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Versions: (draft-chen-opsawg-capwap-extension) 00 01 02 03 04 05 06

OPSAWG                                                           Y. Chen
Internet-Draft                                              China Mobile
Updates: 5416 (if approved)                                       D. Liu
Intended status: Standards Track
Expires: January 7, 2016                                         H. Deng
                                                            China Mobile
                                                                Lei. Zhu
                                                                  Huawei
                                                            July 6, 2015


    CAPWAP Extension for 802.11n and Power/channel Autoconfiguration
                 draft-ietf-opsawg-capwap-extension-06

Abstract

   The CAPWAP binding for 802.11 is specified by RFC5416 and it was
   based on IEEE 802-11.2007 standard.  Several new amendments of 802.11
   have been published since RFC5416 was published in 2009.  802.11n is
   one of those amendments and it has been widely used in real
   deployment.  This document extends the CAPWAP binding for 802.11 to
   support 802.11n and also defines a power and channel auto
   configuration extension.

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 January 7, 2016.

Copyright Notice

   Copyright (c) 2015 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



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   (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
   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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  CAPWAP 802.11n Support  . . . . . . . . . . . . . . . . . . .   3
     3.1.  CAPWAP Extension for 802.11n Support  . . . . . . . . . .   4
       3.1.1.  802.11n Radio Capability Information  . . . . . . . .   4
       3.1.2.  802.11n Radio Configuration Message Element . . . . .   4
       3.1.3.  802.11n Station Information . . . . . . . . . . . . .   6
   4.  Power and Channel Autoconfiguration . . . . . . . . . . . . .   7
     4.1.  Channel Autoconfiguration When WTP Power On . . . . . . .   7
     4.2.  Power Configuration When WTP Power On . . . . . . . . . .   8
     4.3.  Channel/Power Auto Adjustment . . . . . . . . . . . . . .   8
       4.3.1.  IEEE 802.11 Scan Parameters Message Element . . . . .   9
       4.3.2.  IEEE 802.11 Scan Channel Bind Message Element . . . .  11
       4.3.3.  IEEE 802.11 Channel Scan Report . . . . . . . . . . .  12
       4.3.4.  IEEE 802.11 WTP Neighbor Report . . . . . . . . . . .  14
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  15
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  16
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   IEEE Std 802.11n[TM]-2009 [IEEE 802.11n.2009] was published in 2009
   as an amendment to the IEEE 802.11-2007 standard to improve network
   throughput.  The maximum data rate increases to 600Mbps.  In the
   physical layer, 802.11n uses Orthogonal Frequency Division
   Multiplexing (OFDM) and Multiple Input/Multiple Output (MIMO) to
   achieve the high throughput. 802.11n uses multiple antennas to form
   an antenna array which can be dynamically adjusted to improve the
   signal strength and extend the coverage.

   Capabilities of 802.11n such as radio capability, radio configuration
   and station information need to be supported by CAPWAP control
   messages.  The necessary extensions for this purpose are introduced
   in Section 3 and specified in Section 4.




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   For IEEE 802.11 in general, it is desirable to be able to support
   power and channel auto reconfiguration.  Extensions for this purpose
   are specified in Section 5.

2.  Terminology

   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].

   This document uses the following abbreviations:

      AC Access Controller
      A-MSDU Aggregate MAC Service Data Unit
      A-MPDU Aggregate MAC Protocol Data Unit
      AC Access Controller
      GI Guard Interval
      MCS Maximum Modulation and Coding Scheme
      MIMO Multiple Input/Multiple Output
      MPDU MAC Protocol Data Unit
      MSDU MAC Service Data Unit
      OFDM Orthogonal Frequency Division Multiplexing
      TSF timing synchronization function
      WTP Wireless Termination Point

3.  CAPWAP 802.11n Support

   802.11n supports 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 the 2.4GHz band.  In the large
   scale deployment scenario, the operator needs to use 20MHz channel
   configuration in the 2.4GHz band to allow more non-overlapping
   channels.

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

   Another feature in the 802.11 MAC layer is Block ACK. 802.11n can use
   one ACK frame to acknowledge receipt of several MAC Protocol Data
   Units (MPDUs).

   CAPWAP needs to be extended to support the above new 802.11n
   features.  CAPWAP should allow the access controller to know the
   supported 802.11n features and the access controller should be able



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   to configure the different channel binding modes.  This document
   defines extensions of the CAPWAP 802.11 binding to support 802.11n
   features.

3.1.  CAPWAP Extension for 802.11n Support

   Three 802.11n features need to be supported by CAPWAP 802.11 binding:
   802.11n radio capability, 802.11n radio configuration and station
   information.  This section defines the extension of the current
   CAPWAP 802.11 binding to support the 802.11n features.

