CAPWAP Extension for 802.11n and Power/channel Reconfiguration
draft-ietf-opsawg-capwap-extension-00

Network Working Group                                          Y.F. Chen
Internet-Draft                                                  D.L. Liu
Intended status: Standards Track                                 H. Deng
Expires: November 10, 2013                                  China Mobile
                                                                Lei. Zhu
                                                                  Huawei
                                                            May 09, 2013

     CAPWAP Extension for 802.11n and Power/channel Reconfiguration
                 draft-ietf-opsawg-capwap-extension-00

Abstract

   CAPWAP binding for 802.11 is specified by RFC5416 and it was based on
   IEEE 802-11.2007 standard.  After RFC5416 was published in 2009,
   there was several new amendent of 802.11 has been published.  802.11n
   is one of those amendent and it has been widely used in real
   deployment.  This document extends the CAPWAP binding for 802.11 to
   support 802.11n.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 10, 2013.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect

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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   2
   3.  CAPWAP 802.11n support  . . . . . . . . . . . . . . . . . . .   2
   4.  CAPWAP extension for 802.11n support  . . . . . . . . . . . .   3
   5.  Power and Channel auto reconfiguration  . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  13
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   10. Normative References  . . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   IEEE 802.11n standard was published in 2009 and it is an amendment to
   the IEEE 802.11-2007 standard to improve network throughput.  The
   maximum data rate increases to 600Mbit/s physical throughput rate.
   In the physical layer, 802.11n use OFDM and MIMO to achive the high
   throughput.  802.11n use multiple antennas to form antenna array
   which can be dynamically adjusted to imporve the signal strength and
   extend the coverage.

   There are couple of capabilities of 802.11n need to be supported by
   CAPWAP control message such as radio capability, radio configuration
   and station information.

2.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  CAPWAP 802.11n support

   IEEE 802.11n standard was published in 2009 and it is an amendment to
   the IEEE 802.11-2007 standard to improve network throughput.  The
   maximum data rate increases to 600Mbit/s physical throughput rate.
   In the physical layer, 802.11n use OFDM and MIMO to achive the high
   throughput.  802.11n use multiple antennas to form antenna array
   which can be dynamically adjusted to imporve the signal strength and
   extend the coverage.

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   802.11n support three modes of channel usage: 20MHz mode, 40Mhz mode
   and mixed mode.802.11n has a new feature called channel binding.  It
   can bind two adjacent 20MHz channel to one 40MHz channel to improve
   the throughput.If using 40Mhz channel configuration there will be
   only one non-overlapping channel in 2.4GHz.  In the large scale
   deployment scenario, operator need to use 20MHz channel configuration
   in 2.4GHz to allow more non-overlapping channels.

   In MAC layer, a new feature of 802.11n is Short Guard Interval(GI).
   802.11a/g use 800ns guard interval between the adjacent information
   symbols.  In 802.11n, the GI can be configured to 400nm under good
   wireless condition.

   Another feature in 802.11 MAC layer is Block ACK.  802.11n can use
   one ACK frame to acknowledge several MPDU receiving event.

   CAPWAP need to be extended to support the above new 802.11n features.
   For example, CAPWAP should allow the access controller to know the
   supported 802.11n features and the access controller should be able
   to configure the differe channel binding modes.  One possible
   solution is to extend the CAPWAP information element for 802.11n.

4.  CAPWAP extension for 802.11n support

   There are couple of capabilities of 802.11n need to be supported by
   CAPWAP control message such as radio capability, radio configuration
   and station information.  This section defines the extension of
   current CAPWAP 802.11 information element to support 802.11n.

