A QoS-Aware Scheduling Algorithm for High-Speed Railway Communication System

With the rapid development of high-speed railway (HSR), how to provide the passengers with multimedia services has attracted increasing attention. A key issue is to develop an effective scheduling algorithm for multiple services with different quality of service (QoS) requirements. In this paper, we investigate the downlink service scheduling problem in HSR network taking account of end-to-end deadline constraints and successfully packet delivery ratio requirements. Firstly, by exploiting the deterministic high-speed train trajectory, we present a time-distance mapping in order to obtain the highly dynamic link capacity effectively. Next, a novel service model is developed for deadline constrained services with delivery ratio requirements, which enables us to turn the delivery ratio requirement into a single queue stability problem. Based on the Lyapunov drift, the optimal scheduling problem is formulated and the corresponding scheduling service algorithm is proposed by stochastic network optimization approach. Simulation results show that the proposed algorithm outperforms the conventional schemes in terms of QoS requirements.Comment: 6 pages, 3 figures, accepted by IEEE ICC 2014 conferenc

Measurement and Modeling of Subway Near Shadowing Phenomenon.

This paper focuses on one vital aspect in propagation characteristics inside subway tunnels: near shadowing phenomenon in a practical environment. In order to characterize this effect, an accurate measurement has been made at 2.4 GHz in a real environment in Madrid subway. By analyzing the numerical results in this measurement, the characteristic of near shadowing phenomenon in propagation process has been revealed and corresponding engineering suggestions have been given in order to compensate the near shadowing effect. Finally, statistical model including the depth, duration and length of near shadowing, fast fading and attenuation inside wide tunnel and narrow tunnel has been built and simulated

Resource Allocation for Device-to-Device Communications Underlaying Heterogeneous Cellular Networks Using Coalitional Games

Heterogeneous cellular networks (HCNs) with millimeter wave (mmWave) communications included are emerging as a promising candidate for the fifth generation mobile network. With highly directional antenna arrays, mmWave links are able to provide several-Gbps transmission rate. However, mmWave links are easily blocked without line of sight. On the other hand, D2D communications have been proposed to support many content based applications, and need to share resources with users in HCNs to improve spectral reuse and enhance system capacity. Consequently, an efficient resource allocation scheme for D2D pairs among both mmWave and the cellular carrier band is needed. In this paper, we first formulate the problem of the resource allocation among mmWave and the cellular band for multiple D2D pairs from the view point of game theory. Then, with the characteristics of cellular and mmWave communications considered, we propose a coalition formation game to maximize the system sum rate in statistical average sense. We also theoretically prove that our proposed game converges to a Nash-stable equilibrium and further reaches the near-optimal solution with fast convergence rate. Through extensive simulations under various system parameters, we demonstrate the superior performance of our scheme in terms of the system sum rate compared with several other practical schemes.Comment: 13 pages, 12 figure

Evaluation of High-speed Train Communication Handover Models Based on DEA

Broadband communications for high speed train is becoming a main trend in high mobility communications. The main bottleneck of this communication network is handover, since the handover occurs so frequently and the delays are so long that broadband real-time communication cannot apply. Various handover models have been developed and studied recently. However, no comprehensive evaluation method for these models is employed. To this end, we borrow Data Envelopment Analysis (DEA) method to evaluate six typical handover system models. Handover models that to be evaluated are introduced. A brief presentation of DEA and its characters is provided. A specific procedure of the evaluation is proposed. Then the results of the evaluation are obtained by running the DEA. Finally, we give our comments and conclusions to all the handover models. We hope our work will supply a gap in the system evaluation area.Comment: 5 pages, accepted for publication, The IEEE 79th Vehicular Technology Conference (VTC 2014 Spring), May, 201