OVERVIEW OF WIRELESS NETWORK CONTROL PROTOCOL IN SMART PHONE DEVICES

The computer network connection without wire or any cable is referring as wireless network. These wireless local area networks are popular for its worldwide applications. It has covered wide scale wireless local area network. The large scale systems to all applicable areas make large numbers of wireless termination and covering very much area. To reduce the complexity associated with server management, Information Technology organizations begins the process of centralizing servers. It used with architecture principles of centralized management requirement for network to scale, network architecture needs to be able to support enhanced services in addition to just raw connectivity, distributed processing is required both for scalability ability and services, network support continuously increase the level of throughputs etc. Wireless LAN product architectures have evolved from single autonomous access points to systems, consisting of a centralized Access Controller and Wireless Termination Points. The basic goal of centralized control architectures is to move access control, including user authentication and authorization, mobility & radio management, from one access point to centralized controller. The Wireless network Control Protocol allows for access and control of large-scale wireless local area networks. It can allows management of these networks, Control and Provisioning of Wireless Access Points In computer networking, a wireless access point is a device that allows wireless devices to connect to wired network using Wi-Fi, Bluetooth or related standards. The WAP usually connects to a router via a wired network, and can relay data between the wireless devices such as computers or printers and wired devices on the networ

Performance Prediction and Tuning for Symmetric Coexistence of WiFi and ZigBee Networks

Due to the explosive deployment of WiFi and ZigBee wireless networks, 2.4GHz ISM bands (2.4GHz-2.5GHz) are becoming increasingly crowded, and the co-channel coexistence of these two networks is inevitable. For coexistence networks, people always want to predict their performance (e.g. throughput, energy consumption, etc.) before deployment, or even want to tune parameters to compensate unnecessary performance degradation (owing to the huge differences between these two MAC protocols) or to satisfy some performance requirements (e.g., priority, delay constraint, etc.) of them. However, predicting and tuning performance of coexisting WiFi and ZigBee networks has been a challenging task, primarily due to the lack of corresponding simulators and analytical models. In this dissertation, we addressed the aforementioned problems by presenting simulators and models for the coexistence of WiFi and ZigBee devices. Specifically, based on the energy efficiency and traffic pattern of three practical coexistence scenarios: disaster rescue site, smart hospital and home automation. We first of all classify them into three classes, which are non-sleeping devices with saturated traffic (SAT), non-sleeping devices with unsaturated traffic (UNSAT) and duty-cycling devices with unsaturated traffic (DC-UNSAT). Then a simulator and an analytical model are proposed for each class, where each simulator is verified by simple hardware based experiment. Next, we derive the expressions for performance metrics like throughput, delay etc., and predict them using both the proposed simulator and the model. Due to the higher accuracy of the simulator, the results from them are used as the ground truth to validate the accuracy of the model. Last, according to some common performance tuning requirements for each class, we formulate them into optimization problems and propose the corresponding solving methods. The results show that the proposed simulators have high accuracy in performance prediction, while the models, although are less accurate than the former, can be used in fast prediction. In particular, the models can also be easily used in optimization problems for performance tuning, and the results prove its high efficiency

