2nd International IEEE Conference on Communication System Software and Middleware

Research Article

Optimal Scheduling for Dynamic Channel Allocation in Wireless LANs

  • @INPROCEEDINGS{10.1109/COMSWA.2007.382627,
        author={S.  Jamaloddin Golestani and Rajeev  Rastogi and Mark Smith},
        title={Optimal Scheduling for Dynamic Channel Allocation in Wireless LANs},
        proceedings={2nd International IEEE Conference on Communication System Software and Middleware},
        publisher={IEEE},
        proceedings_a={COMSWARE},
        year={2007},
        month={7},
        keywords={Cellular networks  Channel allocation  Geometry  Interference  Optimal scheduling  Radio spectrum management  Telephony  Throughput  Wireless LAN  Wireless networks},
        doi={10.1109/COMSWA.2007.382627}
    }
    
  • S. Jamaloddin Golestani
    Rajeev Rastogi
    Mark Smith
    Year: 2007
    Optimal Scheduling for Dynamic Channel Allocation in Wireless LANs
    COMSWARE
    IEEE
    DOI: 10.1109/COMSWA.2007.382627
S. Jamaloddin Golestani1, Rajeev Rastogi2, Mark Smith3
  • 1: Isfahan University of Technology, Iran.
  • 2: Bell Labs, Lucent Technologies, Bangalore, India.
  • 3: Bell Labs, Lucent Technologies, Murray Hill, NJ 07974

Abstract

Channel allocation schemes that have been used in cellular wireless networks have limited applicability to wireless LANs (WLANs) because of the small number of available channels and irregular cell geometries in WLAN environments. In this paper, we propose a dynamic, frame-based channel allocation architecture for WLANs. In this architecture, time is divided into a sequence of consecutive frames (in the order of milliseconds), and in each frame, only a non-interfering subset of access points (APs) is activated. Under broad traffic assumptions, we prove that the attainable system throughput can be optimized by scheduling APs and allocating channels in each frame such that a weighted sum of queue sizes at the activated APs is maximized. This optimality criterion for AP scheduling and channel allocation leads to a novel graph problem which is a variant of the well-known maximum independent set problem. We develop an approximation algorithm that has quadratic time complexity (in the number of APs) and, under certain conditions, yields a constant (6) factor approximation bound. Using the ns2 simulator we conducted experiments to compare our frame-based approach to static channel allocation. Results of our simulation indicate that our approach is able to deliver system throughput improvements of more than 50%.