Experimental Evaluation of Large Scale WiFi Multicast Rate Control

WiFi multicast to very large groups has gained attention as a solution for multimedia delivery in crowded areas. Yet, most recently proposed schemes do not provide performance guarantees and none have been tested at scale. To address the issue of providing high multicast throughput with performance guarantees, we present the design and experimental evaluation of the Multicast Dynamic Rate Adaptation (MuDRA) algorithm. MuDRA balances fast adaptation to channel conditions and stability, which is essential for multimedia applications. MuDRA relies on feedback from some nodes collected via a light-weight protocol and dynamically adjusts the rate adaptation response time. Our experimental evaluation of MuDRA on the ORBIT testbed with over 150 nodes shows that MuDRA outperforms other schemes and supports high throughput multicast flows to hundreds of receivers while meeting quality requirements. MuDRA can support multiple high quality video streams, where 90% of the nodes report excellent or very good video quality

Video QoS/QoE over IEEE802.11n/ac: A Contemporary Survey

The demand for video applications over wireless networks has tremendously increased, and IEEE 802.11 standards have provided higher support for video transmission. However, providing Quality of Service (QoS) and Quality of Experience (QoE) for video over WLAN is still a challenge due to the error sensitivity of compressed video and dynamic channels. This thesis presents a contemporary survey study on video QoS/QoE over WLAN issues and solutions. The objective of the study is to provide an overview of the issues by conducting a background study on the video codecs and their features and characteristics, followed by studying QoS and QoE support in IEEE 802.11 standards. Since IEEE 802.11n is the current standard that is mostly deployed worldwide and IEEE 802.11ac is the upcoming standard, this survey study aims to investigate the most recent video QoS/QoE solutions based on these two standards. The solutions are divided into two broad categories, academic solutions, and vendor solutions. Academic solutions are mostly based on three main layers, namely Application, Media Access Control (MAC) and Physical (PHY) which are further divided into two major categories, single-layer solutions, and cross-layer solutions. Single-layer solutions are those which focus on a single layer to enhance the video transmission performance over WLAN. Cross-layer solutions involve two or more layers to provide a single QoS solution for video over WLAN. This thesis has also presented and technically analyzed QoS solutions by three popular vendors. This thesis concludes that single-layer solutions are not directly related to video QoS/QoE, and cross-layer solutions are performing better than single-layer solutions, but they are much more complicated and not easy to be implemented. Most vendors rely on their network infrastructure to provide QoS for multimedia applications. They have their techniques and mechanisms, but the concept of providing QoS/QoE for video is almost the same because they are using the same standards and rely on Wi-Fi Multimedia (WMM) to provide QoS

Improving the Performance of Wireless LANs

This book quantifies the key factors of WLAN performance and describes methods for improvement. It provides theoretical background and empirical results for the optimum planning and deployment of indoor WLAN systems, explaining the fundamentals while supplying guidelines for design, modeling, and performance evaluation. It discusses environmental effects on WLAN systems, protocol redesign for routing and MAC, and traffic distribution; examines emerging and future network technologies; and includes radio propagation and site measurements, simulations for various network design scenarios, numerous illustrations, practical examples, and learning aids

