Efficient cooperative relaying in wireless multi-hop networks with commodity WiFi hardware

In wireless multi-hop networks, cooperative relaying exploits temporal and spatial diversity by additionally transmitting via a relay node and then combining direct and relay transmissions at the receiver. While such relaying improves packet error rates, it also costs an extra transmission. Along multi-hop paths, there often are nodes that can be a relay for multiple consecutive transmissions. This allows such a relay to transmit only once rather than on each individual hop along the routing path. We show by simulations that cooperative relaying is more efficient in multi-hop networks than in isolated three-node configurations. We compare our simulation to experimental results by implementing our multi-hop cooperation protocol on commodity Wi-Fi hardware. The appeal of using Wi-Fi is its wide availability. However, today's devices were not designed with cooperation protocols in mind. We explain the necessary steps to implement wireless cooperation protocols, using our multi-hop cooperation protocol as an example.