Probability and Measure

Millimeter wave (mmWave) communications have recently attracted large research interest, since the huge available bandwidth can potentially lead to the rates of multiple gigabit per second per user Though mmWave can be readily used in stationary scenarios, such as indoor hotspots or backhaul, it is challenging to use mmWave in mobile networks, where the transmitting/receiving nodes may be moving, channels may have a complicated structure, and the coordination among multiple nodes is difficult To fully exploit the high potential rates of mmWave in mobile networks, lots of technical problems must be addressed This paper presents a comprehensive survey of mmWave communications for future mobile networks (5G and beyond) We first summarize the recent channel measurement campaigns and modeling results Then, we discuss in detail recent progresses in multiple input multiple output transceiver design for mmWave communications After that, we provide an overview of the solution for multiple access and backhauling, followed by the analysis of coverage and connectivity Finally, the progresses in the standardization and deployment of mmWave for mobile networks are discussed

Millimeter Wave Communications for Future Mobile Networks

Diverse proprietary network appliances increase both the capital and operational expense of service providers, meanwhile causing problems of network ossification. Network function virtualization (NFV) is proposed to address these issues by implementing network functions as pure software on commodity and general hardware. NFV allows flexible provisioning, deployment, and centralized management of virtual network functions. Integrated with SDN, the software-defined NFV architecture further offers agile traffic steering and joint optimization of network functions and resources. This architecture benefits a wide range of applications (e.g., service chaining) and is becoming the dominant form of NFV. In this survey, we present a thorough investigation of the development of NFV under the software-defined NFV architecture, with an emphasis on service chaining as its application. We first introduce the software-defined NFV architecture as the state of the art of NFV and present relationships between NFV and SDN. Then, we provide a historic view of the involvement from middlebox to NFV. Finally, we introduce significant challenges and relevant solutions of NFV, and discuss its future research directions by different application domains.

Software-Defined Network Function Virtualization: A Survey

The fifth generation (5G) mobile communication systems will be in use around 2020. The aim of 5G systems is to provide anywhere and anytime connectivity for anyone and anything. Several new technologies are being researched for 5G systems, such as massive multiple-input multiple-output communications, vehicle-to-vehicle communications, high-speed train communications, and millimeter wave communications. Each of these technologies introduces new propagation properties and sets specific requirements on 5G channel modeling. Considering the fact that channel models are indispensable for system design and performance evaluation, accurate and efficient channel models covering various 5G technologies and scenarios are urgently needed. This paper first summarizes the requirements of the 5G channel modeling, and then provides an extensive review of the recent channel measurements and models. Finally, future research directions for channel measurements and modeling are provided.

A Survey of 5G Channel Measurements and Models

While celebrating the 21st year since the very first IEEE 802.11 “legacy” 2 Mbit/s wireless local area network standard, the latest Wi-Fi newborn is today reaching the finish line, topping the remarkable speed of 10 Gbit/s. IEEE 802.11ax was launched in May 2014 with the goal of enhancing throughput-per-area in high-density scenarios. The first 802.11ax draft versions, namely, D1.0 and D2.0, were released at the end of 2016 and 2017. Focusing on a more mature version D3.0, in this tutorial paper, we help the reader to smoothly enter into the several major 802.11ax breakthroughs, including a brand new orthogonal frequency-division multiple access-based random access approach as well as novel spatial frequency reuse techniques. In addition, this tutorial will highlight selected significant improvements (including physical layer enhancements, multi-user multiple input multiple output extensions, power saving advances, and so on) which make this standard a very significant step forward with respect to its predecessor 802.11ac.

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A Tutorial on IEEE 802.11ax High Efficiency WLANs

Utility maximization of capacity entropy for multi-user access for the next generation WLANs

