A cooperative hierarchical transmission scheme in railway wireless communication networks

Railway wireless communication networks demand good system coverage and high transmission rate. To meet these requirements, in the railway wireless communication networks, we propose a cooperative hierarchical transmission scheme with the deployment of relay nodes. In our scheme, the requested data of each user at its serving evolved NodeB is firstly divided into high priority data stream and low priority data stream. The high priority data stream, which ensures basic service requirements, is sent to the user through both the direct-link and the relay-link so as to provide the reliable transmission by exploiting the time and space diversity gains. For the low priority data, it is only transmitted through the direct-link in order to enhance the service quality. Simulations demonstrate that the proposed scheme outperforms the conventional wireless network without relays in terms of channel capacity, outage probability and system coverage.