Reliable Multicast transport of the video over the WiFi network

Le transport multicast est une solution efficace pour envoyer le même contenu à plusieurs récepteurs en même temps. Ce mode est principalement utilisé pour fournir des flux multimédia en temps réel. Cependant, le multicast classique de l IEEE 802.11 n'utilise aucun mécanisme d acquittement. Ainsi, l échec de réception implique la perte définitive du paquet. Cela limite la fiabilité du transport multicast et impact la qualité des applications vidéo. Pour résoudre ce problème, 802.11v et 802.11aa sont définis récemment. Le premier amendement propose Direct Multicast Service (DMS). D'autre part, le 802.11aa introduit GroupCast with Retries (GCR). GCR définit deux nouvelles politiques de retransmission : Block Ack (BACK) et Unsolicited Retry (UR).Dans cette thèse, nous évaluons et comparons les performances de 802.11v/aa. Nos résultats montrent que tous les nouveaux protocoles multicast génèrent un overhead de transmission important. En outre, DMS a une scalabilité très limitée, et GCR-BACK n'est pas approprié pour des grands groupes multicast. D autre part, nous montrons que DMS et GCR-BACK génèrent des latences de transmission importantes lorsque le nombre de récepteurs augmente. Par ailleurs, nous étudions les facteurs de pertes dans les réseaux sans fil. Nous montrons que l'indisponibilité du récepteur peut être la cause principale des pertes importantes et de leur nature en rafales. En particulier, nos résultats montrent que la surcharge du processeur peut provoquer un taux de perte de 100%, et que le pourcentage de livraison peut être limité à 35% lorsque la carte 802.11 est en mode d économie d'énergie.Pour éviter les collisions et améliorer la fiabilité du transport multicast, nous définissons le mécanisme Busy Symbol (BS). Nos résultats montrent que BS évite les collisions et assure un taux de succès de transmission très important. Afin d'améliorer davantage la fiabilité du trafic multicast, nous définissons un nouveau protocole multicast, appelé Block Negative Acknowledgement (BNAK). Ce protocole opère comme suit. L AP envoi un bloc de paquets suivi par un Block NAK Request (BNR). Le BNR permet aux membres de détecter les données manquantes et d envoyer une demande de retransmission, c.à.d. un Block NAK Response (BNAK). Un BNAK est transmis en utilisant la procédure classique d accès au canal afin d'éviter toute collision avec d'autres paquets. En plus, cette demande est acquittée. Sous l'hypothèse que 1) le récepteur est situé dans la zone de couverture du débit de transmission utilisé, 2) les collisions sont évitées et 3) le terminal a la bonne configuration, très peu de demandes de retransmission sont envoyées, et la bande passante est préservée. Nos résultats montrent que BNAK a une très grande scalabilité et génère des délais très limités. En outre, nous définissons un algorithme d'adaptation de débit pour BNAK. Nous montrons que le bon débit de transmission est sélectionné moyennant un overhead très réduit de moins de 1%. En plus, la conception de notre protocole supporte la diffusion scalable de lavvidéo. Cette caractéristique vise à résoudre la problématique de la fluctuation de la bande passante, et à prendre en considération l'hétérogénéité des récepteurs dans un réseau sans fil.The multicast transport is an efficient solution to deliver the same content to many receivers at the same time. This mode is mainly used to deliver real-time video streams. However, the conventional multicast transmissions of IEEE 802.11 do not use any feedback policy. Therefore missing packets are definitely lost. This limits the reliability of the multicast transport and impacts the quality of the video applications. To resolve this issue, the IEEE 802.11v/aa amendments have been defined recently. The former proposes the Direct Multicast Service (DMS). On the other hand, 802.11aa introduces Groupcast with Retries (GCR) service. GCR defines two retry policies: Block Ack (BACK) and Unsolicited Retry (UR).In this thesis we evaluate and compare the performance of 802.11v/aa. Our simulation results show that all the defined policies incur an important overhead. Besides, DMS has a very limited scalability, and GCR-BACK is not appropriate for large multicast groups. We show that both DMS and GCR-BACK incur important transmission latencies when the number of the multicast receivers increases. Furthermore, we investigate the loss factors in wireless networks. We show that the device unavailability may be the principal cause of the important packet losses and their bursty nature. Particularly, our results show that the CPU overload may incur a loss rate of 100%, and that the delivery ratio may be limited to 35% when the device is in the power save mode.To avoid the collisions and to enhance the reliability of the multicast transmissions, we define the Busy Symbol (BS) mechanism. Our results show that BS prevents all the collisions and ensures a very high delivery ratio for the multicast packets. To further enhance the reliability of this traffic, we define the Block Negative Acknowledgement (BNAK) retry policy. Using our protocol, the AP transmits a block of multicast packets followed by a Block NAK Request (BNR). Upon reception of a BNR, a multicast member generates a Block NAK Response (BNAK) only if it missed some packets. A BNAK is transmitted after channel contention in order to avoid any eventual collision with other feedbacks, and is acknowledged. Under the assumption that 1) the receiver is located within the coverage area of the used data rate, 2) the collisions are avoided and 3) the terminal has the required configuration, few feedbacks are generated and the bandwidth is saved. Our results show that BNAK has a very high scalability and incurs very low delays. Furthermore, we define a rate adaptation scheme for BNAK. We show that the appropriate rate is selected on the expense of a very limited overhead of less than 1%. Besides, the conception of our protocol is defined to support the scalable video streaming. This capability intends to resolve the bandwidth fluctuation issue and to consider the device heterogeneity of the group members.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

