Wireless ultra-dense network( UDN) is one of the important technologies to solve the burst of throughput demand in the forthcoming fifth generation( 5 G) cellular networks. Reusing spectrum resource for the backhaul of small base stations( SBSs) is a hotspot research because of lower cost and rapid implementation with macro base stations( MBSs) in recent years. In heterogeneous UDN,the problem of spectrum allocation for wireless backhaul is investigated. In particular,two different spectrum resource reusing strategies for wireless backhaul are proposed in heterogeneous UDN with the limited bandwidth condition. Using a stochastic geometry-based heterogeneous UDN model,the success probabilities that mobile users communicate with SBSs or MBSs are derived under two different spectrum resource reusing strategies. In addition,the network throughput’s analytical expressions and the optimal ratio of spectrum allocation are derived. Numeral results are provided to evaluate the performance of the proposed strategies at throughput. Thus,the effectiveness of the strategy that mobile users can only communicate with SBSs is validated.
