3 research outputs found
Optimal Routing for the Gaussian Multiple-Relay Channel with Decode-and-Forward
In this paper, we study a routing problem on the Gaussian multiple relay
channel, in which nodes employ a decode-and-forward coding strategy. We are
interested in routes for the information flow through the relays that achieve
the highest DF rate. We first construct an algorithm that provably finds
optimal DF routes. As the algorithm runs in factorial time in the worst case,
we propose a polynomial time heuristic algorithm that finds an optimal route
with high probability. We demonstrate that that the optimal (and near optimal)
DF routes are good in practice by simulating a distributed DF coding scheme
using low density parity check codes with puncturing and incremental
redundancy.Comment: Accepted and to be presented at the 2007 IEEE International Symposium
on Information Theory (ISIT 2007), Acropolis Congress and Exhibition Center,
Nice, France, June 24-29 200
Optimal routing for decode-and-forward based cooperation in wireless networks
We investigate cooperative wireless relay networks in which the nodes can help each other in data transmission. We study different coding strategies in the single-source single-destination network with many relay nodes. Given the myriad of ways in which nodes can cooperate, there is a natural routing problem, i.e., determining an ordered set of nodes to relay the data from the source to the destination. We find that for a given route, the decode- and-forward strategy, which is an information theoretic cooperative coding strategy, achieves rates significantly higher than that achievable by the usual multi-hop coding strategy, which is a point-to-point non-cooperative coding strategy. We construct an algorithm to find an optimal route (in terms of rate maximizing) for the decode-and- forward strategy. Since the algorithm runs in factorial time in the worst case, we propose a heuristic algorithm that runs in polynomial time. The heuristic algorithm outputs an optimal route when the nodes transmit independent codewords. We implement these coding strategies using practical low density parity check codes to compare the performance of the strategies on different routes