  In this paper, we discuss latency reduction techniques for mobile backhaul
over Data Over Cable Service Interface Specifications (DOCSIS) networks. When
the latencies from both the wireless and the DOCSIS networks are added
together, it can result in noticeable end-to-end system latency, particularly
under network congestion. Previously, we proposed a method to improve upstream
user-to-mobile core latency by coordinating the LTE and DOCSIS scheduling. The
method reduces the impact on system latency from the DOCSIS network's
request-grant-data loop, which is the main contributor of backhaul upstream
latency. Since the method reduces latency on the DOCSIS data path, it will
therefore improve performance of latency sensitive applications, particularly
if TCP is used as the transport protocol, especially when the link is
congested. In this paper, we investigate the effect of HARQ failure on system
performance. Through simulation, we show that despite the uncertainty
introduced by the LTE protocol, coordinated scheduling improves overall system
latency.
