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

In order to solve the problem of identification collision in multi-reader Radio Frequency Identification (RFID) systems, this paper proposes a multi-channel anti-collision algorithm based on grouping strategy named McAnCo. In this algorithm, the interference types among readers are classified and modeled, and then the vertex coloring algorithm in graph theory is used to group the readers with mutual interference. The readers in the same group can work at the same frequency and time slot, while the readers in different groups in the same set can work at the same time slot in different frequency, so that the maximum number of readers can work simultaneously without interference. Simulation results show that, compared with distributed color selection (DCS) algorithm, hierarchical Q-learning (HiQ) algorithm and neighborhood friendly anti-collision scheme (NFRA) algorithm, the proposed algorithm effectively prevent reader collision and raise the identification efficiency of the system.

A Multi-channel Anti-collision Algorithm in Multi-reader RFID Networks

Wireless local area network (WLAN) technology has become mature in the past few decades. However, with the development of social application forms, the situation of high-density deployment of cells has become more frequent in recent years, so the next-generation WLANs face the unprecedented challenge of quality of service (QoS) and quality of experience (QoE) of high-density cell users. In response to this challenge, The Overlapping Basic Service Set Power Detection (OBSS PD) mechanism and Spatial Reuse Parameter (SRP) mechanism are proposed in IEEE 802.11ax (Institute of Electrical and Electronics Engineers) to improve spatial multiplexing capability and certain throughput capabilities. But both of them possess inherent drawbacks. Based on this, this paper proposes an enhanced spatial reuse mechanism, named ESR (Enhanced Spatial Reuse), by limiting the value of the CCA threshold in the SRP mechanism to improve the quality of concurrent links, which further improves the average throughput. Compared to traditional SRP, simulation results show that ESR can increase throughput by 10% and reduce packet loss by 10%.

ESR: Enhanced Spatial Reuse Mechanism for the Next Generation WLAN - IEEE 802.11ax

Real-time applications (RTA) develop rapidly these days. Latency sensitive traffic guarantee becomes increasingly important and challenging in wireless local area network (WLAN). In order to tackle the problem, this paper proposes a latency oriented random access scheme, which is compatible with IEEE 802.11 standards, based on orthogonal frequency division multiple access (OFDMA) in the next generation WLAN: IEEE 802.11be. AP utilizes trigger frame (TF) based OFDMA random access and reserves several resource units (RUs) for latency sensitive traffic only. According to the collision status in the past TF as well as the traffic arrival features, we theoretically analyze the estimated number of STAs who will have latency sensitive data to send during the next TF interaction. Thus, AP can allocate appropriate RUs for latency sensitive STAs dynamically. The simulation results show that the proposed dynamic RU adjusting algorithm outperforms the other schemes in both throughput and delay. The throughput utility of the proposed algorithm is 19.69% higher than that of IEEE 802.11ax. And the delay utility is 21.39% lower than that of IEEE 802.11ax, which validates the effectiveness of the proposed algorithm.

Latency Oriented OFDMA Random Access Scheme for the Next Generation WLAN: IEEE 802.11be

Wireless millimeter wave (mmWave) communication technology is promising to meet the low size, low weight and high data rate requirements in body area, Internet of Things (IoTs) networks. To combat the high path loss of mmWave channel, large scale array is employed to form several directional and narrow shape beams to serve multiple users. However, although the beams are narrow overlapping area may exist between multiple directional beams. This paper studies the resource allocation problem for a multi-beams communication system, which is proved to be NP-hard. This paper proposes a group based multi-beams subchannel assignment algorithm based on orthogonal frequency division multiple access (OFDMA). The beam spatial reuse gain is exploited for the groups of nodes deployed in difference coverage area of these beams, named as non-overlapped groups. And the multiple user diversity gain is exploited for the groups of nodes covered simultaneously by several beams, named as overlapped groups. Simulations results show that the throughput of the proposed algorithm outperforms the heuristic algorithm which only exploits the beam spatial reuse gain or the multiple user diversity gain.

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Group Based Multi-beams Subchannel Assignment for mmWave Internet of Things Networks

The next generation wireless local area network (WLAN) needs to significantly improve the area throughput in high dense scenario. Orthogonal Frequency Division Multiple Access (OFDMA), considered as the key technology of next generation WLAN, has been adopted by next generation WLAN communication standard. However, the existing studies on the OFDMA protocol have the interference extensions problem, i.e. multiple users are located in the dispersive area, and then the geographical interference area is enlarged. In this paper, a spatial clustering group based OFDMA multiple access protocol (SCG-OFDMA) is proposed. SCG-OFDMA enables the users in close area to form spatial clustering groups dynamically, then the users in the spatial clustering group access channel and transmit data by OFDMA. It reduces the geographical interference area, and enhances the area throughput. The theoretical analysis of SCG-OFDMA is also carried out. The simulation results of SCG-OFDMA are in agreement with the theoretical analysis. Simulation results show that the area throughput of SCG-OFDMA is higher than existing OFDMA protocol and distributing coordination function by 15.98% and 31.26% respectively. It provides a reference to design media access control protocol of the next generation WLAN.

https://www.jnwpu.org/articles/jnwpu/pdf/2018/05/jnwpu2018365p897.pdf

Zhongjiang Yan

Papers

A Multi-channel Anti-collision Algorithm in Multi-reader RFID Networks

ESR: Enhanced Spatial Reuse Mechanism for the Next Generation WLAN - IEEE 802.11ax

Latency Oriented OFDMA Random Access Scheme for the Next Generation WLAN: IEEE 802.11be

Group Based Multi-beams Subchannel Assignment for mmWave Internet of Things Networks

Spatial Clustering Group Based OFDMA Access Protocol for the Next Generation WLAN