Placement of relayers in wireless industrial sensor networks: An approximation algorithm

We consider the joint problem of relay-aware TDMA scheduling and optimal placement of relays to improve transmission reliability under deadline constraints. We build on existing algorithms for TDMA scheduling. We propose an iterative placement and scheduling algorithm and compare its performance (in terms of the average number of packets not successfully transmitted before their deadline) against two baseline algorithms, one using random relay placement, and another algorithm giving the truly optimal relay positions and schedule on a grid. Our results show that the iterative placement algorithm is substantially better than random placement. Furthermore, we have applied the truly optimal scheduling and placement algorithm to a simple scenario with one relay and found that the iterative placement algorithm gives almost the same performance.