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Ultra-low latency communication for 5G transport networks

Time: Fri 2019-09-20 10.00

Location: Sal 308, ELECTRUM, Kistagången 16, Kista, Stockholm (English)

Subject area: Information and Communication Technology

Doctoral student: Jun Li , Skolan för elektroteknik och datavetenskap (EECS), KTH Royal Institute of Technology

Opponent: Professor Chan Vincent, Massachusetts Institute of Technology

Supervisor: Jiajia Chen, Optical Network Laboratory (ON Lab)

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The fifth generation (5G) mobile communication system is envisioned to serve various mission-critical Internet of Thing (IoT) applications such as industrial automation, cloud robotics and safety-critical vehicular communications. The requirement of the end-to-end latency for these services is typically within the range between 0.1 ms and 20 ms, which is extremely challenging for the conventional cellular network with centralized processing. As an integral part of the cellular network, the transport network, referred to as the segment in charge of the backhaul of radio base stations or/and the fronthaul of remote radio unit, plays an especially important role to meet such a stringent requirement on latency.This thesis investigates how to support the ultra-low latency communications for 5G transport networks, especially for backhaul networks. First, a novel passive optical network (PON) based mobile backhaul is proposed and tailored communication protocols are designed to enhance the connectivity among adjacent base stations (BSs). Simulation results show that an extremely low latency (less than 1 ms packet delay) for communications among the BSs can be achieved, which thereby can be used to support fast handover for users with high mobility (e.g., vehicles).Furthermore, the thesis presents a fog computing enabled cellular networks (FeCN), in which computing, storage, and network functions are provisioned closer to end users, thus the latency on transport networks can be reduced significantly. In the context of FeCN, the high mobility feature of users brings critical challenges to maintain the service continuity with stringent service requirements. In the meanwhile, transmitting the associated services from the current fog server to the target one to fulfill the service continuity, referred to as service migration, has been regarded as a promising solution for mobility management. However, service migration cannot be completed immediately, and may lead to a situation where users experience loss of access to the service. To solve such issues, a quality-of-service (QoS) aware service migration strategy is proposed. The method is based on the existing handover procedures with newly introduced distributed fog computing resource management scheme to minimize the potential negative effects induced by service migration. The performance of the proposed schemes is evaluated by a case study, where realistic vehicle mobility pattern in the metropolitan network scenario of Luxembourg is used to reflect the real world environment. Results show that low end-to-end latency (e.g., 10 ms) for vehicular communication can be achieved with typical vehicle mobility. During service migration, both the traffic generated by migration and other traffic (e.g., control information, video) are transmitted via mobile backhaul networks. To balance the performance of the two kinds of traffic, a delay-aware bandwidth slicing scheme is proposed in PON-based mobile backhaul networks. Simulation results show that, with the proposed method, migration data can be transmitted successfully within a required time threshold, while the latency and jitter for non-migration traffic with different priorities can be reduced significantly.