Backhaul requirements for inter-site cooperation in heterogeneous LTE-Advanced networks

In this paper, we provide an overview on backhaul requirements in mobile networks featuring inter-site cooperation. We consider a heterogeneous deployment, where small cells are embedded into macro-cells. For reducing inter-cell interference, we consider intra- and inter-site joint transmission (JT)-coordinated multi-point (CoMP) in fully flexible cooperation clusters. Backhaul traffic for a macro-cell site scales linearly with the number of small cells and multiplicative by introducing cooperation. All features in LTE-Advanced together push the backhaul traffic up to 100 Gbit/s per site. JT-CoMP is sensitive to the feedback delay.We consider an exemplary rural fiber to the home (FTTH) network as mobile backhaul and find that delays between adjacent sites are below 1 ms. Impairment effects due to the delay can be reduced by feedback compression, shorter delays in the air interface and Doppler-delay based channel prediction.