An efficient MAC protocol based on hybrid superframe for Wireless Sensor Networks

The usage of wireless channels is based on Media Access Control (MAC) protocols, which allocate wireless resources and control the way that sensors access a shared radio channel to communicate with their neighbors. Designing low energy consumption, high efficiency MAC protocols is one of the most important directions in Wireless Sensor Networks (WSN). So far, MAC protocols in WSN are usually divided into two categories: contention-based MAC protocols and schedule-based MAC protocols. However, both protocols have their own advantages and disadvantages that sometimes it is hard to decide which one is better than the other one. A hybrid protocol is concerned a lot now in WSN, which is IEEE 802.15.4. It integrates the advantages of both contention-based and schedule-based mechanisms. However, this protocol has some improving spaces as well, which motivated us to further study it and proposed a new contention reserve MAC protocol, named CRMAC, under the inspiration of IEEE 802.15.4's superframe structure. Through a series of theoretical and simulation analysis, we show that CRMAC performs better in energy consumption, system delay and network throughput than IEEE 802.15.4 and LEACH (Low Energy Adaptive Clustering Hierarchy). CRMAC is especially suitable for short packet transmission under logy traffic networks, which is the main situation in WSN, so this protocol is practical in WSN

Protocol for Extreme Low Latency M2M Communication Networks

As technology evolves, more Machine to Machine (M2M) deployments and mission critical services are expected to grow massively, generating new and diverse forms of data traffic, posing unprecedented challenges in requirements such as delay, reliability, energy consumption and scalability. This new paradigm vindicates a new set of stringent requirements that the current mobile networks do not support. A new generation of mobile networks is needed to attend to this innovative services and requirements - the The fifth generation of mobile networks (5G) networks. Specifically, achieving ultra-reliable low latency communication for machine to machine networks represents a major challenge, that requires a new approach to the design of the Physical (PHY) and Medium Access Control (MAC) layer to provide these novel services and handle the new heterogeneous environment in 5G. The current LTE Advanced (LTE-A) radio access network orthogonality and synchronization requirements are obstacles for this new 5G architecture, since devices in M2M generate bursty and sporadic traffic, and therefore should not be obliged to follow the synchronization of the LTE-A PHY layer. A non-orthogonal access scheme is required, that enables asynchronous access and that does not degrade the spectrum. This dissertation addresses the requirements of URLLC M2M traffic at the MAC layer. It proposes an extension of the M2M H-NDMA protocol for a multi base station scenario and a power control scheme to adapt the protocol to the requirements of URLLC. The system and power control schemes performance and the introduction of more base stations are analyzed in a system level simulator developed in MATLAB, which implements the MAC protocol and applies the power control algorithm. Results showed that with the increase in the number of base stations, delay can be significantly reduced and the protocol supports more devices without compromising delay or reliability bounds for Ultra-Reliable and Low Latency Communication (URLLC), while also increasing the throughput. The extension of the protocol will enable the study of different power control algorithms for more complex scenarios and access schemes that combine asynchronous and synchronous access

Prolonging Network Lifetime of Clustered Wireless Sensor Networks

Wireless Sensor Networking is envisioned as an economically viable paradigm and a promising technology because of its ability to provide a variety of services, such as intrusion detection, weather monitoring, security, tactical surveillance, and disaster management. The services provided by wireless senor networks (WSNs) are based on collaboration among small energy-constrained sensor nodes. The large deployment of WSNs and the need for energy efficient strategy necessitate efficient organization of the network topology for the purpose of balancing the load and prolonging the network lifetime. Clustering has been proven to provide the required scalability and prolong the network lifetime. Due to the bottle neck phenomena in WSNs, a sensor network loses its connectivity with the base station and the remaining energy resources of the functioning nodes are wasted. This thesis highlights some of the research done to prolong the network lifetime of wireless sensor networks and proposes a solution to overcome the bottle neck phenomena in cluster-based sensor networks. Transmission tuning algorithm for a cluster-based WSNs is proposed based on our modeling of the extra burden of the sensor nodes that have direct communication with the base station. Under this solution, a wireless sensor network continues to operate with minimum live nodes, hence increase the longevity of the system. An information theoretic metric is proposed as a cluster head selection criteria for breaking ties among competing clusters, hence as means to decrease node reaffiliation and hence increasing the stability of the clusters, and prolonging the network lifetime. This proposed metric attempts to predict undesired mobility caused by erosion

