Towards the Maximum Traffic Demand and Throughput Supported by Relay-Assisted mmWave Backhaul Networks

Abstract

This paper investigates the throughput performance issue of the relay-assisted mmWave backhaul network. The maximum traffic demand of small-cell base stations (BSs) and the maximum throughout at the macro-cell BS have been found in a tree-style backhaul network through linear programming under different network settings, which concern both the number of radio chains available on BSs and the interference relationship between logical links in the backhaul network. A novel interference model for the relay-assisted mmWave backhaul network in the dense urban environment is proposed, which demonstrates the limited interference footprint of mmWave directional communications. Moreover, a scheduling algorithm is developed to find the optimal scheduling for tree-style mmWave backhaul networks. Extensive numerical analysis and simulations are conducted to show and validate the network throughput performance and the scheduling algorithm.

An efficient distributed scheduling algorithm for relay-assisted mmWave backhaul networks

“…After that, three main components of the algorithm, i.e., the handshaking procedure for exchanging control information, the calculation of the local schedule of a small-cell BS, and the determination of the final valid schedule of a BS, are elaborated one after another. Simulation results show that the average throughput performance of the distributed scheduling algorithm can reach closely to the calculated maximum traffic demand of small-cell BSs (see [19]) in the tree-style mmWave backhaul network. Moreover, simulations are also conducted to show that the distributed algorithm is able to adapt to the dynamic traffic demand (with sharp changes) of BSs in the network as well.…”

“…In our previous work [14], we find that to support the ultra-high data rate in the 5G small-cell backhaul, not only the location of relays need to be carefully selected, but also the scheduling of the logical links between BSs have to be smartly coordinated. Our recent work [19] focuses on optimizing the throughput performance of the relay-assisted mmWave backhaul network with a tree topology in either the downlink or uplink case. However, the scheduling algorithm proposed in [19] only aims to show the feasibility of finding a schedule that is able to satisfy the set of schedule lengths of logical links obtained from solving the optimization problems.…”

“…Our recent work [19] focuses on optimizing the throughput performance of the relay-assisted mmWave backhaul network with a tree topology in either the downlink or uplink case. However, the scheduling algorithm proposed in [19] only aims to show the feasibility of finding a schedule that is able to satisfy the set of schedule lengths of logical links obtained from solving the optimization problems. It is not an algorithm that can be directly deployed into the practical mmWave backhaul network system.…”

“…Furthermore, in the practical cellular network, since the aggregated traffic load may be larger than the network capacity, the backhaul traffic has to be scheduled proportionally to the traffic demand of each small-cell BS, so that a certain level of fairness can be achieved. Besides, similar to the discussion in [19], network level intelligent scheduling has to come into play to handle the scenario where mutual interference exists between logical links and limited number of radio chains are available on BSs. Therefore, it is important to address the scheduling problem in the practical backhaul system.…”

“…In this paper, we propose a novel distributed scheduling algorithm that can be deployed to efficiently schedule the data traffic in the practical relay-assisted mmWave backhaul network with a tree topology. Different from the work in [19], where either downlink or uplink traffic is considered, the proposed distributed algorithm is able to schedule both downlink and uplink traffic in every subframe. Since the mutual interference relationship between a pair of logical links may vary according to different transmission directions of both links, we assume that two logical links are considered always interfering with each other if there exists at least one combination of transmission directions which leads to significant mutual interference when both logical links transmit concurrently.…”