IEEE C802.16m-08/787
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
CID re-organization
Date
Submitted
2008-07-07
Source(s)
Kiseon Ryu
Voice: +82-31-450-7903
E-mail: ksryu@lge.com
sixs@lge.com
ronnykim@lge.com
Youngsoo Yuk
Ronny Yongho Kim
LG Electronic Inc.
LG R&D Complex, 533 Hogye-1dong,
Dongan-gu, Anyang, 431-749, Korea
Re:
IEEE 802.16m-08/024: Call for Contributions on Project 802.16m System Description
Document (SDD).
Specific topic : “Upper MAC Addressing”
Abstract
This contribution proposes a CID re-organization for 802.16m addressing mechanism.
Purpose
For discussion and approval by TGm
Notice
Release
Patent
Policy
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
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Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and
<http://standards.ieee.org/board/pat>.
CID Re-organization
Kiseon Ryu, Youngsoo Yuk, and Ronny Kim
LG Electronics
Introduction
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IEEE C802.16m-08/787
In 802.16m SRD, Section 6.9 and Section 6.10 require user overhead reduction and system overhead reduction
respectively. Because the overhead shall be reduced as compared to the WirelessMAX-OFDMA Referece
System, first it is required to understand the overhead of Reference System and consider possible improvement.
In the Reference System, the size of MAC header is 6 byte and mandatory parameters included in the MAC
header regardless of header type are Header Type (HT) – 1bit, Encryption Control (EC) – 1bit, Length(LEN) –
11bit, Connection Identifier (CID) – 16 bit, and Header Check Sequence(HCS) – 8bit. CID occupies 33% of the
mandatory parameters of the MAC header. CID also occupies substantial portion of MAP control messages. If
the size of CID can be reduced by reorganizing the structure of CID, substantial amount of overhead can be
reduced.
The CID has two major functions such as service flow classification and identification of resource assignment.
The CID represents a certain service flow on the MAC layer after assigned by a BS during service flow creation,
and identifies which connection is used to deliver a MAC PDU. The CID is also used to specify which MS or
connection for the data transmission is allocated radio resources by DL/UL-MAP.
In the reference system, if HARQ is enabled, a basic CID is used for DL/UL burst allocation. If HARQ is not
enabled, a basic CID for UL and CIDs including transport CID for DL are used in the MAP. CID can also be
omitted in a DL-MAP depending on a CID inclusion flag for non-HARQ DL burst allocation. That is, in most
cases, the basic CID is used for identification of resource assignment in a MAP.
The CID specified in a MAP should be unique within a BS so that the MS associated with the CID can
selectively receive and/or transmit DL/UL data burst using the assigned resource. 16 bits CID used in a MAP is
adequate.
However, in order to serve the purpose of service flow classification, the CID specified in a MAC Header
should be unique not within a BS but within an MS. Once the radio resource for the MS is assigned by DL/ULMAP, both an MS and a BS have only to distinguish the service flow related the CID. It means that only 4 to 6
bits can be used in a MAC header to identify the connection for the PDU. If we use 4 bits or 6 bits CID in a
MAC header, we can save 25% or 21% MAC overhead per MAC PDU respectively compared to the legacy CID
in a MAC header.
Therefore, we propose the CID re-organization, dividing CID into two IDs per its purpose. By separating CID
into two kinds of IDs, one for resource assignment (i.e. Scheduling CID) and the other for service flow
classification (i.e. Flow CID), MAC overhead can be substantially reduced.
Furthermore, in the multicarrier system, one common MAC controls multiple frequency channel (PHY), and
one MS can have multiple physical links simultaneously. Therefore, only one SCID is used for one MS in the
multicarrier support system even if USCCH is encoded separately or not.
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IEEE C802.16m-08/787
Proposed Scheme
We propose the new structure for 16m addressing which separates the current CID into two different
identifications; identification of resource assignment named as SCID (Scheduling CID) and identification of
service flow classification named as FCID (Flow CID).
The following figure shows the proposed CID structure.
MAC PDU
concatenation
MAC Header
(FCID)
Payload
DL-MAP
(SCID)
MAC Header
(FCID)
Payload
MAC Header
(FCID)
Payload
DL burst
DL-MAP
(SCID)
DL subframe
DL burst
DL-MAP
(SCID)
DL burst
DL-MAP
(SCID)
DL burst
Figure. Example of usage of the proposed CID structure
The proposed CID structure has two different functions as following:


