60 GHz MAC Standardization: Progress and Way Forward

Communication at mmWave frequencies has been the focus in the recent years. In this paper, we discuss standardization efforts in 60 GHz short range communication and the progress therein. We compare the available standards in terms of network architecture, medium access control mechanisms, physical layer techniques and several other features. Comparative analysis indicates that IEEE 802.11ad is likely to lead the short-range indoor communication at 60 GHz. We bring to the fore resolved and unresolved issues pertaining to robust WLAN connectivity at 60 GHz. Further, we discuss the role of mmWave bands in 5G communication scenarios and highlight the further efforts required in terms of research and standardization

Study on QoS support in 802.11e-based multi-hop vehicular wireless ad hoc networks

Multimedia communications over vehicular ad hoc networks (VANET) will play an important role in the future intelligent transport system (ITS). QoS support for VANET therefore becomes an essential problem. In this paper, we first study the QoS performance in multi-hop VANET by using the standard IEEE 802.11e EDCA MAC and our proposed triple-constraint QoS routing protocol, Delay-Reliability-Hop (DeReHQ). In particular, we evaluate the DeReHQ protocol together with EDCA in highway and urban areas. Simulation results show that end-to-end delay performance can sometimes be achieved when both 802.11e EDCA and DeReHQ extended AODV are used. However, further studies on cross-layer optimization for QoS support in multi-hop environment are required

Improving multiple broadcasting of multimedia traffic in wireless ad-hoc networks

The increasing use of multimedia streaming applications in addition with advent of internet television and radio, demands from today's wireless networks to handle with reliability multiple broadcasting and multicasting sources. However, the way that 802.11 standard, which is the primary technology in wireless networking, handle this type of traffic raises a series of problems mainly related to the lack of an effective feedback mechanism. This lack in turn, limits the capability of random backoff process to eliminate collisions and reduce reliability and fairness. This inherited drawback of the standard is affecting the way broadcast and multicast traffic is transmitted as well as the overall performance of the network. In this paper initially we are highlighting the drawback of the IEEE 802.11 MAC algorithm in handling multiple stations “media type” data broadcasting in an ad-hoc wireless network. Then, we propose two different approaches in alleviating these problems. The first approach is the simple linear increase of the contention window (CW) while the second propose a linear increase of the CW implementing an exclusive backoff number allocation (EBNA) algorithm. In addition we are modifying the 802.11 medium access control (MAC) algorithm to use the clear to send to self (CTS-to-Self) protection mechanism prior to every transmission. Both the above techniques are simulated and compared with the classic 802.11 MAC. The results show that the overall performance of the network can be improved using these alternative MAC methods

Efficient Resource Management Mechanism for 802.16 Wireless Networks Based on Weighted Fair Queuing

Wireless Networking continues on its path of being one of the most commonly used means of communication. The evolution of this technology has taken place through the design of various protocols. Some common wireless protocols are the WLAN, 802.16 or WiMAX, and the emerging 802.20, which specializes in high speed vehicular networks, taking the concept from 802.16 to higher levels of performance. As with any large network, congestion becomes an important issue. Congestion gains importance as more hosts join a wireless network. In most cases, congestion is caused by the lack of an efficient mechanism to deal with exponential increases in host devices. This can effectively lead to very huge bottlenecks in the network causing slow sluggish performance, which may eventually reduce the speed of the network. With continuous advancement being the trend in this technology, the proposal of an efficient scheme for wireless resource allocation is an important solution to the problem of congestion. The primary area of focus will be the emerging standard for wireless networks, the 802.16 or “WiMAX”. This project, attempts to propose a mechanism for an effective resource management mechanism between subscriber stations and the corresponding base station

Detecting Non-Line of Sight to Prevent Accidents in Vehicular Ad hoc Networks

There are still many challenges in the field of VANETs that encouraged researchers to conduct further investigation in this field to meet these challenges. The issue pertaining to routing protocols such as delivering the warning messages to the vehicles facing Non-Line of Sight (NLOS) situations without causing the storm problem and channel contention, is regarded as a serious dilemma which is required to be tackled in VANET, especially in congested environments. This requires the designing of an efficient mechanism of routing protocol that can broadcast the warning messages from the emergency vehicles to the vehicles under NLOS, reducing the overhead and increasing the packet delivery ratio with a reduced time delay and channel utilisation. The main aim of this work is to develop the novel routing protocol for a high-density environment in VANET through utilisation of its high mobility features, aid of the sensors such as Global Positioning System (GPS) and Navigation System (NS). In this work, the cooperative approach has been used to develop the routing protocol called the Co-operative Volunteer Protocol (CVP), which uses volunteer vehicles to disseminate the warning message from the source to the target vehicle under NLOS issue; this also increases the packet delivery ratio, detection of NLOS and resolution of NLOS by delivering the warning message successfully to the vehicle under NLOS, thereby causing a direct impact on the reduction of collisions between vehicles in normal mode and emergency mode on the road near intersections or on highways. The cooperative approach adopted for warning message dissemination reduced the rebroadcast rate of messages, thereby decreasing significantly the storm issue and the channel contention. A novel architecture has been developed by utilising the concept of a Context-Aware System (CAS), which clarifies the OBU components and their interaction with each other in order to collect data and take the decisions based on the sensed circumstances. The proposed architecture has been divided into three main phases: sensing, processing and acting. The results obtained from the validation of the proposed CVP protocol using the simulator EstiNet under specific conditions and parameters showed that performance of the proposed protocol is better than that of the GRANT protocol with regard to several metrics such as packet delivery ratio, neighbourhood awareness, channel utilisation, overhead and latency. It is also successfully shown that the proposed CVP could detect the NLOS situation and solves it effectively and efficiently for both the intersection scenario in urban areas and the highway scenario

