1. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 1 Proposal for Higher Spatial Reuse Date: 2005-03-16 Authors: Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdfpatcom@ieee.org

2. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 2 Issues IEEE802.11s will be based on AP’s using existing standards (IEEE802.11a/b/g) When IEEE802.11s becomes a standard (in 2 years?) the dominant AP’s will most likely use 802.11n and/or other smart antenna techniques –Many AP vendors already have products with MIMO –A primary application of IEEE802.11s is residential systems which may include multimedia distribution, a main area of application of 802.11n

3. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 3 Issues (cont.) IEEE802.11s may not work well with 802.11n AP’s or AP’s with smart antennas: –Addition of smart antenna AP’s into mesh networks designed without smart antenna considerations can actually degrade performance (Even though the link performance is higher, the network performance can be worse).

4. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 4 Issues (cont.) The ability to have higher spatial reuse greatly increases the capacity of a mesh network: –Smart antennas can suppress co-channel interference (up to M-1 co-channel interferers with M antennas), allowing for spatial reuse in the adjacent cell –Spatial multiplexing (as proposed for IEEE802.11n) with MIMO permits multiple channels in the same frequency band

5. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 5 Issues (cont.) The ability to have spatial reuse greatly increases the capacity of a mesh network (cont.): –These techniques can increase the link capacity by a factor of M or more (2, 4, or even 8 times capacity of networks without smart antennas – with 2 or 4 antennas at the AP) –These gains can dwarf the variation of performance of various routing techniques/protocols, but these gains can be lost if IEEE802.11s techniques do not accommodate smart antenna capabilities

6. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 6 Concerns The functional requirements state that "out of scope" are: – Specification of BSS measurements (e.g., 802.11k AP-STA measurements) TGs may use relevant measurements defined in TGk or other groups that are relevant for a WLAN Mesh, but the group does not intend to modify BSS-specific measurements –MAC extension to support the use of dynamic directional antenna. Likely requires high complexity, e.g. TDMA scheduling to know when a neighbor’s antenna is pointed at a node. – Algorithms to steer directional antennas.

7. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 7 Concerns (Cont.) Specification of BSS measurements (e.g., 802.11k AP-STA measurements): –IEEE802.11k (draft) is currently not “antenna aware” –We are working to modify IEEE802.11k to add this feature, not just for mesh networks, as this feature is essential for effective use of smart antennas in any network/system –Smart antennas can be used in current (standard-based) systems. Algorithms to steer directional antennas: –This does not (and should not) be an issue for consideration of smart antennas in IEEE802.11s (and we aren’t proposing this)

8. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 8 Smart Antenna Types SIGNAL OUTPUT BEAM SELECT SIGNAL BEAMFORMER SIGNAL INTERFERENCE BEAMFORMER WEIGHTS Directional Antenna Adaptive Array

9. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 9 Concerns (Cont.) Concern: “MAC extension to support the use of dynamic directional antenna - Likely requires high complexity”: –Consideration of smart antennas can be done without significant increase in complexity (particularly, the consideration of adaptive antenna arrays, rather than dynamic directional antennas – adaptive arrays are the main type of smart antenna to be considered for products by AP vendors) –Since interference suppression/spatial reuse can increase capacity so substantially, consideration of these capabilities can permit an IEEE802.11s standard to use less complex routing algorithms/protocols, yet have performance higher than more complex techniques that don’t consider higher frequency reuse with smart antenna capabilities

10. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 10 Implementation Capabilities that need to be included in a proposal: –Modify frequency assignment techniques to include reusing a frequency (up to M-1 times) if AP’s have M antennas –Modify the inclusion of multiple radio capability to include multiple radios in the same channel

11. doc.: IEEE 802.11-05/0267r0 Submission Jack Winters March 2005 Slide 11 Summary Smart antenna techniques need to be considered in IEEE802.11s Smart antenna capabilities can be included in IEEE802.11s without increasing the complexity of the standard