Nowadays, rail traffic is expected to evolve into a new era of ‘smart rail mobility’, where trains, infrastructure, travellers and goods will be increasingly interconnected. Railway communications are required to support various high-data-rate applications, the communication system should be carefully designed, which makes railway scenario becomes a more and more important communication scenario. In this study, the channel characteristics are analysed for rural railway at 28 GHz. Four different deployments are considered via calibrated ray-tracing simulations in the target environment. The large-scale parameters of the mmWave channel, including the path loss, root-mean-square delay spread, Rician K-factor, angular spreads and cross-polarisation ratio are explored. The statistical properties, decorrelation distance and cross-correlations are analysed as well. The studied channel characteristics can be used to support the link level and system level design of the communication system in the similar environment.

The rising demand of high-capacity wireless services on-board has driven the research interest on radio communications in public transportation systems. In this experimental study, the authors focus on the intra-car communication links in a high-speed train (HST), which have been rarely reported in the literatures. Specifically, the authors have carefully measured and modelled the radio propagation characteristics for intra-train link. Measurements at both 2.4 and 5.8 GHz have shown that propagation losses inside the train car are much lower than free space, where path-loss exponent increases as the receiver moves away from the transmitter. Otherwise, the shielding loss and frequency dependent penetration losses caused by the train car body shell are parameterised. In addition, the small-scale fading is also evaluated to formulate a complete propagation model for intra-car communications. This work aims to support the Internet access for passengers,for onboard sensor networks and broadband moving-relay solutions.

The performance of communication-based train control (CBTC) systems, in terms of frequency of handoffs [changing association from one access point (AP) to another] and duration of service interruptions, strongly depends on the employed handoff algorithm. In this study, the received signal strength used for the calculation of these metrics is generated by a custom vector parabolic equation (VPE) solver explicitly developed to achieve high accuracy in complex tunnel environments. The authors demonstrate that VPE is as effective and accurate as measurements in estimating the performance of CBTC systems. Additionally, they present a methodology for selecting a handoff algorithm that most enhances the performance of a CBTC system, where APs have already been deployed. The impact of handoff algorithms on system performance is investigated by considering multiple system configurations in a 5 km, curved, rectangular tunnel. A multiple-attribute decision making approach is presented to rank handoff algorithms based on their performance. To validate this proposed simulation-based framework, a CBTC system deployed in the London Underground is presented, where measurement-based ranking is compared against the one derived using VPE simulations.

Machine-to-machine communication can realise considerably better information cognition of fixed and mobile equipment during rail transit. To assess the network access performance of the machine-type communication (MTC) of railway signal equipment for next-generation intelligent transportation system, the forecasting model of the machine communication traffic of railway signal equipment was divided into station indoor model, station outdoor model, and section movement model on the basis of cell units, and the traffic quantity and signaling overhead of the three models were calculated respectively. Based on Poisson's distribution and the Markov update process, an improved Markov-modulated Poisson Process (IMMPP) of the source traffic model was designed. Compared with the 3GPP traffic model, the IMMPP model maintains a good balance between the complexity and the relatively high accuracy of the signal equipment in the station outdoor and section scenarios. The simulation experiments showed that the IMMPP consumed 0.44 s more than 3GPP model 2 in the section scenario and 1.99 s in the station outdoor scenario, and the simulation equipment was in accordance with the actual railway signal equipment. The research result can provide a reference for the description of MTC traffic of other specialised equipment in the railway environment.