Research On The Energy Saving Mechanism And Methods Of Mobile Cellular Networks Under Railway Environment

Energy efficiency is an important factor and measurement of wireless communica-tion network development and evolution.Railway is the foundation of the economic development.It's significantly important to research on the energy saving scheme and strategy of wireless cellular networks under railway environment.Both railway dedicated wireless network and public wireless network under railway environment have below specials,users move with high speed,large scale users move at the same time with same routine,user location is predictable and very high QoS re-quirement.As railway wireless network has special requirements on the network design,construction,operation and maintenance,which give big challenges on energy efficiency strategy comparing to wireless network under regular environment,the study result has strong practical value.In this paper,we analyze the existing studies as far as we are concerned,describe the technical requirement on wireless network under railway environment,and provide the energy consumption system and green energy metrics for railway wireless network.Finally,we investigate and evaluate the energy saving scheme and strategy for network equipments,application services and mobile terminals.The paper helps to pave the way for future energy saving studies in railway wireless network.Our contributions are shown below:1)Clarify the typical scenario for wireless communication network under railway en-vironment,analyze the characteristics of network architecture and application ser-vices.Provide the technical challenges for power saving on railway environment wireless network.We also analyze and summarize energy saving strategies and adaption possibility for railway wireless network.2)Based on the research literatures,we classify the power saving catagories and ana-lyze the energy consumption system for railway environment wireless communica-tion network.We propose the green energy metrics and energy consumption system for different levels of equipments in railway wireless communication network.3)Propose a power saving scheme for network equipments in wireless communica-tion network under railway environment.We analyze train schedules and determine that the cellular railway network had considerable potential for energy saving under low traffic scenario.We design a simple train detection strategy using the HAN-DOVER procedure to initiate energy saving and propose a flexible and effective solution based on the Mealy-type finite state machine to transit the cell state be-tween an energy saving mode and a full running mode.The key design principle of the proposed solution consists in forming an orthogonal group and cluster,based on network deployment and train schedules to simplify the state transition.Our evaluations using a real network deployment lead to a significant energy saving of up to 33%with different power saving strategies,train schedules,and train speeds.It's a promising solution for railway wireless network.4)Improve the power saving scheme for application service in wireless communica-tion network under railway environment.There are special characteristics for rail-way network,chain structure network deployment,high speed mobility,frequent and continuous handover,predicable traffic aligned with train schedule and the big group of users concentrated in the train.In enhanced Multimedia Broadcast Multi-cast Service(E-MBMS),which is good at high speed data handling,we propose an optimal power control solution to adjust transmission power adaptively based on actual Signal to Interference plus Noise Ratio(SINR)to achieve energy efficien-cy for the railway wireless network.We establishe the system model and design the new optimization algorithms.We also design the geometry group scheme to significantly reduce the computational burden.And propose the mobility offset pa-rameter to cope with high speed mobility of the train and variation of signal level.Simulation results show that this solution can be a good way for high network ener-gy efficiency and can dynamically adjust the output power for the multicast service in the wireless cellular railway communication network.5)Propose an energy saving scheme for mobile terminal in wireless communication network under railway environment.It's a new application model,each carriage compartment is designed as a femto area,and entire train is under macro network.In this heterogeneous network,different uplink service provides the power sav-ing opportunity.We design a traffic based mobile terminal power saving solution to achieve optimal uplink throughput in the heterogeneous network,and propose an uplink power control algorithm to adjust uplink transmission power adaptive-ly based on the BSR(Buffer Status Reporting)information.Meanwhile,due to less interference from Femto cell,the throughput and SINR of macro network are improved significantly.Our evaluation based on railway communication network shows much better power consumption can be gained by the proposed solution,and system performance is not impacted by amount of mobile terminals.