Abstract
To enhance the throughput of a slotted random access protocol in a radio communication system, we describe the use of a scheme in which multiple power levels are used at the transmitters. We first consider a situation in which n transmitters are simultaneously trying to send a packet to a central receiving station using a time‐slotted access protocol, like slotted ALOHA. Each of these transmitters randomly chooses one of m discrete power levels during each attempt to send a packet. One of the simultaneously sent packets can often be successfully received due to the power capture effect. We consider two types of capture models: (1) one in which the transmitter with the largest received power captures the channel, and (2) one in which the transmitter captures the channel only if its signal‐to‐interference ratio is above some threshold when received at the central station. In this paper, we determine the optimal transmit probabilities for the power levels as well as the optimal values of the power levels themselves, when their range is constrained and for cases both with and without Rayleigh fading. After determining the precise optimal power levels and probabilities for maximizing the capture probabilities (i.e., for a given n), we propose a less complex, but nearly optimal, approximate approach based on using logarithmically equi‐spaced levels. After demonstrating the closeness of our suboptimal results to the optimal results, we apply our approach to the problem of optimizing the throughput of the slotted ALOHA protocol for a case in which the input traffic is generated according to a Poisson process. Several numerical examples are presented along with a demonstration of how the optimal choice of power levels and probabilities can enhance throughput relative to previous ad hoc methodologies.
Similar content being viewed by others
References
J.C. Arnbak and W. van Blitterswijk, Capacity of slotted ALOHA in Rayleigh-fading channels, IEEE Journal on Selected Areas in Communications 5 (February 1987) 261‐269.
F. Borgonovo, M. Zorzi, L. Fratta, V. Trecordi and G. Bianchi, Capture-division packet access for wireless personal communications, IEEE Journal on Selected Areas in Communications 14 (May 1996) 609‐622.
K. Cheun, Optimal arrival-time distribution for delay capture in spread-spectrum packet radio networks, in: Proc. IEEE Veh. Tech. Conf., Stockholm, Sweden (June 1994) pp. 1203‐1207.
I. Cidon, J. Kodesh and M. Sidi, Erasure, capture, and random power level selection in multiple-access systems, IEEE Transactions on Communications 36 (March 1988) 263‐271.
A.R. Conn, N.I.M. Gould and P.L. Toint, LANCELOT: A Fortran Package for Large-Scale Nonlinear Optimization (Release A) (Springer, New York, 1992).
B. Hajek and T. van Loon, Decentralized dynamic control of a multiaccess broadcast channel, IEEE Transactions on Automatic Control 27 (June 1982) 559‐569.
D. Knuth, The Art of Computer Programming, Vol. 1, Fundamental Algorithms (Addison-Wesley, Reading, MA, 2nd ed., 1973).
A. Krishna and R.O. LaMaire, A comparison of radio capture models and their effect on wireless LAN protocols, in: Proc. 3rd IEEE International Conf. on Universal Personal Communications, San Diego, CA (September 1994) pp. 666‐672.
K.S. Kwak and R.R. Rao, Controlled ALOHA with geometric capture probabilities, IEEE Transactions on Automatic Control 35 (November 1990) 1270‐1274.
R.O. LaMaire and A. Krishna, Maximizing throughput in a random access radio system by optimal power level choice, in: Proc. IEEE International Conf. on Commun. (ICC' 96), Dallas, Texas (June 1996) pp. 614‐620.
R.O. LaMaire, A. Krishna and H. Ahmadi, Analysis of a wireless MAC protocol with client-server traffic and capture, IEEE Journal on Selected Areas in Communications 12 (October 1994) 1299‐1313.
R.O. LaMaire, A. Krishna and M. Zorzi, Optimization of capture in multiple access radio systems with Rayleigh fading and random power levels, in: Multiaccess, Mobility and Teletraffic for Personal Communications, eds. B. Jabbari, P. Godlewski and X. Lagrange (Kluwer Academic, Boston, MA, 1996) pp. 321‐336.
C.T. Lau and C. Leung, Capture models for mobile packet radio networks, IEEE Transactions on Commununications 40 (May 1992) 917‐925.
C.C. Lee, Random signal levels for channel access in packet broadcast networks, IEEE Journal on Selected Areas in Communications 5 (July 1987) 1026‐1034.
J.P. Linnartz, Narrowband Land-Mobile Radio Networks (Artech House, Norwood, MA, 1993).
J.J. Metzner, On improving utilization in ALOHA networks, IEEE Transactions on Communications (April 1976) 447‐448.
L.G. Roberts, Aloha packet system with and without slots and capture broadcast channels, Computer Communications Review 5 (April 1975) 28‐42.
N. Shacham, Throughput-delay performance of packet-switching multiple-access channel with power capture, Performance Evaluation 4 (August 1984) 153‐170.
V.Wong and C. Leung, A transmit power control scheme for improving performance in a mobile packet radio system, IEEE Transactions on Vehicular Technology 43 (February 1994) 174‐180.
M. Zorzi and R.R. Rao, Capture and retransmission control in mobile radio, IEEE Journal on Selected Areas in Communications 12 (October 1994) 1289‐1298.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
LaMaire, R.O., Krishna, A. & Zorzi, M. On the randomization of transmitter power levels to increase throughput in multiple access radio systems. Wireless Networks 4, 263–277 (1998). https://doi.org/10.1023/A:1019164308540
Issue Date:
DOI: https://doi.org/10.1023/A:1019164308540