   1.  802.11n Radio Capability Information Element.  Below is an
   example of the 802.11n radio capability information element.  This
   802.11n radio capability information element may also be conveyed
   using the IEEE 802.11 information element by carrying the IEEE 802.11
   HT element information.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Element ID         |              Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Radio ID   |SupChanl width |   Power Save   |  ShortGi20   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  ShortGi40    | HtDelyBlkack  |  Max Amsdu     |  Max RxFactor|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Min StaSpacing | HiSuppDataRate|   AMPDUBufSize |   HtcSupp    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        20MHZ 11gMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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   |                        20MHZ 11gMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        20MHZ 11gMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        20MHZ 11gMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        20MHZ 11aMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        20MHZ 11aMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        20MHZ 11aMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        20MHZ 11aMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        40MHZ 11gMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        40MHZ 11gMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        40MHZ 11gMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        40MHZ 11gMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        40MHZ 11aMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        40MHZ 11aMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        40MHZ 11aMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        40MHZ 11aMCS                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 1: 802.11n Radio Capability Information Element

   1.   SupChanl width: The supported bandwith mode.  0x01: 20MHz
        bandwidth binding mode.  0x02: 40MHz bandwidth binding mode.
   2.   Power Save: 0x00: Static power saving mode.  0x01: Dynamic power
        saving mode.  0x03: Do not support power saving mode.
   3.   ShortGi20: Whether support short GI.  0x00: Do not support short
        GI.  ox01: Support short GI.
   4.   HtDelyBlkack: Whether block Ack support delay mode.  0x00: Do
        not support delay mode.  0x01: Support delay mode.
   5.   Max Amsdu: The maximal AMSDU length.  0: 3839 bytes.  1: 7935
        bytes.
   6.   Max RxFactor: The maximal receiving AMPDU factor.  Default
        value: 3.
   7.   Min StaSpacing: Minimum MPDU Start Spacing.
   8.   HiSuppDataRate: Maximal transmission speed.

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   9.   AMPDUBufSize: AMPDU buffer size.
   10.  HtcSupp: Whether the packet have HT header.
   11.  20MHZ 11gMCS: 128 bitmap.If support should be all zero,
        otherwise all one.
   12.  20MHZ 11aMCS: 128 bitmap.If support should be all zero,
        otherwise all one.
   13.  40MHZ 11gMCS: 128 bitmap.If support should be all zero,
        otherwise all one.
   14.  40MHZ 11aMCS: 128 bitmap.If support should be all zero,
        otherwise all one.
   15.  2.  802.11n Raido Configuration TLV.  Following figure is an
        example of 802.11n radio configuration TLV.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Element ID          |              Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Radio ID   |   Amsdu Cfg   |   Ampdu Cfg   |  11nOnly Cfg  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | ShortGi Cfg   | BandWidth Cfg |  MaxSupp MCS  |  Max MandMCS  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    TxAntenna  |    RxAntenna  |         Reserved              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Reserved                            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 2: 802.11n radio configuration

   1.   A-MSDU CFG: 0x00: Disable 0x01: Enalbe
   2.   A-MPDU CFG: 0x00: Disable 0x01: Enalbe
   3.   11N Only CFG: Whether allow only 11n user access.  0x00: Allow
        non-802.11n user access.  0x01: Do not allow non-802.11n user
        access.
   4.   Short GI CFG: 0x00: Disable 0x01: Enable
   5.   Bandwidth CFG: Bandwidth binding mode.  0x00: 40MHz 0x01: 20MHz
   6.   Max Support MCS: Maximal MCS.
   7.   Max Mandantory MCS: Maximal mandantory MCS.
   8.   TxAntenna: Transmitting antenna configuration.
   9.   RxAntenna: Receiving antenna configuration.
   10.  Each TxAntenna and RxAntenna bit represent one antenna, 1 means
        enable, 0 means disable.

   3.  802.11n Station Information.  Following figure is an example of
   802.11n station information information element.

