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Mobile Information Systems
Volume 2017 (2017), Article ID 5816862, 12 pages
Research Article

Energy Efficiency and Capacity Tradeoff in Cloud Radio Access Network of High-Speed Railways

1State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing 100044, China
2School of Electronic Information Engineering, Beijing Jiaotong University, Beijing 100044, China
3Technology Innovation Center, China Telecom, Beijing 100000, China

Correspondence should be addressed to Siyu Lin

Received 29 July 2016; Revised 23 November 2016; Accepted 18 December 2016; Published 9 January 2017

Academic Editor: Piotr Zwierzykowski

Copyright © 2017 Shichao Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


To meet the increasing demand of high-data-rate services of high-speed railway (HSR) passengers, cloud radio access network (C-RAN) is proposed. This paper investigates the tradeoff between energy efficiency (EE) performance and capacity in C-RAN of HSR. Considering that the train location can be predicted, we propose a predictable path loss based time domain power allocation method (PPTPA) to improve EE performance of HSR communication system. First, we consider that the communication system of HSR only bears the passenger information services (PISs). The energy-efficient power allocation problem with delay constraint is studied. The formulated problem is nonconvex. To deal with it, an equivalent convex problem is reformulated. Based on PPTPA, we propose an iterative algorithm to improve the EE performance. Second, we consider that the PISs and the train control services (TCSs) are all bore. A capacity optimization problem with joint EE and services transmission delay constraints is formulated. Based on PPTPA, we propose a hybrid power allocation scheme to improve the capacity of the system. Finally, we analyze the effect of small-scale fading on EE performance. The effectiveness of the proposed power allocation algorithm is validated by HSR channel measurement trace based emulation results and extensive simulation results.