Massive MIMO precoder for long range in-band wireless backhaul

Extending the coverage in low average revenue per user networks is a challenging task as the constraints are very high in terms of cost of deployment. In order to reduce this cost, part of the optical fiber classically used for the backhaul link can be replaced by a long range wireless link between two base stations. Additionally, an in-band communication, where the same frequency band is used for the access links and the backhaul link, avoids dispensing additional spectral resources. In this paper, a massive multiple-input multiple-output system combined with a new precoding technique is proposed to provide a long-range in-band wireless backhaul link, while controlling the interference on the user side induced by the in-band communication. The proposed precoder, called regularized zero forcing with controlled interference, is analytically compared with the maximum ratio transmission and the zero forcing precoders in terms of received power on the receiving base station and interference level on the user side. Thereby, this work proves that the proposed precoder outperforms the zero forcing precoder in terms of received power on the receiving base station side and limits the interference level on the user side unlike the maximum ratio transmission precoder. Simulation results confirm the analytical study over a realistic scenario.