Summary form only given. It is shown that symbol asynchronism, which represents the case where transmitters are completely asynchronous and their symbol epochs do not coincide, affects channel capacity in a fundamental way. Symbol asynchronism arises when users transmit each codeword symbol by modulating an assigned waveform but they do not cooperate to ensure that the beginning of each symbol transmission coincides. To treat multiuser communication systems in which each user is not assigned the same waveform, a more general model than the scalar Gaussian MAC is obtained by modeling the sufficient statistics observed by the decoder as a K-vector discrete-time process. The symbol-asynchronous channel has finite memory because each transmitted symbol affects two consecutive observed vectors; it is also a decoder-informed compound channel since the encoders do not know the timing of the other users, and hence they ignore the waveform crosscorrelations which determine the degree of interference among them. Interesting features of the symbol-asynchronous capacity region are described.
|Original language||English (US)|
|Title of host publication||Unknown Host Publication Title|
|Number of pages||1|
|State||Published - Dec 1 1986|
All Science Journal Classification (ASJC) codes