Abstract
Smart antennas can improve spatial reuse in a wireless network through interference suppression. However, interference suppression requires support from clients in the form of channel estimation, which existing clients do not support. In this work, we explore practical solutions to obtain spatial reuse with smart antennas without requiring hardware changes to clients. To this end, we design a novel solution for improving spatial reuse in indoor WLANs which uses ‘approximate’ channel estimates and still yields close to ideal performance. Our solution called Light-weight Multi-Antenna Spatial Reuse (LSR) consists of (i) a multi-link channel estimation scheme that can be realized with simple Received Signal Strength (RSSI) measurements that existing WLAN clients provide readily, (ii) a low-complexity scheduler to decide the subset of beamformed links that must be active concurrently. We demonstrate that the estimates obtained using this scheme when used with a multi-link beamforming technique such as Zero Forcing yields significant interference suppression benefits. We implement the channel estimation scheme on a testbed of software radio clients to demonstrate its practical feasibility. Further, we evaluate the performance of LSR using extensive signal strength traces from 802.11g Access Points equipped with eight element antenna arrays in an indoor office environment. The results indicate that LSR achieves close to the performance obtained with an optimal scheme that uses accurate channel estimates and also improves the median sum rate of indoor users by up to 2.7x over competing approaches.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Paulraj, A., Nabar, R., Gore, D.: Introduction to space-time wireless communications. Cambridge University Press (May 2003)
Skjevling, H., Gesbert, D., Hjorungnes, A.: Low-complexity distributed multibase transmission and scheduling. Eurasip Journal on Advances in Signal Processing (2008)
Lakshmanan, S., Sundaresan, K., Rangarajan, S., Sivakumar, R.: Practical beamforming using rssi measurements on off the shelf wireless clients. In: ACM Internet Measurement Conference (November 2009)
Ramanathan, R.: On the Performance of Ad Hoc Networks with Beamforming Antennas. In: ACM MOBIHOC (2001)
Ieee 802.11n working group draft, http://www.ieee802.org/11
Li, Y., Winters, J.H., Sollenberger, N.R.: MIMO-OFDM for Wireless Communications: Signal Detection with Enhanced Channel Estimation. IEEE Transactions on Communication 50(9), 1471–1477 (2002)
Minn, H., Al-dhahir, N.: Optimal training signals for mimo ofdm channel estimation in the presence of frequency offset and phase noise. IEEE Transactions on Communications 54(10) (October 2006)
Yoo, T., Jindal, N., Goldsmith, A.: Multi-antenna broadcast channels with limited feedback and user selection. IEEE JSAC 25(7) (September 2007)
Chae, C.-B., Inoue, T., Mazzarese, D., Heath, R.W.: Non-iterative multiuser mimo coordinated beamforming with limited feedforward. In: IEEE ICASSP (April 2008)
Samardzija, D., Huang, H., Valenzuela, R.A., Sizer, T.: An experimental downlink multiuser mimo system with distributed and coherently-coordinated transmit antennas. In: IEEE ICC (2007)
Kecicioglu, B., Ozdemir, O., Torlak, M.: Opportunistic multiple antenna systems: Channel estimation and experimental results. In: IEEE ICC (2006)
Liu, X., Sheth, A., Kaminsky, M., Papagiannaki, K., Seshan, S., Steenkiste, P.: Dirc: Increasing indoor wireless capacity using directional antennas. In: ACM SIGCOMM (August 2009)
Gollakota, S., Perli, S.D., Katabi, D.: Interference alignment and cancellation. In: ACM SIGCOMM (August 2009)
Lakshmanan, S., Sundaresan, K., Khojastepour, M., Rangarajan, S.: Towards adaptive beamforming in indoor wireless networks: An experimental approach. In: IEEE Infocom (Miniconference) (April 2009)
Lakshmanan, S., Sundaresan, K., Khojastepour, M., Rangarajan, S.: Spatial reuse with smart antennas in indoor wlans (July 2009), http://www.nec-labs.com/~karthiks/papers/tr-lsr.pdf
Fidelity-comtech inc., http://www.fidelity-comtech.com
Ettus inc., http://www.ettus.com
Gnuradio project, http://www.gnuradio.org/trac
Adroit project, https://acert.ir.bbn.com/projects/adroitgrdevel
Ramachandran, K., Kokku, R., Zhang, H., Gruteser, M.: Symphony: Synchronous two-phase rate and power control in 802.11 wlans. In: ACM MOBISYS (2008)
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering
About this paper
Cite this paper
Lakshmanan, S., Sundaresan, K., Khojastepour, M., Rangarajan, S. (2012). Practical Multi-antenna Spatial Reuse in WLANs. In: Tomkos, I., Bouras, C.J., Ellinas, G., Demestichas, P., Sinha, P. (eds) Broadband Communications, Networks, and Systems. BROADNETS 2010. Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, vol 66. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-30376-0_11
Download citation
DOI: https://doi.org/10.1007/978-3-642-30376-0_11
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-30375-3
Online ISBN: 978-3-642-30376-0
eBook Packages: Computer ScienceComputer Science (R0)