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   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Element ID          |              Length          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          MAC Address                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |SupChanl width |   Power Save  |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  ShortGi20    | ShortGi40     | HtDelyBlkack  |  Max Amsdu    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Max RxFactor | Min StaSpacing|            HiSuppDataRate     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            AMPDUBufSize       |    HtcSupp    |     MCS Set   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   MCS Set                                                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   MCS Set                                                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     MCS Set    |
   +-+-+-+-+-+-+-+-+-

   Figure 3: 802.11n Station Information

   1.   SupChanl width: Supporting bandwidth mode.  0x01: 20MHz
        bandwidth mode.  0x02: 40MHz bandwidth binding mode.
   2.   Power Save: 0x00: Static power saving mode.  0x01: Dynamic power
        saving mode.  0x03: Do not support power saving mode.
   3.   ShortGi20: Whether support short GI in 20MHz bandwidth mode.
        0x00: Do not support short GI.  ox01: Support short GI.
   4.   ShortGi40: Whether support short GI in 40MHz bandwidth mode.
        0x00: Do not support short GI.  ox01: Support short GI.
   5.   HtDelyBlkack: Whether block Ack support delay mode.  0x00: Do
        not support delay mode.  0x01: Support delay mode.
   6.   Max Amsdu: The maximal AMSDU length.  0x00: 3839 bytes.  0x01:
        7935 bytes.
   7.   Max RxFactor: The maximal receiving AMPDU factor.
   8.   Min StaSpacing: Minimum MPDU Start Spacing.
   9.   HiSuppDataRate: Maximal transmission speed.
   10.  AMPDUBufSize: AMPDU buffer size.
   11.  HtcSupp: Whether the packet have HT header.
   12.  MCS Set: The MCS bitmap that the station supports.

5.  Power and Channel auto reconfiguration

   Power and channel auto reconfiguration could avoid potential radio
   interference and improve the Wi-Fi performance.  In general, the

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   auto-configuration of radio power and channel could occurre at two
   stages: when the WTP power on or during the WTP running time.

   When the WTP is power-on, it is of necessity to configure a proper
   channel to the WTP in order to achieve best status of radio links.
   IEEE 802.11 Direct Sequence Control elements or IEEE 802.11 OFDM
   Control element defined in RFC5416 should be carried to offer WTP a
   channel at this stage.  Those element should be carried in the
   Configure Status Response message.  If those information element is
   zero, the WTP will determine its channel by itself, otherwise the WTP
   should be configured according to the provided information element.

   When the WTP determines its own channel configuration, it should
   first scan the channel information, then determine which channel it
   will work on and form a channel quality scan report.  The channel
   quality report will be sent to the AC using WTP Event Request message
   by the WTP.  The AC can use IEEE 802.11 Direct Sequence Control or
   IEEE 802.11 OFDM Control information element carried by the configure
   Update Request message to configure a new channel for the WTP.

   IEEE 802.11 Tx Power information element is used by the AC to control
   the transmission power of the WTP.  The 802.11 Tx Power information
   element is carried in the Configure Status Response message during
   the power on phase or in the Configure Update Request message during
   the running phase.

   Channel Scan Procedure.

   The Channel Scan Procedure is illustrated by the following figure.

         WTP              Configure Status Req                 AC
         ------------------------------------------------------->
           Configure Status Res(Scan Para TLV, Chl Bind TLV)
         <------------------------------------------------------
       or

       WTP Configure Update Req(Scan Para, Bind TLV)          AC
         <-----------------------------------------------------
                         Configure Update Res
         ----------------------------------------------------->

   Figure 4: Channel Scan Procedure

   The definition of the Scan Para TLV is as follows:

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   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Element ID          |              Length          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Radio ID |   AP oper mode                       |   Scan Type  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Reserved                              |
   +---------------------------------------------------------------+
   |          Report Time           |      PrimeChlSrvTime         |
   +---------------------------------------------------------------+
   | On Channel ScanTIme            |   Off Channel ScanTime       |
   +---------------------------------------------------------------+
   |L|D|         Flag               |                              |
   +---------------------------------------------------------------+

   Figure 5: Scan Para TLV

   Element ID: TBD; Length:18

   AP oper mode: the work mode of the WTP.  0x01:normal mode.  0x02:
   monitor only mode.

   Scan Type: 0x01: active scan; 0x02: passive scan.

   Report Time: Channel quality report time.

   PrimeChlSrvTime: Service time on the working scan channel.  This
   segment is invalid(set to 0) when WTP oper mode is set to 2.  The
   maximum value of this segment is 10000, the minimum value of this
   segment is 5000, the default value is 5000.

