Joint Bandwidth-Aware Relay Placement and Routing in Heterogeneous Wireless Networks

The relay placement problem has been studied extensively in wireless networks. Existing work typically focuses on connectivity to prolong the network time or to achieve fault-tolerance. In contrast, we tackle the problem with the goal of achieving bandwidth sufficiency when real-time multimedia streams need to be sent to the sink. We consider the critical condition of heterogeneous link capacity and transmission range. Besides, we consider the relay placement and routing jointly because routing decides the path on which a stream traverses; and the bandwidth sufficiency depends on both supply (the link capacity) and demand (which streams use the link given the routing paths). We formulate the problem as a new variant of the Steiner tree problem called the heterogeneous bandwidth Steiner routing problem. Extensive simulations show that our scheme reduces the number of relays by an average of 44% compared to the widely used minimum spanning tree based approximation algorithm for relay placement. We also found that considering heterogeneous range and rate is beneficial in relay placement. Compared to the uniform range and rate placement algorithm, our scheme reduces the number of relays by 25%-39%. Besides, our scheme notably improves the movement efficiency when applied to a real-time multi-robot exploration strategy.