이기종 무선 네트워크에서의 협대역 시스템 보호 기법

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2013. 8. 김종권.최근 다양한 무선 네트워크 기술들(와이파이, 블루투스, 지그비)이 2.4GHz 대역의 ISM 밴드에 공존함으로 인하여 이들 간의 상호공존이 큰 문제로 나타나고있다. 특히 지그비 네트워크는 현저히 높은 전송 파워로 통신하는 와이파이 네트워크가 동일한 주파수 대역에 존재할 때 통신이 불가능해 질 정도의 심각한 성능 저하를 겪게 된다. 본 논문에서는 지그비 네트워크의 통신을 와이파이 네트워크의 간섭으로 부터 보호할 수 있는 좁은 대역 보호 방법(Narrow Band Protection)을 제안한다. 자가 감지 보호자는 좁은 대역 보호 방법의 핵심 기술로 사전에 정의된 PN 시퀀스에 대해 상호 상관 기법을 이용하여 스스로 지그비 패킷을 발견할 수 있어 최소한의 오버헤드로 지그비 네트워크를 보호할 수 있다. 또한, 자가 감지 보호자는 신뢰성 있는 상호 상관 기법을 통해 기존 방법에서 발생하는 제어 패킷 손실로 인한 두 네트워크의 이용효율 감소를 대폭 줄일 수 있다. 마지막으로, 시맨틱이 부여된 PN 코드북을 통해 저전력 동작을 수행하는 지그비 네트워크의 다량 패킷 전송을 효율적으로 감지하여 지그비 네트워크의 높은 처리량을 지원해 줄 수 있는 장점이 있다. 제안하고 있는 자가 감지 보호자는 시맨틱이 부여된 PN 시퀀스를 지그비 패킷의 프리앰블(Preamble) 앞에 임베딩 하는 기법을 사용한다. 이는 해당 기법을 적용하지 않는 지그비 노드들의 동기화를 방해하지 않는다. 즉, 좁은 대역 보호 방법은 기존 지그비 네트워크와 하위 호환성(backward compatibility)을 유지하며 기존 방법에 비해 단일 패킷에 대해서 1.77배 가량 높은 처리량을 제공해 줄 수 있으며, 다량 패킷 전송 보호시 보호하는 패킷의 수가 증가함에 따라 선형으로 이득이 증가하게 된다. 또한, 실제 USRP/GNURadio 플랫폼에 핵심 기능을 구현하여 실효성을 입증하였으며, 수학적인 분석과 확장된 NS-2 시뮬레이션을 통해 다양한 시각에서 상호공존 문제를 해석하고 있어 향 후 관련 분야에 큰 기여를 할 연구이다.Recent deployment of various wireless technologies such as Wi-Fi, Bluetooth, and ZigBee in the 2.4GHz ISM band has led to the heterogeneous devices coexistence problem. The coexistence problem is particularly challenging since wireless technologies use different PHY/MAC specifications. This thesis deals with the ZigBee and Wi-Fi coexistence problem where a less capable ZigBee device may often experience unacceptably low throughput due to the interference from a powerful Wi-Fi device. We propose a novel time reservation scheme called Narrow Band Protection (NBP) that uses a protector to guard ongoing ZigBee transmissions. The NBP protector detects a ZigBee transmission by cross-correlating the ZigBee signals with pre-defined Pseudo-random Noise (PN) sequences. A cross-correlation, designed for apprehending certain patterns in signals, not only reduces the control overhead but also guarantees robustness against collisions. In addition, a ZigBee node can still encode its packet length as a PN sequence such that the protector guards a proper length of channel time. We show the feasibility of NBP by implementing it on the USRP/GNURadio platform. We also evaluate the performance of NBP through mathematical analysis and NS-2 simulations. The results show that NBP enhances the ZigBee throughput by up to 1.77x compared to an existing scheme.1 Introduction 1.1 Background 1.2 Goal and Contribution 1.3 Thesis Organization 2 Related Work 2.1 The Cross-technology Interference Problem 2.2 The Cross-technology Interference Solutions 2.3 Signal Correlation 3 Motivation 3.1 Overview of ZigBee and Wi-Fi 3.2 Collision between ZigBee and Wi-Fi packets 3.3 The Limitation of the Protector Approach 4 A Narrow Band Protection Technique 4.1 Overview 4.2 Cross-correlation with PN Codebook 4.3 Protection Coverage 4.4 Protecting Wireless Sensor Networks 4.5 Security Issues 4.6 Discussions 5 Mathematical Analysis 5.1 Assumptions and Notations 5.2 Collision Probability 5.3 Network Performance 5.4 Multiple Packet Transmissions 6 Performance Evaluation 6.1 USRP Experiments 6.2 NS-2 Simulations 7 Conclusion BibliographyDocto

Mitigating interference coexistence issues in wireless sensor networks

Wireless Sensor Networks (WSNs) comprise a collection of portable, wireless, interconnected sensors deployed over an area to monitor and report a variable of interest; example applications include wildlife monitoring and home automation systems. In order to cater for long network lifetimes without the need for regular maintenance, energy efficiency is paramount, alongside link reliability. To minimise energy consumption, WSN MAC protocols employ Clear Channel Assessment (CCA), to transmit and receive packets. For transmitting, CCA is used beforehand to determine if the channel is clear. For receiving, CCA is used to decide if the radio should wake up to receive an incoming transmission, or be left in a power efficient sleep state. Current CCA implementations cannot determine the device type occupying the media, leaving nodes unable to differentiate between WSN traffic and arbitrary interference from other devices, such as WiFi. This affects link performance as packet loss increases, and energy efficiency as the radio is idly kept in receive mode. To permit WSN deployments in these environments, it is necessary to be able to gauge the effect of interference. While tools exist to model and predict packet loss in these conditions, it is currently not possible to do the same for energy consumption. This would be beneficial, as parameters of the network could be tuned to meet lifetime and energy requirements. In this thesis, methods to predict energy consumption of WSN MAC protocols are presented. These are shown to accurately estimate the idle listening from environmental interference measurements. Further, in order to mitigate the effects of interference, it would be beneficial for a CCA check to determine the device type occupying the media. For example, transmitters may select back-off strategies depending on the observed channel occupier. Receivers could be made more efficient by ignoring all non-WSN traffic, staying awake only after detecting an incoming WSN transmission. P-DCCA is a novel method presented in this thesis to achieve this. Transmitters vary the output power of the radio while the packet is being sent. Receivers are able to identify signals with this characteristic power variation, enabling a P-DCCA check to reveal if the medium is currently occupied by WSN traffic or other interference. P-DCCA is implemented in a common WSN MAC protocol, and is shown to achieve high detection accuracy, and to improve energy efficiency and packet delivery in interference environments