   On Channle ScanTime: The scan time of the working channel.  When the
   WTP oper mode is set to 2, this segment is invalid(set to 0).  The
   maximum value of thi segment is 120, the minimum value of this
   segment is 60, the default value is 60.

   L=1: Open Load Balance Scan.  D=1: Open Rogue WTP detection scan.
   Flag: Bitmap, resered for furture use.

   The definition of the Channel Bind TLV is as follows:

   0                   1                   2                   3

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   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Element ID          |              Length          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Radio ID |                        Flag                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Max Cycles  |      Reserved         |    Channel Count     |
   +---------------------------------------------------------------+
   |                      Scan Channel Set...                      |
   +---------------------------------------------------------------+

   Figure 6: Channel Bind TLV

   Element ID: TBD.  Length>=12

   Flag: bitmap, reserved.

   Max Cycles: Scan repeat times.  255 means continuous scan.

   Channel Count: The number of channel will be scanned.

   Scan Channel Set: The channle information.  the format is as follows:

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Channel ID          |              Flag            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 7: Channle Information Format

   Channel ID: the channel ID of the channel which will be scanned.

   Flag: bitmap, reserved for future use.

   The channle scan procedure:

   The WTP has two work mode: the first one is normal mode.  In this
   mode, the WTP can provide service for the STA access and scan the
   channel at the same time.  Whether the WTP will scan the channel is
   determined by the Max Cycles segment in the Channle Bind TLV.  When
   this segment is set to 0, the WTP will not scan the channle.  If this
   segment is set to 255, the WTP will continuous scan the channel.  The

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   type of the scan is determined by the Sacn Type segment.  In the
   passive scan type, the WTP monitor the airinterface, based on the
   received beacon frame to determine the nearby WTPs.  In the active
   scan type, the WTP will send probe message and receive the probe
   response message.  In the normal scan mode, the WTP will use 3
   parameters: PrimeChlSrvTime, OnChannelScanTIme, OffChannelScnTIme.
   The WTP will provide access service for the STAs for PrimeChlSrvTime
   duration and then start to scan the channel for On Channel ScnTime
   duration.  Back to the working channel, provide STA access service
   for PrimeChlSrvTime, then leave the working channel, start to scan
   the next channel for Off Channel ScanTime duration.  This process
   will be repeated until all the channel is scanned.

   When the WTP work in the scan only mode, there is no difference
   between the working channel and scan channel.  Every channel's scan
   duration will be OffChannelScnTime and the PrimeChlSrvTime and
   OnChannelScanTime is set to 0.

   Scan Report.  THe WTP send the scan report to the AC through WTP
   Event Request message.  The information element that used to carry
   the scan report is Channel Scan Report TLV and Neighbor WTP Report
   TLV.  The example definition of the Channel Scan Report TLV is as
   following figure.  The channel scan report may also be conveyed by
   IEEE 802.11 information element by carrying the IEEE 802.11 beacon
   report message element.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Element ID          |             Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Radio ID     | Report Count    | Channel Scan Report          |
   +---------------------------------------------------------------+

   Figure 8: Channel Scan Report TLV

   Element ID: 133; Length: >= 20.

   Report Count: the channle number will be reported.  The definition of
   the channel scan report is as follows:

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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   |     Channel Number   |      Radar Statistics       | Mean     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Time    | Mean RSSI    | Screen Packet Count             |
   +---------------------------------------------------------------+
   | NeighborCount| Mean Noise   | Interference  | Self Tx Occp    |
   +---------------------------------------------------------------+
   | SelfStaOccp  | Unknown Occp |  CRC Err Cnt  | Decrypt Err Cnt |
   +---------------------------------------------------------------+
   |Phy Err Cnt   | Retrans Cnt  |
   +-----------------------------+

   Figure 9: Channel Scan Report

   Channel Number: The channel number.

   Radar Statistics: Whether detect radar signal in this channel.  0x00:
   detect radar signal.  0x01: no radar signal is detected.

   Mean Time: Channel measurement duration.

   Mean RSSI: The signal strength of the scanned channel.

   Screen Packet Count: Received packet number.

