Mari Carmen Domingo

Energy analysis of routing protocols for underwater wireless sensor networks

Underwater wireless sensor networks consist of a certain number of sensors and vehicles that interact to collect data and perform collaborative tasks. Designing energy-efficient routing protocols for this type of networks is essential and challenging because sensor nodes are powered by batteries, which are difficult to replace or recharge, and because underwater communications are severely affected by network dynamics, large propagation delays and high error probability of acoustic channels. The goal of this paper is to analyze the total energy consumption in underwater acoustic sensor networks considering two different scenarios: shallow water and deep water. We propose different basic functioning principles for routing protocols in underwater wireless sensor networks (relaying, direct transmission and clustering) and analyze the total energy consumption for each case, establishing a comparison between them.

A Distributed Clustering Scheme for Underwater Wireless Sensor Networks

Underwater wireless sensor networks (UWSNs) pose many challenges due to the intrinsic properties of underwater environments such as large propagation delays, node mobility and limited bandwidth capacity of acoustic channels. In this paper we present DUCS (distributed underwater clustering scheme), a new GPS-free routing protocol for UWSNs that does not use flooding techniques, minimizes the proactive routing message exchange and uses data aggregation to eliminate redundant information. Besides, DUCS assumes random node mobility and compensates the high propagation delays of the underwater medium using a continually adjusted timing advance combined with guard time values to minimize data loss and maintain communication quality. The simulations carried out demonstrate the effectiveness of the proposed scheme.

Design and Analysis of a GPS-free Routing Protocol for Underwater Wireless Sensor Networks in Deep Water

In this paper we present DUCS (distributed underwater clustering scheme), a new GPS-free clustering scheme specifically designed for underwater wireless sensor networks. DUCS is adapted to the intrinsic properties of underwater environments, such as long propagation delays, low data rates and difficulty of synchronization. DUCS minimizes the proactive routing message exchange, and compensates the high propagation delays of the underwater medium using a continually adjusted timing advance combined with guard time values to minimize data loss and maintain communication quality. The simulations carried out in deep water demonstrate the effectiveness of the proposed scheme in these environments.

A simple routing scheme for improving ad hoc network survivability

This article presents a new version of the dynamic source routing (DSR) protocol that favours the selection of a route containing nodes with high battery levels, in order to maximize the lifetime of the ad hoc mobile network as a whole. This proposal implies little modifications to the original algorithm. After a quantitative analysis, we see simulation results that indicate that the proposed scheme, SEADSR (simple energy aware DSR), outperforms the standard DSR in terms of network survivability and network capacity.

An Adaptive Gateway Discovery Algorithm to support QoS When Providing Internet Access to Mobile Ad Hoc Networks

When a node in an ad hoc network wants Internet access, it needs to obtain information about the available gateways and it should select the most appropriate of them. In this work we propose a new gateway discovery scheme suitable for real-time applications that adjusts the frequency of gateway advertisements dynamically. This adjustment is related to the percentage of real-time sources that have quality of service problems because of excessive end-to-end delays. The optimal values for the configuration parameters (time interval and threshold) of the proposed adaptive gateway discovery mechanism for the selected network conditions have been studied with the aid of simulations. The scalability of the proposed scheme with respect to mobility as well as the impact of best-effort traffic load have been analyzed. Simulation results indicate that the proposed scheme significantly improves the average end-to-end delay, jitter and packet delivery ratio of real-time flows; the routing overhead is also reduced and there is no starvation of best-effort traffic.

An interaction model between ad-hoc networks and fixed IP networks for QoS support

We propose a new protocol, named DS-SWAN (Differentiated Services-Stateless Wireless Ad Hoc Networks), to support end-to-end QoS (Quality of Service) in ad hoc networks connected to fixed DiffServ domains. DS-SWAN warns nodes in the ad hoc network when congestion is excessive for the correct functioning of real-time applications. These nodes react by slowing down best-effort traffic. Simulation results indicate that DS-SWAN significantly improves end-to-end delays for real-time flows without starvation of background traffic. In this work we introduce different conditions to force that a wireless node throttles its best-effort traffic and study their behaviour and differences.

A cooperation model between ad hoc networks and fixed networks for service differentiation

We propose a new protocol, named DS-SWAN (differentiated services-stateless wireless ad hoc networks), to support end-to-end QoS (quality of service) in ad hoc networks connected to fixed DiffServ domains. DS-SWAN warns nodes in the ad hoc network when congestion is excessive for the correct functioning of real-time applications. These nodes react by slowing down best-effort traffic. Simulation results indicate that DS-SWAN significantly improves end-to-end delays for real-time flows without starvation of background traffic.

QoS support between ad hoc networks and fixed IP networks

We propose a new protocol, named DS-SWAN (Differentiated Services-Stateless Wireless Ad Hoc Networks), to support end-to-end Quality of Service (QoS) in ad hoc networks connected to a fixed DiffServ domain. When congestion is excessive for the correct functioning of real-time applications, DS-SWAN determines the source of the problem, warns the nodes in the ad hoc network if it is the case and the nodes react by slowing down best-effort traffic. Furthermore, we present an associated routing protocol for the ad hoc network in this context, named SD-AODV (Service Differentiation-Ad Hoc On-Demand Distance Vector), where new route requests are suppressed at certain nodes to maintain the desired QoS requirements for real-time flows. A simulation study is presented for the case when traffic is sent from the ad hoc network towards the fixed network as well as in the opposite direction. The scalability of DS-SWAN with respect to the network size, number of real-time traffic sources, node mobility and best-effort traffic load is analyzed. Simulation results indicate that DS-SWAN and SD-AODV significantly improve end-to-end delays and jitter for real-time flows without starvation of background traffic.

Analysis of VBR VoIP traffic for ad hoc connectivity with a fixed IP network

We study how to provide end-to-end QoS (quality of service) between nodes in a mobile ad hoc network and a fixed IP network that supports differentiated services (DiffServ). The ad hoc network incorporates a stateless wireless ad hoc networks (SWAN) scheme to support service differentiation. SWAN uses local rate control for best-effort traffic and sender-based admission control for real-time traffic. Best-effort traffic and real-time flows that have not yet been admitted as real-time sessions are delayed by a best-effort traffic shaper. In this paper, we propose FA-SWAN (fast admission-SWAN), a modified version of the SWAN QoS scheme. In contrast to SWAN, FA-SWAN enables the real-time flows to bypass the traffic shaper during the admission control process. Only after a real-time session is rejected as such, will the traffic be considered as best-effort and will have to be rate controlled. The results indicate that the modifications improve the performance of the voice application in comparison with the original SWAN.

Quality of Service Support in Wireless Ad Hoc Networks Connected to Fixed DiffServ Domains

This paper analyzes the provision of end-to-end Quality of Service between nodes in a mobile ad hoc network and a fixed IP network that supports Differentiated Services. The ad hoc network incorporates the Stateless Wireless Ad Hoc Networks (SWAN) model to perform admission control for real-time traffic flows. We propose a new protocol, named DS-SWAN (Differentiated Services-SWAN), where end-to-end delays and loss rates of real-time traffic are monitored continuously at the destination nodes in the fixed network and at the edge routers respectively. In this way, nodes in the ad hoc network are warned when congestion is excessive for the correct functioning of a real-time application (specifically, Variable Bit Rate Voice-over-IP), so that the nodes restrain best-effort traffic in order to favour real-time flows. The results indicate that DS-SWAN significantly improves end-to-end delays without starvation of background traffic, adapting itself to changing traffic and network conditions in a relatively small ad hoc network. Besides, we compare different notification procedures in DS-SWAN aimed to improve scalability.