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

Recently, IEEE drew up a new task group named TGax to draft out the standard IEEE 802.11ax for next generation WLANs. However, the average throughput is very low due to the current medium access control (MAC) protocol. A promising solution for this problem is to draw Orthogonal Frequency Division Multiple Access (OFDMA) into IEEE 802.11ax to enable multiuser access. The key challenges of adopting OFDMA are synchronization and overhead reduction. In this paper, we propose an OFDMA based Multiple Access for IEEE 802.11ax (OMAX) protocol to solve both two challenges above. The whole channel physical channel sensing and fast backoff are adopted to ensure synchronization, while enhanced RTS/CTS mechanism and new frame structure are designed to reduce overhead. Moreover, the mathematic model of OMAX is formulated, and the performance of OMAX is analyzed. The analysis and simulation result indicate that the proposed OMAX protocol increases the throughput to 160%.

An OFDMA based concurrent multiuser MAC for upcoming IEEE 802.11ax

With the ever-increasing demand for wireless traffic and quality of services (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, IEEE 802.11 will release the upcoming next generation WLANs standard amendment: IEEE 802.11ax. Thus, this article briefly surveys the key technologies of IEEE 802.11ax. Furthermore, performance requirements of IEEE 802.11ax are evaluated via a 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) of IEEE 802.11ax by four times compared to the legacy IEEE 802.11. To the best of our knowledge, this article is 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 WLANs Standard - IEEE 802.11ax

The physical (PHY) layer peak rate of the wireless local area network (WLAN) has been almost exponentially improved over the past 15 years since 1999. However, it is proved that the throughput is very low comparing to the PHY peak rate, and the media access control (MAC) efficiency is very low in the current WLANs specification, especially in dense deployment scenarios. Therefore, to achieve high MAC efficiency the IEEE Standards Association Standards Board (IEEE-SA) approves IEEE 802.11ax in March 2014, to draw up a brand new amendment for the next generation WLAN. One of the promising technologies to improve MAC efficiency is Orthogonal Frequency Division Multiple Access (OFDMA). In this paper, we firstly investigate the existing OFDMA based MAC protocols in the literature. Then, a framework of OFDMA based MAC protocol for the next generation WLAN is proposed. Finally, all of the existing OFDMA based MAC protocols listed in this paper are compared according to the proposed design issues. To the best of our knowledge this paper is the first survey focusing on OFDMA based MAC protocols for the next generation WLAN.

Survey on OFDMA based MAC protocols for the next generation WLAN

Wireless sensor networks (WSNs) are widely used for various applications. In some applications, it is very likely that the number of sensors is limited, the initial deployment is random, and deployment “holes” (i.e., subareas where there is no sensor) may exist. Therefore, a major challenge in WSNs is to improve the network coverage. A viable solution is to enhance some sensors with mobility capability so that they can move inside the WSNs after the initial deployment, which is referred to as mobile sensor redeployment. In this paper, we target at a generic framework for the optimal mobile sensor redeployment problem in WSNs. In particular, in this paper, the area of a WSN is partitioned into a number of grids, and the gap of each grid is defined as the difference of the number of sensors in the grid from the desired number of sensors. Then, the mobile sensor redeployment problem is formulated as an optimization problem with three optimization requirements: to minimize the sum of gaps of all grids, to minimize the Lp-norm (1 ≤ p ≤ ∞) of the gap vector (where Lp-norm represents a family of optimization objectives when p takes different values), and to minimize the total movement cost of all mobile sensors. Bipartite matching-based redeployment (BMrD) algorithms are provided to solve the optimization problems with different values of p. In this paper, the framework is generic for mobile sensor redeployment because 1) the mobility capabilities of the sensors, the initial sensor distribution, the movement cost measures, and the sensor types are all arbitrary; 2) the coverage requirements in different grids can be heterogeneous; and 3) the BMrD algorithms are generic for different p values. The effectiveness of the BMrD algorithms is validated through theoretical proofs and extensive simulations.

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A Generic Framework for Optimal Mobile Sensor Redeployment

Proliferating networking demands require the wireless local area networks (WLANs) to keep evolving. In May 2019, the IEEE 802 standards committee formally established the working group of the next generation WLAN: IEEE 802.11be. To satisfy the ultra-high definition video traffic and achieve the objective of extremely high throughput (EHT), multi-band operation (MB-Opr) is considered as one important technology. However, after deep analysis, simply adapting MB-Opr is not enough for the extremely high throughput requirements of IEEE 802.11be. This paper analyzes the possible schemes of AP coordination and full-duplex enabled MB-Opr, where AP coordination is also one key technology introduced by IEEE 802.11be. After that, we propose a MAC framework for AP coordination and full-duplex enabled MB-Opr that fits for all types of device capabilities. This framework is general enough that it has high scalability and good backward and forward compatibility. The simulation results confirm the performance advantages of proposed MAC framework and show that multi-band aggregation (MBA) and multi-band channel bonding (MBCB) outperform IEEE 802.11ax in throughput by 200% and 80.7%, respectively.

Zhongjiang Yan

Papers

An OFDMA based concurrent multiuser MAC for upcoming IEEE 802.11ax

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

Survey on OFDMA based MAC protocols for the next generation WLAN

A Generic Framework for Optimal Mobile Sensor Redeployment

AP Coordination and Full-duplex enabled Multi-band Operation for the Next Generation WLAN: IEEE 802.11be (EHT)