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.

/pdf/a-tutorial-on-ieee-802-11ax-high-efficiency-wlans-53scy74xu9.pdf

A Tutorial on IEEE 802.11ax High Efficiency WLANs

With the rapid popularization of wireless communication devices, wireless local area network (WLAN) is ubiquitous in daily life. However, the demand for wireless communication services is growing rapidly and brings new challenges to WLAN technology. The problem of performance degradation under dense deployment network scenarios is an important topic in the next generation WLAN (NGW). This paper proposes fractional backoff algorithm, named eat-B, to enhance area throughput. Eat-B introduces fractional backoff and enables the nodes who provide more contributions for the area throughput to finish their backoff process faster. Simulation results indicate that the area throughput of the eat-B algorithm outperforms the binary exponential backoff (BEB) algorithm adopted by the traditional IEEE 802.11, especially under dense deployment scenarios.

Fractional Backoff Algorithm for the Next Generation WLAN

In directional ad hoc networks, the character of directional transmission and directional reception of the links makes it difficult to let one directional link aware of the other concurrent transmission links, so that the collision probability of the concurrent transmission links need to be reduced. In this paper, a pseudo random sequence (PRS) based multi-channel multiple access control (MAC) protocol is proposed to reduce the collision probability of the concurrent transmission links. The proposed PRS MAC protocol is based on the time division multiple access (TDMA) frame structures. After the neighbour discovering sub-frame, the proposed PRS MAC protocol works in the reservation sub-frame, and in each time slot it works in a three-way handshake method to reserve the data slots in the data transmission sub-frame. On one hand, with the introduction of multiple channels, the concurrent transmission links can be distributed to different channels such that the collision probability of each channel can be reduced. On the other hand, with the introduction of the pseudo random sequence, each of the concurrent transmission links may take different PRS such that the collisions of the concurrent transmission links are randomized. Simulation results show that the proposed PRS MAC protocol outperforms the existing DTRA protocol in terms of lower collision probability and higher aggregated throughput.

A Pseudo Random Sequence Based Multichannel MAC Protocol for Directional Ad Hoc Networks

Wireless local area network (WLAN) achieves rapidly development over the last 20 years. WLAN operated on 60GHz has become an increasingly hot topic in wireless networking for both the academia and industry because of large amount of unlicensed unlicensed bandwidth. The next generation mmWave WLAN standard, IEEE 802.11ay, is expected to achieve 20 Gbps data rate. It introduces the channel bonding (CB), MIMO and enhanced beamform training. In this paper, we model IEEE 802.11ay with channel bonding technology and theoretically analyze the system throughput and delay. After that, we build the mmWave WLAN simulation platform. To verify the validity and reliability of the simulation platform, we compare the simulation results with the practical experimental results. The results show that the simulation results highly match the practical experimental results, while the theoretical analysis of CB also matches the simulation results quite well.

System Analysis and Performance Evaluation for the Next Generation mmWave WLAN: IEEE 802.11ay

Several typical synchronous directional media access control (DMAC) protocols are proposed for directional ad hoc networks (DAHN), e.g., directional transmission and reception algorithms (DTRA) [4]. One of the slot allocation problems of these DMACs is the unfairness between links, or link starvation, which is caused by the distributed feature of DAHN. That is the earlier discovered link reserve much more slots which results in the later discovered links have few slots to reserve. To address the unfairness problem, in this paper a classified slot re-allocation algorithm (CSRA) is proposed. The basic idea is to classify the data slots into four types according to their status in the data transmission phase, and then when the unfairness problem is found different types of slots are re-allocated. The re-allocation order of these four types of these slots are free slots, sending slots, neighbour transmitting slots, and receiving slot. Extensive simulation are carried out to evaluate the performance of the proposed CSRA. The simulation results show that the Jain’s fairness index is improved with little loss of the network throughput.

A Classified Slot Re-allocation Algorithm for Synchronous Directional Ad Hoc Networks

In wireless networks, the capability of sensing the received power variation on wireless channel is named as channel sensing capability (CSC). However, as wireless networks become increasingly dense, it decreases the reliability of multiuser transmission if only CSC is simply used for indicating channel state. Thus, in this paper, a novel conception named as neighbor channel sensing capability (NCSC) is proposed to describe the capability of nodes for sensing the channel state of their neighbor nodes. We prove that the consistency of NCSC, defined as the variable of the difference of the received power of two neighboring nodes, obeys a Gaussian distribution when the location of all transmitting nodes obeys a homogeneous Poisson point process. Moreover, we derive the mean and variance of the consistency of NCSC, and give the expression of NCSC to accurately describe the capability of sensing the channel state of neighbor nodes. The simulation results show that NCSC can efficiently indicate and validate our analysis model and derivation.

Zhongjiang Yan

Papers

Fractional Backoff Algorithm for the Next Generation WLAN

A Pseudo Random Sequence Based Multichannel MAC Protocol for Directional Ad Hoc Networks

System Analysis and Performance Evaluation for the Next Generation mmWave WLAN: IEEE 802.11ay

A Classified Slot Re-allocation Algorithm for Synchronous Directional Ad Hoc Networks

The neighbor channel sensing capability for wireless networks