05 2004

Marco Naeve, Eaton Corp.Slide 1

IEEE 15-04-0218-01-004a

Submission

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

Submission Title: [IEEE 802.15.4 MAC Overview]Date Submitted: [10 May, 2004]Source: [Marco Naeve] Company [Eaton Corporation]Address [4201 North 27th Street, Milwaukee, WI 53216, USA]Voice:[414-449-7270], FAX: [414-449-6131], E-Mail:[marconaeve@eaton.com]

Re: [Reflector discussions. References: IEEE 802.15.4-2003 standard, 03036r0P802-15_WG-802-15-4-TG4-Tutorial.ppt by Jose Gutierrez, and 03057r0P802-15_TG4-Specification_summary.ppt by Pat Kinney, Paul Gorday, Phil Jamieson]

Abstract: [This document presents an overview of the IEEE 802.15.4 MAC sub-layer as currently specified in the 2003 version of the standard.]

Purpose: [For informative purpose for the IEEE 802.15.4a task group.]

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

05 2004

Marco Naeve, Eaton Corp.Slide 2

IEEE 15-04-0218-01-004a

Submission

Content

• Overview• Topologies• Superframe structure• Frame formatting• Data service• Management service• Interframe spacing• CSMA procedure

05 2004

Marco Naeve, Eaton Corp.Slide 3

IEEE 15-04-0218-01-004a

Submission

IEEE 802.15.4 MAC

Upper Layers

IEEE 802.15.4 SSCSIEEE 802.2LLC, Type I

IEEE 802.15.42400 MHz

PHY

IEEE 802.15.4868/915 MHz

PHY

802.15.4 Architecture

05 2004

Marco Naeve, Eaton Corp.Slide 4

IEEE 15-04-0218-01-004a

Submission

Protocol Drivers

Extremely low cost

Ease of installation

Reliable data transfer

Short range operation

• Reasonable battery life

05 2004

Marco Naeve, Eaton Corp.Slide 5

IEEE 15-04-0218-01-004a

Submission

MAC Overview

• Star and peer-to-peer topologies• Optional frame structure• Association• CSMA-CA channel access mechanism• Packet validation and message rejection• Optional guaranteed time slots• Guaranteed packet delivery• Facilitates low-power operation• Security

05 2004

Marco Naeve, Eaton Corp.Slide 6

IEEE 15-04-0218-01-004a

Submission

IEEE 802.15.4 Device Classes• Full function device (FFD)

– Any topology– PAN coordinator capable– Talks to any other device– Implements complete protocol set

• Reduced function device (RFD)– Limited to star topology or end-device in a peer-to-

peer network. – Cannot become a PAN coordinator– Very simple implementation– Reduced protocol set

05 2004

Marco Naeve, Eaton Corp.Slide 7

IEEE 15-04-0218-01-004a

Submission

IEEE 802.15.4 Definitions

• Network Device: An RFD or FFD implementation containing an IEEE 802.15.4 medium access control and physical interface to the wireless medium.

• Coordinator: An FFD with network device functionality that provides coordination and other services to the network.

• PAN Coordinator: A coordinator that is the principal controller of the PAN. A network has exactly one PAN coordinator.

05 2004

Marco Naeve, Eaton Corp.Slide 8

IEEE 15-04-0218-01-004a

Submission

Low-Power Operation

• Duty-cycle control using superframe structure– Beacon order and superframe order– Coordinator battery life extension

• Indirect data transmission• Devices may sleep for extended period over

multiple beacons• Allows control of receiver state by higher

layers

05 2004

Marco Naeve, Eaton Corp.Slide 9

IEEE 15-04-0218-01-004a

Submission

Star Topology

FFD

RFD Communications flow

Master/slave

PANcoordinator

05 2004

Marco Naeve, Eaton Corp.Slide 10

IEEE 15-04-0218-01-004a

Submission

Peer-Peer Topology

Communications flow

Point to point Cluster tree

FFD

RFD

PANcoordinators

05 2004

Marco Naeve, Eaton Corp.Slide 11

IEEE 15-04-0218-01-004a

Submission

Combined Topology

FFD

RFD

Communications flow

Clustered stars - for example,cluster nodes exist between roomsof a hotel and each room has a star network for control.

05 2004

Marco Naeve, Eaton Corp.Slide 12

IEEE 15-04-0218-01-004a

Submission

Optional Frame Structure

15ms * 2n

where 0 n 14

GTS 3 GTS 2

Network beacon

Transmitted by PAN coordinator. Contains network information,frame structure and notification of pending node messages.

Beaconextension

periodSpace reserved for beacon growth due to pending node messages

Contentionperiod

Access by any node using CSMA-CA

GuaranteedTime Slot

Reserved for nodes requiring guaranteed bandwidth [n = 0].