Design of a 2.4 Ghz BAW-Based CMOS Transmitter

In recent years, bulk acoustic wave resonators (BAW) in combination with RF circuits have shown a big potential in achieving the low-power consumption and miniaturization level required to address wireless sensor nodes (WSN) applications. A lot of work has been focused on the receiver side, by integrating BAW resonators with low noise amplifiers (LNA) and in frequency synthesis with the design of BAW-based local oscillators, most of them working at fixed frequency due to their limited tuning range. At the architectural level, this has forced the implementation of several single channel transceivers. This thesis aims at exploring the use of BAW resonators in the transmitter, proposing an architecture capable of taking full advantage of them. The main objective is to develop a transmitter for WSN multi-channel applications able to cover the whole 2.4 GHz ISM band and enable the compatibility with wide-spread standards like Bluetooth and Bluetooth Low Energy. Typical transmissions should thus range from low data rates (typically tens of kb/s) to medium data rates (1 Mb/s), with FSK and GFSK modulation schemes, should be centered on any of the channels provided by these standards and cover a maximum transmission range of some tens of meters. To achieve these targets and circumvent the limited tuning range of the BAW oscillator, an up-conversion transmitter using wide IF is used. The typical spurs problems related to this transmitter architecture are addressed by using a combined suppression based on SSB mixing and selective amplification. The latter is achieved by cointegration of a high efficiency power amplifier with BAW resonators, which allows performing spurs filtering while preserving the efficiency. In particular the selective amplifier is designed by including in the PA analysis the BAW resonator parameters, which allows integrating the BAW filter into the passive network loading the amplifier, participating in the drain voltage shaping. Finally, the frequency synthesis section uses a fractional division plus LC PLL filtering and further integer division to generate the IF signals and exploit the very-low BAW oscillator phase noise. The transmitter has been integrated in a 0.18 µm standard digital CMOS technology. It allows addressing the whole 80 MHz wide 2.4 GHz ISM band. The unmodulated RF frequency carrier demonstrates a very-low phase noise of –136 dBc/Hz at 1 MHz offset. The IF spurs are maintained lower than –48 dBc, satisfying the international regulations for output power up to 10 dBm without the use of any quadrature error compensation in the transmitter. This is achieved thanks to the rejection provided by the SSB mixer and the selective amplifier, which can reach drain efficiency of up to 24% with integrated inductances, including the insertion losses of the BAW filter. The transmitter consumes 35.3 mA at the maximum power of 5.4 dBm under 1.6 V (1.2 V for the PA), while transmitting a 1 Mb/s GFSK signal and complying with both Bluetooth and Bluetooth Low Energy relative and absolute spectrum requirements

Test and evaluation of a prototyped sensor-camera network for persistent intelligence, surveillance, and reconnaissance in support of tactical coalition networking environments

This thesis investigated the feasibility of deploying an integrated sensor-camera network in military and law enforcement applications. The system was built using entirely commercial-off-the-shelf technologies. The prototype used the unattended ground sensors combined with digital video surveillance cameras to provide accurate real-time situational awareness, persistent intelligence and remote security. A robust testing and evaluation plan was created to measure the system's performance based on specific metrics. The tests focused primarily on the capabilities of the sensor aspect of the network. Tests were conducted to determine the maximum detection range, probabilities of detection, maximum communications range, and battery life. Mathematical models were created to assist network planners. Additionally, the prototyped system was tested through field exercises as part of the Naval Postgraduate School's Coalition Operating Area Surveillance and Targeting System field demonstrations in California and northern Thailand. Although the sensing capabilities exceeded the minimum metrics, the system was not suitable for use in military applications. However, the prototyped network would work well in less demanding law enforcement environments. Additionally, the feasibility and the need to develop an integrated sensor-camera network were demonstrated.http://archive.org/details/testndevaluation109452780US Navy (USN) author.Approved for public release; distribution is unlimited

