IEEE C802.16m-09/1913
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Proposed Text Related to common MAC handover for the IEEE 802.16m/D1
(15.2.5.10.5.1)
Date
Submitted
2009-08-29
Source(s)
Eunjong Lee, Kiseon Ryu, Inuk Jung,
Youngsoo Yuk, Ronny Kim
Voice : +82-31-450-1876
LG Electronics
E-mail: mehappy3@lge.com
Re:
IEEE 802.16 Working Group Letter Ballot #30 on P802.16m/D1
Abstract
The contribution proposes the text of handover to be included in the 802.16m amendment.
Purpose
To be discussed and adopted by TGm for the 802.16m DRAFT amendment.
Notice
Release
Patent
Policy
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Proposed Text Related to common MAC handover
for the IEEE 802.16m/D1 (15.2.5.10.5.1)
Eunjong Lee, Kiseon Ryu, Inuk Jung, Youngsoo Yuk and Yongho Kim
LG Electronics
1. Introduction
According to the current AWD [6], an AMS should perform the network re-entry procedure to target ABS
during HO procedure. The ABS is able to omit some reentry phases (such as, CDMA HO ranging,
AAI_SBC-REQ/RSP or PKM Authentication) for the HO process optimization, but should perform at least the
exchange of AAI_RNG-REQ/RSP messages during network reentry procedure. This contribution proposes a
handover procedure that can omit even the AAI_RNG-REQ/RSP, when the single carrier supported AMS
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IEEE C802.16m-09/1913
performs the inter-frequency handover between two carriers managed by a common MAC at multi-carrier
supported ABS.
2. Discussions
IEEE 802.16m uses the common MAC concept which controls a PHY spanning over multiple frequency
channels to support the multi-carrier operation. With this concept, a multi-carrier AMS can efficiently utilize
radio resources in one or more carriers controlled by a common MAC at multi-carrier ABS. In addition to the
multi-carrier AMS, a single-carrier AMS can utilize radio resource in the one carrier under the same common
MAC as multi-carrier AMS uses. In here, we can consider the scenario that both a multi-carrier AMS and a
single-carrier AMS are supposed to change their primary carrier to one of frequency channels managed by the
common MAC for load balancing purpose, carriers’ varying channel quality or other reasons. Then, the
multi-carrier AMS performs the primary carrier change which does not require performing the network reentry
procedure to the target carrier, as described in 15.2.7.2.11.2 primary carrier change. However, the single-carrier
AMS shall perform the inter-frequency handover by using the generic HO procedure. Figure 1 illustrates the
generic HO procedure. As shown in Figure 1, the AMS must perform the network re-entry procedure to target
ABS. During the network re-entry procedure, some phases (i.e., CDMA HO ranging, AAI_SBC-REQ/RSP or
PKM Authentication phase) can be omitted by the indication in the AAI_HO-CMD, but the AMS should
certainly exchange RNG-REQ/RSP messages with the target ABS.
ABS (common MAC)
S-carrier
T-carrier
AMS
HO-REQ
ABS
initiated HO
AAI_BSHO-CMD
or
AAI_MSHO-REQ
HO-RSP
HO-REQ
AMS
initiated HO
HO-RSP
AAI_BSHO-CMD
AAI_HO-IND
Network re-entry to T-carrier
Action time
Data communication with
S-carrier during network re-entry
Disconnection
time
HO-COMPLT
Data path established
Figure 1. Generic HO procedure
3. Common MAC HO procedure
In the similar manner with the primary carrier change in multi-carrier operation, we can consider the
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IEEE C802.16m-09/1913
inter-frequency HO which omits the network reentry procedure (termed as common MAC HO, hereafter).
Firstly, we can simply figure a procedure that the AMS disconnects the data path with serving carrier at the
disconnection time and establishes the data path with target carrier at action time. However, this can lead to a
problem of data loss when AMS fails receiving the AAI_BSHO-CMD or does not transmit AAI_HO-IND
message to serving carrier. In order for an ABS to ensure HO complete of AMS, it is necessary to transmit a
confirm message to the target carrier before establishing the data path.
Figure 2 shows two options for the proposed common MAC HO. As illustrated in Figure 2 (a) and (b), both two
options disconnect the data path at the disconnection time and do not any reentry messages at the action time. In
order to provide the confirmation for HO complete of AMS, the AMS in option 1 transmits the AAI_HO-IND
message at the action time to target carrier, not serving carrier. However, we can consider transmitting the CQI
report because the AAI_HO-IND is optional feature in the current HO. In general, an AMS communicates with
the target ABS after reporting channel quality information (CQI) for the target carrier, as shown in option 2.
Consequently, we propose that the AMS performs the common MAC HO procedure using CQI report. The
details of proposed common MAC HO procedure are as follows.

AMS recognizes that a common MAC HO will be performed, via one of the following methods.
-
HO mode indication in AAI_BSHO-CMD
-
or BSID (the same BSID might be assigned to the carriers within common MAC)

AMS and ABS disconnect the data path with the serving carrier at the disconnection time.

