Abstract
In this paper, we study resource allocation in buffer-aided relay-assisted OFDMA networks. We consider utility-based stochastic optimization framework where there are constraints to be met either instantaneously or in average sense. Using the well-known Lyapunov drift-plus-penalty policy, we extract the instantaneous problem that needs to be solved in each slot to control the data admission and allocate the time slots, power, and subchannels. We propose the parameters that should be taken into account in utilizing the drift-plus-penalty policy in relay-assisted cellular networks, for providing fair data admission and satisfying the average power constraints. We introduce a low-complexity strategy for power and subchannel allocation and propose distributed and centralized algorithms to utilize it. Specifically, the proposed efficient dynamic distributed resource allocation (EDDRA) scheme is suitable for use in practice as it imposes less overhead on the system and splits the resource allocation tasks among the base station (BS) and the relays. Extensive simulation results show the effectiveness of the proposed parameters in meeting the objective and the constraints of the studied problem. We also show that the proposed EDDRA scheme has close performance to the proposed centralized one and outperforms an existing centralized scheme.
Highlights
1 Introduction Relay-assisted orthogonal frequency division multiple access (OFDMA) networks are the promising solutions for providing high-speed data services in wide coverage areas and they have been accepted in the standardization bodies such as IEEE 802.16 [1] and long term evolution-advanced (LTE-A) [2] for providing wireless access to the customers
Resource allocation is an important factor in utilizing the capacities of these networks; while the combination of OFDMA and relaying techniques results in high benefits and opportunities, it brings challenges and issues that need to be addressed for exploiting those opportunities [3]
Using the Lyapunov drift-plus-penalty policy, we have transformed the problem into instantaneous subproblems while introducing several parameters related to cellular networks
Summary
Relay-assisted orthogonal frequency division multiple access (OFDMA) networks are the promising solutions for providing high-speed data services in wide coverage areas and they have been accepted in the standardization bodies such as IEEE 802.16 [1] and long term evolution-advanced (LTE-A) [2] for providing wireless access to the customers. The work in [21] is a pioneer in utilizing the Lyapunov drift-plus-penalty framework [22, Chapter 5] for data admission and resource allocation in OFDMA relay networks It does not take into account some constraints and challenges that arise in practice in such networks. We assume that the BS and relays use M-ary QAM modulation for their transmissions; the achievable transmission rate on the link of user k from node m on subchannel n in time slot t can be computed as follows [23]: rkmn(t) = B log2 1 + pmn (t)emkn(t) ,. Capacity of MAC layer buffer of user k in node m and the queue size in it in time slot t, respectively amk (t). The discussions can be extended to the cases where the queueing in different layers are taken into account
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