High-Speed Railway Wireless Communications: Efficiency Versus Fairness

Abstract

High speed railways (HSRs) have been deployed widely all over the world in\nrecent years. Different from traditional cellular communication, its high\nmobility makes it essential to implement power allocation along the time. In\nthe HSR case, the transmission rate depends greatly on the distance between the\nbase station (BS) and the train. As a result, the train receives a time varying\ndata rate service when passing by a BS. It is clear that the most efficient\npower allocation will spend all the power when the train is nearest from the\nBS, which will cause great unfairness along the time. On the other hand, the\nchannel inversion allocation achieves the best fairness in terms of constant\nrate transmission. However, its power efficiency is much lower. Therefore, the\npower efficiency and the fairness along time are two incompatible objects. For\nthe HSR cellular system considered in this paper, a trade-off between the two\nis achieved by proposing a temporal proportional fair power allocation scheme.\nBesides, near optimal closed form solution and one algorithm finding the\n$\\epsilon$-optimal allocation are presented.\n