Estimating the mobile backhaul traffic in distributed coordinated multi-point systems

Optical and microwave engineers ask for the required data rates when developing fourth generation (4G) mobile backhaul solutions. Backhauling emerges into an important question since advanced interference mitigation techniques are used to improve the performance at the cost of higher backhaul traffic. In this paper, we provide an efficient method for estimating the backhaul traffic when using joint transmission (JT) coordinated multi-point (CoMP). With this technique, a cluster of base stations (BSs) performs joint signal processing to cancel the mutual interference between adjacent cells. The information exchange between the BSs depends on the cluster size that can be very dynamic depending on the actual interference situation at the mobile terminal. We observe that, on average, 2/3 of the exchange requires inter-site links. This simplifies the analysis and we can refer to the cluster size distribution to compute the backhaul traffic. Results depend on a threshold in the mobility management and on the antenna down-tilt. During busy hours, operators can serve up to 1.3 Gb/s per cell in 50 MHz bandwidth. Backhaul traffic for JT CoMP can reach 5 and 20 Gb/s per triple-sector site for up- and downstream, respectively.