Backoff as Performance improvements Algorithms - A Comprehenssive Review

As a significant part of the Media Access Control protocol, the backoff algorithm purpose is to minimize number of collisions if not totally avoid any collision in Mobile Ad Hoc Networks, in the case of contention between nodes to access a channel. Researchers have proposed many algorithms for backoff to enhance the network performance and improve it. This paper aims at exploring the main and most studied backoff algorithms and how do these algorithms lead to an enhancement of the MANETs performance. This paper also compares between the algorithms proposed in the literature and evaluates to what extent they have affected the performance and enhance it

Polling-Based Downlink Communication Protocol for LoRaWAN using Traffic Indication

학위논문 (석사)-- 서울대학교 대학원 : 공과대학 컴퓨터공학부, 2019. 2. 김종권.LPWAN (Low Power Wide Area Network) technologies such as LoRa and SigFox are emerging as a technology of choice for the Internet of Things (IoT) applications where tens of thousands of untethered devices are deployed over a wide area. In such operating environments, energy conservation is one of the most crucial concerns and network protocols adopt various power saving schemes to lengthen device lifetimes. For example, to avoid idle listening, LoRaWAN restricts downlink communications. However, the confined design philosophy impedes the deployment of IoT applications that require asynchronous downlink communications. In this thesis, we design and implement an energy efficient downlink communication mechanism, named TRILO, for LoRaWAN. We aim to make TRILO be energy efficient while obeying an unavoidable trade-off that balances between latency and energy consumption. TRILO adopts a beacon mechanism that periodically alerts end-devices which have pending downlink frames. We implement the proposed protocol on top of commercially available LoRaWAN components and confirm that the protocol operates properly in real-world experiments. Experimental results show that TRILO successfully transmits downlink frames without losses while uplink traffic suffers from a slight increase in latency because uplink transmissions should halt during beacons and downlink transmissions. Computer simulation results also show that the proposed scheme is more energy efficient than the legacy LoRaWAN downlink protocol.전력 공급이 제한적인 수 만개의 디바이스들을 이용하여 넓은 지역을 바탕으로 운영되는 사물인터넷 시스템을 구축하는 데에 있어서 LoRa, SigFox와 같은 저전력 광역 네트워크 기술(LPWA)이 주목받고 있다. 이러한 시스템 환경에서 에너지 절약은 중요한 관심사 중 하나이며 네트워크 프로토콜들은 다양한 절전 방식을 채택하여 디바이스의 수명을 보장하려 하고 있다. 예를 들어, 불필요한 대기 청취로 인한 에너지 손실을 방지하기 위해서 LoRaWAN은 다운링크 통신을 제한하고 있는데, 이러한 설계 철학은 비동기적인 다운링크 통신을 필요로 하는 IoT 애플리케이션의 요구 사항을 충족시키지 못하는 문제점을 가지고 있다. 따라서 본 논문에서는 LoRaWAN에서 다운링크를 효과적으로 컨트롤할 수 있도록 TRILO라는 에너지 효율적인 다운링크 통신 메커니즘을 설계하고 구현하였다. TRILO는 다운링크 프레임이 팬딩되어 있는 엔드 디바이스들의 리스트 정보를 주기적으로 네트워크에 알리는 비콘 메커니즘을 채택하였고, 서버와 디바이스들이 각각 정해진 순서에 따라 다운링크 전송 및 수신을 스케줄링하도록 하였다. 설계한 프로토콜이 제대로 동작하는지 검증하기 위해서 기존 LoRaWAN의 구성 요소 위에 제안된 프로토콜을 구현한 후 실제 테스트 베드를 구축하여서 실험을 진행하였다. 실험 결과에 따르면 TRILO는 기존 프로토콜의 업링크 통신 성능을 저해하지 않으면서도 추가적인 다운링크 프레임을 손실 없이 성공적으로 전송 및 수신하였고, 컴퓨터 시뮬레이션 결과 또한 제안된 기법이 기존의 LoRaWAN 다운링크 프로토콜보다 더 에너지 효율적으로 동작하는 것을 보여주었다.ABSTRACT ........................................................................................................... ⅰ CONTENTS ........................................................................................................... ⅲ LIST OF FIGURES ............................................................................................ ⅳ LIST OF TABLES .............................................................................................. ⅵ CHAPTER Ⅰ: Introduction ................................................................................ 1 CHAPTER Ⅱ: Related Work ............................................................................. 8 CHAPTER Ⅲ: A Primer on LoRa and LoRaWAN .................................. 11 CHAPTER Ⅳ: Downlink Communications Scheme .................................. 17 4.1 Comparison of Two Polling Schemes ..................................... 19 4.2 Proposed Downlink Communications Scheme ....................... 26 CHAPTER Ⅴ: Implementation ........................................................................ 28 CHAPTER Ⅵ: Evaluation ................................................................................. 31 6.1 Experimental Results .................................................................... 32 6.2 Simulation Results ......................................................................... 37 CHAPTER Ⅶ: Discussion ................................................................................. 42 CHAPTER Ⅷ: Conclusion ................................................................................. 45 BIBLIOGRAPHY ................................................................................................... 47 초록 ........................................................................................................................... 51Maste

