Joint Path Selection and Rate Allocation Framework for 5G Self-Backhauled mm-wave Networks

Abstract

Owing to severe path loss and unreliable transmission over a long distance at higher frequency bands, this paper investigates the problem of path selection and rate allocation for multi-hop self-backhaul millimeter wave (mmWave) networks. Enabling multi-hop mmWave transmissions raises a potential issue of increased latency, and thus, this work aims at addressing the fundamental questions: "how to select the best multi-hop paths and how to allocate rates over these paths subject to latency constraints?". In this regard, a new system design, which exploits multiple antenna diversity, mmWave bandwidth, and traffic splitting techniques, is proposed to improve the downlink transmission. The studied problem is cast as a network utility maximization, subject to an upper delay bound constraint, network stability, and network dynamics. By leveraging stochastic optimization, the problem is decoupled into: (i) path selection and (ii) rate allocation sub-problems, whereby a framework which selects the best paths is proposed using reinforcement learning techniques. Moreover, the rate allocation is a nonconvex program, which is converted into a convex one by using the successive convex approximation method. Via mathematical analysis, a comprehensive performance analysis and convergence proof are provided for the proposed solution. Numerical results show that the proposed approach ensures reliable communication with a guaranteed probability of up to 99.9999%, and reduces latency by 50.64% and 92.9% as compared to baseline models. Furthermore, the results showcase the key trade-off between latency and network arrival rate.

Energy Efficient User Association, Power, and Flow Control in Millimeter Wave Backhaul Heterogeneous Networks

“…Many researchers have investigated BH solutions for future HetNets. Wireless BH solutions for HetNets have been studied in [14], [15], [27]- [39], and can be implemented in two ways. Firstly, the use of multiple antenna technology at the MBS to support in-band wireless BH connections to each LPN has been investigated in [27]- [35].…”

“…Firstly, the use of multiple antenna technology at the MBS to support in-band wireless BH connections to each LPN has been investigated in [27]- [35]. Secondly, a cluster-based multi-hop wireless BH technology, where the LPNs are divided into several clusters with a head that connects to the MBS, has been explored in [14], [15], [36]- [39]. In the cluster-based architecture, LPNs connect to the MBS through the cluster head either directly or through one or more neighboring LPNs.…”

“…Moreover, the authors did not consider realistic channel impairments like rain attenuation and atmospheric gaseous effects on the mmWave signal propagation. Only the works in [15] and [36] considered the problem of flow control for the multi-hop mmWave BH HetNet. As mentioned in [15], one important suggestion can be to randomly re-select some BH links from the set of available links and shift between the links with higher payoff (which can be minimum power consumption or highest throughput).…”

“…Only the works in [15] and [36] considered the problem of flow control for the multi-hop mmWave BH HetNet. As mentioned in [15], one important suggestion can be to randomly re-select some BH links from the set of available links and shift between the links with higher payoff (which can be minimum power consumption or highest throughput). However, splitting data into too many paths may lead to increased signaling overhead and cause traffic congestion.…”

“…Some LPNs must connect to the MBS through neighboring nodes. To that end, a multi-hop architecture of point-to-point mmWave LOS links is required to enable the reliable backhauling of traffic from the MBS to the LPNs and subsequently to the associated users [14], [15]. In such a multi-hop BH network architecture, where the BH links are power as well as capacity limited and the traffic generated at the LPNs varies depending on the throughput requirements of the users, it becomes necessary to devise a flow control strategy for the BH network.…”