Layer-Encoding Multicasts in Wireless Relay Networks Using Cooperative Communications
Date Issued
2012
Date
2012
Author(s)
Hsu, Tsu-Jung
Abstract
Today, demands for video multicasts increase rapidly in wireless mobile networks. In such a resource-limiting system, cooperative communication is a promising technique to improve multicast performance. Scalable video coding (SVC) also suits for video delivery, such that it can differentiate users and send different video quality according to their channel quality. Hence in this thesis, we study the layered multicasts destination assignment problem with relay cooperation to maximize total utility.
First, we consider a subproblem of multicasts with relay cooperation and formulate the problem as minimizing required resource subject to the subscribed user set and the channel conditions of users. We propose an algorithm which can yield the optimal solution under the assumption that the user channel condition trend viewed from each RS is either in increasing order, decreasing order or the combination of the two. Then the optimality proof and complexity analysis are derived. Also, the method for exception handling is provided.
Afterwards, we go back to the original problem by incorporating the SVC and aim at finding destination assignment of each layer. The objective is to maximize the system utility under the resource constraint and the SVC rule that a layer is valid only if all layers lower than it has been received. The designed algorithm allocates resource to the BS and RSs in each layer according to a defined utility index and models the resource contention between layers through dynamic programming. Then we trim the destination assignment based on our previous devised algorithm that minimizes the total required resource.
For the two problems we tackled, we evaluate our proposed methods through simulation. The results show that the devised resource minimizing algorithm greatly outperformed the other two greedy methods and the devised utility maximizing achieves a high system utility in all settings, indicating our method can adjust assignment strategy according to the utility functions.
Index Terms – wireless relay networks, relay cooperation, layered multicast, scalable video coding, OFDMA
Subjects
wireless relay networks
relay cooperation
layered multicast
scalable video coding
OFDMA
Type
thesis
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