Using Wireless Network Coding to Replace a Wired With Wireless Backhaul

Cellular networks are evolving toward dense deployment of small cells, which requires flexible and efficient backhauling solutions. A viable solution that reuses the same spectrum is wireless backhaul where the small base station acts as a relay. In this letter, we consider a reference system that uses wired backhaul, and each mobile station in the small cell has its uplink and downlink rates defined. The central question is: if we remove the wired backhaul, how much extra power should the wireless backhaul use in order to support the same uplink/downlink rates? We introduce the idea of wireless-emulated wire, based on two-way relaying and network coding. This setup leads to a new type of broadcast problem, with decoding conditions that are specific to the requirement for equivalence to the wired backhaul. We formulate and solve the associated optimization problems. The proposed approach is a convincing argument that wireless backhauling solutions should be designed and optimized for two-way communication.