Cooperation-Multiuser Diversity Tradeoff in Wireless Cellular Networks

Abstract

Abstract-We introduce a new multiuser diversity scheme for interference management in cellular networks. A base station with K antennas communicates with at most K out of M mobile stations. It is proven that, if K M , then K independent data streams can be transmitted to K mobile stations with no need for cooperative joint decoding by such stations. This result is based on a new multiuser diversity concept that allows parallel communication in the network without any cooperation among mobile stations. If the network does not have enough mobile stations, then some of the users need to jointly decode their corresponding data streams. The result suggests the existence of a tradeoff between multiuser diversity and cooperation in the downlink of cellular networks. Our interference management approach is based on a new multiuser diversity concept that achieves the capacity of dirty paper coding (DPC) asymptotically. Surprisingly, this gain is achieved without requiring full channel state information (CSI) and only K integers related to CSI are fed back from mobile stations to the base station. An additional advantage of this scheme is the fact that the encoding and decoding of signals for this distributed MIMO system is based on simple point-to-point communications.

Antenna selection for opportunistic interference management in MIMO broadcast channels

“…The OIM technique [8] provides a new scheduling scheme which requires only minimum finite-rate feedback K and yet retains the optimal multiplexing and multiuser diversity gains achievable by dirty paper coding. To the best of our knowledge, [9] and [4] are the only two publications with some similarities to our approach.…”

“…We first review the method developed in [8] and discuss its main drawback: the logarithmic relationship between K and M . The main contribution of this paper is to reduce the minimum required number of mobile users M while achieving the maximum multiplexing gain.…”

“…Therefore, OIM is capable of achieving the maximum multiplexing gain as long as there are enough mobile stations in the network. The feedback requirement to transmit K independent data streams is proportional to K [8]. The original multiuser diversity concept was based on searching for the best channel to communicate, while our approach shows that searching simultaneously for the best and worst channels can lead to significant capacity gains.…”

“…We present the OIM [8] technique for the downlink of wireless cellular networks, in which d 1 (d ≤ K) independent data streams can be broadcasted to d (d ≪ M ) mobile stations with single antenna such that these data streams do not 1 d is a random variable.…”

“…Furthermore, the mean value of d, i.e. D = E[d], can be any number up to the maximum value of K as long as M is large enough [8]. Therefore, OIM is capable of achieving the maximum multiplexing gain as long as there are enough mobile stations in the network.…”