Providing broadband wireless services over high-speed railways with Distributed Antenna Systems (DAS) has attracted much attention in recent years. In this paper, we analyze the issues of Time Division Duplex (TDD) DAS, including coverage of Remote Antenna Units (RAUs) and echo channel effect. Also, the timing drift problem while solving the effects of echo on the channel with moving cell in TDD-DAS is investigated. To overcome these problems, we propose techniques for antenna selection with timing compensation. Simulation results show that both the echo channel issue and dilemma between coverage and cost can be solved effectively. Finally, further research studies on enhancing DAS with more intelligence functions such as power saving and resource management are discussed.