3.1.1.  802.11n Radio Capability Information

   [RFC5416] defines the IEEE 802.11 binding for the CAPWAP protocol.
   It defines the IEEE 802.11 Information Element, which is used to
   communicate any information element (IE) defined in the IEEE 802.11
   protocol.  This document specifies that the IEEE 802.11 Information
   Element defined in section 6.6 of [RFC5416] SHALL be used to
   transport the IEEE 802.11 HT information element defined in section
   8.4.2.58 of [IEEE-802.11.2012].  The HT IE MAY in this way be
   included in CAPWAP Configuration Status Request/Response messages.

3.1.2.  802.11n Radio Configuration Message Element

   The 802.11n Radio Configuration message element is used by the AC to
   provide IEEE 802.11n-specific configuration for a Radio on the WTP,
   and by the WTP to deliver its radio configuration to the AC.  This
   supplements the IEEE 802.11 WTP WLAN Radio Configuration message
   element defined in [RFC5416].  The format of the 802.11n Radio
   Configuration message element is shown in Figure 1.  The 802.11n
   Radio Configuration message element MAY be included in the CAPWAP
   Configuration Update Request/Response message.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Radio ID   |S|P|N|G|B|     |    MaxSup MCS | Max MandMCS   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    TxAntenna  |    RxAntenna  |         Reserved              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Figure 1: 802.11n Radio Configuration Message Element

   Type: TBD1 for 802.11n Radio Configuration Message Element.

   Length: 16.




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   Radio ID: An 8-bit value representing the radio, whose value is
   between one (1) and 31.

   S bit: A-MSDU configuration: Enable/disable Aggregate MAC Service
   Data Unit (A-MSDU).  Set to 0 if disabled.  Set to 1 if enabled.

   P bit: A-MPDU configuration: Enable/disable Aggregate MAC Protocol
   Data Unit (A-MPDU).  Set to 0 if disabled.  Set to 1 if enabled.

   N bit: 11n Only configuration: Whether to allow only 11n user access.
   Set to 0 if non-802.11n user access is allowed.  Set to 1 if non-
   802.11n user access is not allowed.

   G bit: Short GI configuration: Set to 0 if Short Guard Interval is
   disabled.  Set to 1 if enabled.

   B bit: Bandwidth binding mode configuration: Set to 0 if 40MHz
   binding mode.  Set to 1 if 20MHz binding mode.

   Maximum supported MCS: Maximum Modulation and Coding Scheme (MCS)
   index.  It indicates the maximum MCS index that the WTP or the STA
   can support.

   Max Mandatory MCS: Maximum Mandatory Modulation and Coding Scheme
   (MCS) index.  Mandatory rates must be supported by the WTP and the
   STA that want to associate with the WTP.

   TxAntenna: Transmitting antenna configuration.  Each TxAntenna bit
   represents a certain number of antennas.  Set to 1 if enabled, set to
   0 if disabled.

   RxAntenna: Receiving antenna configuration.  Each RxAntenna bit
   represents a certain number of antennas.  Set to 1 if enabled, set to
   0 if disabled.

   The detail definition of TxAntenna/RxAntenna is as follows:


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


   Figure 2: Definition of TxAntenna/RxAntenna






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   Each bit when enabled will represent the number of antennas
   correspondent to that bit.  Only one bit is allowed to be set to 1.
   For example, when the first bit is enabled,it represents 8 antennas.

3.1.3.  802.11n Station Information

   The 802.11n Station Information message element is used to deliver
   IEEE 802.11n station policy from the AC to the WTP.  The definition
   of the 802.11n Station Information message element is in figure 3.
   The format of 802.11n Station Information MAY be included in the
   CAPWAP Station Configuration Request message.


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          MAC Address                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            MAC Address        |S| P |T|F|H|M| |  Max RxFactor |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Min StaSpacing|       HiSuppDataRate          | AMPDUBufSize  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | AMPDUBufSize  |    HtcSupp    |           MCS Set             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   MCS Set                                                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   MCS Set                                                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Figure 3: 802.11n Station Information

   MAC Address: The station's MAC Address.

   Type: TBD2 for 802.11 Station Information.

   Length: 24.

   S bit: Supporting bandwidth mode.  0x00: 20MHz bandwidth mode.  0x01:
   40MHz bandwidth binding mode.

   P flag: Power Saving mode: 0x00: Static.  0x01: Dynamic.  0x03: Do
   not support power saving mode.