ABS allocates the CQICH for the AMS on the target carrier at the action time.

AMS transmits the CQI report through CQICH allocated by ABS. ABS recognizes the successful
HO of the AMS by receiving the CQI report on the target carrier.

The data path for AMS is established with the target carrier.
ABS (common MAC)
S-carrier
T-carrier
AMS
ABS
initiated HO
or
ABS
initiated HO
or
AAI_BSHO-CMD
AAI_BSHO-CMD
AAI_MSHO-REQ
AAI_MSHO-REQ
AMS
initiated HO
ABS (common MAC)
S-carrier
T-carrier
AMS
AMS
initiated HO
AAI_BSHO-CMD
AAI_BSHO-CMD
AAI_HO-IND
Disconnection
time
Action time
AAI_HO-IND
Disconnection
time
Data path established
Action time
CQICH allocation / CQI report
Data path established
(a) Option 2
(b) Option 1
Figure 2. Common MAC HO procedures
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IEEE C802.16m-09/1913
4. References
[1] IEEE 802.16m-07/002r8, “802.16m System Requirements Document (SRD)”
[2] IEEE 802.16m-09/0034, “The Draft IEEE 802.16m System Description Document”
[3] IEEE P802.16 Rev2 / D9, “Draft IEEE Standard for Local and Metropolitan Area Networks: Air Interface
for Broadband Wireless Access,” January. 2009.
[4] IEEE 802.16m-08/043, “Style guide for writing the IEEE 802.16m amendment”
[5] IEEE 802.16m-09/0010r2, “IEEE 802.16m Amendment Working Document”
[6] IEEE P802.16m/D1, “DRAFT Amendment to IEEE Standard for Local and metropolitan area networks”
5. Text proposal for the 802.16m DRAFT amendment
-----------------------------------------------------------Start of the Text--------------------------------------------------------[Modify the text at line 62 on page 56 as follows:]
15.2.6.9 AAI_HO-CMD
HO process optimization: For each Bit location, a value of 0 indicates the associated reentry management
messages shall be required, a value of 1 indicates the reentry management message may be omitted.
Bit #0: Omit AAI_SBC-REQ/RSP management messages during reentry processing
Bit #1: Omit PKM Authentication phase except TEK phase during current reentry processing
Bit #2: Seamless HO
Bit #3: TBD Common MAC HO.
[Modify the text and the Figure at line 36 on page 97 as follows:]
15.2.5.10 HO procedure
15.2.5.10.5 Network Re-entry
15.2.5.10.5.1 CDMA-based HO Ranging Procedure
The serving ABS indicates in the AAI_HO-CMD how CDMA HO ranging shall be performed by MS during
network re-entry, as shown in Figure 405.
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IEEE C802.16m-09/1913
N
Y
Seamless HO
N
CDMA_RNG_flag
N
CDMA_RNG_flag
Y
Y
Use dedicated ranging
code or opporunity
Dedicate ranging code
or opportunity
Y
Use it
N
AAI_RNG-ACK
success
Pick randomly
continue
Data communication with T-ABS
and RNG-REQ/RSP transaction
RNG-REQ/RSP transaction
HO complete
Figure 405—MS State machine during HO network re-entry
5
success
AAI_RNG-ACK
Wait for
BR opportunity
IEEE C802.16m-09/1913
N
Y
Seamless HO
N
N
CDMA_RNG_flag
CDMA_RNG_flag
Y
Y
Use dedicated ranging
code or opporunity
Dedicate ranging code
or opportunity
Y
Use it
AAI_RNG-ACK
AAI_RNG-ACK
Pick randomly
success
continue
success
N
N
Common MAC HO
Y
Data communication with T-ABS
and RNG-REQ/RSP transaction
RNG-REQ/RSP transaction
CQICH allocation/report
transaction via target carrier
HO complete
Figure 405—AMS State machine during HO network re-entry
If the serving ABS indicates in AAI_HO-CMD that CDMA-based HO ranging is not omitted by setting
CDMA_RNG_FLAG=1 and a dedicated ranging code/opportunity is assigned to the AMS by target ABS, the
AMS shall transmits the dedicated ranging code to the target ABS during network re-entry. If a ranging channel
is scheduled by the target ABS for handover purpose only, the AMS should use that ranging channel in order to
avoid excessive multiple access interference. Upon reception of the dedicated ranging code and if ranging is
successful, the target ABS shall allocate uplink resources for AMS to send AAI_RNG-REQ message and/or UL
data. If inter-frequency HO occurs within the common MAC, the target ABS shall allocate CQICH for AMS in
the target carrier at action time specified in AAI_BSHO-CMD message and the AMS shall report the CQI for
the target carrier. During the common MAC HO, the RNG-REQ/RSP transaction is omitted. If the target ABS
does not receive the dedicated ranging code within Ranging_Initiation_Deadline Timer, the target ABS shall
discard the pre-assigned STID of the AMS.
-----------------------------------------------------------End of the Text---------------------------------------------------------
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