Doc.: IEEE 802.11-11/1274r1 November 2011 Padam Kafle, Nokia Submission Neighboring Network Information Sharing through RLSS Authors: Date: Nov 7, 2011

doc.: IEEE 802.11-11/1274r1

November 2011

Padam Kafle, NokiaSubmission

Neighboring Network Information Sharing through RLSS

Authors: Date: Nov 7, 2011

Name Company Address Phone email

Padam Kafle Nokia6021 Connection Drive, Irving, TX, 75039

+1 214 673 6232 [email protected]

Mika Kasslin NokiaItämerenkatu 11-13, 00180 Helsinki, Finland

+358 50 4836294 [email protected]

Prabodh Varshney Nokia6021 Connection Drive, Irving, TX, 75039 +1 469 9512745 [email protected]

Zhou Lan NICT3-4, Hikarino-oka, Yokosuka, Kanagawa, Japan, 239-0847 [email protected]

Hiroshi Harada NICT3-4, Hikarino-oka, Yokosuka, Kanagawa, Japan, 239-0847 [email protected]

doc.: IEEE 802.11-11/1274r1

November 2011

Submission Padam Kafle, NokiaSlide 2

Contents

• Abstract

• Comments

• Discussion

• The OBSS Problem in TVWS

• Deployment Scenarios

• RLSS for Neighboring Network Information Sharing

• Network Coexistence through RLSS with Centralized Decision

• Summary

doc.: IEEE 802.11-11/1274r1

November 2011


• There are many comments asking to specify the coexistence mechanisms to avoid interference between overlapping BSS in TVWS band. This presentation discusses the problems and proposed solution from 11-11-1272r3 to provide resolution for the following CIDs on coexistence:

CIDs: 8, 500, 733 and 811.

Abstract

doc.: IEEE 802.11-11/1274r1

November 2011


CommentsCID Clause

Number(C)Page(C) Line(C) Comment Proposed Change

8 4.5.5.2 Need a mechanism for a portable BSS to detect presence of co-channel fixed devices so that it can move into a different channel. This is because there is a 16dB EIRP difference between the fixed and portable. So fixed APs may never detect a portable devices in the co-channel and thereby cause interference to the portable device BSS.

Make transmission of unsolicited TPC report element mandatory for fixed TVWS devices. Also see 11/0265r0 for suggested text.

500 10.af1 50 20 The channel power management currently provides mechanisms for advertising available channels or changes to channel(s) or constrained maximum transmit power level(s). However, the problem of potential interference among multiple overlapping BSSs while operating on the allocated channel and transmit power levels are not taken in to account.

Given the greater coverage range in TVWS band to more likely incur interferences, options for interference management among multiple overlapping networks should be specified in the specification.

733 General there is no specification for how the 5 and 10 MHz mode would coexist in a same TVWS channel, since the preambles cannot interoperate

add detailed coexistence mechanisms

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November 2011


Comments ..CID Clause

Number(C)Page(C) Line(C) Comment Proposed Change

811 General 66 36 802.11af is intended for increased range. However with that comes increased OBSS interference.

Recommend studying interference mitigation schemes between OBSS

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November 2011


• The larger cell coverage in TVWS band exacerbates the problem of overlapping BSS with hidden node STAs. In order to improve the utilization of limited available spectrum in TVWS band, enhanced coexistence mechanisms are required

• There are many possible scenarios for which, the legacy mechanisms currently available in 802.11 (e.g. CSMA/CA, RTS/CTS etc) are not sufficient

• We had discussed some possible solutions in 11-11-1049r1 during SFO meeting. This presentation is built upon the RLSS based approach, which had received good support from the straw poll:

• Do you support the use of RLSS to allow exchange of neighbourhood knowledge to address some of coexistence related comments? 7 Yes, 2 No, 5 Abstains

• Interference avoidance among multiple networks served by a common RLSS is considered here with two possible options for implementation:

• Distributed decision making• Centralized decision making

Discussion

doc.: IEEE 802.11-11/1274r1

November 2011


There are two main problems:1)When the transmit power levels in two overlapping BSS are significantly different

(4 W Fixed vs 100 mW/40 mW Personal/Portable operation), the conventional RTS/CTS protection can not solve the interference from a hidden STA.