GTS 1

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Slot

Battery life extension

Contention Access Period Contention Free Period

05 2004

Marco Naeve, Eaton Corp.Slide 13

IEEE 15-04-0218-01-004a

Submission

Optional Frame Structure

• Superframe may have inactive period

15ms * 2BO

where SO BO 14

15ms * 2SO

where 0 SO 14

SO = Superframe orderBO = Beacon order

Inactive Period

05 2004

Marco Naeve, Eaton Corp.Slide 14

IEEE 15-04-0218-01-004a

Submission

General MAC Frame FormatOctets:2 1 0/2 0/2/8 0/2 0/2/8 variable 2

Destination PAN

identifier

Destination address

Source PAN

identifier

Source address

MAC payload

MAC footer

Frame check

sequence

MAC header

Addressing fields

Frame control

Sequence number

Frame payload

Bits: 0-2 3 4 5 6 7-9 10-11 12-13 14-15

Frame typeSequrity enabled

Frame pending

Ack. Req. Intra PAN ReservedDest.

addressing mode

ReservedSource

addressing mode

Frame control field

05 2004

Marco Naeve, Eaton Corp.Slide 15

IEEE 15-04-0218-01-004a

Submission

Beacon Frame Format

Bits: 0-3 4-7 8-11 12 13 14 15Beacon

orderSuperframe

orderFinal CAP

slotBattery life extension

ReservedPAN

coordinatorAssociation

permit

Octets:2 1 4 or 10 2 variable variable variable 2

MAC footer

Frame check

sequence

MAC header

Source address information

MAC payload

Superframe specification

GTS fields

Pending address

fields

Frame control

Beacon sequence number

Beacon payload

05 2004

Marco Naeve, Eaton Corp.Slide 16

IEEE 15-04-0218-01-004a

Submission

MAC Command Frame

• Command Frame Types– Association request– Association response– Disassociation notification– Data request– PAN ID conflict notification

– Orphan Notification– Beacon request– Coordinator realignment– GTS request

Octets:2 1 4 to 20 1 variable 2

MAC footer

Frame check

sequence

Frame control

Data sequence number

Address information

MAC header MAC payload

Command type

Command payload

05 2004

Marco Naeve, Eaton Corp.Slide 17

IEEE 15-04-0218-01-004a

Submission

Data Frame Format

Acknowledgement Frame FormatOctets:2 1 2

MAC footer

Frame check

sequence

MAC header

Frame control

Data sequence number

Octets:2 1 4 to 20 variable 2

MAC PayloadMAC

footer

Data payloadFrame check

sequence

MAC header

Frame control

Data sequence number

Address information

05 2004

Marco Naeve, Eaton Corp.Slide 18

IEEE 15-04-0218-01-004a

Submission

Data Service

• Data transfer to neighboring devices– Acknowledged or unacknowledged– Direct or indirect– Using GTS service

• Maximum data length (MSDU) aMaxMACFrameSize (102 bytes)

05 2004

Marco Naeve, Eaton Corp.Slide 19

IEEE 15-04-0218-01-004a

Submission

MAC Data Primitives

Primitive Request Confirm Indication Response

MCPS-DATA Required Required Required

MCPS-PURGEOptional for

RFDOptional for

RFD

05 2004

Marco Naeve, Eaton Corp.Slide 20

IEEE 15-04-0218-01-004a

Submission

Data TransferMessage Sequence Diagram

Originator

MAC Recipient

MAC

Data frame

Acknowledgment (if requested)

Originator higher layer

Recipient higher layer

MCPS-DATA.request

MCPS-DATA.indication

MCPS-DATA.confirm

05 2004

Marco Naeve, Eaton Corp.Slide 21

IEEE 15-04-0218-01-004a

Submission

Indirect Data TransferMessage Sequence Diagram

Coordinator

MAC Device MAC

Data frame

Acknowledgment

Coordinator higher layer

Device higher layer

MCPS-DATA.request (indirect)

MCPS-DATA.indication

MCPS-DATA.confirm

Beacon frame

Data request

Acknowledgement

05 2004

Marco Naeve, Eaton Corp.Slide 22

IEEE 15-04-0218-01-004a

Submission

Management Service

• Access to the PIB• Association / disassociation• GTS allocation• Message pending • Node notification• Network scanning/start• Network synchronization/search

