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MPDU format

MAC PDU formats

Connections are identified by a 16-bit CID.

HT=0 HT=1 Bandwidth Request Generic

CRC capability is mandatory for SCa, OFDM and OFDMA PHY layers

6 octets

HT: Head Type

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Generic MAC Header

Management frame Question: No CRC, how to decide the correctness for frame ??

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Type encodings (in Generic Header)

Bit mapping

Type bits

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Bandwidth Request MAC Header

000 : incremental (BS adds the needed quantity of CID) 001 : aggregate (BS replaces the needed quantity of CID)

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Bandwidth Request

• The Bandwidth Request shall have the following properties:

a) length of the header = 6 bytes b) EC field = 0 (indicating no encryption) c) CID indicates the connection for which uplink bandwidth is

requested. d) Bandwidth Request (BR) field indicates the number of bytes

requested. e) The allowed types for bandwidth requests are “000” for

incremental and “001” for aggregate.

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Subheader Types • Five types of subheaders

– Mesh – Fragmentation – FASTFEEDBACK_Allocation (MIMO) – Grant Management – Packing – Extended subheader field (defined in 16e : 11 additional

subheaders) » ESF bit in the Generic MAC header is set

• The subheaders are inserted in MAC PDUs immediately following the Generic MAC header.

– Sequence » Grant -> Fragmentation » Extended subheader -> others (defined in 16e) » Mesh -> others » others -> FastFeedback_allocation

– The Packing and Fragmentation subheaders are mutually exclusive and shall not both be present within the same MAC PDU

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MAC header formats in 802.16e

HT EC MAC PDU Type

0 0 Generic MAC header for DL and UL w/ data payload, no encryption (6-bit type field)

0 1 Generic MAC header for DL and UL w/ data payload, w/ encryption (6-bit type field)

1 0 DL: This encoding is not defined UL: MAC signaling header type I (slide page 9) MAC PDU w/o data payload (3-bit type field)

1 1 DL: Compressed/Reduced Private DL-MAP UL: MAC signaling header type II. MAC PDU w/o data payload (1-bit type field)

• Headers with HT=1 shall not be encrypted • EC field is used to distinguish between Feedback MAC header (UL) / Compress MAP (DL), and all other type headers

Data Payload

Control No encrypt

(OFDMA only)

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Generic MAC header format in 802.16e

ESF : Extended subheader field. (for UL/DL) (in slide pages 26 and 27) (0): the extended subheader is absent. (1): the extended subheader is present and will follow the GMH All extended subheaders are not encrypted

Extended subheaders

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3-bit Type Field in MAC Signaling Header Type I (Bandwidth Request )

• 000 : BR incremental • 001 : BR aggregate • 010 : PHY channel report • 011 : BR with UL Tx Power Report (piggyback) • 100 : BR and CINR report (piggyback) • 101 : BR with UL sleep control (piggyback) • 110 : SN Report • 111 : CQICH allocation request

• Support of subheaders is negotiated during

registration (REG-REQ/RSP)

Carrier to Interference-plus-Noise Ratio (CINR) Channel Quality Indicator Channel (CQICH)

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MPDU Transmission long Ethernet packet Short ATM cells

SDU

PDU

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MAC Subheader

• Three types of MAC subheaders may be present.

– The grant management subheader is used by an SS to convey bandwidth management needs to its BS.

– The fragmentation subheader contains information that indicates the presence and orientation in the payload of any fragments of SDUs. (e.g. long Ethernet packet)

– The packing subheader is used to indicate the packing of multiple SDUs into a single PDU. (e.g. ATM cells)

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Concatenation • Mandatory capability • Multiple MAC PDUs may be concatenated into a

single transmission in either the uplink or downlink directions.

• each MAC PDU is identified by a unique CID

Bandwidth stealing

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Packing

• The capability of unpacking is mandatory. • pack multiple MAC SDUs into a single MAC PDU.

– Differs from concatenation (1 CID vs. Multiple CIDs)

• Packing makes use of the connection attribute indicating whether the connection carries fixed-length or variable-length packets.

• The construction of PDUs varies for ARQ and non-ARQ connections with respect to packing and fragmentation syntax.

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Packing for non-ARQ connections • Packing fixed-length MAC SDUs

– the Request/Transmission Policy shall be set to allow packing and prohibit fragmentation, and the SDU size shall be included in DSA-REQ message when establishing the connection

– If the MAC SDU size is n bytes, the receiver unpacks simply by knowing that the length field in the MAC header will be n×k+j, where k is the number of MAC SDUs packed into the MAC PDU and j is the size of the MAC header and any prepended MAC subheaders.

