Geometric Programming Based Resource Allocation for Mobile Relays on Vehicles

Mobile relay stations (MRSs) which are mounted in a high-speed train (HST) is popular system architecture for high-speed mobile communications. However, sharing spectrums between the macro cell and the MRS cell, interference exists in this hybrid system. In this paper, we investigate the downlink of a multi-cellular decode and forward (DF) relayed orthogonal frequency division multiple access (OFDMA) system and formulate the problem to maximize the system sum rate of all cells subject to a total power constraint and a new proposed time delay constraint. An effective resource allocation scheme combined by greedy sub-carriers allocation and geometric programming (GP) based power allocation algorithm is proposed to optimize subcarrier allocation and power allocation. Particularly, a rigid time delay constraint is introduced to accommodate the high speed mobile environment except for the common power constraint. Numerical experiments verify that the proposed resource allocation scheme outperforms the other traditional approaches and the necessity of introducing the time delay constraint.