mmWave Access Points Research Articles

MmWave Networking and Edge Computing for Scalable 360° Video Multi-User Virtual Reality.

We investigate a novel multi-user mobile Virtual Reality (VR) arcade system for streaming scalable 8K 360° video with low interactive latency, while providing high remote scene immersion fidelity and application reliability. This is achieved through the integration of embedded multi-layer 360° tiling, edge computing, and wireless multi-connectivity that comprises sub-6 GHz and mmWave (millimeter wave) links. The sub-6 GHz band is used for broadcast of the base layer of the entire 360° panorama to all users, while the directed mmWave links are used for high-rate transmission of VR-enhancement layers that are specific to the viewports of the individual users. The viewport-specific enhancements can comprise compressed and raw 360° tiles, decoded first at the edge server. We aim to maximize the smallest immersion fidelity for the delivered 360 content across all VR users, given rate, latency and computing constraints. We characterize analytically the rate-distortion trade-offs across the spatiotemporal 360° panorama and the computing power required to decompress 360° tiles. The proposed solution consists of geometric programming algorithms and an intermediate step of graph-theoretic VR user to mmWave access point assignment. The results reveal a significant improvement (8 - 10 dB) in delivered VR user immersion fidelity and spatial resolution (8K vs. 4K) compared to a state-of-the-art method based on sub-6 GHz transmission only. We also show that an increasing number of raw 360° tiles are sent, as the mmWave network link data rate or the edge server/user computing power increase. Finally, we demonstrate that in order to hypothetically deliver the same immersion fidelity, the reference method would incur a much higher (2.5-4.5x) system latency.

Adaptive Beamforming and Power Allocation for mmWave Communication in High‐Speed Railway

AbstractMillimeter wave (mmWave)‐based massive multiple‐input multiple‐output (MIMO) beamforming technology is one of the key technologies in the fifth‐generation (5G) network. In this paper, we apply mmWave to high‐speed railway (HSR) communication scenario to meet its increasingly growing demands for tremendous data rate and reliable mobile services. The HSR mmWave communication system uses a control/user (C/U) plane separation structure; that is, control information and user information are transmitted through the high‐frequency micro base station (BS) and the low‐frequency macro BS, respectively. Then, an optimized beam width and power allocation scheme is proposed, which is combined with the mobile relay (MR) technology to utilize the architecture of the large‐scale antenna beamforming. In the proposed scheme, we introduce a power factor related to the change of train speed. According to the power factor, the service beam width is adjusted dynamically and the transmit power of the beams from two simultaneously served mmWave access points (APs) is jointly calculated. Simulation results show that, compared with the traditional uniform beam width scheme, the proposed adaptive beam width and power allocation scheme can maximize the total service volume within the maximum transmit power range.

Resource Allocation for mmWave-NOMA Communication Through Multiple Access Points Considering Human Blockages

In this paper, a new framework for optimizing the resource allocation in a millimeter-wave-non-orthogonal multiple access (mmWave-NOMA) communication for crowded venues is proposed. MmWave communications suffer from severe blockage caused by obstacles such as the human body, especially in a dense region. Thus, a detailed method for modeling the blockage events in the in-venue scenarios is introduced. Also, several mmWave access points are considered in different locations. To maximize the network sum rate, the resource allocation problem is formulated as a mixed-integer non-linear programming (MINLP) problem, which is NP-hard in general. Hence, a three-stage low-complex solution is proposed to solve the problem. At first, a user scheduling algorithm, i.e., modified worst connection swapping (MWCS), is proposed. Secondly, the antenna allocation problem is solved using the simulated annealing algorithm. Afterward, to maximize the network sum rate and guarantee the quality of service constraints, a non-convex power allocation optimization problem is solved by adopting the difference of convex programming approach. The simulation results show that, under the blockage effect, the proposed mmWave-NOMA scheme performs on average 23% better than the conventional mmWave-orthogonal multiple access scheme. Moreover, the proposed solution’s performance is close to the optimal value while reducing complexity by 96%.

AI-empowered millimeter wave communication and networking

Thanks to the abundant and attractive spectrum resource in the millimeter-wave (mmWave) band, mmWave technologies have been widely applied to the fifth-generation (5G) mobile communication system and will continuously evolve towards the future beyond 5G systems as well. However, achieving the pervasive application of mmWave for 5G and beyond still faces many challenges, for example, the severe path-loss and vulnerability in blockage of mmWave propagation may have a great impact on mmWave communication and networking. In addition, the dense deployment of mmWave access points (APs) might be necessary to support a mmWave network with good coverage performance, which however involves very high capital and operation expenditures. Moreover, the highly directional narrow beam transmission may also complicate the mmWave link establishment and maintenance procedure, especially in the mobile scenario. To this end, efficient and cost-effective solutions are urgently called for to address the new challenges in mmWave communication and networking.

