Abstract
Cellular based M2M systems generate massive number of access requests which create congestion in the cellular network. The contention-based random access procedures are designed for cellular networks which cannot accommodate a large number of M2M traffic. Moreover, M2M systems share same radio resources with cellular users. Resource allocation problem becomes a challenging issue in cellular M2M systems. In this thesis, we address these two problems by analyzing a contention-based slotted Aloha random access procedure for M2M networks using different performance metrics. The impact of massive M2M traffic over cellular traffic is studied based on different arrival rate, random access opportunity and throughput. An analytical model of selecting a base station (eNB) along with load balancing is developed. Finally, two methods have been presented and evaluated with M2M traffic. First one is dynamic access class barring method which controls RAN level congestion by selecting an appropriate eNB and applying load balancing method. Second one is relay-assisted radio resource allocation method which maximizes the sum throughput of the system by utilizing the available radio resource blocks and relay nodes to the MTC systems. Numerical results show that frame transmission rate influences the selection probability of the base stations. Moreover, the dynamic access class barring parameter along with frame transmission rate improve the overall throughput and access success probability among base stations as well as avoid overload situation in a particular base station.
Highlights
1.1 Context of our studyThis thesis deals with two general problems of machine-to-machine (M2M) or machine-type communication (MTC) systems, referred to as massive access problem and radio resource allocation problem
We have proposed a dynamic access class barring method taking into account the eNB selection and load balancing strategies to deal with massive access problem
(a) Randomized Access Control Method: - Backoff Timer Method: In the backoff timer method, the MTC devices set a large value of backoff time and random access channel (RACH) overload is controlled by delaying random access (RA) attempts for radio access network (RAN) overload control method
Summary
This thesis deals with two general problems of machine-to-machine (M2M) or machine-type communication (MTC) systems, referred to as massive access problem and radio resource allocation problem. We have proposed, implemented, and evaluated two solution strategies, namely dynamic access class barring method (DACB) and relay assisted radio resource allocation method (RARRA) to deal with these problems in a MTC-enabled cellular network. One of the major challenging issues is contention-based random access procedure which is designed for cellular networks, cannot accommodate a large number of M2M traffic. Contentionbased random access procedure such as slotted Aloha for cellular networks creates congestion when cellular networks support traffic from a large number of M2M devices. After a randomized backoff period, conflicting devices start the same RA procedure This problem is regarded as massive access problem in cellular M2M networks. Another challenging issue is radio resource allocation in cellular M2M systems in which M2M devices compete with H2H users for the same radio resources. We consider data rate maximization and relay allocation for the problem of resource allocation in cellular M2M systems which has not studied adequately before
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