이동셀이 포함된 이종 셀룰러 네트워크에서 자원 관리 연구

학위논문 (석사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 8. 이용환.Deployment of small cells has received a great attention as one of feasible technologies to support explosively increasing traffic demands in cellular communication systems. However, it may involve technical issues, including the management of handovers and cross-tier interference near the cell boundary. In this thesis, we consider deployment of small moving cells (SMCs) in a heterogeneous cellular communication system that employs fixed small cells such as femto- and pico-cells. SMCs can have mobility while providing services for a small number of users in a very short transmission range. We assume that SMCs can make communications among them through a side-haul link for their cooperative operation and make communications with the macro cell through a wireless back-haul. We also assume that the macro cell and SMCs orthogonally share resource to avoid cross-tier interference. We consider resource management for SMCs to maximize the transmission performance by exploiting the mobility of SMCs. For ease of implementation, we consider the resource allocation by coordination among SMCs without involvement of the macro cell. Exploiting that the peak-to-average load ratio (PALR) is larger than 1, we can minimize the resource utilization for SMCs, while allowing them to utilize the resource orthogonal to each other. Thus, the proposed scheme can make SMCs operate without experiencing inter-cell interference. It also virtually reduce the PALR of cells, which is one of major concerns for resource saving operation. Finally, the performance of the proposed scheme is verified by computer simulation.Abstract i Contents iii List of Figures iv List of Tables v 1. Introduction 1 2. System model 4 2.1. Resource allocation for SMCs 4 2.2. Resource structure 6 2.3. Signal-to-interference plus noise ratio 8 2.4. Traffic load 10 3. Previous works 13 3.1. Conventional resource management 13 3.2. Dynamic radio resource allocation 16 4. Proposed resource management 17 4.1. FA size 17 4.2. Resource management 18 4.3. Cooperative resource allocation 20 5. Performance evaluation 23 6. Conclusions 31 References 33 1. 초 록 37Maste

Scheduling M2M traffic over LTE uplink of a dense small cell network

We present an approach to schedule Long Term Evolution (LTE) uplink (UL) Machine-to-Machine (M2M) traffic in a densely deployed heterogeneous network, over the street lights of a big boulevard for smart city applications. The small cells operate with frequency reuse 1, and inter-cell interference (ICI) is a critical issue to manage. We consider a 3rd Generation Partnership Project (3GPP) compliant scenario, where single-carrier frequency-division multiple access (SC-FDMA) is selected as the multiple access scheme, which requires that all resource blocks (RBs) allocated to a single user have to be contiguous in the frequency within each time slot. This adjacency constraint limits the flexibility of the frequency-domain packet scheduling (FDPS) and inter-cell interference coordination (ICIC), when trying to maximize the scheduling objectives, and this makes the problem NP-hard. We aim to solve a multi-objective optimization problem, to maximize the overall throughput, maximize the radio resource usage and minimize the ICI. This can be modelled through a mixed-integer linear programming (MILP) and solved through a heuristic implementable in the standards. We propose two models. The first one allocates resources based on the three optimization criteria, while the second model is more compact and is demonstrated through numerical evaluation in CPLEX, to be equivalent in the complexity, while it performs better and executes faster. We present simulation results in a 3GPP compliant network simulator, implementing the overall protocol stack, which support the effectiveness of our algorithm, for different M2M applications, with respect to the state-of-the-art approaches