Adoption of vehicular ad hoc networking protocols by networked robots

This paper focuses on the utilization of wireless networking in the robotics domain. Many researchers have already equipped their robots with wireless communication capabilities, stimulated by the observation that multi-robot systems tend to have several advantages over their single-robot counterparts. Typically, this integration of wireless communication is tackled in a quite pragmatic manner, only a few authors presented novel Robotic Ad Hoc Network (RANET) protocols that were designed specifically with robotic use cases in mind. This is in sharp contrast with the domain of vehicular ad hoc networks (VANET). This observation is the starting point of this paper. If the results of previous efforts focusing on VANET protocols could be reused in the RANET domain, this could lead to rapid progress in the field of networked robots. To investigate this possibility, this paper provides a thorough overview of the related work in the domain of robotic and vehicular ad hoc networks. Based on this information, an exhaustive list of requirements is defined for both types. It is concluded that the most significant difference lies in the fact that VANET protocols are oriented towards low throughput messaging, while RANET protocols have to support high throughput media streaming as well. Although not always with equal importance, all other defined requirements are valid for both protocols. This leads to the conclusion that cross-fertilization between them is an appealing approach for future RANET research. To support such developments, this paper concludes with the definition of an appropriate working plan

A Bandwidth-Efficient Dissemination Scheme of Non-Safety Information in Urban VANETs

The recent release of standards for vehicular communications will hasten the development of smart cities in the following years. Many applications for vehicular networks, such as blocked road warnings or advertising, will require multi-hop dissemination of information to all vehicles in a region of interest. However, these networks present special features and difficulties that may require special measures. The dissemination of information may cause broadcast storms. Urban scenarios are especially sensitive to broadcast storms because of the high density of vehicles in downtown areas. They also present numerous crossroads and signal blocking due to buildings, which make dissemination more difficult than in open, almost straight interurban roadways. In this article, we discuss several options to avoid the broadcast storm problem while trying to achieve the maximum coverage of the region of interest. Specifically, we evaluate through simulations different ways to detect and take advantage of intersections and a strategy based on store-carry-forward to overcome short disconnections between groups of vehicles. Our conclusions are varied, and we propose two different solutions, depending on the requirements of the application.This work was partially founded by the Spanish Ministry of Science and Innovation within the framework of projects TEC2010-20572-C02-01 “CONSEQUENCE” and TEC2014-54335-C4-2-R “INRISCO” and by the Regional Government of Madrid within the “eMadrid” project under Grants S2009/TIC-1650 and S2013/ICE-2715, including the costs to publish in open access

Mobile Ad Hoc Networks

Guiding readers through the basics of these rapidly emerging networks to more advanced concepts and future expectations, Mobile Ad hoc Networks: Current Status and Future Trends identifies and examines the most pressing research issues in Mobile Ad hoc Networks (MANETs). Containing the contributions of leading researchers, industry professionals, and academics, this forward-looking reference provides an authoritative perspective of the state of the art in MANETs. The book includes surveys of recent publications that investigate key areas of interest such as limited resources and the mobility of mobile nodes. It considers routing, multicast, energy, security, channel assignment, and ensuring quality of service. Also suitable as a text for graduate students, the book is organized into three sections: Fundamentals of MANET Modeling and Simulation—Describes how MANETs operate and perform through simulations and models Communication Protocols of MANETs—Presents cutting-edge research on key issues, including MAC layer issues and routing in high mobility Future Networks Inspired By MANETs—Tackles open research issues and emerging trends Illustrating the role MANETs are likely to play in future networks, this book supplies the foundation and insight you will need to make your own contributions to the field. It includes coverage of routing protocols, modeling and simulations tools, intelligent optimization techniques to multicriteria routing, security issues in FHAMIPv6, connecting moving smart objects to the Internet, underwater sensor networks, wireless mesh network architecture and protocols, adaptive routing provision using Bayesian inference, and adaptive flow control in transport layer using genetic algorithms