Single- and Multiple-Access Point Indoor Localization for Millimeter-Wave Networks

Millimeter-wave (mm-wave) location systems not only provide accurate positioning for location-based services but can also help optimize network operations, for example, through location-driven beam steering and access point association. In this paper, we design and evaluate localization schemes that exploit the characteristics of mm-wave communication systems. We propose two range-free algorithms belonging to the broad classes of triangulation and angle difference of arrival. The schemes work both with multiple anchors and with as few as a single anchor, under the only assumption that the floor plan and the positions of the mm-wave access points are known. Moreover, they are designed to be lightweight so that even computationally-constrained devices can run them. We evaluate our proposed algorithms against two benchmark approaches based on fingerprinting and angles of arrival, respectively. Our results, obtained both by means of simulations and through measurements involving commercial 60-GHz mm-wave devices, show that sub-meter accuracy is achieved in most of the cases, even in the presence of only a single access point. The availability of multiple access points substantially improves the localization accuracy, especially for large indoor spaces.

On the Degree of Multi-Connectivity in 5G Millimeter-Wave Cellular Urban Deployments

Outage event caused by dynamic link blockage at millimeter-wave (mmWave) frequencies is a challenging problem for cell-edge users. To address it, 3GPP is currently working on multi-connectivity mechanisms that allow a user to remain connected to several mmWave access points simultaneously, as well as switch between them in case its active connection drops. However, the actual number of such simultaneous links-named the degree of multi-connectivity-to reach the desired tradeoff between the system design simplicity and the outage probability levels remains an open research question. In this work, we characterize the outage probability and spectral efficiency associated with different degrees of multi-connectivity in a typical 5G urban scenario, where the line-of-sight propagation path can be blocked by buildings as well as humans. These results demonstrate that the degrees of multi-connectivity of up to 4 offer higher relative gains. Our analytical framework can be further employed for the performance analysis of multi-connectivity-capable mmWave systems across their different deployment configurations.

Improving Session Continuity With Bandwidth Reservation in mmWave Communications

Unexpected fluctuations in radio resource demands of active sessions in millimeter-wave (mmWave) systems caused by dynamic blockage of the line-of-sight path may lead to accidental session drops. Existing solutions addressing this problem incorporate multi-connectivity operation that reroutes an ongoing session to another mmWave access point nearby. We introduce and analyze an alternative approach for improving session continuity based on the concept of bandwidth reservation. We develop an analytical model for the mmWave system that employs the proposed technique and quantify its benefits and drawbacks. We show that even a small fraction of reserved bandwidth may significantly improve session continuity.

A Hierarchical SDN Architecture for Ultra-Dense Millimeter-Wave Cellular Networks

To cope with the tremendous growth in mobile data traffic, ultra-dense networks (UDNs) will be deployed in the future cellular network. Meanwhile, the enormous amount of available spectrum in millimeter-wave (mmWave) bands can be also exploited to increase the wireless link capacity. In accordance with these trends, this article introduces a novel hierarchical software-defined networking (SDN) architecture to facilitate the deployment of UDNs with both microwave base stations and mmWave access points. Aimed at reducing the cost of computational complexity and signaling overhead, the novel SDN architecture employs a semi-distributed design approach by configuring two levels of controllers: the centralized superior SDN controller and the localized subordinate SDN controller. Some practical challenges posed by the characteristics of mmWave transmissions, such as high propagation loss, channel blockage, and directional beamforming, are also discussed. To deal with such challenges, we then propose several important network operations for the hierarchical SDN, including dynamic subordinate SDN management, mobility management, and user-centric design. We finally provide simulation results to demonstrate the performance advantages of our proposals.

Maximising the utility of enterprise millimetre-wave networks

Millimetre-wave (mmWave) technology is a promising candidate for meeting the intensifying demand for ultra fast wireless connectivity, especially in high-end enterprise networks. Very narrow beam forming is mandatory to mitigate the severe attenuation specific to the extremely high frequency (EHF) bands exploited. Simultaneously, this greatly reduces interference, but generates problematic communication blockages. As a consequence, client association control and scheduling in scenarios with densely deployed mmWave access points become particularly challenging, while policies designed for traditional wireless networks remain inappropriate. In this paper we formulate and solve these tasks as utility maximisation problems under different traffic regimes, for the first time in the mmWave context. We specify a set of low-complexity algorithms that capture distinctive terminal deafness and user demand constraints, while providing near-optimal client associations and airtime allocations, despite the problems’ inherent NP-completeness. To evaluate our solutions, we develop an NS-3 implementation of the IEEE 802.11ad protocol, which we construct upon preliminary 60GHz channel measurements. Simulation results demonstrate that our schemes provide up to 60% higher throughput as compared to the commonly used signal strength based association policy for mmWave networks, and outperform recently proposed load-balancing oriented solutions, as we accommodate the demand of 33% more clients in both static and mobile scenarios.

