Cross-Layer Performance of Channel Scheduling Mechanisms in Small-Cell Networks With Non-Line-of-Sight Wireless Backhaul Links

Small-cell networks (SCNs) have emerged as a potential solution to the rapidly increasing demand for high-data-rate services over wireless networks. The small-cell access nodes (SANs) provide service to users through the access link and can be connected to the core/global network, preferably, via a wireless backhaul link. In this paper, we develop a queuing analytical model that considers the channel scheduling mechanisms in both links of SCNs, the time-varying nature of the channels, bursty packet arrivals, and the network topology e.g., the number of SANs and the coverage of the small cells. For the access link, we consider the so-called max rate/opportunistic channel scheduling mechanism, while for the backhaul link, we consider three different channel scheduling mechanisms, namely, fixed channel scheduling, round-robin channel scheduling, and access-link-dependent channel scheduling. Our developed analytical model is useful for gauging various data-link-layer performance measures, such as packet loss probability and average queuing delay of the packets, for the channel scheduling mechanisms under consideration. Presented numerical examples show that the choice of channel scheduling mechanism in the backhaul link is not unique and it depends on the operating scenario and required quality-of-service (QoS) parameters. The developed queuing model can also facilitate cross-layer design to meet the required QoS parameters. Presented simulation results validate the accuracy of the developed model.