Telecommunications Networks

This book guides readers through the basics of rapidly emerging networks to more advanced concepts and future expectations of Telecommunications Networks. It identifies and examines the most pressing research issues in Telecommunications and it contains chapters written by leading researchers, academics and industry professionals. Telecommunications Networks - Current Status and Future Trends covers surveys of recent publications that investigate key areas of interest such as: IMS, eTOM, 3G/4G, optimization problems, modeling, simulation, quality of service, etc. This book, that is suitable for both PhD and master students, is organized into six sections: New Generation Networks, Quality of Services, Sensor Networks, Telecommunications, Traffic Engineering and Routing

Optical Synchronization of Time-of-Flight Cameras

Time-of-Flight (ToF)-Kameras erzeugen Tiefenbilder (3D-Bilder), indem sie Infrarotlicht aussenden und die Zeit messen, bis die Reflexion des Lichtes wieder empfangen wird. Durch den Einsatz mehrerer ToF-Kameras können ihre vergleichsweise geringere Auflösungen überwunden, das Sichtfeld vergrößert und Verdeckungen reduziert werden. Der gleichzeitige Betrieb birgt jedoch die Möglichkeit von Störungen, die zu fehlerhaften Tiefenmessungen führen. Das Problem der gegenseitigen Störungen tritt nicht nur bei Mehrkamerasystemen auf, sondern auch wenn mehrere unabhängige ToF-Kameras eingesetzt werden. In dieser Arbeit wird eine neue optische Synchronisation vorgestellt, die keine zusätzliche Hardware oder Infrastruktur erfordert, um ein Zeitmultiplexverfahren (engl. Time-Division Multiple Access, TDMA) für die Anwendung mit ToF-Kameras zu nutzen, um so die Störungen zu vermeiden. Dies ermöglicht es einer Kamera, den Aufnahmeprozess anderer ToF-Kameras zu erkennen und ihre Aufnahmezeiten schnell zu synchronisieren, um störungsfrei zu arbeiten. Anstatt Kabel zur Synchronisation zu benötigen, wird nur die vorhandene Hardware genutzt, um eine optische Synchronisation zu erreichen. Dazu wird die Firmware der Kamera um das Synchronisationsverfahren erweitert. Die optische Synchronisation wurde konzipiert, implementiert und in einem Versuchsaufbau mit drei ToF-Kameras verifiziert. Die Messungen zeigen die Wirksamkeit der vorgeschlagenen optischen Synchronisation. Während der Experimente wurde die Bildrate durch das zusätzliche Synchronisationsverfahren lediglich um etwa 1 Prozent reduziert.Time-of-Flight (ToF) cameras produce depth images (three-dimensional images) by measuring the time between the emission of infrared light and the reception of its reflection. A setup of multiple ToF cameras may be used to overcome their comparatively low resolution, increase the field of view, and reduce occlusion. However, the simultaneous operation of multiple ToF cameras introduces the possibility of interference resulting in erroneous depth measurements. The problem of interference is not only related to a collaborative multicamera setup but also to multiple ToF cameras operating independently. In this work, a new optical synchronization for ToF cameras is presented, requiring no additional hardware or infrastructure to utilize a time-division multiple access (TDMA) scheme to mitigate interference. It effectively enables a camera to sense the acquisition process of other ToF cameras and rapidly synchronizes its acquisition times to operate without interference. Instead of requiring cables to synchronize, only the existing hardware is utilized to enable an optical synchronization. To achieve this, the camera’s firmware is extended with the synchronization procedure. The optical synchronization has been conceptualized, implemented, and verified with an experimental setup deploying three ToF cameras. The measurements show the efficacy of the proposed optical synchronization. During the experiments, the frame rate was reduced by only about 1% due to the synchronization procedure