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Self-organized Wireless Access Networks (SWAN) |
The increased popularity of IEEE 802.11 WLANs has led to dense deployments in urban areas. Such high density leads to sub-optimal performance unless the interfering networks learn how to optimally share the spectrum. In this project we look into distributed algorithms that allow (i) multiple interfering 802.11 WLANs to select their operating frequency in a way that minimizes global interference, (ii) clients to choose their Access Point so that the bandwidth of all interfering networks is shared optimally, (iii) APs and clients to select their transmission power and Clear Channel Assessment (CCA) threshold so as to maximize the overall network capacity. The proposed algorithms optimize global network performance based on local information. They do not require explicit coordination among the wireless devices, and can thus operate in diverse environments with no single administrative authority. We study implementation requirements and show that significant benefits can be gained even within incremental deployments and in the presence of non-cooperating wireless clients.
Future steps involve the migration of our self-organization algorithms from the infrastructure wireless LAN space to address self-organization of mesh networks.Throughout the course of the project we evaluate the performance of the proposed algorithms using two different approaches: (i) Simulations (in Opnet and Qualnet) addressing the performance of the proposed schemes in large scale environments, and (ii) real implementations on the Intel 2915ABG wireless cards.
The proposed functionality has so far been tested in a 80-node testbed deployed across the 3 stories of the William Gates building at University of Cambridge, in a 40 node testbed deployed in the computer science department of University California Riverside (UCR), and in a 60 node testbed deployed in the computer science department of University of Wisconsin in Madison. All testbeds consist of Soekris 4825 nodes with two mini-PCI interfaces hosting the Intel 2915 ABG cards. The wireless NICs implement a proprietary version of the firmware and microcode facilitating the measurement of PHY and MAC layer parameters that cannot be accessed in commercial cards.
Publications produced by SWAN are the following:
Current collaborators are:
Past collaborators are: