Emulating Wired Backhaul with Wireless Network Coding

In this paper we address the need for wireless network densification. We propose a solution wherein the wired backhaul employed in heterogeneous cellular networks is replaced with wireless links, while maintaining the rate requirements of the uplink and downlink traffic of each user. The first component of our solution consists of a two-way, two-phase communication between the macro base station and a user in a small cell through the small cell base station. The second component consists of an optimized adjustment of the transmit power from the macro base station during the multiple access phase of the two-way protocol. The transmit power is set high enough to enable successive decoding at the small cell base station where the downlink data to the user is first decoded and its contribution removed from the received signal followed by the uplink data from the user. The decoding of the second layer, the uplink traffic to the user, remains identical to the one performed in a wired system. In the broadcast phase, the decoding of the downlink traffic can also be guaranteed to remain identical. Hence, our solution claims an emulation of a wired backhaul with wireless network coding with same performance. We provide numerical examples involving a macro base stations serving a single small cell or two small cells.