Resource Assignment (SCID)
•
Unique within a BS
•
Basic CID/Broadcast CID/MCID can be re-used for the commonality with legacy system
•
Used to configure a MAP
•
The length can be optimized with 12 – 14 bits
Service Flow classification (FCID)
•
Unique within an MS
•
An element of MAC header
•
The length can be optimized with 4 – 6 bits
RACID and FCID are assigned through the similar procedure with the legacy CID assignment. SCID should
be first assigned during initial network entry, and FCID should be assigned when the service flow is created.
Related procedures are as follows.

SCID is assigned by BS during initial network entry.
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IEEE C802.16m-08/787

FCID is assigned by BS during service flow creation.

FCID is included in the MAC header.

BS allocates DL/UL resource to an MS by using SCID in the MAP

Management FCID for the management message transmission can be fixed
•
Basic management FCID for the transmission of delay intolerant management message
has a fixed value.
•
Primary management FCID for the transmission of delay tolerant management message
has a fixed value.
In the multi-carrier system, one common MAC controls multiple frequency channel (PHY), and one MS can
have multiple physical links simultaneously. Therefore, only one SCID is used for one MS in the multi-carrier
support system even if USCCH is encoded separately or not.
Conclusions
The proposed new CID structure provides the significant overhead reduction for 16m addressing compared to
the reference system.
Text Proposal
---------------------------------------------------
Text Start
---------------------------------------------------
10.x. Addressing
IEEE 802.16m defines two different identifications for data addressing; identification of resource assignment
named as SCID (Scheduling CID) and identification of service flow classification named as FCID (Flow CID).
SCID and FCID have the following characteristics.


For Resource Assignment (SCID)
•
Unique within a BS
•
Basic CID/Broadcast CID/MCID can be re-used for the commonality with legacy system
•
Used to configure a MAP
•
The length can be optimized with 12 – 14 bits
For Service Flow classification (FCID)
•
Unique within an MS
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IEEE C802.16m-08/787
•
An element of MAC header
•
The length can be optimized with 4 – 6 bits
Figure shows the usage of SCID and FCID.
MAC PDU
concatenation
MAC Header
(FCID)
MAC Header
(FCID)
Payload
DL-MAP
(SCID)
Payload
MAC Header
(FCID)
Payload
DL burst
DL-MAP
(SCID)
DL subframe
DL burst
DL-MAP
(SCID)
DL burst
DL-MAP
(SCID)
DL burst
Figure. Usage of SCID and FCID
SCID/FCID related procedures are as follows.

SCID is assigned by BS during initial network entry.

FCID is assigned by BS during service flow creation.

FCID is included in the MAC header.

BS allocates DL/UL resource to an MS by using SCID in the MAP

Management FCID for the management message transmission can be fixed
•
Basic management FCID for the transmission of delay intolerant management message
has a fixed value.
•
Primary management FCID for the transmission of delay tolerant management message
has a fixed value.
In the multi-carrier system, one common MAC controls multiple frequency channel (PHY), and one MS can
have multiple physical links simultaneously. Therefore, only one SCID is used for one MS in the multi-carrier
support system even if USCCH is encoded separately or not.
---------------------------------------------------
Text End
---------------------------------------------------
References
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IEEE C802.16m-08/787
[1] IEEE 802.16Rev2/D4, April 2008
6