A scheme for throughput maximization in a dual-class CDMA system

The uplink of a CDMA system with two user classes is considered. One of the classes consists of delay intolerant users requiring support for a constant information bit rate R, while the other consists of delay tolerant users needing support for an information bit rate of at least R/sub m/. It is assumed that when not transmitting information, both classes maintain synchronization contact with the base station at a rate R/sub 0/. The objective is to maximize the throughput of the delay tolerant users, while ensuring that the interference to other cells is as low as possible by minimizing the sum of all the transmit powers used by the mobiles. Two transmission modes for the delay tolerant users are considered. In the first mode, which is used in conventional CDMA systems, all the users are allowed to transmit information when they wish. In the second mode, the transmissions of the delay tolerant users are scheduled, so that only a limited number of them are transmitting information at any given time instant. It is shown that the second transmission mode, which tends towards a hybrid CDMA/TDMA scheme for the delay tolerant users, affords a better throughput while imposing the same average power requirements as conventional transmission. The results can be interpreted using the results from previous work based on information theory.

[1]  T. Ojanpera,et al.  FRAMES-hybrid multiple access technology , 1996, Proceedings of ISSSTA'95 International Symposium on Spread Spectrum Techniques and Applications.

[2]  Weimin Zhang,et al.  Multiple Access Options for Multi-Media Wireless Systems , 1993 .

[3]  D. G. Messerschmitt,et al.  Power control for variable QOS on a CDMA channel , 1994, Proceedings of MILCOM '94.

[4]  Uwe-Carsten Fiebig,et al.  Design study for a CDMA-based third-generation mobile radio system , 1994, IEEE J. Sel. Areas Commun..

[5]  P. Whiting,et al.  Information-theoretic capacity of multi-receiver networks , 1993, Telecommun. Syst..

[6]  David G. Messerschmitt,et al.  Variable quality of service in CDMA systems by statistical power control , 1995, Proceedings IEEE International Conference on Communications ICC '95.

[7]  Norman C. Beaulieu,et al.  Estimating the distribution of a sum of independent lognormal random variables , 1995, IEEE Trans. Commun..

[8]  A. Sampath,et al.  On setting reverse link target SIR in a CDMA system , 1997, 1997 IEEE 47th Vehicular Technology Conference. Technology in Motion.

[9]  Jack M. Holtzman,et al.  Access control of data in integrated voice/data CDMA systems: benefits and tradeoffs , 1997, Proceedings of ICC'97 - International Conference on Communications.

[10]  I Chih-Lin,et al.  Variable spreading gain CDMA with adaptive control for true packet switching wireless network , 1995, Proceedings IEEE International Conference on Communications ICC '95.

[11]  Jack M. Holtzman,et al.  Power control and resource management for a multimedia CDMA wireless system , 1995, Proceedings of 6th International Symposium on Personal, Indoor and Mobile Radio Communications.

[12]  U. Madhow,et al.  Hybrid intra-cell TDMA/inter-cell CDMA with inter-cell interference suppression for wireless networks , 1993, IEEE 43rd Vehicular Technology Conference.

[13]  Aaron D. Wyner,et al.  Shannon-theoretic approach to a Gaussian cellular multiple-access channel , 1994, IEEE Trans. Inf. Theory.