무선 통신 네트워크 환경에서의 효과적인 비디오 스트리밍 기법 연구

학위논문 (박사)-- 서울대학교 대학원 : 전기정보공학부, 2013. 8. 최성현.오늘날 무선 네트워크 통신 기술의 발달로 인해 고품질의 비디오 스트리밍 서비스에 대한 요구가 급증하고 있다. 새로운 60~GHz 광대역 고속 무선 통신 기술은 기존의 무선 통신 기술에서는 불가능했던, 고품질의 무압축 비디오 스트리밍을 가능하게 한다. 제한된 무선 자원 환경에서 고품질의 비디오 서비스를 지원하기 위해 주어진 채널 환경에서 적절한 변조 및 코딩 기술을 선택하는 효율적인 링크 적응 기법이 필요하다. 비디오 스트리밍의 품질을 수치로 평가하는 ePSNR을 정의하고, 불평등 오류 보호 기법(UEP)을 추가로 도입하여 보다 세밀한 링크 적응 기법을 가능케 한다. 정의한 ePSNR을 기반으로 (1) 주어진 무선 자원에서 비디오 품질을 최대화, 혹은 (2) 목표 비디오 품질을 만족하는 무선 자원 사용을 최소화, 하는 두가지 링크 적응 기법들을 제안한다. 다양한 시뮬레이션 결과를 통해, 정의한 ePSNR이 비디오 품질을 잘 표현하고 있음을 확인하였다. 또한, 제안한 링크 적응 기법들이 비디오 스트리밍 서비스를 위한 적절한 품질을 제공하면서, 동시에 자원 효율성을 향상시킴을 검증하였다. 한편, 순방향 오류 정정 기법(FEC)은 무선랜 환경에서 고품질의 신뢰성있는 비디오 멀티캐스트를 지원한다. 무선랜 환경에서 복수개의 액세스포인트(AP)간의 조정을 통한 신뢰성있는 비디오 멀티캐스트 기법을 제시한다. 복수개의 AP간의 조정을 통해 각각의 AP들이 (1) 완전히 서로 다른, 혹은 (2) 부분적으로 서로 다른, 인코딩된 패킷들을 전송하게 하여, 공간 및 시간적 다양성을 멀티캐스트 유저에게 제공할 수 있다. 추가로, 제한된 무선 자원을 보다 효율적으로 사용하기 위해, 순방향 오류 정정 기법의 코딩 비율 적응 기법을 위한 자원 할당 알고리즘을 제안한다. 또한, FEC 디코딩 후의 비디오 패킷의 전송율를 예측할 수 있는 방법을 제안한다. 다양한 시뮬레이션과 실험을 통해 제안한 기법들의 우수성을 확인하였다. 멀티캐스트 전송은 기본적으로 무선 채널 오류로 인해 전송 실패가 발생할 가능성을 내포한다. 그러나 기존의 무선랜 표준에서는 멀티캐스트 환경에서 자동 반복 요청 기법(ARQ)을 통한 손실 조정 방법을 제공하지 않았다. 멀티캐스트 전송의 비신뢰성 문제를 해결하기 위해, 자동 반복 요청 기법(ARQ)과 순방향 오류 정정 기법(FEC)를 함께 고려한 신뢰성 있는 멀티캐스트 전송 기법을 제안한다. 신뢰성 있는 멀티캐스트 전송을 위한 피드백 교환의 오버헤드를 줄이기 위한 복수개의 효율적인 피드백 기법을 제시한다. 제안한 피드백 기법은 액세스포인트(AP)가 멀티캐스트 유저들의 손실된 패킷들의 복원을 위해 필요한 패리티(parity) 패킷의 개수를 쉽게 알 수 있도록 한다. 피드백 간의 충돌을 감안한 의도적인 동시 전송을 통해 피드백 오버헤드를 감소시킬 수 있다. 추가로, 효율적인 피드백 프로토콜을 활용하여, 변조 및 코딩 기법(MCS)의 폐쇄적 피드백 기반의 물리 전송 속도 적응 기법을 제안한다. 성능 검증을 통해 제안한 기법들이 효율적으로 피드백 오버헤드를 감소시키며, 동시에 신뢰성있는 멀티캐스트 전송을 보장함을 검증하였다.Today, along with the rapid growth of the network performance, the demand for high-quality video streaming services has greatly increased. The emerging 60 GHz multi-Gbps wireless technology enables the streaming of high-quality uncompressed video, which was not possible with other existing wireless technologies. To support such high quality video with limited wireless resources, an efficient link adaptation policy, which selects the proper Modulation and Coding Scheme (MCS) for a given channel environment, is essential. We introduce a new metric, called expected Peak Signal-to-Noise Ratio (ePSNR), to numerically estimate the video streaming quality, and additionally adopt Unequal Error Protection (UEP) schemes that enable flexible link adaptation. Using the ePSNR as a criterion, we propose two link adaptation policies with different objectives. The proposed link adaptation policies attempt to (1) maximize the video quality for