Toward Traffic Patterns in High-Speed Railway Communication Systems: Power Allocation and Access Selection

Abstract

In high-speed railway (HSR) communication systems, distributed antenna is usually employed to support frequent handover and enhance the signal to noise ratio to user equipments. In this case, dynamic time-domain power allocation and antenna selection (PAWAS) could be jointly optimized to improve the system performances. This paper consider this problem in such a simple way where dynamic switching between multiple-input-multiple-output (MIMO) and single-input-multiple-output (SIMO) is allowed and exclusively utilized, while the channel states and traffic demand are taken into account. The channel states includes sparse and rich scattering terrains, and the traffic patterns includes delay-sensitive and delay-insensitive as well as hybrid. Some important results are obtained in theory. In sparse scattering terrains, for delay-sensitive traffic, the PAWAS can be viewed as the generalization of channel-inversion associated with transmit antenna selection. On the contrary, for delay-insensitive traffic, the power allocation with MIMO can be viewed as channel-inversion, but with SIMO, it is traditional waterfilling. For the hybrid traffic, the PAWAS can be partitioned as delay-sensitive and delay-insensitive parts by some specific strategies. In rich scattering terrains, the corresponding PAWAS is derived by some amendments in sparse scattering terrains and similar results are then presented.

Fast Handover Algorithm Based on Location and Weight in 5G-R Wireless Communications for High-Speed Railways

“…SS-RSRP i and SS-RSRQ i are normalized into P i and Q i , and SS-RSRP and SS-RSRQ of all sampling points of UE are normalized into sets {P} and {Q}. The result d i of the weight calculation of the sampling point i is shown in Equation (15), where W N i and W S i are the weights of NCell and Scell, respectively.…”

“…A simple but effective algorithm of distributed load balancing is presented to reduce the service interruption ratio due to frequent handovers in high-speed scenarios [ 14 ]. Adjusting power in the time domain relieves the “uncertainty” of the received strength of the signal and requires less energy transmission in the procedure of handovers [ 15 , 16 ]. The latest research on C/U-plane staggered handover suggests a methodology to achieve soft and fast handovers [ 17 ].…”

Research on High-Speed Railway Communication Strategy Based on LIFI Technology

“…Higher signal-to-noise ratio. It is a relatively simple method to calculate the beamforming weight vector based on DOA [17]. Reference [18] proposed that in a wireless environment with a small angular spread, the beam should not be directed toward the user DOA in order to ensure the maximum array gain, but a pair of beams should be generated to symmetrically fall on both sides of the user DOA.…”

Low-Complexity Energy-Efficient Power Allocation With Buffer Constraint in HSR Communications

“…For HSR, Liu et al in [31] proposed an effective handover scheme in DAS for ground-train communication. In [32] and [33], the authors investigated the HSR communication system with distributed RAUs and proposed joint optimal power allocation and antenna selection methods.…”