Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS)

Submission Title: [Considerations for Supporting the 802.15.3 MAC Over a UWB PHY]

Date Submitted: [September 2002]Revised: []

Source: [Daniel Peters, Roberto Aiello, Naiel Askar, Jason Ellis, Susan Lin, Gopal Racherla, Larry Taylor] Company [General Atomics Inc.] Address [General Atomics- Advanced Wireless Group, 10240 Flanders Ct, San Diego, CA 92121-2901] Voice [(858) 457-8700], Fax [(858) 457-8740], E-mail [jason.ellis@ga.com]

Re: [Ultra-Wideband System Design Considerations]

Abstract: [UWB technology is characterized by parameters different from narrowband systems. This tutorial analyzes the relevant MAC features as they pertain to PHY selection.]

Purpose: [IEEE 802.15.3SGa Tutorial September 10, 2002]

Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual or organization. The material in this document is subject to change in form and content after further study. The contributor reserves the right to add, amend or withdraw material contained herein.

Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

September 2002

General Atomics- Advanced Wireless GroupSlide 2

doc.: IEEE 802.15-02/379r0

Submission

General AtomicsAdvanced Wireless Group

Daniel Peters, (Daniel.Peters@GA.com)

Roberto Aiello, Ph.D. (Aiello@IEEE.org)Naiel Askar, Ph.D. (Naiel.Askar@GA.com)

Jason Ellis, (Jason.Ellis@GA.com)Susan Lin, Ph.D. (Susan.Lin@GA.com)

Gopal Racherla, Ph.D. (Gopal.Racherla@GA.com) Larry Taylor (Larry.Taylor@ACM.org)

www.ga.com/uwb

Considerations for Supporting the 802.15.3 MAC Over a UWB PHY

September 2002

General Atomics- Advanced Wireless GroupSlide 3

doc.: IEEE 802.15-02/379r0

Submission

Tutorial’s Objectives

• Highlight the most important features that the MAC expects to be provided by the PHY

• Compare and contrast narrowband and UWB PHYs only as far as they affect these features

• Investigate how different UWB approaches will provide necessary support

• Stimulate dialog and discussion within SG3a

• Assist PHY selection process

September 2002

General Atomics- Advanced Wireless GroupSlide 4

doc.: IEEE 802.15-02/379r0

Submission

PHY Service

Primitive Request Indication ConfirmPHY-DATA 6.7.1.1 6.7.1.2 6.7.1.3PHY-TX-START 6.7.2.1 6.7.2.2PHY-TX-END 6.7.2.3 6.7.2.4PHY-CCA-START 6.7.3.1 6.7.3.2PHY-CCA-END 6.7.3.3 6.7.3.4PHY-CCA 6.7.3.5PHY-RX-START 6.7.4.1 6.7.4.3 6.7.4.2PHY-RX-END 6.7.4.4 6.7.4.6 6.7.4.5PHY-PS 6.7.5.1 6.7.5.2

Table 35—Summary of PHY SAP service primitives

Key considerations for UWB PHY include CCA and error reporting

CCA: Clear Channel AssessmentReference: 802.15.3 MAC draft 11

Parameter Type Valid range DefinitionData Octet 0-255 The data that is part of the frame body including

the FCS.CCAStatus Enumeration BUSY, IDLE The status of the channel.TXDataRate Octet PHY dependent. Data rate to be used in transmitting the frame.TXLength 2 octets 0-aMaxFrameSize Length of the MAC frame to be transmitted, 7.2.TXPowerLevel Octet PHY dependent The transmitter power to be used for the frame.TXMACHead 10 octets Any valid MAC header The MAC header of the frame to be transmitted.

Note that the MAC header does not include the HCS, as indicated in 7.2

TXAntSelect Octet 0-255 The antenna to use for transmitting the data. The value 0 is always valid, other values are implementation dependent.

RXDataRate Octet PHY dependent The data rate of the received frame.RXLength 2 octets 0-aMaxFrameSize Length of the frame that was received.RXMACHead 10 octets Any valid MAC header The MAC header of the frame that was received.

Note that the MAC header does not include the HCS, as indicated in 7.2.

RSSI Octet PHY dependent The power level of the received signal.LQI Octet PHY dependent The quality of the received signal.RXERROR Enumeration NO_ERROR,

CARRIER_LOST, FORMAT_VIOLATION, UNSUPPORTED_RATE

The result of the receive process.

PSLevel Integer 0-PHYPIB_NumPSLevels Numeric value of one of the supported power save levels of the PHY. PSLevel value 0 is used by the MAC to instruct the PHY to return from a reduced power state, or off state, to a state where it is ready to receive command. Other values are implementation

PSResultCode Enumeration SUCCESS, FAILED, UNSUPPORTED_MODE

Indicates the result of the MLME request.

