IEEE C802.16m-10/0650
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Handover Functionality with Legacy ASN-GW Configuration (Sections 16.2.6.3.3 and
16.2.6.3.4)
Date
Submitted
2010-04-30
Source(s)
Stavros Tzavidas
Motorola
Re:
P802.16m, Letter Ballot 31a
Abstract
The concept of network configuration and of Legacy ASN-GW support was introduced in the
last meeting and some functionality was made dependent on the “Network Configuration” bit in
S-SFH. However the impact on handover functionality was not addressed. This contribution
proposes to disable some advanced handover features when the “Network Configuration” bit is
equal to “WirelessMAN-OFDMA network configuration”.
Purpose
Adoption of proposed text by P802.16m TG.
Notice
Release
Patent
Policy
stavros.tzavidas@motorola.com
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Handover Functionality with Legacy ASN-GW Configuration
(Sections 16.2.6.3.3 and 16.2.6.3.4)
Stavros Tzavidas
Motorola
Introduction
Several contributions in the last meeting introduced the concept of a 16m ABS that is connected to a legacy
ASN-GW. To this effect, the “Network Configuration” bit was introduced in S-SFH and a number of features
are not supported if the “Network Configuration” bit is equal to “WirelessMAN-OFDMA network
configuration”. The changes made in D4 failed, however, to identify the Handover-related features that should
not be supported in this case. This contribution addresses which handover features should be disabled when the
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network operates in legacy ASN-GW mode.
More specifically the following features should be disabled when an ABS is connected to a legacy ASN-GW:

Pre-assignment of dedicated ranging code.

Transferring of residual BW-REQ from serving ABS to target ABS.

No EBB support.
Proposed Text
[Change the text in section 16.2.6.3.3 “HO Preparation”, on page 275, line 45 and on page
276, line 1, as indicated:]
16.2.6.3.3 HO Preparation
During HO preparation phase, the serving ABS communicates with target ABS(s) selected for HO. The
AAI_HO-CMD message should not include an ABS with cell bar bit =1. A Femto ABS shall follow the
handover procedure described in section 16.4.8. The target ABS may obtain AMS information from the serving
ABS via backbone network for HO optimization.
During HO preparation phase, the target ABS may allocate a dedicated ranging code and dedicated ranging
opportunity to the AMS via the serving ABS through the AAI_HO-CMD message, indicated by both
Dedicated_Ranging_Code_Flag and Dedicated_Ranging_Opportunity_Flag. The dedicated code and
opportunity is assigned to the AMS until the Ranging Initiation Deadline. The AMS may reuse the pre-assigned
dedicate ranging code and opportunity during network re-entry. If the AMS fails to perform ranging before
expiration of Ranging Initiation Deadline, it shall stop using the dedicated code and opportunity but randomly
pick a ranging code if further ranging is necessary. The target ABS shall select the dedicated ranging code from
the group of codes which are allocated for dedicated handover ranging purpose.
The target ABS shall not allocate dedicated ranging code or dedicated ranging opportunity to the AMS
via the serving ABS through the AAI_HO-CMD message when the network configuration bit in the SSFH is set to 0b1, indicating a WirelessMAN-OFDMA network configuration. The
Dedicated_Ranging_Code_Flag and the Dedicated_Ranging_Opportunity_Flag shall be set to 0 if the If
the Network Configuration bit in the S-SFH is set to 0b1.
Information regarding AMS identity (e.g.STID) and security context should be pre-updated during HO
preparation. Any mismatched system information between AMS and the target ABS, if detected, may be
provided to the AMS by the Serving ABS during HO preparation. For AMS initiated HO, the ABS may detect
an S-SFH mismatch by referring to the AAI_NBR-ADV change count of AMS included in AAI_HO-REQ
message. In such case, the ABS should include mismatching delta SFH information in AAI_HO-CMD, or it
should cancel the HO.
For ABS initiated HO, the AMS may detect an SFH mismatch by referring to the S-SFH change count included
in the AAI_HO-CMD message. The AMS should not select a T-ABS with mismatched SFH information. If the
AMS does not have the latest SFH for any of the T-ABS included in AAI_HO-CMD, it should cancel the HO by
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sending AAI_HO-IND with event code, the ABS should cancel the HO. If pre-allocated at target ABS, the
serving ABS shall include an STID to be used at target ABS in the AAI_HO-CMD message. The pre-allocated
STID shall be used in the target ABS by the AMS to communicate with the target ABS. The FIDs which are
used to distinguish different connections are not updated during the handover procedure. If the network decides
that certain service flow will not exist at the target ABS, this shall also be indicated in the AAI_HO-CMD
message.
The ABS shall not set HO_Reentry_Mode to 1 when the the network configuration bit in the S-SFH is set
to 0b1, indicating a WirelessMAN-OFDMA network configuration .
If HO_Reentry_Mode is set to 1, the serving ABS shall negotiate with the target ABS the EBB HO parameters.
In the single carrier handover case, the EBB HO parameters include HO_Reentry_Interleaving_Interval and
HO_Reentry_Iteration for the AMS to communicate with the serving ABS during network reentry, in which
case HO_Reentry_Interleaving_Interval must be no less than the minimal values defined in AMS capability. In
the multicarrier handover case, the EBB_HO parameters include the carrier information in the target ABS for
the AMS performing network reentry while continuing communication with the serving ABS concurrently.
The ABS shall not set HO_Reentry_Mode to 1 unless EBB Support was declared (set to 1) by the AMS in
AAI_REG-REQ.
When only one target ABS is included in the AAI_HO-CMD message, the HO preparation phase completes
when serving ABS informs the AMS of its handover decision via an AAI_HO-CMD message. When multiple
target ABSs are included in the AAI_HO-CMD message, the HO preparation phase completes when the AMS
informs the ABS of its target ABS selection via an AAI_HO-IND message with HO Event code 0b00. The
AAI_HO-CMD message shall include Action Time of each target ABS for the AMS to start network reentry.
The AAI_HO-CMD message shall also include a Disconnect Time Offset for each AMS to calculate disconnect
time for each candidate target ABS which is the time instant when the data communication with the Serving
ABS will be terminated. When HO_Reentry_Mode is set to 0, the Disconnect Time will be (Action time Disconnect Time Offset). For HO_Reentry_Mode = 1, Disconnect time will be (Action time + Disconnect Time
Offset).
The AAI_HO-CMD message indicates if the static and/or dynamic context and its components of the AMS are
available at the target ABS.
All on-going DSx transaction during HO shall be cancelled, and shall be re-started after HO completion. After
an ABS receives the AAI_HO-REQ message from an AMS, the ABS shall not send any DSx message to the
AMS until HO completion. After an ABS sends the AAI_HO-CMD message to an AMS, the ABS shall not
send any DSx message to the AMS until HO completion.
[Change the text in section 16.2.6.3.4 “HO Execution”, on page 277, line 39 as indicated:]
16.2.6.3.4 HO Execution
[text omitted]
An AMS may request bandwidth for the residual data in the buffer before the Disconnect Time. The serving
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ABS may send information about any unallocated requested bandwidth to the target ABS over the backhaul so
that the target ABS may allocate uplink resource immediately after receiving the dedicated ranging code from
the AMS or after Action Time if CDMA ranging is omitted when the seamless HO is enabled. Sending
information about unallocated requested bandwidth from the serving ABS to the target ABS is not
supported when the network configuration bit in the S-SFH is set to 0b1, indicating a WirelessMANOFDMA network configuration .
4