UBC Theses and Dissertations

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UBC Theses and Dissertations

Congestion control for M2M communications in LTE networks Duan, Suyang


When incorporating machine-to-machine (M2M) communications into the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) networks, one of the challenges is the traffic overload due to a large number of machine type communication (MTC) devices with bursty traffic. One approach to tackle this problem is to use the access class barring (ACB) mechanism to regulate the opportunity of MTC devices to transmit request packets. In this thesis, we first present an analytical model to determine the expected total service time. For the ideal case that the LTE base station (eNodeB) has the information of the number of backlogged users, we determine the optimal value of the ACB factor, which can reduce congestion and access delay. For the practical scenario, we propose a heuristic algorithm to adaptively change the ACB factor without the knowledge of the number of backlogged users. Results show that the proposed heuristic algorithm achieves near optimal performance. We also study the scenario where the number of preambles dedicated to M2M traffic is not fixed and investigate whether dynamic resource allocation can reduce the average number of random access opportunities per MTC device. Simulation results show that the fixed resource allocation scheme can achieve as good performance as the dynamic scheme in reducing the number of opportunities and thus dynamic resource allocation is not necessary.

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