Multi-Relay Assignment Algorithms in Cooperative Cellular Networks
Date Issued
2012
Date
2012
Author(s)
Tang, Ming-Fu
Abstract
Cooperative communication is a well-known technique to exploit the spatial diversity and extend the coverage area in cellular networks. In cooperative communication, the relay node (RN) can help user equipment (UE) to transmit its information to the destination. Relay assignment is to assign the proper RNs to the UEs in order to optimize the system performance. The traditional research works on relay assignment are with matching architecture, which yields that each UE can only be matched with single RN. This is obviously a suboptimal solution since the free UEs can be deployed as RNs. With multi-relay assignment architecture described in this work, the aggregate capacity of overall system can be power-efficiently raised at the price of power consumption on originally leisure RNs. For multi-relay assignment problem, to maximize the aggregate capacity or instantaneous information rate, the particle swarm optimization (PSO) is introduced to obtain a close-global optimal solution with given number of iteration instead of exhausted search algorithm, which is with computational complexity of exponential growth as the number of RNs increases when tackling the problem of maximizing the aggregate capacity. As the number of iteration grows, the local-optimally solution of PSO converges to the globally optimum. However, the number of particle and iteration required by PSO to converge to the global optimal solution grows exponentially when the number of RN increases. Therefore, this work aim at finding a computationally efficient algorithm to coordinate a better tradeoff between computational complexity and aggregate instantaneous information rate of each UE. The residual RN assignment algorithm is therefore proposed. The simulation results have shown that as the number of RN increases, the multiple relay-assisted system with the multi-relay assignment algorithm proposed in this work can be power-efficiently raised. The topology is in LTE-Advanced cellular networks. Simulation results have shown that PSO and RRNA provides great performance enhancement comparing with the optimal solution of single-relay assignment with efficient power consumption. Meanwhile, the fairness index is improved in such a resource allocation problem.
Subjects
Cooperative communiaction
Cellular networks
Multi-relay assignment
Hungarian algorithm
Power efficiency
Type
thesis
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