Single-radio location-based multihop packet relaying

In wireless multihop networks, all nodes falling within the reception neighborhood of a certain packet transmission are candidate relays. Existing schemes that are based on a CSMA/CA MAC were not originally designed to have the capability of discriminating between similar and dissimilar packets. Nodes attempting to relay the same packet will contend for medium access as much as they will do when relaying dissimilar packets. Exchanging information between nodes will obviously resolve this issue. However, as the node density or communication range increase, the coordination overhead increases and thus reducing bandwidth efficiency. To overcome this problem, we propose a packet relaying scheme. The proposed scheme offers a cross-layer design approach where location-based relaying criteria is integrated with an OFDM-based MAC. It utilizes the fact that the OFDM receivers are tolerant to signal delays. This allows for the design of a connectionless and distributed relaying scheme where the relaying decision is locally taken at each node. For the injection of newly generated packets, clear channel assessment (CCA) is utilized in this scheme.