given wireless resources, or (2) minimize the required wireless resources while meeting the video quality. Our extensive simulation results demonstrate that the introduced variable, i.e., ePSNR, well represents the level of video quality. It is also shown that the proposed link adaptation policies can enhance the resource efficiency while achieving acceptable quality of the video streaming. Meanwhile, Forward Error Correction (FEC) can be exploited to realize reliable video multicast over Wi-Fi with high video quality. We propose reliable video multicast over Wi-Fi networks with coordinated multiple Access Points (APs) to enhance video quality. By coordinating multiple APs, each AP can transmit (1) entirely different or (2) partially different FEC-encoded packets so that a multicast receiver can benefit from both spatial and time diversities. The proposed scheme can enlarge the satisfactory video multicast region by exploiting the multi-AP diversity, thus serving more multicast receivers located at cell edge with satisfactory video quality. We propose a resource-allocation algorithm for FEC code rate adaptation, utilizing the limited wireless resource more efficiently while enhancing video quality. We also introduce the method for estimating the video packet delivery ratio after FEC decoding. The effectiveness of the proposed schemes is evaluated via extensive simulation and experimentation. The proposed schemes are observed to enhance the ratio of satisfied users by up to 37.1% compared with the conventional single AP multicast scheme. The multicast transmission is inherently unreliable due to the transmission failures caused by wireless channel errors, however, the error control with Automatic Repeat reQuest (ARQ) is not provided for the multicast transmission in legacy IEEE 802.11 standard. To overcome the unreliability of multicast transmission, finally, we propose the reliable multicast protocols considering both ARQ and packet-level FEC together. For the proposed reliable multicast protocol, to reduce the overheads of feedback messages while providing the reliable multicast service, the multiple efficient feedback protocols, i.e., Idle-time-based feedback, Slot-based feedback, Flash-based feedback, and Busy-time-based feedback, are proposed. The proposed feedback protocols let the AP know easily the number of requiring parity frames of the worst user(s) for the recovery of the lost packets. The feedback overheads can be reduced by intending the concurrent transmissions, which makes the collisions, between feedback