Delay Bound Analysis Using Martingale for Multimedia DTN under Heterogeneous Network for High-Speed Trains

Recently, high-speed train is rapidly developed as a popular public transportation to carry passengers and goods with low cost and energy consumption. How to provide passengers's broadband mobile communication services efficiently, such as voice over IP (VoIP) or other multimedia services, is receiving more and more attention nowadays. To fulfill the passenger's demand, we consider a heterogeneous network (HetNet) structure consisting track-side access points (TAPs) and cellular networks for the high-speed rail communication system (HRCS). End-to-end delay is one of the most important quality of service (QoS) indicators to evaluate the HetNet performance. Therefore, this paper investigates the joint end-to-end delay of VoIP and multimedia services in this HetNet architecture. Intermittent connectivity of TAPs and scheduling of multiple on-demand services are considered. In order to obtain the theoretic value of queueing delay bounds, we utilize the martingale theory by analyzing the Markov arrival processes. By combing the arrival-martingale and service- martingale concepts, the theoretic delay bounds under the first in first out (FIFO) scheduling scenario are obtained. For the simulation, we use three kinds of real wireless data traces, VoIP, gaming and UDP to evaluate our algorithm by using Nakagami fading channel and LTE fading channel. From the results we can see that the martingale end-to- end delay bounds are tight to the real data trace simulation results.