TY - JOUR
T1 - The Effect of Asynchronism on the Total Capacity of Gaussian Multiple-Access Channels
AU - Cheng, Roger S.
AU - Verdú, Sergio
N1 - Funding Information:
Manuscript received October 18, 1990; revised June 12, 1991. This work was supported by the Office of Naval Research under Grant N00014-90-J-1734. This work was presented at the IEEE International Symposium on Information Theory, Budapest, Hungary, June 24-78, 1991. The authors are with the Department of Electrical Engineering, Princeton University, Princeton, NJ 08544. IEEE Log Number 9102763.
PY - 1992/1
Y1 - 1992/1
N2 - The degradation due to complete asynchronism (at the codeword and symbol levels) in the total capacity, maximum rate-sum, of white Gaussian multiple-access channels is investigated. It is shown that asynchronism reduces the total capacity of a /f-user channel by at most a factor of K. Moreover, this bound is achieved, in asymptotically high signal-to-noise ratios, by the TDMA signalling strategy. When the signalling strategies are optimally designed to maximize the asynchronous total capacity under bandwidth constraints, we find that in a two-user channel 1) for a certain set of signal-to-noise ratios there is no degradation due to asynchronism, 2) for any bandwidth and signal-to-noise ratios the asynchronous total capacity is at least 88% of the synchronous total capacity, and 3) asynchronism has a vanishing small effect on total capacity for both low and high signal-to-noise ratios. Index Terms: Multiple-access channels, asynchronous channels, code-division multiple-access, time-division multiple-access.
AB - The degradation due to complete asynchronism (at the codeword and symbol levels) in the total capacity, maximum rate-sum, of white Gaussian multiple-access channels is investigated. It is shown that asynchronism reduces the total capacity of a /f-user channel by at most a factor of K. Moreover, this bound is achieved, in asymptotically high signal-to-noise ratios, by the TDMA signalling strategy. When the signalling strategies are optimally designed to maximize the asynchronous total capacity under bandwidth constraints, we find that in a two-user channel 1) for a certain set of signal-to-noise ratios there is no degradation due to asynchronism, 2) for any bandwidth and signal-to-noise ratios the asynchronous total capacity is at least 88% of the synchronous total capacity, and 3) asynchronism has a vanishing small effect on total capacity for both low and high signal-to-noise ratios. Index Terms: Multiple-access channels, asynchronous channels, code-division multiple-access, time-division multiple-access.
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U2 - 10.1109/18.108244
DO - 10.1109/18.108244
M3 - Article
AN - SCOPUS:0026705998
SN - 0018-9448
VL - 38
SP - 2
EP - 13
JO - IEEE Transactions on Information Theory
JF - IEEE Transactions on Information Theory
IS - 1
ER -