– no added overhead

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Packing for non-ARQ connections

• Packing variable-length MAC SDUs – indication of where one MAC SDU ends and another begins. – the MAC attaches a Packing subheader (PSH) to each

MAC SDU (extra overhead) – unfragmented MAC SDUs and MAC SDU fragments may

both be present in the same MAC PDU

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Packing for non-ARQ connections

• Simultaneous fragmentation and packing allows efficient use of the airlink

• when a Packing subheader (PSH) is present, the fragmentation information for individual MAC SDUs or MAC SDU fragments is contained in the corresponding Packing subheader.

• Else (If no PSH is present), the fragmentation information for individual MAC SDU fragments is contained in the corresponding Fragmentation subheader (FSH)

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Packing for non-ARQ connections

PSH (Fixed)

PSH (Variable

FSH

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Packing for ARQ-enabled connections • Each of the packed MAC SDU or MAC SDU fragments

or ARQ feedback payload requires its own Packing subheader

• A MAC SDU may be partitioned into multiple fragments that are then packed into the same MAC PDU for the first transmission.

• MAC PDUs may have fragments from the same or different SDUs, including a mix of first transmissions and retransmissions.

• The 11-bit BSN and 2-bit FC fields uniquely identify each fragment or non-fragmented SDU.

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Hybrid-ARQ • Optional part and may be support for OFDMA PHY • The parameters are negotiated during initialization procedure • Each H-ARQ packet is encoded according the PHY

specification at the FEC block level – Subpacket identifier (SPID) is used to distinguish the four

subpackets – A BS can send one of the subpackets in a burst transmission – When SS received more than one subpackets, it tries to decode

from ever-received subpackets – If transmission failure, SS sends a NACK, BS transmit one more

from the four subpackets

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Payload Type • Payload Type indicates whether MAC subheaders

(Packing/Fragmentation/Grant) present or not.

packing/ fragmentation

packing/ fragmentation/

grant/ p+g/ f+g

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Fragmentation Subheader format

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Packing Subheader Format

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Grant Subheader Format (2004)

(incremental mode only – 16bits vs. 19 bits)

set when service flow has exceeded its transmit queue depth

is used to request to be polled for a different, non-UGS connection

Slip Indictor Poll- Me

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Grant Subheader Format (2005)

Frame latency indication Frame latency

incremental

In case of the Extended rtPS, if the MSB (most significant bit) is 1, BS changes its polling size into the size specified in the LSBs (least significant bit) of this field.

Slip Indicator

Frame latency indication Frame latency

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Extended Subheader Format total length in bytes

Refer to page 8

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Extended Subheader Format (DL)

(DL)

The support of each extended subheader is negotiated between BS and MS as part of the registration dialog (REG-REQ/RSP).

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Extended Subheader Format (UL)

(UL)

The support of each extended subheader is negotiated between BS and MS as part of the registration dialog (REG-REQ/RSP).

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Mesh Subheader Format

• Node ID

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FAST-FEEDBACK allocation subheader

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MAC Management Messages

• MAC Management messages on the Basic, Broadcast, and Initial Ranging connections shall neither be fragmented nor packed.

– Primary Management is allowed!

1 byte

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MAC Management Messages

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MAC Management Messages

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MAC Management Messages

AAS : adaptive antenna system

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MAC Management Messages (16e)

Amended Parts

Fragmentable Broadcast

for MBS

MOB - Mobile

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SS Initialization Overview

Downlink Sync

Get Uplink Parameters

Ranging

Capability Negotiation

Auth. Key Xchange

Register

Setup Time

DHCP

Download Configuration File

Setup connection and service flow (provisioned BE first)

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Steps

1) Scan for downlink channel and establish synchronization with the BS (retrieve DL-MAP / DCD)

2) Obtain transmit parameters (from UCD message) (uplink channel descriptor)

3) Perform ranging (RNG-REQ and RNG-RSP) 4) Negotiate basic capabilities 5) Authorize SS and perform key exchange 6) Perform registration 7) Establish IP connectivity (DHCP) optional 8) Establish time of day optional 9) Transfer operational parameters (TFTP) optional 10) Set up connections

Option : indicated by REG-REQ message