05 2004

Marco Naeve, Eaton Corp.Slide 23

IEEE 15-04-0218-01-004a

Submission

MAC Management PrimitivesPrimitive Request Confirm Indication Response

MLME-GET Required Required

MLME-SET Required Required

MLME-ASSOCIATE Required Required Optional for RFD Optional for RFD

MLME-DISASSOCIATE Required Required Required

MLME-GTS Optional for RFD Optional for RFD Optional for RFD

MLME-BEACON-NOTIFY Required

MLME-POLL Required Required

MLME-COMM-STATUS Required

MLME-ORPHAN Optional for RFD Optional for RFD

MLME-SCAN Required Required

MLME-START Optional for RFD Optional for RFD

MLME-RX-ENABLE Required Required

MLME-SYNC Required

MLME-SYNC-LOSS Required

MLME-RESET Required Required

05 2004

Marco Naeve, Eaton Corp.Slide 24

IEEE 15-04-0218-01-004a

Submission

AssociationMessage Sequence Diagram

Device MAC

Coordinator MAC

Association request

Acknowledgment

Device higher layer

Coordinator higher layer

MLME-ASSOCIATE.request

MLME-ASSOCIATE.indication

MLME-ASSOCIATE.response

Acknowledgement

Association response

MLME-ASSOCIATE.confirm

aResponseWaitTime

MLME-COMM-STATUS.indication

Data request

Acknowledgment

05 2004

Marco Naeve, Eaton Corp.Slide 25

IEEE 15-04-0218-01-004a

Submission

DisassociationMessage Sequence Diagram

= Originator

MAC Recipient

MAC

Disassociation notification

Acknowledgment

Originator higher layer

Recipient higher layer

MLME-DISASSOCIATE.request

MLME-DISASSOCIATE.indication MLME-DISASSOCIATE.confirm

05 2004

Marco Naeve, Eaton Corp.Slide 26

IEEE 15-04-0218-01-004a

Submission

Data PollingMessage Sequence Chart

Device MAC

Coordinator MAC

Data request

Acknowledgment (FP = 0)

Device higher layer

MLME-POLL.request

MLME-POLL.confirm

No data pending at the coordinator

05 2004

Marco Naeve, Eaton Corp.Slide 27

IEEE 15-04-0218-01-004a

Submission

Data PollingMessage Sequence Chart

Device MAC

Coordinator MAC

Data request

Acknowledgment (FP = 1)

Device higher layer

MLME-POLL.request

MLME-POLL.confirm

Data

Acknowledgement

MCPS-DATA.indication

Data pending at the coordinator

05 2004

Marco Naeve, Eaton Corp.Slide 28

IEEE 15-04-0218-01-004a

Submission

Passive Scan

Device MAC

Coordinator MAC

Device higher layer

MLME-SCAN.request

MLME-SCAN.confirm

ScanDuration Beacon

Set 1st Channel

Set 2nd Channel

05 2004

Marco Naeve, Eaton Corp.Slide 29

IEEE 15-04-0218-01-004a

Submission

Active Scan

Device MAC

Coordinator MAC

Beacon request

Device higher layer

MLME-SCAN.request

MLME-SCAN.confirm

ScanDuration Beacon

Set 1st Channel

CSMA

Set 2nd Channel

Beacon request

05 2004

Marco Naeve, Eaton Corp.Slide 30

IEEE 15-04-0218-01-004a

Submission

OrphaningMessage Sequence Diagram

= Coordinator

MAC Device MAC

Coordinator realignment

Orphan notification

Coordinator higher layer

MLME-ORPHAN.response

MLME-COMM-STATUS.indication

MLME-ORPHAN.indication

05 2004

Marco Naeve, Eaton Corp.Slide 31

IEEE 15-04-0218-01-004a

Submission

Inter-frame Spacing

For frames ≤ aMaxSIFSFrameSize use short inter-frame spacing (SIFS)For frames > aMaxSIFSFrameSize use long inter-frame spacing (LIFS)

Long frame ACK Short frame ACK

tack LIFS tack SIFS

Acknowledged transmission

Long frame Short frame

LIFS SIFS

Unacknowledged transmission

aTurnaroundTime tack (aTurnaroundTime (12 symbols) + aUnitBackoffPeriod (20 symbols))LIFS > aMaxLIFSPeriod (40 symbols)SIFS > aMacSIFSPeriod (12 symbols)

05 2004

Marco Naeve, Eaton Corp.Slide 32

IEEE 15-04-0218-01-004a

Submission

Slotted CSMA Procedure

NB = 0, CW = 0

Battery lifeextension?

BE = macMinBE

BE = lesser of(2, macMinBE)

Locate backoffperiod boundary

Delay forrandom(2BE - 1) unit

backoff periods

Perform CCA onbackoff period

boundary

Channel idle?

CW = 2, NB = NB+1,BE = min(BE+1, aMaxBE)

CW = CW - 1

CW = 0?NB>

macMaxCSMABackoffs?

Failure Success

Slotted CSMA

Y

Y Y

Y

N

N

N

N

Used in beacon enabled networks.

05 2004

Marco Naeve, Eaton Corp.Slide 33

IEEE 15-04-0218-01-004a

Submission

Un-slotted CSMA Procedure

NB = 0,BE = macMinBE

Delay forrandom(2BE - 1) unit

backoff periods

Perform CCA

Channel idle?

NB = NB+1,BE = min(BE+1, aMaxBE)

NB>macMaxCSMABackoffs

?

Failure Success

Un-slotted CSMA

Y

Y

N

N

Used in non-beacon networks.

05 2004

Marco Naeve, Eaton Corp.Slide 34

IEEE 15-04-0218-01-004a

Submission

Thank you!

Questions