   T bit: Whether to support short GI in 20MHz bandwidth mode.  0x00: Do
   not support short GI.  0x01: Support short GI.





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   F bit: ShortGi40: Whether to support short GI in 40MHz bandwidth
   mode.  0x00: Do not support short GI.  0x01: Support short GI.

   H bit: Whether Block Ack supports delay mode.  0x00: Do not support
   delay mode.  0x01: Support delay mode.

   M bit: The maximal A-MSDU length.  0x00: 3839 bytes.  0x01: 7935
   bytes.

   Max RxFactor: The maximal receiving A-MPDU factor.

   Min StaSpacing: Minimum MPDU Start Spacing.

   HiSuppDataRate: Maximal transmission speed (Mbps).

   AMPDUBufSize: A-MPDU buffer size (Byte).

   HtcSupp: Whether to place HT headers on the packets forwarded from
   this station.

   MCS Set: The MCS bitmap that the station supports.

4.  Power and Channel Autoconfiguration

   Power and channel autoconfiguration could avoid potential radio
   interference and improve the WLAN performance.  In general, the auto-
   configuration of radio power and channel could occur at two stages:
   when the WTP power on or during the WTP running time.

4.1.  Channel Autoconfiguration When WTP Power On

   Power and channel auto reconfiguration avoids potential radio
   interference and improves the WLAN performance.  In general, the
   auto- configuration of radio power and channel can occur at two
   stages: when the WTP powers on or while the WTP is in running state.
   When the WTP is powered-on, it needs to configure a proper channel.
   IEEE 802.11 Direct Sequence Control elements or IEEE 802.11 OFDM
   Control element defined in RFC5416 SHOULD be carried in the Configure
   Status Response message to offer WTP a channel at this stage.  If the
   channel field of those information element is set to 0, the WTP will
   need to 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.  As shown in
   Figure 3, the AC can control the scanning process by sending the IEEE
   802.11 Scan Parameters message element defined in Section 5.1 to the



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   WTP in a Configure Status Response message or in a WTP Configure
   Update Request message.  The WTP will send the channel quality report
   to the AC using the WTP Event Request message.

   AC will determine whether to change the channel configuration based
   on the received channel quality report.  The AC MAY use a IEEE 802.11
   Direct Sequence Control or IEEE 802.11 OFDM Control message element
   carried by the configure Update Request message to configure a new
   channel for the WTP.

4.2.  Power Configuration When WTP Power On

   The IEEE 802.11 Tx Power message element defined in section 6.18 of
   [RFC5416] 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 or in the Configure Update Request
   message.

4.3.  Channel/Power Auto Adjustment

   The Channel Scan Procedure is illustrated by the figure 4.


                              WTP              Configure Status Reqest              AC
                              ------------------------------------------------------->
        Configure Status Res(Scan Parameter Message Element, Channel Bind Message Element)
                              <------------------------------------------------------
                            or

                            WTP                                                     AC
        Configure Update Req(Scan Parameter Message Element, Channel Bind Message Element )
                              <-----------------------------------------------------
                                              Configure Update Response
                              ----------------------------------------------------->



   Figure 4: Channel Scan Procedure

   The WTP has two work modes: normal mode and scan only mode.  In
   normal mode, the WTP can provide service for station access and scan
   channels at the same time.  Whether the WTP will scan a given set of
   channels is determined by the Max Cycles field in the IEEE 802.11
   Channel Bind message element defined in Section 4.3.2.  When this
   field is set to 0, the WTP will not scan the channel.  If this field
   is set to 255, the WTP will scan the channel continuously.  The type
   of the scan is determined by the Scan Type field.  With the passive
   scan type, the WTP monitors the air interface, using the received



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   beacon frames to determine the nearby WTPs.  With the active scan
   type, the WTP will send a probe message and receive probe response
   messages.  In this case, the WTP may need to operate in station mode
   which means it is not a WTP function only device, it also has part of
   station function.

   In normal mode, the WTP behaviour is controlled by three parameters:
   PrimeChlSrvTime, OnChannelScanTIme, and OffChannelScnTIme.  These are
   provided by the IEEE 802.11 Scan Parameters message element defined
   in Section 4.3.1.  The WTP will provide access service for stations
   for the duration given by PrimeChlSrvTime.  It then scans the working
   channel for the duration given by OnChannelScnTime.  It returns to
   servicing station access requests on the working channel for another
   period of length PrimeChlSrvTime, then moves to a different channel
   and scans it for duration OffChannelScnTime.  It repeats this cycle,
   scanning a new non-working channel each time, until all the channels
   have been scanned.  This channel scan procedure can be used to
   determine the interference of both the current working channel and
   non-working channel to avoid potential interference.

