Routing Metrics Based on Soft-Output Decoding

Physical layer constrained routing takes the conditions of the physical layers of a network into account when finding an appropriate route. The constraints are usually given by a routing metric, which describes the cost arising when transmitting via a link between two nodes. In nearly all wireless networks, on the physical layer channel coding is used to correct errors and to establish a reliable transmission in terms of error probabilities. In this paper, we introduce new routing metrics that are based on reliability information provided by a soft-output channel decoder. This is different from other approaches calculating error probabilities or link states by using channel statistics. In this paper, the actual error probability is calculated for a decoded packet rather than using a look-up table for a certain SNR or averages for certain channel statistics. The calculation and utilization of bit error probability, packet error probability, and the expected number of hops for a certain path or link are explained. Monte Carlo simulations indicate that using these routing metrics in wireless communications result in a significantly lower average packet delivery time than shortest path routing.