Vehicular ad hoc networks (VANETs) are highly mobile wireless networks that are designed to support vehicular safety, traffic monitoring, and other commercial applications. Within VANETs, vehicle mobility will cause the communication links between vehicles to frequently be broken. Such link failures require a direct response from the routing protocols, leading to a potentially excessive increase in the routing overhead and degradation in network scalability. In this paper, we propose a new hybrid location-based routing protocol that is particularly designed to address this issue. Our new protocol combines features of reactive routing with location-based geographic routing in a manner that efficiently uses all the location information available. The protocol is designed to gracefully exit to reactive routing as the location information degrades. We show through analysis and simulation that our protocol is scalable and has an optimal overhead, even in the presence of high location errors. Our protocol provides an enhanced yet pragmatic location-enabled solution that can be deployed in all VANET-type environments.

A key design issue in routing for wireless ad hoc networks is scalability. By scalability we mean the ability of the network to support increases in node numbers without significantly degrading network performance. In this work we introduce a new hybrid wireless routing protocol specifically designed to address this issue. Our new protocol combines features of reactive routing with location-based geographic routing, in such a manner so as to efficiently use all the location information available. The protocol is designed to gracefully exit to reactive routing as the location information degrades. Another aspect of our protocol is that it can be spatially dependent - meaning different physical areas of the network can be using quite different routing procedures at the same epoch. That our protocol can dramatically increase scalability can be measured via the routing control overhead which we show, through analysis and simulation, to be significantly reduced relative to current protocols. This is particularly so when a large fraction of nodes possess up-to-date accurate location information. Our new protocol operates even though nodes can be mobile, and it provides an enhanced, yet pragmatic, location-enabled solution that can be deployed in all emerging wireless ad hoc networks.

In the proposed work, we present a secure low-cost speech communication system for long-distance communication. The system utilizes long range (LoRa) technology to transmit speech signals. LoRa technology uses spread-spectrum modulation to enable long-range communication with low power consumption. LoRa modulation allows for data transfer at a slow speed, typically below 22 kbps, which makes it infeasible for transmitting speech. To address this limitation, we suggest a speech coding technique that reduces the overall data rate of speech signals to below 7.5 kbps. This lower rate is more compatible with the LoRa module and ideal for transmitting speech. Moreover, this technique can improve the LoRa transmission range. Additionally, we have developed an encryption-decryption method to ensure the privacy of the messages and prevent unauthorized access by third parties.

In this work we introduce a new routing protocol for Wireless Ad hoc Networks specifically designed for VoIP. Based on modifications to standard geographic routing protocols, our new protocol is designed to deliver two key attributes that hitherto are not simultaneously present in any other single ad hoc routing protocol. Specifically, our protocol maximizes VoIP capacity whilst remaining scalable. Prior to this work, state-of-the-art routing protocols which best address the issue of maximizing VoIP capacity in ad hoc networks can be considered to be those based on the Expected Transmission Count (ETX) metric. As such, the performance benefits of our protocol relative to protocols using ETX are detailed. In the context of VoIP, the most important performance improvement for our protocol relative to ETX protocols, is an up-to factor of two improvement in VoIP capacity for anticipated ad hoc network scenarios. Although designed primarily for wireless VoIP, our protocol can be readily adapted to any real-time application deployed over wireless architectures which contain an ad hoc component.

Vehicular ad hoc networks (VANETs) are highly mobile wireless networks that are designed to support vehicular safety, traffic monitoring, and other applications. Within VANETs, vehicle mobility will cause the communication links between vehicles to be broken frequently. Such link failures require a direct response from the routing protocols, leading to an excessive increase in the routing control overhead and a degradation in network scalability. In this work we investigate how such high link failure rates impact the scalability and performance of a recently proposed hybrid location-based routing protocol, HLAR. A novel feature of HLAR is its ability to possess effective routing strategies which are a spatial function of the location information quality. We show that even in the presence of high link failure rates, HLAR shows high scalability performance, making it an ideal candidate for future routing within emerging intelligent transportation systems. The optimality of HLAR and the impact of location error on its scalability is also discussed.

Cost-effective long-range secure speech communication system for internet of things-enabled applications