Cross-Layer Design for Video Transmissions in Metro Passenger Information Systems

In metro passenger information systems (PISs), frequent train handoffs can cause severe video distortion. In this paper, we take an integrated design approach to jointly optimize application-layer parameters and handoff decisions to improve video transmission quality over PISs. We present a train-ground video communication network based on fountain codes and IEEE 802.11p for metro PISs. The metro PIS channel is modeled as a finite-sate Markov chain, and the channel-state transition probability matrix is calculated from the data that were measured in real field tests. The handoff decision and application-layer parameters adaptation problem is formulated as a stochastic semi-Markov decision process (SMDP). Minimizing the end-to-end total video distortion is the objective in our model. Simulation results show that the proposed SMDP-based optimization algorithm can significantly improve the end-to-end video transmission quality in metro PISs.