messages. In addition, utilizing the efficient feedback protocols, we propose the PHY rate adaptation based on the close-loop MCS feedback in multicast transmissions. From the performance evaluations, the proposed protocols can efficiently reduce the feedback overheads, while the reliable multicast transmissions are guaranteed.1 Introduction 1 1.1 Video Streaming over Wireless Networks 1 1.1.1 Uncompressed Video Streaming over 60 GHz band 2 1.1.2 Video Multicast over IEEE 802.11 WLAN 3 1.2 Overview of Existing Approaches 5 1.2.1 Link Adaptation over Wireless Networks 5 1.2.2 Video Streaming over IEEE 802.11 WLAN 6 1.2.3 Reliable Multicast over IEEE 802.11 WLAN 8 1.3 Main Contributions 9 1.4 Organization of the Dissertation 11 2 Link Adaptation for High-Quality Uncompressed Video Streaming in 60 GHz Wireless Networks 12 2.1 Introduction 12 2.2 ECMA-387 and Wireless HDMI 17 2.2.1 ECMA-387 18 2.2.2 Wireless HDMI (HDMI PAL) 21 2.2.3 UEP Operations 22 2.2.4 ACK Transmissions for Video Streaming 23 2.2.5 Latency of Compressed and Uncompressed Video Streaming 24 2.3 ePSNR-Based Link Adaptation Policies 25 2.3.1 ePSNR 28 2.3.2 PSNR-based Link Adaptation 30 2.4 Performance Evaluation 33 2.4.1 Evaluation of ePSNR 34 2.4.2 Performance of Link Adaptation 40 2.5 Summary 45 3 Reliable Video Multicast over Wi-Fi Networks with Coordinated Multiple APs 47 3.1 Introduction 47 3.2 System Environments 50 3.2.1 Time-Slotted Multicast 50 3.2.2 FEC Coding Schemes 52 3.3 Reliable Video Multicast with Coordinated Multiple APs 52 3.3.1 Proposed Video Multicast 52 3.3.2 Video Multicast Procedure 55 3.4 FEC Code Rate Adaptation 58 3.4.1 Estimation of Delivery Ratio 59 3.4.2 Greedy FEC Code Rate Adaptation 61 3.5 Performance Evaluation 63 3.5.1 Raptor Code Performance 64 3.5.2 Simulation Results: No Fading 66 3.5.3 Simulation Results: Fading Channel 69 3.5.4 Simulation Results: Code Rate Adaptation 70 3.5.5 Experimental Results 74 3.5.6 Prototype Implementation 76 3.6 Summary 79 4 Reliable Video Multicast with Efficient Feedback over Wi-Fi 81 4.1 Introduction 81 4.2 Motivation 85 4.3 Proposed Feedback Protocols for Reliable Multicast 87 4.3.1 Idle-time-based Feedback 88 4.3.2 Slot-based Feedback 89 4.3.3 Flash-based Feedback 91 4.3.4 Busy-time-based Feedback 92 4.4 PHY Rate Adaptation in Multicast Transmission 93 4.5 Performance Evaluation 96 4.5.1 Performance evaluation considering feedback error 104 4.6 Summary 109 5 Conclusion and Future Work 110 5.1 Research Contributions 110 5.2 Future Research Directions 111 Abstract (In Korean) 121Docto