With the ever-increasing demand for wireless traffic and quality of serives (QoS), wireless local area networks (WLANs) have developed into one of the most dominant wireless networks that fully influence human life. As the most widely used WLANs standard, Institute of Electrical and Electronics Engineers (IEEE) 802.11 will release the upcoming next generation WLANs standard amendment: IEEE 802.11ax. This article comprehensively surveys and analyzes the application scenarios, technical requirements, standardization process, key technologies, and performance evaluations of IEEE 802.11ax. Starting from the technical objectives and requirements of IEEE 802.11ax, this article pays special attention to high-dense deployment scenarios. After that, the key technologies of IEEE 802.11ax, including the physical layer (PHY) enhancements, multi-user (MU) medium access control (MU-MAC), spatial reuse (SR), and power efficiency are discussed in detail, covering both standardization technologies as well as the latest academic studies. Furthermore, performance requirements of IEEE 802.11ax are evaluated via a newly proposed systems and link-level integrated simulation platform (SLISP). Simulations results confirm that IEEE 802.11ax significantly improves the user experience in high-density deployment, while successfully achieves the average per user throughput requirement in project authorization request (PAR) by four times compared to the legacy IEEE 802.11. Finally, potential advancement beyond IEEE 802.11ax are discussed to complete this holistic study on the latest IEEE 802.11ax. To the best of our knowledge, this article is the first study to directly investigate and analyze the latest stable version of IEEE 802.11ax, and the first work to thoroughly and deeply evaluate the compliance of the performance requirements of IEEE 802.11ax.

Survey and Performance Evaluation of the Upcoming Next Generation WLAN Standard - IEEE 802.11ax

In this paper, a grouping-based uplink orthogonal frequency division multiple access (OFDMA) random access method is studied which can improve users’ satisfaction in the next generation wireless local area networks (WLANs). The next generation WLANs standard, IEEE 802.11ax introduces a random access mechanism, uplink OFDMA random access (UORA), to allow users to access channel randomly. Although UORA has the advantages of low signaling overhead, no need to report uplink transmission requirements, it does not have any characteristics to improve users’ satisfaction. Because the AP can’t allocate resources to users adopting UORA, some users’ quality of experience (QoE) will decline greatly. In this paper, a grouping-based UORA (G-UORA) method is proposed. The AP determines the number of groups, and then clusters users to different groups according to their utility. Then, the AP assigns resources to these groups to maximize the total utility of all users. We present a theoretical utility prediction model of G-UORA and propose the corresponding resource allocation algorithm based on utility. According to simulation results, the algorithm achieves better users’ satisfaction and fairness than the traditional UORA mechanism in IEEE 802.11ax and the user utility gain is 1.6 times. Therefore, the proposed method has greater practical significance.

Utility optimization of grouping-based uplink OFDMA random access for the next generation WLANs

In this paper, the timeslot based traffic scheduling problem is considered with the objectives to fairly and energy efficiently serve the vehicles. The contact durations between the vehicles and the RSU are slotted into timeslots, during each of which one unit of the traffic can be transmitted from the RSU to one vehicle, and then one unit of vehicle's requirement can be satisfied. The downlink traffic scheduling cost is defined as the transmission energy cost to deliver the traffic. The fairness of the traffic scheduling strategy is evaluated by the Jain's fairness index of the unsatisfied vehicle requirements. The proposed problem is formulated as a three-step optimization problem. To address the difficulty of the three-step optimization problem, a flow network based algorithm is proposed. Both the offline and the online traffic schedule strategies are derived. Simulation results show that the derived offline traffic scheduling strategy outperforms the original energy optimal traffic scheduling strategy in terms of fairness, while the transmitted traffic and the transmission energy cost remains almost the same. The derived online traffic scheduling strategy outperforms the existing GMCF algorithms in terms of fairness, at the expense of larger transmission energy, and with the same total transmission traffic.

Fair downlink traffic scheduling for energy sustainable vehicular roadside infrastructure

With the increasing of smart devices such as mobile phones and tablets, the scenario of multiple video users watching video streaming simultaneously in one wireless local area network (WLAN) becomes more and more popular. However, the quality of experience (QoE) and the fairness among multiple users are seriously impacted by the limited bandwidth and shared resources of WLAN. In this paper, we propose a novel bi-level resource allocation algorithm. To maximize the total throughput of the network, the WLAN is firstly tuned to the optimal operation point. Then the wireless resource is carefully allocated at the first level, i.e., between AP and uplink background traffic users, and the second level, i.e., among downlink video users. The simulation results show that the proposed algorithm can guarantee the QoE and the fairness for all the video users, and there is little impact on the average throughput of the background traffic users.

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Zhongjiang Yan

Papers

Utility maximization of capacity entropy for multi-user access for the next generation WLANs

Survey and Performance Evaluation of the Upcoming Next Generation WLAN Standard - IEEE 802.11ax

Utility optimization of grouping-based uplink OFDMA random access for the next generation WLANs

Fair downlink traffic scheduling for energy sustainable vehicular roadside infrastructure

A QoE aware fairness bi-level resource allocation algorithm for multiple video streaming in WLAN