Syed R. Rizvi

A Novel Approach to Reduce Traffic Chaos in Emergency and Evacuation Scenarios

This paper proposes a novel chaos reducing information dissemination approach for spatio-temporal traffic information related to first responders and evacuation scenarios using Vehicular Ad Hoc Networks (VANETs). In our approach, we provide an emergency vehicle path clearing technique. Therefore, traffic confusion and chaos is lowered on evacuation and emergency vehicle routes. Simulation results show that our approach works efficiently without fully relying on any message relaying infrastructure.

A durable sensor enabled lifeline support for firefighters

Traditionally, firefighters used to use lifelines (example, ropes) when moving through places on fire under impaired visibility. However, these lifelines have their inherent drawbacks like they sometimes get stuck and limit the operational range. A recent research proposed that firefighters automatically deploy sensor nodes along their paths to establish an ad hoc network that promotes the required level of navigation and communication between firefighters who interact to the system using wearable computing devices. An alternative way to implement such system, is to deploy sensors during building construction or later to build a mission critical network that can be used for emergency purposes. Durability with respect to energy available is one of the primary challenges to the success of such networks. Workforce selection strategies which unevenly consume sensor energy can reduce the lifetime of the network significantly. This work proposes and evaluates a new class of strategies that provides an energy efficient workforce management for mission-critical WSNs (e.g. on-site indoor-navigation support system for slow moving firefighters under impaired visibility). Analytical and simulation results demonstrate that the proposed approach significantly increases network lifetime by evenly consuming sensors energy.

Q-Win --- A New Admission and Handoff Management Scheme for Multimedia LEO Satellite Networks

Low Earth Orbit (LEO) satellite networks are deployed as an enhancement to terrestrial wireless networks in order to provide broadband services to users regardless of their location. In addition to global coverage, these satellite systems support communications with hand-held devices and offer low cost-per-minute access cost, making them promising platform for Personal Communication Services (PCS). LEO satellites are expected to support multimedia traffic and to provide their users with the negotiated Quality of Service (QoS). However, the limited bandwidth of the satellite channel, satellite rotation around the Earth and mobility of end-users makes QoS provisioning and mobility management a challenging task. One important mobility problem is the intra-satellite handoff management. The main contribution of this work is to propose Q-Win, a novel call admission and handoff management scheme for LEO satellite networks. A key ingredient in our scheme is a companion predictive bandwidth allocation strategy that exploits the topology of the network and contributes to maintaining high bandwidth utilization. Our bandwidth allocation scheme is specifically tailored to meet the QoS needs of multimedia connections. The performance of Q-Win is compared to that of two recent schemes proposed in the literature. Simulation results show that our scheme offers low call dropping probability, providing for reliable handoff of on-going calls, good call blocking probability for new call requests, while maintaining bandwidth utilization high.

Energy efficient workforce selection in special-purpose wireless sensor networks

Sensors are typically powered by non-renewable energy sources (e.g. batteries). This fact makes sensors energy very precious resource that must be saved and used wisely. Many protocols have been proposed to optimize energy consumption in different areas of WSNs (e.g. MAC, routing, data aggregation, etc). However, literature has paid less attention to energy efficient workforce management, namely the way sensors are being recruited. In this work, we show that tasking sensors improperly may result in severely uneven consumption of sensors energy. This can negatively impact network performance through reducing network density, creating energy holes or reducing network lifetime. For the limited communication capabilities of sensors, communication in WSNs deployed in large areas is multihop by nature. However for some special WSN applications (e.g firefighting and handicapped assistance) where the central Aggregating Node (AN) (mounted on the firefighter helmet or the handicapped stick) has low mobility, the monitored area of interest is temporarily limited to a small disk that is centered at the AN. Sensors that reside on that moving disk and the AN form a dynamic WSN where a single hop communication model is appropriate and beneficial. For such scenarios, we propose and evaluate a new protocol that provides an energy efficient workforce management for single and multihop WSNs. Analytical and simulation results demonstrate that the proposed approach significantly increases network lifetime by evenly consuming sensors energy. We also propose an algorithm to extend the single hop version of the protocol to a multihop environment.

Tiling-Based Localization Scheme for Sensor Networks Using a Single Beacon

We propose and evaluate a new localization protocol for sensor networks. Contrary to most current localization schemes, this protocol relies on the existence of only a single beacon node. The main idea is to hypothetically tile the deployment area with identical equilateral geometric shapes (e.g. hexagons, triangles... etc). Tiling should be such that the positions of the centers of these shapes can be easily computed relative to the position of the beacon node. After that, the set of nodes that are as close as possible to the centers of these shapes is determined. We refer to these nodes as central nodes. Basically, the positions of these central nodes can be approximated by the positions of the centers of the geometric shapes which can be calculated mathematically. These central nodes can be treated as beacons and the positions of all non-central nodes can be estimated using any range-free protocol (e.g. the centroid). Simulation results show that the accuracy of the proposed protocol is comparable to the accuracy of current localization protocols especially near the beacon node. In addition to this, the achieved localization accuracy increases significantly as the network density increases.

A Traffic Chaos Reduction Approach for Emergency Scenarios

This paper proposes an efficient chaos-reducing information dissemination approach for spatiotemporal traffic information related to first responders and planned evacuation scenarios using vehicular ad hoc networks (VANETs). VANETs have recently been proposed as one of the promising ad-hoc networking techniques that can be used to provide a safe and enjoyable driving experience. In our approach, we provide an emergency vehicle path clearing technique, and real-time resource (e.g. shelter) availability information. Therefore, traffic confusion and chaos is lowered on evacuation and emergency vehicle routes. Simulation results show that our approach works efficiently without fully relying on any message relaying infrastructure.

