mmWave communication has been recognized as a highly promising technology for 5G wireless backhaul, which is capable of providing multi-gigabit per second transmission rates. However, in urban wireless backhaul environments, unforeseen events can cause short-term blockages or node failures and, therefore, network survivability is extremely important. In this paper, we investigate a novel relay-assisted mmWave backhaul network architecture, where a number of small-cell BSs and relays are deployed, e.g. on the lampposts of urban streets. Relays are used to provide multi-hop line-of-sight paths between small-cell BSs, which form logical links of the network. In this scenario, the interconnected logical links make up a mesh network, which offers opportunities for both link-level and network-level reconfiguration. We propose two joint link-network level reconfiguration schemes for recovery after exceptional events. One prioritizes relay path (link-level) reconfiguration and uses alternate network-level paths only if necessary. The other splits traffic on both reconfigured links and backup paths to improve network throughput. Simulation results demonstrate that the proposed schemes significantly outperform purely link-level and purely network-level reconfiguration schemes. The proposed approaches are shown to not only maintain high network throughput but to also provide robust blockage/fault tolerance across a range of scenarios for urban mmWave backhaul networks.
more »
« less
Analysis of Blockage Effects on Roadside Relay-Assisted mmWave Backhaul Networks
mmWave communication is a highly promising technology for 5G wireless backhaul. However, network performance is hard to predict due to the sensitivity of mmWave signals to blockages. In this paper, we propose an analytical framework to incorporate blockage effects and evaluate blockage robustness within a previously proposed interference-free topology for roadside relay-assisted mmWave backhaul. Through stochastic geometric analysis, the blockage probabilities for four types of blockages identified in prior work are derived as a function of the topology parameters and obstacle density. Analysis of the effect of topology parameters on blockage probability yields insight that leads to a modified topology, which maintains the desirable interference-free property but has better blockage robustness than the original topology. Simulation results demonstrate that the modified topology can maintain very high throughput and has significantly improved robustness as compared to the original topology, while using the same number of relays.
more »
« less
- Award ID(s):
- 1813242
- NSF-PAR ID:
- 10108253
- Date Published:
- Journal Name:
- IEEE International Conference on Communications
- ISSN:
- 1938-1883
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Millimeter-wave wireless LANs are targeted for use with bandwidth-intensive applications such as virtual/augmented reality and real-time high-definition video. To maintain high throughput while addressing mmWave signal blockages, multiple access points (APs) within one room to improve line-of-sight conditions is considered a promising approach. In a scenario with fixed and mobile (human) obstacles, we mathematically analyze LoS blockages produced by mobility, and use the analysis to develop a multi-AP association scheme. Our scheme statically assigns primary and backup APs in order to maximize blockage robustness and perform load balancing among APs. Simulation results show that: 1) our static approach can provide blockage tolerance close to that of an expensive dynamic probing approach while achieving higher throughput, 2) the use of client mobility patterns, if known, can improve our static approach even further, and 3) our approach achieves significantly better fairness and load balancing than existing approaches.more » « less
-
In this paper, we investigate the design of high throughput relay-assisted millimeter-wave (mmWave) backhaul networks in urban areas. Different from most related works, we consider the deployment of dedicated simple mmWave relay devices to help enhance the line-of-sight (LoS) connectivity of the backhaul network in urban areas with abundant obstacles. Given a set of (logical) backhaul links between base stations in the network, we propose an algorithm to find high-throughput LoS paths with relays for all logical links by minimizing interference within and between paths. We also propose methods to modify the backhaul topology to increase the probability of finding high-throughput paths using our algorithm. Extensive simulations, based on a 3-D model of a section of downtown Atlanta, demonstrate that high-throughput topologies, with minimal inter-path and intra-path interference, are feasible in most cases. The analyses also yield some insights on the mmWave backhaul network design problem.more » « less
-
Although the millimeter wave (mmWave) band has great potential to address ever-increasing demands for wireless bandwidth, its intrinsically unique propagation characteristics call for different scheduling strategies in order to minimize performance drops caused by blockages. A promising approach to mitigate the blockage problem is proactive scheduling, which uses blockage predictions to schedule users when they are experiencing good channel conditions. In this paper, we formulate an optimal scheduling problem with fairness constraints that allows us to find a schedule with maximum aggregate rate that achieves approximately the same fairness as the classic proportional fair scheduler. The results show that, for the problem settings studied, up to around 30% increase in aggregate rate compared to classic proportional fair scheduling (PFS) is possible with no decrease in fairness when blockages can be accurately predicted 0.5 seconds in advance. Furthermore, aggregate rate could be doubled compared to PFS if blockages can be accurately predicted 5 seconds in advance. While these results demonstrate the very promising potential of proactive scheduling, we also discuss several future research directions that must be pursued to effectively realize the approach.more » « less
-
more » « less
5G Millimeter Wave (mmWave) technology holds great promise for Connected Autonomous Vehicles (CAVs) due to its ability to achieve data rates in the Gbps range. However, mmWave suffers from a high beamforming overhead and requirement of line of sight (LOS) to maintain a strong connection. For Vehicle-to-Infrastructure (V2I) scenarios, where CAVs connect to roadside units (RSUs), these drawbacks become apparent. Because vehicles are dynamic, there is a large potential for link blockages. These blockages are detrimental to the connected applications running on the vehicle, such as cooperative perception and remote driver takeover. Existing RSU selection schemes base their decisions on signal strength and vehicle trajectory alone, which is not enough to prevent the blockage of links. Many modern CAVs motion planning algorithms routinely use other vehicle’s near-future path plans, either by explicit communication among vehicles, or by prediction. In this paper, we make use of the knowledge of other vehicle’s near future path plans to further improve the RSU association mechanism for CAVs. We solve the RSU association algorithm by converting it to a shortest path problem with the objective to maximize the total communication bandwidth. We evaluate our approach, titled B-AWARE, in simulation using Simulation of Urban Mobility (SUMO) and Digital twin for self-dRiving Intelligent VEhicles (DRIVE) on 12 highway and city street scenarios with varying traffic density and RSU placements. Simulations show B-AWARE results in a 1.05× improvement of the potential datarate in the average case and 1.28× in the best case vs. the state-of-the-art. But more impressively, B-AWARE reduces the time spent with no connection by 42% in the average case and 60% in the best case as compared to the state-of-the-art methods. This is a result of B-AWARE reducing nearly 100% of blockage occurrences.
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/https://doi.org/10.1109/ICC.2019.8761486