• The larger coverage range in TVWS makes it more difficult problem than in the legacy WLAN bands (limited channels but increased interference area)

The OBSS Problem in TVWS

Victim network

Interfering network

STA – 1 (100 mW max)

STA –2 (100 mWmax)

STA – 3 (4 W max)

RTS

CTS

CTS

doc.: IEEE 802.11-11/1274r1

November 2011


2. Overlapping BSS with different channel bandwidths will be common due to limited TV channels in many locations. • One BSS with 5 MHz bandwidth may be adjacent with another using 10 MHz channel

overlapping to it (refer to .11af channelization in next slide). However, OBSS scanning and coexistence notifications like in 802.11n can not work due to non-interoperable preambles

The OBSS Problem in TVWS ..

5 MHz width in Own BSS (BSS # A)

10 MHz width in Overlapping BSS

(BSS # B)

Non-member STAMember STAs

5 MHz width in Own BSS (BSS # A)


(BSS # B)


10/20 MHz width in Own BSS (BSS # A)


(BSS # B)


10/20 MHz width in Own BSS (BSS # A)


(BSS # B)


doc.: IEEE 802.11-11/1274r1

November 2011


The OBSS Problem in TVWS ..

512 MHz

518 MHz

524 MHz

530 MHz

536 MHz

542 MHz

548 MHz

554 MHz

560 MHz

TV CH # 21

TV CH # 22

TV CH # 23

TV CH # 24

TV CH # 25

TV CH # 26

TV CH # 27

TV CH # 28

# 65 # 71 # 77 # 83 # 89 # 95 # 101 # 1075 MHz

512.5 MHz

559.5 MHz

# 68

# 74

# 80

# 86 # 98

# 92 # 104

# 108

……..

……..

10 MHz

10 MHz520 MHz

……..560 MHz

# 7 # 8 # 9 # 10

……..20 MHz

# 8 # 10

520 MHz 560 MHz

……..

Current channelization in .11af for US

doc.: IEEE 802.11-11/1274r1

November 2011


Deployment Scenarios• In many deployments, networks of different coverage range and capacity (e.g.

low data rate coverage for parking lots/campus, and high-data rate indoor service) may be managed through a common RLSS

Assumption: multiple APs are served by the same RLSS within one service provider’s domain, or AP from one SP’s network can request information from another AP with other SP’s network

Geo-location DB

1. Channel Query

DB Access

GDC Dependent STA

AP-2

(Fixed/Mode II)

0. Hear enabling signal

RLSS

1. Channel Query

GDC Dependent STA

AP-1 (fixed or Mode II

capable)

0. Hear enabling signal

GAS or public

action frames

2. Receive contact verification

signal (< each 60 s)

AP-3

(Fixed/Mode II) AP-N

(Fixed/Mode II)

2. Receive contact verification

signal (< each 60 s)

….

doc.: IEEE 802.11-11/1274r1

November 2011


• A registered location secure server (RLSS) entity has been specified in current 802.11af specification:

• RLSS is an advertisement server to support RLQP using inter-working capability of 802.11u. RLSS can be implemented inside an AP or can reside outside

• It can provide the following functions for white space operation: • proxy to external geo-location database• a network management service node that facilitates the operational controls

• Once an AP (Mode II/Fixed) obtains the list of authorized frequencies and transmit power levels for the network initiation, additional information about other networks around its area becomes important for selection of its actual operational parameters (e.g. channel, bandwidth, power)

• How the RLSS can support/manage to avoid OBSS interference?• Provide additional information about neighbouring networks to the APs. The decisions

(network initiation or changes during operation) are local to the AP• Control the operating parameters of the APs. The decisions on parameters are centralized

to the RLSS

Deployment Scenarios ..

