3 research outputs found
Approximately Optimal Wireless Broadcasting
We study a wireless broadcast network, where a single source reliably
communicates independent messages to multiple destinations, with the aid of
relays and cooperation between destinations. The wireless nature of the medium
is captured by the broadcast nature of transmissions as well as the
superposition of all transmit signals plus independent Gaussian noise at the
received signal at any radio. We propose a scheme that can achieve rate tuples
within a constant gap away from the cut-set bound, where the constant is
independent of channel coefficients and power constraints.
The proposed scheme operates in two steps. The inner code, in which the
relays perform a quantize-and-encode operation, is constructed by lifting a
scheme designed for a corresponding discrete superposition network. The outer
code is a Marton code for the non-Gaussian vector broadcast channel induced by
the relaying scheme, and is constructed by adopting a ``receiver-centric''
viewpoint
Interference Mitigation through Limited Transmitter Cooperation
Interference limits performance in wireless networks, and cooperation among
receivers or transmitters can help mitigate interference by forming distributed
MIMO systems. Earlier work shows how limited receiver cooperation helps
mitigate interference. The scenario with transmitter cooperation, however, is
more difficult to tackle. In this paper we study the two-user Gaussian
interference channel with conferencing transmitters to make progress towards
this direction. We characterize the capacity region to within 6.5 bits/s/Hz,
regardless of channel parameters. Based on the constant-to-optimality result,
we show that there is an interesting reciprocity between the scenario with
conferencing transmitters and the scenario with conferencing receivers, and
their capacity regions are within a constant gap to each other. Hence in the
interference-limited regime, the behavior of the benefit brought by transmitter
cooperation is the same as that by receiver cooperation.Comment: Submitted to Special Issue of the IEEE Transactions on Information
Theory on Interference Networks
Reciprocity in Linear Deterministic Networks under Linear Coding
Abstract—The linear deterministic model has been used recently to get a first order understanding of many wireless communication network problems [1][3][4][8]. In many of these cases, it has been pointed out that the capacity regions of the network and its reciprocal (where the communication links are reversed and the roles of the sources and the destinations are swapped) are the same. In this paper, we consider a linear deterministic communication network with multiple unicast information flows. For this model and under the restriction to the class of linear coding, we show that the rate regions for a network and its reciprocal are the same. This can be viewed as a generalization of the linear reversibility of wireline networks, already known in the network coding literature [10]. I