Relay Deployment And Frequency Reuse In Multi-Hop Relay Network

Recently, multi-hop relay network attracts the increasing research attention for the future networks, since the relay station (RS) can be deployed flexibly to enhance the system throughput and extend cell coverage. Compare with the conventional wireless network, multi-hop relay network have more factors to be take into consideration for exploiting the advantages of RS abundantly, such as the number of hops, the number of RSs, RSs location, resource allocation and so on. Presently, many works focus on two cases in multi-hop relay network, which is uniform distribution of mobile station (MS) and non-uniform distribution. In this paper, for the downlink in multi-hop relay network, the RSs location is investigated in the first case, and moreover, the number of RSs, the RSs location and the frequency reuse scheme are investigated in the second case.Up to now, in multi-hop relay networks with uniform distribution of MS, there are some papers that address the RS deployment problem by simulate approach. However, the theoretical analysis for the system performance with variable RSs location is left unconsidered. In this paper, with decode-and-forward scheme, the problem of RSs location is considered in two-hop relay network. Firstly, we study the path selection algorithm based on distance and reduce the cellular networks into a single sector mode. In the single sector mode, four theorems are proposed to illustrate different coverage with variable RSs location. Through the proposed theorems, the closed-form of the number of disconnect MSs and the expression of system capacity are obtained for varying RSs location. Lastly, the Monte-Carlo simulations are performed to verify the theoretical results and get the optimal RSs location with different objective functions.In addition, in multi-hop relay networks with non-uniform distribution of MS, only a few papers address the integrated problem about RS deployment but none of them focus on the joint RS deployment and frequency reuse scheme problem. In this paper, in two-hop relay networks covering hotspots which is a kind of non-uniform distribution of MS, the RSs locations and the frequency reuse scheme are optimized simultaneously to maximize the system capacity for deploying minimum number of RSs and satisfying system demand. The joint RSs deployment and frequency reuse scheme (JRDFR) problem is formulated into a mixed integer nonlinear programming, which is non-deterministic polynomial-time hard in general. And, a heuristic approach based on genetic algorithm and ergodic search algorithm is proposed to tackle the JRDFR problem. The computational experiment of the heuristic approach is achieved and optimized RS deployment and frequency reuse scheme is obtained. Contrast with the traditional planning scheme, our planning scheme can enhance the system performance. Finally, we discuss the impacts of the maximum number of outage demand nodes and the number of RSs on the system performance.