ZOOMOUT GEOGRAPHIC LOCATION SERVICE (ZGLS): A FLAT QUORUM-BASED AND RELIABLE LOCATION MANAGEMENT PROTOCOL FOR VANETs

By using position-based routing in VANET, a vehicle makes forwarding decision based on the geographic position of destination and single-hop neighbours. The position of a destination is obtained through location service, while the positions of single-hop neighbours are obtained through neighbour discovery. Location service is a process where a destination sends its location updates towards location server vehicles through hop-by-hop forwarding, and a source obtains this information from such location servers through location query. Neighbour discovery is a process where a vehicle advertises its position to all neighbours within a broadcast range. In many cases, adaptive neighbour discovery schemes are more suitable, but they suffer from high channel load and stale neighbour information

ZOOMOUT GEOGRAPHIC LOCATION SERVICE (ZGLS): A FLAT QUORUM-BASED AND RELIABLE LOCATION MANAGEMENT PROTOCOL FOR VANETs

By using position-based routing in VANET, a vehicle makes forwarding decision based on the geographic position of destination and single-hop neighbours. The position of a destination is obtained through location service, while the positions of single-hop neighbours are obtained through neighbour discovery. Location service is a process where a destination sends its location updates towards location server vehicles through hop-by-hop forwarding, and a source obtains this information from such location servers through location query. Neighbour discovery is a process where a vehicle advertises its position to all neighbours within a broadcast range. In many cases, adaptive neighbour discovery schemes are more suitable, but they suffer from high channel load and stale neighbour information

Machine-Learning Based Channel Quality and Stability Estimation for Stream-Based Multichannel Wireless Sensor Networks

Wireless sensor networks (WSNs) have become more and more diversified and are today able to also support high data rate applications, such as multimedia. In this case, per-packet channel handshaking/switching may result in inducing additional overheads, such as energy consumption, delays and, therefore, data loss. One of the solutions is to perform stream-based channel allocation where channel handshaking is performed once before transmitting the whole data stream. Deciding stream-based channel allocation is more critical in case of multichannel WSNs where channels of different quality/stability are available and the wish for high performance requires sensor nodes to switch to the best among the available channels. In this work, we will focus on devising mechanisms that perform channel quality/stability estimation in order to improve the accommodation of stream-based communication in multichannel wireless sensor networks. For performing channel quality assessment, we have formulated a composite metric, which we call channel rank measurement (CRM), that can demarcate channels into good, intermediate and bad quality on the basis of the standard deviation of the received signal strength indicator (RSSI) and the average of the link quality indicator (LQI) of the received packets. CRM is then used to generate a data set for training a supervised machine learning-based algorithm (which we call Normal Equation based Channel quality prediction (NEC) algorithm) in such a way that it may perform instantaneous channel rank estimation of any channel. Subsequently, two robust extensions of the NEC algorithm are proposed (which we call Normal Equation based Weighted Moving Average Channel quality prediction (NEWMAC) algorithm and Normal Equation based Aggregate Maturity Criteria with Beta Tracking based Channel weight prediction (NEAMCBTC) algorithm), that can perform channel quality estimation on the basis of both current and past values of channel rank estimation. In the end, simulations are made using MATLAB, and the results show that the Extended version of NEAMCBTC algorithm (Ext-NEAMCBTC) outperforms the compared techniques in terms of channel quality and stability assessment. It also minimizes channel switching overheads (in terms of switching delays and energy consumption) for accommodating stream-based communication in multichannel WSNs

A Driver Safety Information Broadcast Protocol for VANET

Due to the highly mobile nature of VANET, especially on highways, a reliable and fast penetration of emergency messages is required so that in-time decisions can be performed. A broadcast routing protocol can perform flooding in sparse network but it will suffer from high control overhead, higher delay and lower packet delivery ratio in dense environment. Since, a significant number of VANET messages including neighbour discovery, safety, destination discovery, location and service advertisements is broadcast, therefore, the area of broadcast routing is important and needs careful design considerations. In this article, we propose ZoomOut Broadcast Routing Protocol for driver safety information dissemination in VANET. In ZBRP, 1-hop neighbour discovery messages are used in an intelligent way based on the speed and inter-vehicle distance of 1-hop neighbours to select a front and a behind vehicle. A neighbour from the front area is called front relative while the neighbour from behind area is called behind relative. During the processing of multi-hop safety messages, only a front or a behind relative rebroadcasts a safety message whereas non-relatives drop it. ZBRP is compared with G-AODV, PGB and DV-CAST through ns-2 simulations. The results show that ZBRP performs better than the stated protocols in terms of network penetration time, packet delivery and broadcast suppression

Congestion Detection and Alleviation in Multihop Wireless Sensor Networks

Multiple traffic flows in a dense environment of a mono-sink wireless sensor network (WSN) experience congestion that leads to excessive energy consumption and severe packet loss. To address this problem, a Congestion Detection and Alleviation (CDA) mechanism has been proposed. CDA exploits the features and the characteristics of the sensor nodes and the wireless links between them to detect and alleviate node- and link-level congestion. Node-level congestion is detected by examining the buffer utilisation and the interval between the consecutive data packets. However, link-level congestion is detected through a novel procedure by determining link utilisation using back-off stage of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). CDA alleviates congestion reactively by either rerouting the data traffic to a new less congested, more energy-efficient route or bypassing the affected node/link through ripple-based search. The simulation analysis performed in ns-2.35 evaluates CDA with Congestion Avoidance through Fairness (CAF) and with No Congestion Control (NOCC) protocols. The analysis shows that CDA improves packet delivery ratio by 33% as compared to CAF and 54% as compared to NOCC. CDA also shows an improvement in throughput by 16% as compared to CAF and 36% as compared to NOCC. Additionally, it reduces End-To-End delay by 17% as compared to CAF and 38% as compared to NOCC