A QoS-Aware Ad Hoc Wireless Network for Isolated Rural Environments

Abstract

Abstract. Ad-hoc wireless networks are constituted by routers enabled to establish wireless links among them in a mesh topology. This kind of networks are becoming very popular because of their potential, low cost and ease of deployment, specially when IEEE 802.11b wireless technology is used. There has been a lot of research in the design of protocols and algorithms for improving the performance of this kind of networks, and there have also been many efforts in studying the particular characteristics of their behavior for packet switching, specially when realtime traffic is a concern. However, real implementations and testbeds are scarce, and even those few well known interesting experiences are not QoS-aware and their implementation details are not consistent. This paper presents the design of a 802.11b multi-hop QoS-aware mesh network specifically designed for isolated rural environments by means of adapting the most appropriated software implementations available for IP auto-configuration, QoS-aware traffic control and dynamic multi-hop routing. This proposed network is used as a testbed for driving some initial experiments that aim to measure its performance when supporting both elastic and real-time traffic. The evaluation includes guidelines for a QoS-aware deployment of the network and recommendations for further work that can improve these results.

The design of a wireless solar-powered router for rural environments isolated from health facilities

“…VoIP calls using SIP phones are possible from any point of the wireless network to the Internet or the PSTN, even through seven wireless hops covering a total of 130 km (Cusco network). However, as soon as the network becomes saturated even with low-priority traffic, VoIP calls suffer a negative impact from that saturation unless QoS support is implemented at the IP level, especially in point to multipoint links [9]. The results of QoS tests in the laboratory (using Diffserv architecture) have allowed us to guarantee the QoS to VoIP calls in case of saturation due to less priority traffic.…”

“…The olsrd implementation of OLSR [12] was chosen due to its remarkable maturity and stability, as well as its support of the ETX metric. Our work in [9] mentions lab tests that enabled us to use the OLSR successfully in static ad hoc chains with one wireless interface per node. An important handicap will be that the throughput of wireless links must be estimated to perform bandwidth sharing in a fair way, though the throughput may be variable due to the distance between nodes or to the presence of interferences.…”

“…An important handicap will be that the throughput of wireless links must be estimated to perform bandwidth sharing in a fair way, though the throughput may be variable due to the distance between nodes or to the presence of interferences. Some experiments made by our group with mesh node chains permitted us to demonstrate that a differentiated quality of service of voice, video, and elastic data could be guaranteed if it is possible to delimit the performance of the link [9]. Based on the previous considerations, a simplified DiffServ-like scheme was implemented with the following elements:…”

Modelado y optimización de IEEE 802.11 para su aplicación en el despliegue de redes extensas en zonas rurales aisladas de países en desarrollo

“…Tanto las experiencias citadas como los resultados de investigaci ón te órica debidamente contrastados han sido difundidos en varios congresos científicos internacionales [SDMR06, SOQS06, SOSM06c, SOSM06a, SOSM06b, JJR05], dos contribuciones en monografías (una coincidente con [JJR05] y una pendiente de publicaci ón) y publicaciones en revistas [RMD + 05]. M ás all á del cumplimiento de requisitos formales del doctorado, esta línea de difusi ón ha estado motivada por la certeza, avalada por nuestra experiencia, de que el conocimiento adquirido en el tema de esta tesis es de utilidad real en zonas rurales de países en desarrollo.…”