Experimenting with commodity 802.11 hardware: overview and future directions

The huge adoption of 802.11 technologies has triggered a vast amount of experimentally-driven research works. These works range from performance analysis to protocol enhancements, including the proposal of novel applications and services. Due to the affordability of the technology, this experimental research is typically based on commercial off-the-shelf (COTS) devices, and, given the rate at which 802.11 releases new standards (which are adopted into new, affordable devices), the field is likely to continue to produce results. In this paper, we review and categorise the most prevalent works carried out with 802.11 COTS devices over the past 15 years, to present a timely snapshot of the areas that have attracted the most attention so far, through a taxonomy that distinguishes between performance studies, enhancements, services, and methodology. In this way, we provide a quick overview of the results achieved by the research community that enables prospective authors to identify potential areas of new research, some of which are discussed after the presentation of the survey.This work has been partly supported by the European Community through the CROWD project (FP7-ICT-318115) and by the Madrid Regional Government through the TIGRE5-CM program (S2013/ICE-2919).Publicad

무선랜 비디오 멀티캐스트의 문제 발견 및 성능 향상 기법

학위논문 (박사)-- 서울대학교 대학원 공과대학 전기·컴퓨터공학부, 2017. 8. 최성현.Video multicast, streaming real-time videos via multicast, over wireless local area network (WLAN) has been considered a promising solution to share common venue-specific videos. By virtue of the nature of the wireless broadcast medium, video multicast basically enables scale-free video delivery, i.e., it can deliver a common video with the fixed amount of wireless resource regardless of the number of receivers. However, video multicast has not been widely enjoyed in our lives due to three major challenges: (1) power saving-related problem, (2) low reliability and efficiency, and (3) limited coverage. In this dissertation, we consider three research topics, i.e., (1) identification of practical issues with multicast power saving, (2) physical (PHY) rate and forward erasure correction code (FEC) rate adaptation over a single-hop network, and (3) multi-hop multicast, which deal with the three major challenges, respectively. Firstly, video multicast needs to be reliably delivered to power-saving stations, given that many portable devices are battery-powered. Accordingly, we investigate the impact of multicast power saving, and address two practical issues related with the multicast power saving. From the measurement with several commercial WLAN devices, we observe that many devices are not standard compliant, thus making video multicast performance severely degraded. We categorize such standard incompliant malfunctions that can result in significant packet losses. We also figure out a coexistence problem between video multicast and voice over Internet protocol (VoIP) when video receivers runs in power saving mode (PSM). The standard-compliant power save delivery of multicast deteriorates the VoIP performance in the same WLAN. We analyze the VoIP packet losses due to the coexistence problem, and propose a new power save delivery scheme to resolve the problem. We further implement the proposed scheme with an open source device driver, and our measurement results demonstrate that the proposed scheme significantly enhances the VoIP performance without sacrificing the video multicast performance. Second, multi-PHY rate FEC-applied wireless multicast enables reliable and efficient video multicast with intelligent selection of PHY rate and FEC rate. The optimal PHY/FEC rates depend on the cause of the packet losses. However, previous approaches select the PHY/FEC rates by considering only channel errors even when interference is also a major source of packet losses.We propose InFRA, an interference-aware PHY/FEC rate adaptation framework that (1) infers the cause of the packet losses based on received signal strength indicator (RSSI) and cyclic redundancy check (CRC) error notifications, and (2) determines the PHY/FEC rates based on the cause of packet losses. Our prototype implementation