The competing priorities of safety-critical messages and infotainment messages present a significant challenge when designing effective IEEE 1609.4 protocol enhancements. In this paper, we investigate the latency reduction provided by an additional CCH check back midway through the Service Channel interval. Mathematical analysis and experimentation using simulations have shown that this method results in significant latency reduction. The maximum transmission delay for safety-critical messages can be reduced by approximately half whilst only reducing the Service Channel capacity by one quarter. As the work progresses, we will optimise the duration of the check back to find the best compromise between safety and infotainment