Architectures pour la mobilité et la qualité de service dans les systèmse satellites DVB-S2/RCS

Nos travaux de thèse ont pour objectif la conception, la mise en œuvre et l'évaluation d'architectures pour la mobilité et la qualité de service (QoS) dans des systèmes satellites DVB-S2/RCS. Ces systèmes peuvent constituer une solution alternative efficace aux réseaux terrestres dans des zones reculées à faible densité de population mais ils doivent pour cela offrir les mêmes services tout en tenant compte de leurs caractéristiques spécifiques, en particulier leur long délai de transmission qui peut s'avérer problématique dans le cadre d'applications multimédias interactives. Notre première contribution a donc été de développer une architecture de QoS adaptée à ce type d'applications, utilisant le modèle DiffServ et se basant essentiellement sur l'interaction entre l'architecture liée au protocole d'initiation de session SIP et différentes entités du système satellite. La QoS peut alors être configurée de façon précise au niveau des STs, par le biais de l'outil TC, en analysant les descripteurs de session SDP compris dans les messages SIP et en déduisant leurs caractéristiques (débit, gigue max, délai max, etc...) soit localement si elles sont connues, soit à partir d'un service Web que nous avons développé. Nous avons ensuite proposé et développé une solution de mobilité basée sur SIP, adaptée au système satellite ainsi qu'à la solution de QoS précédemment décrite. Les performances de cette solution ont alors été comparées, en termes de temps d'interruption et de consommation de ressources, avec celles obtenues par Mobile IPv6 et certaines de ses extensions, démontrant ainsi de réelles améliorations pour le cas des applications multimédias interactives. Enfin, notre dernière contribution a été de développer deux architectures couplant QoS et mobilité, une spécifiquement conçue pour les applications interactives et basée sur la combinaison de notre solution de mobilité SIP avec notre architecture de QoS SIP et une autre basée sur Mobile IPv6 ou FMIPv6 et sur l'interaction d'un QoS Agent mobile avec les entités de QoS du système satellite. Ces architectures ont été évaluées et comparées sur la plateforme d'émulation PLATINE développée dans le cadre du projet SATSIX.Our thesis work aims at the design, the implementation and the evaluation of architectures for mobility and quality of service (QoS) in DVB-S2/RCS satellite systems. These systems can be an effective alternative to terrestrial networks in remote and sparsely populated areas but, for that, they have to offer the same services while taking into account their specific characteristics, particularly their long transmission delay that can be problematic in the context of interactive multimedia applications. Our first contribution has been to develop a QoS architecture adapted to such applications, using the DiffServ model and relying heavily on the interaction between the architecture related to the Session Initiation Protocol (SIP) and various entities of the satellite system. The QoS of satellite terminals (STs) can then be configured precisely, by using the TC tool and analyzing the SDP session descriptors included in the SIP messages and deducting their characteristics (throughput, jitter max, delay max, etc. ...) either locally, if they are known, or from a Web service that we have developed. We then proposed and developed a mobility solution based on SIP, adapted to the satellite system and to the QoS solution described above. The performances of this solution were compared in terms of handover time and resources consumption, with those obtained by Mobile IPv6 and some of its extensions, showing real improvements in the case of interactive multimedia applications. Finally, our last contribution was to develop two architectures combining QoS and mobility: the first one is specifically designed for interactive applications and based on the combination of our SIP-based mobility solution with our SIP QoS architecture and the another is based on Mobile IPv6 or FMIPv6 for the mobility part and on the interaction of a mobile QoS agent with QoS entities of the satellite system. These architectures have been evaluated and compared on the emulation platform PLATINE developed under the project SATSIX