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

A rising demand for larger network capacity is leading to the rapid development of the 5th Generation Mobile Communications System (5G). Due to the scarcity of spectrum resources of the conventional licensed band, 3GPP launched the research project of Licensed-Assisted Access using LTE (LAA) in September 2014, aiming to design a single global solution framework and protocol to ensure the efficient operation of LAA on unlicensed band (e.g. 5 GHz spectrum band). However, existing studies indicate that it is difficult to improve the performance of LAA and WiFi at the same time. In this paper, we propose a Power Control based Spacial Reuse scheme (PC-based SR) aiming at increasing the probability of concurrent transmissions in coexisting scenarios of LAA and WiFi. For LAA network, after recognizing existing WiFi signal, it should raise its Energy Detection (ED) threshold and transmit with adjusted power, and vice versa. Our simulation results show that, using the proposed method, the performance of both LAA and WiFi are improved and the fairness to WiFi is enhanced, with respect to throughput and latency.

Power Control Based Spatial Reuse for LAA and WiFi Coexistence

Neighbor node discovery is one of the important steps in a wireless directed ad hoc network. Improving the efficiency of neighbor node discovery can not only reduce the collision during node communication, but also improve the performance of the wireless ad hoc network as a whole. In the Ad-hoc network of directional antennas, by analyzing and summarizing the deficiencies of the neighbor discovery algorithm, this paper proposes a probing and p-probability based two round directional neighbor discovery algorithm (PPTR). The second round adjusts the probability of neighboring neighbor nodes competing for slots based on the number of free slots, successful slots, and collision slots in the first round, thereby reducing the collision of neighboring nodes to reach the maximum number of neighbors discovered within a fixed time. We verified the protocol through network simulation. The simulation results show that the PPTR algorithm and the traditional neighbor discovery algorithm have the same neighbor discovery efficiency when the number of network nodes and the number of time slots are consistent. But The neighbor discovery efficiency increases on average 81.3% when the number of nodes increases to five times the number of timeslots.

A Probing and p-Probability Based Two Round Directional Neighbor Discovery Algorithm

Coordinated multi-points (CoMP) transmission has been widely proved to be effective to combat inter-cell interference in 3GPP LTE-Advanced systems. However, implementation complexity of inter-site CoMP and relatively low capacity gain of intra-site CoMP motivate us propose a beam coordinated multipoints (Beam-CoMP) transmission scheme for 5G millimeter-wave cellular network. Considering the specific inter-beam interference model, we evaluate the performance of intra-site Beam-CoMP, which only involves coordination among the beams in the same sector of the base station. Simulation results demonstrate that the Beam-CoMP scheme can achieve much better capacity than traditional random beamforming Non-CoMP system with relatively low complexity.

Beam coordinated multi-points transmission for 5G millimeter-wave network

With the rapid development of wireless communications, Wireless Local Area Network (WLAN) has entered thousands of households and has become one of the most important ways of carrying data business. In recent years, delay sensitive applications and services such as real-time game and wireless meeting have been increasing sharply. These applications and services require low latency. However, the traditional WLAN can hardly satisfy the needs of this requirement. The next generation WLAN standard: IEEE 802.11be which was established in 2019 regards low latency as one important technical objective. In this paper, we propose a delay sensitive priority adjustment scheme for the next generation WLAN to improve the latency performance of delay sensitive services. In the Media Access Control (MAC) layer, if there is still some time left before deadline, the priority of delay sensitive packets will be normal. Conversely, as the deadline approaches, the priority of delay sensitive packets will be upgraded. The priority related mechanisms in MAC layer include queuing policy, channel access parameters, and Modulation and Coding Scheme (MCS) selection.

A Dynamic Priority Adjustment Scheme for the Next Generation WLAN Supporting Delay Sensitive Services

In recent years, people have put forward higher and higher requirements for high-speed communications within a local area. Millimeter-wave WLAN has attracted much attention from academia and industry by virtue of its ultra-large bandwidth and short-range coverage. Beam training is a key technology of millimeter wave WLAN. The quality of beam training is related to communication performance and even communication. However, as the number of nodes continues to increase, the beam training efficiency of the traditional millimeter wave WLAN is very low, which affects system performance. This paper proposes a beamforming training method based on dynamic time slot adjustment for the next generation millimeter wave WLAN. The beam training slot in the subsequent beacon interval (BI) can be adjusted according to the completion of the beam training in the previous BI, thereby improving the efficiency of beam training. The simulation results prove that the method proposed in this paper can effectively improve the beam training efficiency and has a small impact on the performance of the system.

Zhongjiang Yan

Papers

Power Control Based Spatial Reuse for LAA and WiFi Coexistence

A Probing and p-Probability Based Two Round Directional Neighbor Discovery Algorithm

Beam coordinated multi-points transmission for 5G millimeter-wave network

A Dynamic Priority Adjustment Scheme for the Next Generation WLAN Supporting Delay Sensitive Services

Dynamic Time Slot Adjustment Based Beamform Training for the Next Generation Millimeter Wave WLAN