Beam Discovery Signal-Based Beam Selection in Millimeter Wave Heterogeneous Networks

Most beam selection algorithms determine the best beam according to the methods of feedback and exhaustive search in a millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) system. However, the exhaustive search and the redundant feedback will result in high computational complexity. This paper proposes a mmWave massive MIMO beam selection algorithm based on the beam discovery signal (BDS), where each beam transmitted by the mmWave access point is identified by a specific BDS, and the best beam for the user equipment is then determined by detecting the BDS. In addition, in mmWave heterogeneous networks with densely deployed small cells, strong interference beams are determined through inter-cell cooperation, and orthogonal codes are allocated to the optimal beams and strong interference beams to reduce beam interference from adjacent cells. Simulation results show that the proposed algorithm can avoid the computational complexity caused by exhaustive search, thus simplifying the beam selection process. Furthermore, the algorithm can effectively suppress inter-cell beam interference in multi-cell scenario, and the sum-rate can be further increased.

On the Temporal Effects of Mobile Blockers in Urban Millimeter-Wave Cellular Scenarios

Millimeter-wave (mmWave) propagation is known to be severely affected by the blockage of the line-of-sight (LoS) path. In contrast to microwave systems, at shorter mmWave wavelengths such blockage can be caused by human bodies, where their mobility within environment makes wireless channel alternate between the blocked and non-blocked LoS states. Following the recent 3GPP requirements on modeling the dynamic blockage as well as the temporal consistency of the channel at mmWave frequencies, in this paper, a new model for predicting the state of a user in the presence of mobile blockers for representative 3GPP scenarios is developed: Urban micro cell street canyon and park/stadium/square. It is demonstrated that the blockage effects produce an alternating renewal process with exponentially distributed non-blocked intervals, and blocked durations that follow the general distribution. The following metrics are derived 1) the mean and the fraction of time spent in blocked/non-blocked state, 2) the residual blocked/non-blocked time, and 3) the time-dependent conditional probability of having blockage/no blockage at time t1 given that there was blockage/no blockage at time t0. The latter is a function of the arrival rate (intensity), width, and height of moving blockers, distance to the mmWave access point (AP), as well as the heights of the AP and the user device. The proposed model can be used for system-level characterization of mmWave cellular communication systems. For example, the optimal height and the maximum coverage radius of the mmWave APs are derived, while satisfying the required mean data rate constraint. The system-level simulations corroborate that the use of the proposed method considerably reduces the modeling complexity.

Cloud Cooperated Heterogeneous Cellular Networks for Delayed Offloading using Millimeter Wave Gates

Abstract Increasing the capacity of wireless cellular network is one of the major challenges for the coming years. A lot of research works have been done to exploit the ultra-wide band of millimeter wave (mmWave) and integrate it into future cellular networks. In this paper, to efficiently utilize the mmWave band while reducing the total deployment cost, we propose to deploy the mmWave access in the form of ultra-high capacity mmWave gates distributed in the coverage area of the macro basestation (Macro BS). Delayed offloading is also proposed to proficiently exploit the gates and relax the demand of deploying a large number of them. Furthermore, a mobility-aware weighted proportional fair (WPF) user scheduling is proposed to maximize the intra-gate offloading efficiency while maintaining the long-term offloading fairness among the users inside the gate. To efficiently link the mmWave gates with the Macro BS in a unified cellular network structure, a cloud cooperated heterogeneous cellular network (CC-HetNet) is proposed. In which, the gates and the Macro BS are linked to the centralized radio access network (C-RAN) via high-speed backhaul links. Using the concept of control/user (C/U) plane splitting, signaling information is sent to the UEs through the wide coverage Macro BS, and most of users’ delayed traffic is offloaded through the ultra-high capacity mmWave gates. An enhanced access network discovery and selection function (eANDSF) based on a network wide proportional fair criterion is proposed to discover and select an optimal mmWave gate to associate a user with delayed traffic. It is interesting to find out that a mmWave gate consisting of only 4 mmWave access points (APs) can offload up to 70 GB of delayed traffic within 25 sec, which reduces the energy consumption of a user equipment (UE) by 99.6 % compared to the case of only using Macro BS without gate offloading. Also, more than a double increase in total gates offloaded bytes is obtained using the proposed eANDSF over using the conventional ANDSF proposed by 3GPP due to the optimality in selecting the associating gate.