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November 2011


• For setting up a network, an AP first obtains list of available channels at its location by performing channel availability query. It can then request additional Neighboring Network Information (NNI) from the RLSS for other networks in its neighbourhood served by the same RLSS

• NNI Query from a GDC AP to RLSS:• Device ID, estimated maximum transmit power, geo-location (optional)• Request Type:

• 0 for Neighboring Network Information Request• values 1-255 are reserved

• NNI Response from RLSS to the requesting AP: • The response message contains current operational parameters of networks which are

around the neighbourhood of the requesting STA (BSSID, used frequency channels, used channel widths, used transmit power levels, relative path losses, device classes)

Neighboring Network Information through RLSS

doc.: IEEE 802.11-11/1274r1

November 2011


• How RLSS can provide the relevant information?• From the known information about identity, device class and geo-location of each

TVBD, RLSS internally determines the possible interfering networks in its service zone

• An exclusion zone may be calculated using the knowledge of available channels, and propagation ranges of other BSS from the types of devices and their current transmit power levels

• Actual algorithms for deriving the information is implementation specific, and not specified by the standard

•After receiving the response for the NNI Query from RLSS, the AP can select its operating frequency, channel width and transmit power to minimize interference to itself, as well as, possible interference to its neighbouring networks

• What is required in .11af specification ? • New RLQP elements to allow query and response messages for neighbouring

network information

Neighboring Network Information through RLSS ..

doc.: IEEE 802.11-11/1274r1

November 2011


RLQP ID

Length Requester STA Address

Request Type

Device Identification

Estimated Maximum Transmit Power

Device Location Information

1 octet

2 octets

6 octets 1 octet 18 octets 1 octet 18 octets (only if location is changed)

• Neighboring Network Information Response

• Neighboring Network Information Query

These fields are repeated as determined by the length field

RLQP ID

Length Requester STA Address

Status Code

BSSID Operating Class

Channel Number

Device Class

Operating Transmit Power

Relative Path Loss

1 octet

2 octet

6 octet 1 octet

6 octets

1 octet 1 octet 1 octet

1 octet 1 octet

Neighboring Network Information through RLSS ..

doc.: IEEE 802.11-11/1274r1

November 2011


• Once an AP (Mode II or Fixed) obtains the list of authorized frequencies and transmit power levels for the network initiation, it sends an NCC to RLSS to request a set of network channels

• The RLSS determines these set of channels based on information of neighboring APs to avoid coexistence problems

• Assumption: multiple APs are served by the same RLSS within one service provider’s domain and they use the network channels as determined by the RLSS

• Network Channel Control procedure in D1.04 can be already used (with some additional description on the usage)

Network Coexistence through RLSS with Centralized Decision

doc.: IEEE 802.11-11/1274r1

November 2011


• The first message sent by the NCC requesting STA asserts identity and requests NCC.• The NCC requesting STA may select its preferred frequencies from the WSM and

request usage of the selected frequencies for multiple WLAN network channels usage.• The NCC responding STA may grant permission of using the selected frequencies, or

provides its recommended set of frequencies, for multiple WLAN network channels to the NCC requesting STA by using the NCC response frame

• The recommendation of the NCC responding STA is based on the effort to minimize coexistence issue. The actual algorithm of deriving the recommended channels, however, will not be specified in 802.11af.

• RLQP Network Channel Control (NCC) request and response frame in 8.4.5.4

Network Coexistence through RLSS with Centralized Decision ..

These three fields are repeated, as determined by the Number of Network Channel Triplets field

RLQP ID Length Requester STA address

Responder STA Address

Reason Result Code

Number Of NetworkChannel Triplets

Operating Class

Channel Number Maximum Transmit Power

Octets: 1 2 6 6 1 1 1 1 1

doc.: IEEE 802.11-11/1274r1

November 2011


• The interference management among multiple BSS is more challenging in TVWS band due to larger coverage range

• Neighboring network information query through RLSS allows distributed decision making for APs

• RLSS shares the operating parameters of neighbours relevant for the requesting AP• Each AP selects its operating parameters, but the network coexistence can be improved

from the additional knowledge about other networks

• In addition, RLSS can also be used to enable centralized decision making for network coexistence management

• RLSS makes decisions for multiple APs for allocating operating parameters in order to resolve any coexistence problems

• Each AP uses NCC to obtain a set network channels as decided by the RLSS, so that all networks linked to the RLSS can coexist

• For flexibility in implementations, .11af should enable both of the above options

Summary

doc.: IEEE 802.11-11/1274r1

November 2011

Padam Kafle, NokiaSubmission

Comments/Questions?

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Doc.: IEEE 802.11-11/1274r1 November 2011 Padam Kafle, Nokia Submission Neighboring Network Information Sharing through RLSS Authors: Date: Nov 7, 2011