a time-slotted system in which class-2 terminals operate in a random access fashion. We show that under optimal (through-put maximizing) dynamic SGC: 1) the optimal retransmission probability is equal to one, and 2) the optimal spreading gain increases linearly, or equivalently, the transmission rate decreases inverse linearly, as the MAI level increases. We then model the system as a continuous-time finite-source queueing system with processor sharing, and obtain an explicit (closed-form) expression for the stationary distribution of the number of active class-1 and class-2 terminals, that is, the MAI level. This distribution is used to derive expressions for various QoS measures and define a capacity or admissible region. The results obtained by simulation and analysis are in extremely close agreement. This work contributes to a better understanding of the relationships between QoS, multiple access interference, and allocation of radio resources in DS-CDMA networks.
AB - In this paper, we consider a direct-sequence code division multiple access (DS-CDMA) network consisting of a single radio access point and a collection of wireless terminals. The network offers two classes of service: class-1 (real-time) and class-2 (reliable). We are interested in studying the effect of dynamic spreading gain control (SGC) on the dynamics of multiple access interference (MAI), spectral efficiency, and the quality of service (QoS) experienced by each service class. We first consider a time-slotted system in which class-2 terminals operate in a random access fashion. We show that under optimal (through-put maximizing) dynamic SGC: 1) the optimal retransmission probability is equal to one, and 2) the optimal spreading gain increases linearly, or equivalently, the transmission rate decreases inverse linearly, as the MAI level increases. We then model the system as a continuous-time finite-source queueing system with processor sharing, and obtain an explicit (closed-form) expression for the stationary distribution of the number of active class-1 and class-2 terminals, that is, the MAI level. This distribution is used to derive expressions for various QoS measures and define a capacity or admissible region. The results obtained by simulation and analysis are in extremely close agreement. This work contributes to a better understanding of the relationships between QoS, multiple access interference, and allocation of radio resources in DS-CDMA networks.
UR - http://www.scopus.com/inward/record.url?scp=0032659204&partnerID=8YFLogxK
U2 - 10.1109/49.768205
DO - 10.1109/49.768205
M3 - Article
AN - SCOPUS:0032659204
SN - 0733-8716
VL - 17
SP - 918
EP - 927
JO - IEEE Journal on Selected Areas in Communications
JF - IEEE Journal on Selected Areas in Communications
IS - 5
ER -