III. BACKHAUL TRAFFIC MODELS
Although the backhaul traffic is comprised of different types of traffic in small cell networks,
most of traffic is originated from the user data traffic. However, the overhead backhaul traffic
caused by transmission protocols at S1 interfaces and the handover backhaul traffic between
adjacent small cells are important parts in the backhaul traffic. In addition, the wireless traffic
used for management and synchronization is ignored in this paper since these traffic are obviously
less than other traffic in small cell networks. Considering ideal wireless backhaul links between
small cells and the MBS or the specified SBS, the user data traffic is assumed to be only
related with the bandwidth and the average spectrum efficiency in every cell. Without loss of
generality, all small cells are assumed to have the same bandwidth and the same average spectrum
efficiency. In this case, the backhaul throughput of a small cell is simplified as the production