with off-the-shelf chipsets demonstrates that InFRA enhances the multicast delivery under various network scenarios. InFRA enables 2.3x and 1.8x more nodes to achieve a target video packet loss rate with a contention interferer and a hidden interferer, respectively, compared with the state-of-theart PHY/FEC rate adaptation scheme. To the best of our knowledge, InFRA is the first work to take the impact of interference into account for the PHY/FEC rate adaptation. Finally, collaborative relaying that enables selected receiver nodes to relay the received packets from source node to other nodes enhances service coverage, reliability, and efficiency of video multicast. The intelligent selection of sender nodes (source and relays) and their transmission parameters (PHY rate and the number of packets to send) is the key to optimize the performance. We propose EV-CAST, an interference and energy-aware video multicast system using collaborative relays, which entails online network management based on interference-aware link characterization, an algorithm for joint determination of sender nodes and transmission parameters, and polling-based relay protocol. In order to select most appropriate set of the relay nodes, EV-CAST considers interference, battery status, and spatial reuse, as well as other factors accumulated over last decades. Our prototype-based measurement results demonstrate that EV-CAST outperforms the state-of-the-art video multicast schemes. In summary, from Chapter 2 to Chapter 4, the aforementioned three pieces of the research work, i.e., identification of power saving-related practical issues, InFRA for interference-resilient single-hop multicast, and EV-CAST for efficient multi-hop multicast, will be presented, respectively.1 Introduction 1 1.1 Video Multicast over WLAN 1 1.2 Overview of Existing Approaches 4 1.2.1 Multicast Power Saving 4 1.2.2 Reliability and Efficiency Enhancement 4 1.2.3 Coverage Extension 5 1.3 Main Contributions 7 1.3.1 Practical Issues with Multicast Power Saving 7 1.3.2 Interference-aware PHY/FEC Rate Adaptation 8 1.3.3 Energy-aware Multi-hop Multicast 9 1.4 Organization of the Dissertation 10 2 Practical Issues with Multicast Power Saving 12 2.1 Introduction 12 2.2 Multicast & Power Management Operation in IEEE 802.11 14 2.3 Inter-operability Issue 15 2.3.1 Malfunctions of Commercial WLAN Devices 17 2.3.2 Performance Evaluation 20 2.4 Coexistence Problem of Video Multicast and VoIP 21 2.4.1 Problem Statement 21 2.4.2 Problem Identification: A Measurement Study 23 2.4.3 Packet Loss Analysis 27 2.4.4 Proposed Scheme 32 2.4.5 Performance Evaluation 33 2.5 Summary 37 3 InFRA: Interference-Aware PHY/FEC Rate Adaptation for Video Multicast over WLAN 39 3.1 Introduction 39 3.2 Related Work 42 3.2.1 Reliable Multicast Protocol 42 3.2.2 PHY/FEC rate adaptation for multicast service 44 3.2.3 Wireless Video Transmission 45 3.2.4 Wireless Loss Differentiation 46 3.3 Impact of Interference on Multi-rate FEC-applied Multicast 46 3.3.1 Measurement Setup 47 3.3.2 Measurement Results 47 3.4 InFRA: Interference-aware PHY/FEC Rate Adaptation Framework 49 3.4.1 Network Model and Objective 49 3.4.2 Overall Architecture 50 3.4.3 FEC Scheme 52 3.4.4 STA-side Operation 53 3.4.5 AP-side Operation 61 3.4.6 Practical Issues 62 3.5 Performance Evaluation 65 3.5.1 Measurement Setup 66 3.5.2 Small Scale Evaluation 67 3.5.3 Large Scale Evaluation 70 3.6 Summary 74 4 EV-CAST: Interference and Energy-aware Video Multicast Exploiting Collaborative Relays 75 4.1 Introduction 75 4.2 Factors for Sender Node and Transmission Parameter Selection 78 4.3 EV-CAST: Interference and Energy-aware Multicast Exploiting Collaborative Relays 80 4.3.1 Network Model and Objective 80 4.3.2 Overview 81 4.3.3 Network Management 81 4.3.4 Interference and Energy-aware Sender Nodes and Transmission Parameter Selection (INFER) Algorithm 87 4.3.5 Assignment, Polling, and Re-selection of Relays 93 4.3.6 Discussion 95 4.4 Evaluation 96 4.4.1 Measurement Setup 96 4.4.2 Micro-benchmark 98 4.4.3 Macro-benchmark 103 4.5 Related Work 105 4.5.1 Multicast Opportunistic Routing 105 4.5.2 Multicast over WLAN 106 4.6 Summary 106 5 Conclusion 108 5.1 Research Contributions 108 5.2 Future Research Directions 109 Abstract (In Korean) 121Docto

