Fine-grained channel access in wireless LAN

  • Authors:

  • Ji Fang;Kun Tan;Yuanyang Zhang;Shouyuan Chen;Lixin Shi;Jiansong Zhang;Yongguang Zhang;Zhenhui Tan

  • Affiliations:

  • Institute of BroadbandWireless Mobile Communications, Beijing Jiaotong Univ., Beijing, China and State Key Lab. of Railway Traffic Control and Safety, Beijng Jiaotong Univ., Beijing, China and Sch ...;Microsoft Research Asia, Beijing, China;University of California, Santa Barbara, Goleta, CA and Microsoft Research Asia, Beijing, China;Chinese University of Hong Kong, Hong Kong, China and Microsoft Research Asia, Beijing, China;Massachusetts Institute of Technology, Cambridge, MA and Microsoft Research Asia, Beijing, China;Microsoft Research Asia, Beijing, China;Microsoft Research Asia, Beijing, China;Institute of Broadband Wireless Mobile Communications, Beijing Jiaotong University, Beijing, China and State Key Laboratory of Railway Traffic Control and Safety, Beijng Jiaotong University, Beiji ...

  • Venue:
  • IEEE/ACM Transactions on Networking (TON)
  • Year:
  • 2013

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Abstract

With the increasing of physical-layer (PHY) data rate in modern wireless local area networks (WLANs) (e.g., 802.11n), the overhead of media access control (MAC) progressively degrades data throughput efficiency. This trend reflects a fundamental aspect of the current MAC protocol, which allocates the channel as a single resource at a time. This paper argues that, in a high data rate WLAN, the channel should be divided into separate subchannels whose width is commensurate with the PHY data rate and typical frame size. Multiple stations can then contend for and use subchannels simultaneously according to their traffic demands, thereby increasing overall efficiency. We introduce FICA, a fine-grained channel access method that embodies this approach to media access using two novel techniques. First, it proposes a new PHY architecture based on orthogonal frequency division multiplexing (OFDM) that retains orthogonality among subchannels while relying solely on the coordination mechanisms in existing WLAN, carrier sensing and broadcasting. Second, FICA employs a frequency-domain contention method that uses physical-layer Request to Send/Clear to Send (RTS/CTS) signaling and frequency domain backoff to efficiently coordinate subchannel access. We have implemented FICA, both MAC and PHY layers, using a software radio platform, and our experiments demonstrate the feasibility of the FICA design. Furthermore, our simulation results show FICA can improve the efficiency of WLANs from a few percent to 600% compared to existing 802.11.