Table 36—PHY SAP service primitive parameters

September 2002

General Atomics- Advanced Wireless GroupSlide 5

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Submission

MLME ServiceAnother key consideration for UWB PHY is scan and remote scan

Name Request Indication Response ConfirmMLME-RESET 6.3.1.1MLME-SCAN 6.3.2.1 6.3.2.2MLME-START 6.3.3.1 6.3.3.2MLME-START-DEPENDENT 6.3.3.3 6.3.3.4MLME-SYNCH 6.3.4.1 6.3.4.2MLME-SYNCH-LOST 6.3.4.3MLME-ASSOCIATE 6.3.5.1 6.3.5.2 6.3.5.3 6.3.5.4MLME-DEV-ASSOCIATION-INFO 6.3.5.5MLME-DISASSOCIATE 6.3.6.1 6.3.6.2 6.3.6.3MLME-AUTHENTICATE 6.3.7.1 6.3.7.2 6.3.7.3 6.3.7.4MLME-CHALLENGE 6.3.7.5 6.3.7.6 6.3.7.7 6.3.7.8MLME-REQUEST-KEY 6.3.8.1 6.3.8.2 6.3.8.3 6.3.8.4MLME-DISTRIBUTE-KEY 6.3.9.1 6.3.9.2 6.3.9.3 6.3.9.4MLME-DE-AUTHENTICATE 6.3.10.1 6.3.10.2 6.3.10.3MLME-SECURITY-ERROR 6.3.11.1MLME-PNC-HANDOVER 6.3.12.1 6.3.12.2 6.3.12.3 6.3.12.4MLME-NEW-PNC 6.3.12.5MLME-PNC-INFO 6.3.13.1 6.3.13.2 6.3.13.3 6.3.13.4MLME-PROBE 6.3.14.1 6.3.14.2 6.3.14.3 6.3.14.4MLME-CREATE-STREAM 6.3.15.1 6.3.15.2MLME-MODIFY-STREAM 6.3.15.3 6.3.15.4MLME-TERMINATE-STREAM 6.3.15.5 6.3.15.6 6.3.15.7MLME-MULTICAST-RX-SETUP 6.3.16.1MLME-CHANNEL-STATUS 6.3.17.1 6.3.17.2 6.3.17.3 6.3.17.4MLME-REMOTE-SCAN 6.3.18.1 6.3.18.2 6.3.18.3 6.3.18.4MLME-PICONET-PARM-CHANGE 6.3.19.1 6.3.19.2MLME-TX-POWER-CHANGE 6.3.20.1 6.3.20.2 6.3.20.3MLME-SPS-SET-INQUIRY 6.3.21.1 6.3.21.2MLME-SPS-SET-CONFIGURE 6.3.21.3 6.3.21.4MLME-PS-MODE-CHANGE 6.3.21.5 6.3.21.6MLME-PS-MODE-ACTIVE 6.3.21.7

Table 2—Summary of MLME Primitives

MLME: MAC Layer Management EntityReference: 802.15.3 MAC draft 11

September 2002

General Atomics- Advanced Wireless GroupSlide 6

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Submission

Channelization

• Proakis defines the communications channel as the physical medium that is used to send the signal from transmitter to receiver

• Channelization is the means of sharing the physical medium between multiple disjoint communications channels

• Large bandwidth enables short pulses; low duty cycle signaling allows for new types of channels

*Source: FCC 02-48, UWB Report & Order, released 22 April 02

Attribute Comment

Frequency At most 15 channels as per FCC*

Based on 20% fractional bandwidth or 500MHz

Time Synchronized sequence of discrete pulses

May be interleaved if low duty cycle

Code Spreading codes Same as narrowband case

Hybrid Combination of other approaches

Ch

ann

eliz

atio

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Op

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ns

There are many methods for establishing UWB channels

September 2002

General Atomics- Advanced Wireless GroupSlide 7

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Submission

Clear Channel Assessment

• Needed for CSMA/CA during the Contention Access Period (CAP) of the superframe

• Utilized by 802.11 systems to detect a medium-busy signal

• CCA may be estimated by

• Energy above a certain threshold

• Detection of the preamble

• CCA procedure will be different for UWB systems depending on their channelization

Energy is not a good measurement for UWB due to wideband receiver

CSMA/CA: Carrier Sense Multiple Access with Collision Avoidance

September 2002

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Submission

SynchronizationSynchronization critically depends on channelization

• Utilize PHY preamble for synchronization• In a narrowband system needed for

–Symbol level timing –Carrier frequency error estimation–Carrier phase estimation for coherent demodulation–Channel sounding and equalization

• Different for UWB– Frequency and phase

estimation may not be required

– For time interleaved channels, MAC concept of channel identifiers can only have local scope

• Careful design of preamble allows compatibility of multiple modulation schemes

• Different for UWB– Frequency and phase

estimation may not be required

– For time interleaved channels, MAC concept of channel identifiers can only have local scope

• Careful design of preamble allows compatibility of multiple modulation schemes

September 2002

General Atomics- Advanced Wireless GroupSlide 9

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Submission

Location Awareness

• Definition of location awareness

– Location awareness is the ability to determine information about the range and perhaps relative location of one device with respect to another

• Attributes of location awareness

– Resolution of measurement

• Inversely proportional to bandwidth

– Accuracy of measurement

• Proportional to SNR

– Time to compute

• Implications to the MAC

– The MAC does not presently support location awareness and the PHY can’t support it alone

New feature that is currently not supported

Where ismy closest

printer?

I wonder what’s

for lunch?

September 2002

General Atomics- Advanced Wireless GroupSlide 10

doc.: IEEE 802.15-02/379r0

Submission

Conclusions and Discussion

• CCA and Channel Scanning are the main PHY Service procedures that require careful consideration

• UWB PHYs may introduce significant new channel concepts

• Synchronization and channel naming may require re-evaluation

• CCA for UWB systems may not be possible without preamble detection

• Support for location awareness can not be confined solely to the PHY