A QoE adaptive management system for high definition video streaming over wireless networks

[EN] The development of the smart devices had led to demanding high-quality streaming videos over wireless communications. In Multimedia technology, the Ultra-High Definition (UHD) video quality has an important role due to the smart devices that are capable of capturing and processing high-quality video content. Since delivery of the high-quality video stream over the wireless networks adds challenges to the end-users, the network behaviors 'factors such as delay of arriving packets, delay variation between packets, and packet loss, are impacted on the Quality of Experience (QoE). Moreover, the characteristics of the video and the devices are other impacts, which influenced by the QoE. In this research work, the influence of the involved parameters is studied based on characteristics of the video, wireless channel capacity, and receivers' aspects, which collapse the QoE. Then, the impact of the aforementioned parameters on both subjective and objective QoE is studied. A smart algorithm for video stream services is proposed to optimize assessing and managing the QoE of clients (end-users). The proposed algorithm includes two approaches: first, using the machine-learning model to predict QoE. Second, according to the QoE prediction, the algorithm manages the video quality of the end-users by offering better video quality. As a result, the proposed algorithm which based on the least absolute shrinkage and selection operator (LASSO) regression is outperformed previously proposed methods for predicting and managing QoE of streaming video over wireless networks.This work has been partially supported by the "Ministerio de Economia y Competitividad" in the "Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia, Subprograma Estatal de Generacion de Conocimiento" with in the Project under Grant TIN2017-84802-C2-1-P. This study has been partially done in the computer science departments at the (University of Sulaimani and Halabja).Taha, M.; Canovas, A.; Lloret, J.; Ali, A. (2021). A QoE adaptive management system for high definition video streaming over wireless networks. Telecommunication Systems. 77(1):63-81. https://doi.org/10.1007/s11235-020-00741-2638177

Framework for Content Distribution over Wireless LANs

Wireless LAN (also called as Wi-Fi) is dominantly considered as the most pervasive technology for Intent access. Due to the low-cost of chipsets and support for high data rates, Wi-Fi has become a universal solution for ever-increasing application space which includes, video streaming, content delivery, emergency communication, vehicular communication and Internet-of-Things (IoT). Wireless LAN technology is defined by the IEEE 802.11 standard. The 802.11 standard has been amended several times over the last two decades, to incorporate the requirement of future applications. The 802.11 based Wi-Fi networks are infrastructure networks in which devices communicate through an access point. However, in 2010, Wi-Fi Alliance has released a specification to standardize direct communication in Wi-Fi networks. The technology is called Wi-Fi Direct. Wi-Fi Direct after 9 years of its release is still used for very basic services (connectivity, file transfer etc.), despite the potential to support a wide range of applications. The reason behind the limited inception of Wi-Fi Direct is some inherent shortcomings that limit its performance in dense networks. These include the issues related to topology design, such as non-optimal group formation, Group Owner selection problem, clustering in dense networks and coping with device mobility in dynamic networks. Furthermore, Wi-Fi networks also face challenges to meet the growing number of Wi Fi users. The next generation of Wi-Fi networks is characterized as ultra-dense networks where the topology changes frequently which directly affects the network performance. The dynamic nature of such networks challenges the operators to design and make optimum planifications. In this dissertation, we propose solutions to the aforementioned problems. We contributed to the existing Wi-Fi Direct technology by enhancing the group formation process. The proposed group formation scheme is backwards-compatible and incorporates role selection based on the device's capabilities to improve network performance. Optimum clustering scheme using mixed integer programming is proposed to design efficient topologies in fixed dense networks, which improves network throughput and reduces packet loss ratio. A novel architecture using Unmanned Aeriel Vehicles (UAVs) in Wi-Fi Direct networks is proposed for dynamic networks. In ultra-dense, highly dynamic topologies, we propose cognitive networks using machine-learning algorithms to predict the network changes ahead of time and self-configuring the network