   Neighbor Count: The neighbor number of this channel.

   Mean Noise: the average noise on this channel.

   Interference: The interference of the channel.

   Self Tx Occp: The time duration for transmission.

   Unknown Occp: TBD.

   CRC Err Cnt: CRC err packet number.

   Decrypt Err Cnt: Decryption err packet number.

   Phy Err Cnt: Physical err packet number.

   Retrans Cnt: Retransmission packet number.

   The example definition of neighbor WTP report TLV is as follows:

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   The neigbor WTP report message element may also be conveyed using
   IEEE 802.11 information element by carrying 802.11 neighbor report
   information element.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Element ID          |             Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Radio ID     | Reserved        | Number of Neighbor Report    |
   +---------------------------------------------------------------+
   | Neighbor Infor...                                             |
   +---------------------------------------------------------------+

   Figure 10: Neighbor WTP Report TLV

   Element ID: 134; Length:>=16

   The definition of Neighbor info is as follows:

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            BSSID                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            BSSID               |        Channel Number        |
   +---------------------------------------------------------------+
   | 2rd Offset    |  Mean RSSI     | Sta Intf     |    AP Intf    |
   +---------------------------------------------------------------+

   Figure 11: Neighbor info

   BSSID: The BSSID of this neighbor channel.

   Channel Number: The channel number of this neighbor channel.

   2rd channel offset: TBD.

   Mean RSSI: The average signal strength of the channel.

   Sta Intf: TBD.

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   AP Intf: TBD.

6.  Security Considerations

   This document is based on RFC5415/RFC5416 and it doesn't increase any
   security risk.  The security considerations of this document aligns
   with RFC5415/5416.

7.  IANA Considerations

   The extension defined in this document need to extend IEEE 802.11
   binding message element which is defined in RFC 5416.  the
   corresponding type values need to be defined by IANA.

8.  Contributors

   This draft is a joint effort from the following contributors:

   Gang Chen: China Mobile chengang@chinamobile.com

   Naibao Zhou: China Mobile zhounaibao@chinamobile.com

   Chunju Shao: China Mobile shaochunju@chinamobile.com

   Hao Wang: Huawei3Come hwang@h3c.com

   Yakun Liu: AUTELAN liuyk@autelan.com

   Xiaobo Zhang: GBCOM

   Xiaolong Yu: Ruijie Networks

   Song zhao: ZhiDaKang Communications

   Yiwen Mo: ZhongTai Networks

9.  Acknowledgements

   The authors would like to thanks Ronald Bonica,Romascanu Dan, Benoit
   Claise and Margaret Wasserman for their usefull suggestions.  The
   authors also thanks Dorothy Stanley's review and useful comments.

10.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

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   [RFC4564]  Govindan, S., Cheng, H., Yao, ZH., Zhou, WH., and L. Yang,
              "Objectives for Control and Provisioning of Wireless
              Access Points (CAPWAP)", RFC 4564, July 2006.

   [RFC5415]  Calhoun, P., Montemurro, M., and D. Stanley, "Control And
              Provisioning of Wireless Access Points (CAPWAP) Protocol
              Specification", RFC 5415, March 2009.

   [RFC5416]  Calhoun, P., Montemurro, M., and D. Stanley, "Control and
              Provisioning of Wireless Access Points (CAPWAP) Protocol
              Binding for IEEE 802.11", RFC 5416, March 2009.

Authors' Addresses

   Yifan Chen
   China Mobile
   No.32 Xuanwumen West Street
   Beijing  100053
   China

   Email: chenyifan@chinamobile.com

   Dapeng Liu
   China Mobile
   No.32 Xuanwumen West Street
   Beijing  100053
   China

   Email: liudapeng@chinamobile.com

   Hui Deng
   China Mobile
   No.32 Xuanwumen West Street
   Beijing  100053
   China

   Email: denghui@chinamobile.com

   Lei Zhu
   Huawei
   No. 156, Shi-Chuang-Ke-Ji-Shi-Fan-Yuan Beiqing Road, Haidian District
   Beijing 100095
   China

   Email: lei.zhu@huawei.com

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