Mobility Management for IEEE 802.16m
Document Number: C802.16m-08/563r2
Date Submitted: 2008-07-14
Source:
Kelvin Chou
Yih-Shen Chen
I-Kang Fu
Paul Cheng
Kelvin.Chou@mediatek.com
Yihshen.Chen@mediatek.com
IK.Fu@mediatek.com
Paul.Cheng@mediatek.com
MediaTek Inc.
No.1, Dusing Rd. 1, Hsinchu Science-Based Industrial Park,
Hsinchu, Taiwan 300, R.O.C.
Venue:
IEEE 802.16m-08/024 “Call for Comments and Contributions on Project 802.16m System Description Document (SDD)”
In response to the topic: Upper MAC concepts and methods (mobility management)
Base Contribution: N/A
Purpose: To be discussed and adopted by TGm for the 802.16m SDD
Notice:
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16e Mobility Management Overview
Scanning
Normal scanning
Scanning neighbor BSs within scheduled scanning intervals
Autonomous scanning
MS initiated scanning
No serving BS scheduled scanning period is required
No need to send scanning report to the serving BS
The MS may scan different frequency bands
Handover
Normal handover with/without optimization
Seamless handover
Pre-update CID and TEK during HO preparation
Proceeds to data transmission immediately without association or initial ranging
Target BS is fully synchronized (in time and in frequency) with the serving BS
MS is assumed to be synchronized with the UL/DL channel of the target BS
MDHO/FBSS
2
16m Scanning Scenarios (1/2)
Different cell type should be considered in scanning process
Neighbor cell advertisement should take into account different cell types to
reduce broadcast overhead
Macro cell
Micro cell
Femto cell
3
16m Scanning Scenarios (2/2)
During cell reselection, the MS scans primary (fully-configured) carriers of
neighbor BSs
The MS may also scan other primary carriers of its serving BS
S-BS
Partial conf
Full conf
Partial conf
Full conf
Scanning
interval
BS #3
Partial conf
Full conf
Partial conf
Full conf
Partial conf
Full conf
Partial conf
RF
Full conf
MS
BS #2
DL synchronization with
carrier #3 of the Serving BS
DL synchronization with carrier #1 of BS #2
initial ranging
Scanning
interval
Scanning
interval
DL synchronization with carrier #3 of BS #2
initial ranging
DL synchronization with carrier #1 of BS #3
Initial ranging
DL synchronization with carrier #3 of BS #3
Initial ranging
4
16m Handover Scenarios
Possible handover scenarios
Inter-BS-Intra-frequency HO
Inter-BS-Inter-frequency HO
Intra-BS-Inter-frequency HO
(or carrier switch? carrier change?)
Target BS
Serving BS
Target BS
Serving BS
BS
RF #2
RF #1
RF #2
RF #1
RF #2
RF #1
RF #2
RF #1
RF #4
RF #3
RF #2
RF #1
FA #2
FA #1
FA #2
FA #1
FA #2
FA #1
FA #2
FA #1
FA #4
FA #3
FA #2
FA #1
MS
Fully configured carrier
Primary carrier
MS
Partially configured carrier
Primary carrier
MS
Fully configured carrier
Primary carrier
MS
Partially configured carrier
Primary carrier
MS
MS
5
16m User Scenarios
Different HO procedures for different user scenarios
16e HO Procedures
16m User Scenario
Normal HO (with/without optimization)
Low mobility users
Seamless HO
Cell edge users
Seamless HO with initial ranging or association
Pre-update CID and TEK during HO preparation just
like seamless HO
Proceeds to data transmission right after DL
synchronization and CDMA initial ranging
The DL synchronization and CDMA initial ranging
may be done beforehand (e.g. during scanning with
association)
Serving BS
Low mobility user:
Normal HO
(w/wo optimization)
High mobility user:
Seamless HO with initial ranging or association
- CID/TEK pre-update
- DL synchronization & CDMA initial ranging
- Data transmission after DL/UL synchronization
High mobility users
Cell edge user:
Seamless HO
- CID/TEK pre-update
- Data transmission before initial ranging
Target BS
6
Reduction of Handover Interruption Time
Schedule sleeping intervals with the Serving BS
Network reentry to the Target BS within sleeping intervals
Advantage
Make-before-break HO
MS
S-BS
T-BS
Primary carrier
Request sleeping
intervals for HO
HO request
HO response
N1 frames
HO indication
(Serving BS leaving)
S-BS: sleep
T-BS: NW reentry
Network reentry
N2 frames
Normal operations
S-BS: sleep
T-BS: NW reentry
Network reentry
connection established
Sleeping interval
terminates right after
the new primary carrier
is established
HO indication
(Serving BS release)
7
Other Handover Design Considerations
More complete handover exception handling
Loss of HO messages is not well handled in 16e
In case of HO exception occurs, the MS may “handover back” to its serving BS, i.e. serving
BS becomes the target BS
More parameters and criteria for handover decision making
PHY signaling report
Loading (system loading, carrier loading)
MS Mobility pattern (e.g. speed, direction)
MS location
Cross-layer design to minimize the handover interruption time
Link-layer HO should notify upper layers to establish the new data path as early as possible
Handover optimization between different cell types
16e cell, 16m cell, macro cell, micro cell, femto cell
Handover with multi-carrier support
Multi-carrier HO provides better efficiency and QoS guarantee as compared with singlecarrier HO
See C80216m-08/564 for multi-carrier HO design
8
SDD Text Proposal
Add the following text into Session 10 of the SDD (IEEE 802.16m-08/003)
----------------------- text begin ----------------------------------------------------------------------------10.x Data/Control plane
10.x.y MAC Handover Procedures
10.x.y.1 Network topology acquisition
The BS should take into account types of the neighbor cells to be advertised in order to reduce
the overhead from the broadcast of neighbor cell advertisement messages.
During cell reselection, the MS may prioritize the BSs to be scanned according to their cell
types. The MS scans primary (fully-configured) carriers of neighbor BSs. The MS may also
scan other primary carriers of its serving BS.
10.x.y.2 Handover Process
User scenarios (e.g. mobility, location) should be taken into account in the selection of proper
handover procedures. In order to reduce the handover interruption time, the MS may request a
scheduled sleeping interval for the purpose of network reentry. Multiple RF carriers may also
be used for handover operations to reduce the handover interruption time.
10.x.y.3 Handover with Multi-Carrier Support
----------------------- text end ------------------------------------------------------------------------------9