doc.: ieee 802.22-07/0052r0 submission january 2007 steve shellhammer, qualcommslide 1 the spectrum...

January 2007

Steve Shellhammer, Qualcomm

Slide 1

doc.: IEEE 802.22-07/0052r0

Submission

The Spectrum Sensing FunctionIEEE P802.22 Wireless RANs Date: 2007-01-15

Name Company Address Phone email Steve Shellhammer Qualcomm 5775 Morehouse Dr

San Diego, CA 92121 (858) 658-1874 [email protected]

Authors:

Notice: This document has been prepared to assist IEEE 802.22. 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 802.22.

Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf 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 Carl R. Stevenson 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 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at [email protected].>

January 2007


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Submission

Abstract

• This presentation is to describe the Spectrum Sensing “Black Box”

• It defines the inputs and outputs of the spectrum sensing function without specifying the specific techniques used within the black box.

January 2007


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Submission

Acronyms

ACL Available Channel List

ACSF Available Channel Selection Function

CM Confidence Metric

CV Confidence Vector

EV Error Variance

EVV Error Variance Vector

FSE Field Strength Estimate

FSEV Field Strength Estimate Vector

January 2007


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Submission

Acronyms

SPD Signal Present Decision

SPV Signal Present Vector

SSF Spectrum Sensing Function

SWS Sensing Window Specification

SWSV Sensing Window Specification Vector

January 2007


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Definitions

Available Channel List

A list of which TV channels are available for use by the WRAN. The list is sorted in order of preference. The first channel in the list is the most preferred channel for use by the WRAN. The last channel in the list is the least preferred channel. Any channel not on the list shall not be used by the WRAN.

Available Channel Selection Function

The function that combines the outputs of the spectrum scanning function from the base station and the CPEs and produces the available channel list

Confidence Metric A metric indicating the confidence in a signal present decision

Confidence Vector A vector of confidence metrics

January 2007


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Submission

Definitions

Error Variance The variance of the error of a field strength estimate

Error Variance Vector

A vector of error variances

Field Strength Estimate

An estimate of the field strength of a specific signal at the WRAN station

Field Strength Estimate Vector

A vector of field strength estimates

Sensing Mode A mode that specifies the output of the spectrum sensing function

Signal Type Vector A vector of bits. If a bit is set to a 1 then that signal type is to be sensed. If a bit is set to a 0 then that signal type is not to be sensed.

January 2007


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DefinitionsSpectrum Scanning Function

The function of scanning a TV channel for a set of signal types and generating a set of metrics indicating the presence of each of the signal types in the specified TV channel

Sensing Window Specification

A specification of the number of sensing intervals and the duration of the intervals

Sensing Window Specification Vector

A vector of sensing window specifications

January 2007


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Requirement for the SSF

• The spectrum sensing function (SSF) shall be present in the base station and each CPE

January 2007


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SSF InputsChannel Number The TV channel number specifying which channel to

sense.

Signal Type Vector A vector of bits. The i-th entry in the vector corresponds to the i-th signal type specified in Table 70 in the working document. A 1 in the i-th element in the vector indicates the SSF should sense for the i-th signal type. A 0 in the i-th element of the vector indicates that the SSF should not sense for the i-th signal type


A vector of sensing window specifications

Sensing Mode The mode specifies the output of the SSF. There are three modes.

Maximum probability of false alarm

The maximum probability of false alarm for the SSF when operating in Mode 1 or Mode 2

January 2007


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SSF Modes

• Three modes of the SSF have been defined

• The output of the SSF is different depending on the sensing mode

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• A sensing window consists of N sensing intervals– If a continuous window is required N is set to 1

• Each sensing interval is of duration T1

• The spacing between sensing (T2 ) intervals is not necessarily a fixed time. It is specified to between a minimum and maximum value

2MIN MAXT T T

January 2007


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I1 I2 IN

...T2

T1

January 2007


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Summary of Sensing Modes

• Mode 0– Signal present vector: A vector indicating the whether specific

signal types are present in the channel

• Mode 1– Signal present vector

– Confidence vector – A vector of confidence metrics

• Mode 2– Field strength estimate vector: A vector of field strength estimates

– Error variance vector: A vector consisting of the variance of the estimation errors

January 2007


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Submission

SSF in Mode 0

Spectrum Sensing FunctionSensing Mode 0

Channel Number

Signal Type Vector


Sensing Mode = 0

Maximum Probability of False Alarm

Signal Present Vector

January 2007


Slide 15

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Submission

Specifications on SSF Outputs in Mode 0

• The SSF shall sense channel specified by the channel number with a sensing window according to the sensing window specification for each signal type being sensed

• When the i-th signal type is not present in the channel then the probability that the signal present decision is TRUE shall be less than the specified “Maximum probability of false alarm”

• When the i-th signal type is present in the channel at the signal power level defined in Table TBD then the probability that the signal present decision is TRUE shall be greater than 0.9

January 2007


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Submission

SSF in Mode 1


Channel Number

Signal Type Vector


Sensing Mode = 1


Signal Present Vector

Confidence Vector

January 2007


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Submission


• In addition to the specification for the SSF in Mode 0 we have the following specifications

• For each signal type being sensed according to the signal type vector we have,– The confidence metric will be a number greater than 0 and less

than CMMAX (TBD)

– When SPD = TRUE the CM increases with increasing SNR

– When SPD = FALSE the CM increases with decreasing SNR

January 2007


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Submission

SSF in Mode 2


Channel Number

Signal Type Vector


Sensing Mode = 2


Field Strength Estimate Vector

Error Variance Vector

January 2007


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• The field strength estimate shall be an unbiased estimator

• The range of the field strength estimate shall be between FSMIN (TBD) and FSMAX (TBD)

• The average error variance shall decrease with increasing SNR

• The range of the error variance shall be between EVMIN (TBD) and EVMAX (TBD)

January 2007


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Submission


• A list of available channels

• Sorted from most preferred to least preferred

• Preference is measured in terms of potential interference– Systems close to but outside the keep-out region would likely be

low on the list

January 2007


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Submission

Available Channel Selection Function

• The ACSF resides within the WRAN base station

• The ACSF collect outputs of the SSF in the base station and all the CPEs

• The ACSF generates the available channel list (ACL)

January 2007


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doc.: IEEE 802.22-07/0052r0

Submission

ACSF Input/Output

Base StationSSF

CPE 1SSF

CPE 2SSF

CPE NSSF

…

Base StationACSF


January 2007


Slide 23

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Submission

Conclusions

• The Spectrum Sensing Function has been introduced with the inputs and outputs defined

• The Available Channel Selection Function has been introduced with its inputs and outputs

• A first-cut at Acronyms and Definitions has been generated

• Preliminary specifications for the SSF and the ACSF have been generated

January 2007


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Submission

Next Steps

• Generate a document with the details of the SSF and ACSF

• Review the document with the Sensing Team on conference calls

• Hold a vote in the WG (hopefully in March) to incorporate the text into the working document

doc.: ieee 802.22-07/0052r0 submission january 2007 steve shellhammer, qualcommslide 1 the spectrum...

Documents

statement ieee standards

steve shellhammer

070052r0 submission

preferred channel

definitions spectrum

number of sensing intervals

specific signal

patent policy