   When the WTP works in scan only mode, it does not distinguish between
   the working channel and scan channel.  Every channel's scan duration
   will be OffChannelScnTime and PrimeChlSrvTime and OnChannelScanTime
   MUST be set to 0.

   As shown in Figure 4, the AC can control the scan behaviour at the
   WTP by including the IEEE 802.11 Scan Parameters and IEEE 802.11
   Channel Bind message elements in a Configure Status Response or WTP
   Configure Update Request message.

   Scan Report.  After completing its scan, the WTP MAY send the scan
   report to the AC using a WTP Event Request message.  The scan report
   information is carried in the IEEE 802.11 Channel Scan Report message
   element (Section 4.3.3) and an instance of the IEEE 802.11
   Information Element message element carrying a copy of theIEEE 802.11
   Neighbor WTP Report information element (Section 4.3.4).

4.3.1.  IEEE 802.11 Scan Parameters Message Element

   The format of the IEEE 802.11 Scan Parameters Message Element is as
   shown in Figure 5:










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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
                        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                        |    Radio ID   |M|S|L|D|       |         Report Time           |
                        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                        |      PrimeChlSrvTime          |     On Channel ScanTime       |
                        +-------------------------------+-------------------------------+
                        |   Off Channel ScanTime        |
                        +-------------------------------+



   Figure 5: IEEE 802.11 Scan Parameters Message Element

   Type: TBD3 for IEEE 802.11 Scan Parameters Message Element.

   Length: 10.

   Radio ID: An 8-bit value representing the radio, whose value is
   between one (1) and 31.

   M bit: Work mode of the WTP. 0:normal mode. 1: scan only mode, no
   service is provided in this mode.

   S bit: Scan Type: 0: active scan; 1: passive scan.

   L bit: L=1: Open Load Balance Scan.  L=0: Disable Load Balance Scan.

   D bit: D=1: Open Rogue WTP detection scan.  D=0: Disable Rouge WTP
   detection scan.

   Report Time: Channel quality report time (unit: second).

   PrimeChlSrvTime: Service time (unit: millisecond) on the working scan
   channel.  This segment is invalid(set to 0) when WTP oper mode is set
   to 1.  The maximum value of this segment is 10000, the minimum value
   of this segment is 5000, the default value is 5000.

   On Channel ScanTime: The scan time (unit: millisecond) of the working
   channel.  When the M bit is set to 1 (active scan), this segment is
   invalid(set to 0).  The maximum value of this segment is 120, the
   minimum value of this segment is 60, the default value is 60.

   Off Channel ScanTime: The scan time (unit: millisecond) of the
   working channel.  When the WTP operating mode is set to 2, this
   segment MUST be set to 0.  The maximum value of this segment is 120,
   the minimum value of this segment is 60, the default value is 60.




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4.3.2.  IEEE 802.11 Scan Channel Bind Message Element

   The format of the IEEE 802.11 Scan Channel Bind Message Element 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
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |   Radio ID    |   Flag        |   Max Cycles  |Channel Count  |ScanChannelSet.|
         +---------------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Figure 6: IEEE 802.11 Scan Channel Bind Message Element

   Type: TBD4 for IEEE 802.11 Scan Channel Bind Message Element.

   Length: variable.

   Radio ID: An 8-bit value representing the radio, whose value is
   between one (1) and 31.

   Flag: reserved.

   Max Cycles: Number of times the scanning cycle is repeated for the
   set of channels identified by this message element. 255 means
   continuous scan.

   Channel Count: The number of channels will be scanned.

   Scan Channel Set: identifies the members of the set of channels to
   which this message element instance applies.  The format for each
   channel 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: Channel Information Format

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

   Flag: Bitmap, reserved for future use.




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4.3.3.  IEEE 802.11 Channel Scan Report

   There are two types of scan report: Channel Scan Report and WTP
   Neighbor Report.  Channel Scan Report is used to channel
   autoconfiguration while WTP Neighbor Report is used to power
   autoconfiguration.  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 Message Element and WTP
   Neighbor Report Message Element.

   The format of the IEEE 802.11 Channel Scan Report message element is
   in Figure 8.



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


   Figure 8: IEEE 802.11 Channel Scan Report Message Element

   Type: TBD5 for IEEE 802.11 Channel Scan Report message element.

   Length: >=29.

   Radio ID: An 8-bit value representing the radio, whose value is
   between one (1) and 31.

   Report Count: The number of channels for which a report is provided.

   Channel Scan Report: The format of each Channel Scan Report is shown
   in Figure 9.
















