End-to-end transmission time-based opportunistic routing protocols for bus networks

Single path routing protocols for Internet access in bus networks (composed of traveling city public buses) may not achieve satisfactory performance because of frequent bus mobility. This paper studies the opportunistic routing protocols in bus networks to improve the system throughput and reduce the access delay. In this paper, we first propose an end-to-end transmission time (EET)-based opportunistic routing (OR) framework. We then derive 3 EET-based OR protocols, EETOR (EET-based OR), EETMcOR (EET-based OR with MAC contention consideration), and EETCcOR (EET-based OR with congestion control consideration), which consider 3 different EET metrics. EETOR considers the network layer transmission behavior to approximately estimate the EET without the knowledge of the MAC layer; EETMcOR calculates the EET by considering the MAC contention and builds a 3-dimensional Markov chain model to quantize the MAC behavior; and EETCcOR takes the congestion effect into account to evaluate the EET and hence decreases congestion by controlling the MAC layer transmission time. Simulations under a real city environment scenario with a bus mobility model are conducted to demonstrate the effectiveness of our OR protocols.