Publications [#235967] of Robert Calderbank

Journal articles or Book chapters PUBLISHED
  1. Applebaum, L; Bajwa, WU; Duarte, MF; Calderbank, R, Multiuser detection in asynchronous on-off random access channels using lasso, 2010 48th Annual Allerton Conference on Communication, Control, and Computing, Allerton 2010 (2010), pp. 130-137 [doi] .

    Abstract:
    This paper considers on-off random access channels where users transmit either a one or a zero to a base station. Such channels represent an abstraction of control channels used for scheduling requests in third-generation cellular systems and uplinks in wireless sensor networks deployed for target detection. This paper introduces a novel convex-optimization-based scheme for multiuser detection (MUD) in asynchronous on-off random access channels that does not require knowledge of the delays or the instantaneous received signal-to-noise ratios of the individual users at the base station. For any fixed number of temporal signal space dimensions N and maximum delay τ in the system, the proposed scheme can accommodate M ≲ exp(O(N1/3)) total users and k ≲ N/log M active users in the system-a significant improvement over the k ≤ M ≲ N scaling suggested by the use of classical matched-filtering- based approaches to MUD employing orthogonal signaling. Furthermore, the computational complexity of the proposed scheme differs from that of a similar oracle-based scheme with perfect knowledge of the user delays by at most a factor of log(N+τ). Finally, the results presented in here are non-asymptotic, in contrast to related previous work for synchronous channels that only guarantees that the probability of MUD error at the base station goes to zero asymptotically in M. ©2010 IEEE.