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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
                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                   |     Channel Number   |      Radar Statistics       | Mean     |
                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                   |      Time    | Mean RSSI    | Screen Packet Count             |
                   +---------------------------------------------------------------+
                   | NeighborCount| Mean Noise   | Interference  |  WTP Tx Occp    |
                   +---------------------------------------------------------------+
                   | WTP Rx Occp  | 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 (ms).

   Mean RSSI: The average signal strength of the scanned channel
   (dBm(2's complement)).

   Screen Packet Count: Received packet number.

   Neighbor Count: The neighbor number of this channel.

   Mean Noise: the average noise on this channel (dBm(2's complement)).

   Interference: The interference of the channel.

   WTP Tx Occp: (The WTP transmission time/Monitor time)*255.  The WTP
   transmission time is the total sending time of the WTP during the
   period of channel scan.

   WTP Rx Occp: (The WTP receiving duration time/Monitor time)*255.  THe
   WTP receiving duration time is the total receiving time of the WTP
   during the period of channel scan.

   Unknown Occp: (All other packet transmission time duration/Monitor
   time)*255.

   CRC Err Cnt: CRC err packet number.



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   Decrypt Err Cnt: Decryption err packet number.

   Phy Err Cnt: Physical err packet number.

   Retrans Cnt: Retransmission packet number.

   Note:The values of the above four count fields for a non-operational
   channel can be ignored

4.3.4.  IEEE 802.11 WTP Neighbor Report



                                    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
                                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                   | Radio ID     | Reserved        | Number of Neighbor Report    |
                                   +---------------------------------------------------------------+
                                   | Neighbor Infor...                                             |
                                   +---------------------------------------------------------------+




   Figure 10: WTP Neighbor Report TLV

   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        |
                                   +---------------------------------------------------------------+
                                   | 2nd Offset    |  Mean RSSI     | Sta Occp     |    WTP Occp   |
                                   +---------------------------------------------------------------+


   Figure 11: Neighbor info

   BSSID: The BSSID of this neighbor WTP.

   Channel Number: The channel number of this WTP neighbor.

   2nd channel offset: The auxiliary channel offset of this WTP.




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   Mean RSSI: The average signal strength of this WTP (dbm).

   Sta Occp: (The station air interface occupation time/Monitor
   time)*255.The station air interface occupation time is the air
   interface occupation time caused by the stations which are connected
   to this WTP.

   WTP Occp: (The WTP air interface occupation time/Monitor time)*255.
   The WTP air interface occupation time is the air interface occupation
   time caused by the WTP.

5.  Security Considerations

   This document is based on RFC5415/RFC5416 and adds no new security
   considerations.

6.  IANA Considerations

   The extension defined in this document need to extend CAPWAP IEEE
   802.11 binding message element which is defined in section 6 of
   [RFC5416].  The following IEEE 802.11 specific message element type
   need to be defined by IANA.

   TBD1: 802.11n Radio Configuration Message Element type value
   described in section 4.1.2.

   TBD2: 802.11n Station Message Element type value described in section
   4.1.3.

   TBD3: 802.11 Scan Parameter Message Element type value described in
   section 4.3.1.

   TBD4: 802.11 Channel Bind Message Element type value described in
   section 4.3.2.

   TBD5: Channel Scan Report Message Element type value described in
   section 4.3.3.

   TBD6 entry for WTP Neighbor Report as descrbed in section 4.3.4 .

7.  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




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   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

   Dorothy Stanley: dstanley1389@gmail.com

   Tom Taylor: tom.taylor.stds@gmail.com

8.  Acknowledgements

   The authors would like to thanks Ronald Bonica,Romascanu Dan, Benoit
   Claise, Melinda Shore and Margaret Wasserman for their useful
   suggestions.  The authors also thanks Dorothy Stanley and Tom Taylor
   for their review and useful comments.

9.  Normative References

   [IEEE-802.11.2009]
              "IEEE Standard for Information technology -
              Telecommunications and information exchange between
              systems Local and metropolitan area networks - Specific
              requirements Part 11: Wireless LAN Medium Access Control
              (MAC) and Physical Layer (PHY) Specifications,
              Enhancements for Higher Throughput (Amendment 5)", 2009.

   [IEEE-802.11.2012]
              "IEEE Standard for Information technology -
              Telecommunications and information exchange between
              systems Local and metropolitan area networks - Specific
              requirements Part 11: Wireless LAN Medium Access Control
              (MAC) and Physical Layer (PHY) Specifications", March
              2012.

   [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
   Beijing
   China

   Email: maxpassion@gmail.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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