Energy-Aware Task Assignment and Data Aggregation Protocols in Wireless Sensor Networks

In a typical sensor network environment, sensor energy is considered a precious resource that must be used wisely and only if necessary. Energy-unaware task assignment protocols can deplete the energy of some sensors much more than they do for others. This results in reducing network density around those heavily loaded sensors and eventually creates energy holes that isolate the network into separated islands. These problems have negative impacts on network durability and reliability. To avoid these problems, we propose and evaluate a lightweight management protocol that assigns tasks to sensors based on their energy so that energy consumption is almost even among network sensors. In addition, we propose another mechanism to aggregate data collected by sensors before sending them back to the base station. Our aggregation mechanism supports different aggregation functions including exact evaluation of the minimum, the maximum, and the logical OR and an approximation of the average of the collected sensory data. Using simulation, we compare the lifetime achieved by assigning tasks to network sensors using the proposed protocol against another energy-neutral protocol. Simulation results verified that the proposed approach increases network durability by balancing task load among sensors. Also simulation shows that, under reasonable parameters, the error in the approximated value of the average is less than %3.

Towards maximum longevity of energy limited SANETs

One of the major challenges in wireless sensor networks (WSNs) design lies in the constrained energy available to sensor nodes. Workforce selection strategies which unevenly consume sensor energy can reduce the lifetime of the network significantly. This work proposes and evaluates a new class of strategies that provides an energy efficient workforce management for WSNs. Analytical and simulation results demonstrate that the proposed approach significantly increases network lifetime by evenly consuming sensors power.

A time-critical information diffusion model in vehicle ad hoc networks

The diffusion of time-critical information, like traffic alert messages, is critical and challenging in Vehicle Ad hoc Networks (VANETs). It is critical because lives of people on the road are at stake and is challenging due to a combination of highly dynamic mobility patterns, which result in rapidly changing network topologies, combined with the fast movement of vehicles and highly dynamic traffic patterns. Flooding-based alert diffusion among vehicles has a strong similarity with diffusion of a new product among people. Applying a diffusion model to alert messages enables the dissemination modeling of the alert messages among vehicles, and thus opening an opportunity to adopt appropriate strategies to recovery from the traffic accidents. In this paper, a diffusion model is developed for a flooding-based alert message diffusion algorithm and the diffusion speed is explored. The fact that information value (or importance) is decreasing with time and distance, is also considered in the proposed model. We analytically investigate the impact parameters on time-critical information diffusion by mapping to the classic BASS diffusion model [1, 2]. The analytical model allows the evaluation at runtime and enables vehicles to dynamically adapt their diffusion strategies depending on the local node density.

Microcontroller programming : an introduction

Number Systems, Operations, and Codes Digital versus Analog Quantities Digital Numbering System (Base 10) Binary Numbering System (Base 2) Octal Numbering System (Base 8) Hexadecimal Numbering System (Base 16) Binary-Coded-Decimal System Binary Conversions Binary Operations Octal Conversions Hexadecimal Conversions Hexadecimal Operations 1s and 2s Complements of Binary Numbers Signed Numbers The ASCII Code Semiconductors and Digital Logic Diode Logic The Inverter The AND Gate The OR Gate The NAND Gate The NOR Gate The Exclusive-OR Gate The Exclusive-NOR Gate Microcontroller Hardware A Transistor as a Switch The TTL Integrated Circuit The CMOS Integrated Circuit Using Integrated-Circuit Logic Gates Seven-Segment Displays Liquid-Crystal Displays Keypads The 68HC11/68HC12 Microcontroller EVBU/BUFFALO Microcontroller Software Programming Concepts System Software Developing a Program Flow and State Diagrams HC11 Programming Model HC11 Memory-Addressing Modes Instructions Data Movement Arithmetic Logic Shifting and Rotating Multiplication and Division CCR (Flag) Manipulation Bit-Level Operations Control Structures and Subroutines Indexed Addressing Mode Jumping and Branching Compare Instructions Conditional Flow and Program Loops Stack Operation Subroutines BUFFALO Subroutine Hello, World! Creating Source Code Files Assembling Programs Ten Useful Programs Input/Output (I/O) Ports Data Transfer Mode Port A Port B Port C Port D and Port E I/O Using Handshaking A Project Using Port B Interrupts Basics of an Interrupt Servicing an Interrupt Interrupt Control Maskable Interrupts Output Compare Nonmaskable Interrupts Interrupts on the EVBU A Project with Interrupts Analog Capture Analog-to-Digital Conversion A/D Tools A/D Operation A Project with Analog Capture Input Capture Basic Modules of Input Capture Input-Capture Registers Input Edge Detection Logic Interrupt Generation Logic A Project with Input Capture Higher-Level Programming Levels in Programming Languages C Programming Examples A Project with C Appendix 1-Supplemental Website Appendix 2-States and Resolution for Binary Numbers Appendix 3-Basic Boolean Theorems and Identities Appendix 4-The Resistor Color Code Appendix 5-Waterfall Software Development Lifecycle Model Appendix 6-Loading Your Program into the EEPROM Appendix 7-Pulse-Width Modulation Appendix 8-HC11 Instruction Set Appendix 9-Comprehensive Glossary