Downlink resource allocation for on-demand multimedia services in high-speed railway communication systems

With the rapid development of high-speed railway (HSR) system, there is an increasing demand on providing high throughput and continuous multimedia (CM) services for HSR passengers. In this paper, we investigate the downlink resource allocation problem for on-demand CM services in HSR OFDMA systems with a cellular/infostation integrated network architecture. Considering both the integrity and continuity of service transmission, the resource allocation problem is formulated as a two-stage optimization programming. The aim of this study is to maximize the total reward of delivered services then to minimize the weighted total number of cumulative discontinuity packets over the trip of the train. To resolve the difficulty of multi-stage optimization, an equivalent one-stage programming is proposed. Since the resultant mixed integer programming is NP-hard in general, we reformulate it as a sparse $$\ell _{0}$$ ℓ 0 -minimization problem and then relax it to a linear programming. Furthermore, a reweighted $$\ell _1$$ ℓ 1 -minimization technique is applied to improve the system performance. Guided by the proposed optimization approaches, we next develop two efficient online resource allocation algorithms for practical systems,where a-priori knowledge of future service arrivals and channel gains is not available. Finally, simulation results are provided to validate the feasibility and effectiveness of the proposed algorithms.