Fundamental Issues of Multiple Accessing
Abstract
Fundamental issues of multiple accessing are identified. These issues include transmitter asynchronism, variability of the set of active users, feedback, and degree of codebook knowledge among the users. Various multiple access schemes are examined under these issues. These issues are subsequently modeled and analysed using an information theoretic framework. We discover that the capacity region of the asynchronous multiple access channel is different from that of the synchronous channel. For communication systems with users having random message generation time, we demonstrate that its channel capacity resembles that of an asynchronous channel even though the users are synchronous, if decoding delay is constrained to be much smaller than the message inter- arrival time. We investigate communication with restricted decoder structure. New information theoretic quantities that incorporate the decoding metric used are discovered and examined. Using these quantities, we provide a rigorous and novel treatment for the theory of jamming. These mathematical techniques provide insight for achieving reliable communication in a multiple access environment where each user may not know the codebook of the other users and a jammer may be present. We then apply the general theory developed to three specific asynchronous channel without feedback, namely the OR channel, the spread spectrum channel and the collision channel. Practical and novel coding schemes are suggested. Maximum throughput, error rate and decoding complexity are analysed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1983
- Accession Number
- ADA136676
Entities
People
- Joseph Y. Hui
- Joseph Y. Ngai-hui
Organizations
- Massachusetts Institute of Technology