PDU Handling in IEEE 802.16m

IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number:

IEEE C802.16m-08/924Date Submitted:

2008-09-5Source:

Sungcheol Chang, kwangjae Lim, and Chulsik Yoon Voice: +82-42-860-5456E-mail: {scchang, csyoon}@etri.re.kr

ETRI161 Gajeong-dong Yusong-gu Daejeon, Korea

Venue:Re : MAC: Data Plane in IEEE 80216m-08/033 : Call for Comments and Contributions on Project 802.16m SDD

Base Contribution:IEEE C802.16m-08/924

Purpose:To discuss and adopt the proposed text in the revision of the 802.16m SDD

Notice:This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who 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 802.16.

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Motivations

• Efficient MAC PDU Header– 6-byte fixed MAC header with HCS => Small overhead.

– Single type for GMH with payload => Multiple PDU types

• Efficiently Handling MAC PDU Payload– PDU construction per connection => Multiplexing

– Overhead for short data, i.e. VoIP packet. => Small overhead• GMH + Fragmentation SH

• Retransmission and Fragmentation– NO ARQ on unidirectinal MAC management message => ARQ

– BSN for ARQ-enabled connection and FSN for ARQ-disabled connection => Use unified numbering scheme

MAC PDU Header

• No MAC CRC if PHY CRC exists– Removal of HCS in GMH

• Flow ID to identify a connection within a user

• Encryption Control– Removal of the EC (Encryption Control) field

– EC&Key Sequence=0 means “No Encryption”

– Three encryption identifier, EC&Key Sequence=1,2,3

• Type encodings– Five indications for ARQ Feedback Payload, Fragment SH, Packing

SH, Extended Type, and Grant management SH

MAC PDU Types

• Three MAC PDU Types– Optimize MAC PDU to Payloads

– Generic MAC PDU• Handling MAC Payload to 2048 bytes

• Packing SH; Fragment SH; Extended SH; Grant Management SH for UL

– Light MAC PDU• Handling short size data to 128 bytes (i.e. VoIP)

• Small overhead

• No SH– All the information for PDU handling is in Light MAC PDU header

– Control MAC PDU• Carry control information with fixed-sized PDU

Control PDU Payloads (Examples)

• Null Padding• Aggregated bandwidth request• Average DL CINR• Preferred DL TF• UL transmit power• Band CINR: BITMAP + n CQIs• Differential Band CINR• Post-Rx CINR I: CQI for MS• Post-Rx CINR II: 4 CQIs• Precoding I: Codebook + CQI• Precoding II: Codebook + 4 CQIs• BR and UL transmit power• BR and average DL CINR• SDU SN report• Incremental bandwidth request

• Rate change request for ertPS• CINR standard deviation• MIMO type• Anchor change request: BSID• CQICH allocation request• NBR CINR and RSSI• UGS grant management:

SI+PM+FLI+FL• ERTPS grant management:

PSI+PSOBR+FLI+FL• BR and sleep control• PHY channel report: Tx Power +

Headroom• CINR statistics: Average + Standards• BR and NACK request

SDU Handling

• Use a BSN for both ARQ-enabled and ARQ-disabled connections– Unified numbering with BSN

• Allow MAC PDU to multiplex DATA from other connection with packing SH– Insert the indication, “Flow ID Included (or not)”

– If set, Flow ID is added prior to DATA.

• Allow unidirectional MAC management messages to be retransmitted with ARQ function– Ex) EAP Transfer

• Encrypt Fragmented SDU or Packing SDUs for relay function– No encryption of Subheaders.

Proposed PDU Handling

Concatenation

Packet ClassifierAnd

ROHC(PHS?)

ARQ

Encryption/Authentication

ARQ

Fragment & Packing

Encryption/Authentication

Generic PDU Handling

Light PDU Handling

Control PDU Handling

Encryption

Control Messages

Upper Layers

MA

C L

ayer

ARQ

If Same Security Association

SF

Subheaders

Packet ClassifierAnd

ROHC(PHS?)

Packet ClassifierAnd

ROHC(PHS?)

An Example for Headers (1/2)

Fragment Subheader Packing SubheaderField Size Description

FC 2 bits

BSN 10 bits Block Sequence Number

Reserved 4 bits

Field Size Description

PDU Type 2 bits Value = 01

Enc & Key Sequence

2 bits 00: No Encryption01,10,11: Encryption Key Sequence Number

Flow ID 4 bits

Type Encoding 5 bits 5 indicators

Length 11 bits

Generic PDU Header

Field Size Description

FC 2 bits

BSN 10 bits Block Sequence Number

Flow ID Included 1 bit

Length 11 bits

Flow ID 4 bits Exists if Flow ID Included is set.

Reserved 4 bits Exists if Flow ID Included is set.

An Example for Headers (2/2)

Light PDU Header Control PDU

Field Size Description

PDU Type 2 bits Value = 00

Contents Type 4 bits

Contents 34 bits

CRC 8 bits

Field Size Descripton

PDU Type 1 bit Value = 1

Enc & Key Sequence

2 bits 00: No Encryption01,10,11: Encryption Key Sequence Number

Flow ID 4 bits

BSN 10 bits

Length 7 bits

Numerical Results of The Example

0

10

20

30

40

50

60

70

80

90

100

1 2 3

PDU

Hea

der/

SH R

atio

to th

e le

gacy

(%)

# of SDUs in a PDU

legacy Generic PDU

proposed Generic PDU

Proposed Light PDU

SDD Texts10.X Construction of MAC PDU A MAC PDU header contains minimal information required for handling MAC PDU such as PDU type, Flow ID, Encryption Control, and Type Encoding, Length, and etc. Multiple PDU formats are designed to optimize overhead according to payloads. Generic MAC PDU and Control MAC PDU are to manage full PDU handling functions and to carry uplink control functions for uplink, respectively. Additionally Light MAC PDU with small overhead is to transport short data for VoIP, etc.

Encryption on MAC PDU is applied only to MAC SDUs and/or fragments except subheaders including fragmentation and packing subheaders. All the SDUs and/or fragments are numbered by by block sequence numbers(BSNs). A MAC PDU may concatenate SDUs and/or fragments from other flows, which Flow ID is added to packing SH.

Unidirectional MAC management messages may be retransmitted using ARQ function.