Comprehensive Cost Optimized Scheduling with QoS Guarantees for Optical Slot Switching Xhaul
16 October 2017
The optical slot switching networks, such as recently proposed N-GREEN network, target to propose a low-cost and low-energy consumption solution, and the alternative to the Ethernet fronthaul/xhaul of the 5G network. In the xhaul network, both the time sensitive and the non time sensitive traffic might be present, which impacts on the scheduling method that shall be used in such networks. Furthermore, a presence of the SDN controller will induce a problem of the scalability to the scheduling, if the scheduling decision is based on the centralized slot reservation. In this paper, for a first time, a comprehensive scheduling is proposed for supporting both the time sensitive and non time sensitive traffic in the optical slot switched xhaul network. The scheduling offers the quality of service guarantees for all traffic types, while the SDN scalability problem is solved by distributed operation of the slot use and the new method of using the control channel in optical slot switching networks. For the time sensitive traffic zero jitter and fixed latency are provided, while for the non time sensitive traffic, the token bucket mechanism guarantees of quality of service are provided. The resources are allocated by an algorithm implemented as a cost optimal integer linear programming solution. The numerical results show that N-GREEN network has lower cost and lower power consumption than Ethernet in the xhaul, while in the same time it provides better guarantees for the time sensitive traffic. Next, the quality of service guarantees for the non time sensitive traffic by the scheduler have been confirmed by the ns3 simulations. Finally, the paper discusses for a first time the joint operation of the token bucket and timeout mechanisms in the optical slot switching rings.
