From single radio access technology to heterogeneous wireless networks

Filali, Fethi
Habilitation à diriger des recherches (French qualification for conducting Phd theses)

We present in this dissertation our research contributions in the area of wireless networking. The first part is devoted to our works on the area of single radio access technology networks including WLANs, MANETs, WiMAX, wireless sensor networks, and wireless vehicular networks. For WLAN and MANETs, we addressed several research issues such as distributed multihop medium access and the interactions of TCP with the 802.11 MAC protocol. A multi-hop distributed QoS-aware MAC protocol has been designed and extensively evaluated. For wireless vehicular communications, we tacked two issues: (geographic) unicast routing and vehicular movement modeling. A movement prediction cross-layer architecture called MOPR has been developed and applied for reactive, proactive, and position-based routing protocols as well as to enhance the performance of the 802.11 MAC protocol. We also designed a new open-source vehicular mobility simulator called VanetMobiSim integrating several realistic macroscopic and microscopic features. For wireless sensor networks, we focused on stability, routing, and topology management issues. We addressed the problem of optimal routing that aims at minimizing the end-to-end delays. Since we allowed the traffic splitting at source nodes, we proposed an algorithm that seeks the Wardrop equilibrium instead of a single least delay path. For WiMAX, we designed a novel QoS architecture which includes a call admission control policy and a hierarchical scheduling algorithm. The CAC policy we proposed adopts a Min-Max fairness approach making efficient and fair use of the available resources. The scheduling algorithm flexibly adjusts uplink and downlink bandwidth to serve unbalanced traffic. Furthermore, an original analytical framework has been developed based on technical properties and system profiles specified by the IEEE 802.16 standard for systems using the WirelessMAN-OFDM air interface. This framework has been the basis of a quantitative study of the performances bounds of WiMAX and the impact of some operational features like fragmentation and packing. The second part focuses on heterogeneous wireless networks. We designed, developed, and experimented a flexible abstraction architecture for the support of heterogeneous wireless technologies including 802.11, UMTS, DVB-T, and EDGE. This architecture integrates a Joint Radio Resource Management module allowing a mobile terminal to be always connected, in a transparent fashion, to the ``best'' access point/base station of the ``best'' available wireless technology. To guide the selection of the most convenient WLAN AP, we developed and experimented a novel technique for the estimation of the available bandwidth in a 802.11-based wireless LAN (WLAN). The proposed technique is implemented in a sniffing-based tool (called wimeter) which captures and analyzes on real-time the frames sent in a pre-configured WLAN. Finally, we proposed a complete self-organizing framework for wireless heterogeneous sensor-actor networks (SANETs) which includes an actuator discovery and selection protocol and sensor-sensor/sensor-actuator/actuator-actuator coordination protocols. Moreover, a MAC protocol has been developed for sensor-sensor and actuator-sensor wireless transmissions

Systèmes de Communication
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