1. [Multiple Handover Parameters for Handover to Another Type ABSs]
Document Number: IEEE S802.16m-09/1922r1
Date Submitted:
Source:
Youngbo Cho, Jaehee Cho, Jaehyuk Jang Voice: [ ]
Samsung Electronics
Re:
IEEE Working Group Letter Ballot #30
Base Contribution : IEEE C802.16m-09/1832
Purpose:
To be discussed and adopted by TGm for the m Advanced Air Interface (Draft 1)
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2. Motivation
In the hierarchical cell structure, the received signal strength (RSS) level on an AMS from a micro ABS (ABS with small cell coverage like HZ, femto, etc) becomes high rapidly when the AMS goes near to the microcell coverage.
On the macro AMS (AMS connected with macro ABS), DL interference level from micro ABS is dramatically increased at the coverage of microcell
Severe uplink interference is occurred on the micro ABS due to the UL signal from macro AMS at the coverage edge of the microcell. In micro ABS
It is important that fast HO to micro ABS is carried out because seamless communication is interrupted without this fast HO
In the hierarchical cell structure, characteristics of received signal from micro ABS is very distinct to those from macro ABS
Path-loss, shadowing, fading, etc
For fast and accurate HO to another type ABS, different HO parameters are required in measuring RSS levels, averaging them and comparing them

3. Ex) Path-loss (1) Path-loss model: Ref 802.16m EMD
HO case: Macro-to-Macro
Path-loss model: Ref m EMD
Tx power (macro, HZ)
46 dBm, 3 dBm
HO case: Macro-to-Macro HZ

4. Ex) Path-loss (2) [Between 20m of distances from S-ABS]
Macro-to-macro case (from 750 to 770m):
RSS from T-ABS is increased 0.34 dB
RSS from S-ABS is reduced 0.34 dB
Macro-to-HZ case (from 580 to 600m) :
RSS from T-ABS is increased 3.52 dB
RSS from S-ABS is reduced 0.36 dB
HO case: Macro-to-Macro
HO case: Macro-to-HZ

5. Multiple HO parameters
AMS can decide HO to micro ABS rapidly by
Reduction average duration of measured signal strength
The measurement from the micro ABS is robust to fast fading because signal strength increment from the micro ABS is faster than that from macro ABS
Unnecessary HO due to reduction average duration can be constrained by adjusting hysteresis margin
Attainment time to hysteresis margin is faster than that to macro ABS
Because signal strength increment from the micro ABS is faster than that from macro ABS.

6. Remedies
The S-ABS may define trigger conditions for HO from S-ABS to T-ABS
For case that T-ABS is same ABS type with S-ABS, HO parameters are defined ‘Trigger TLV’ encodings in AAI-SCD.
For case of HO to another type ABS, HO parameters are defined ‘Trigger TLV for another ABS type’ encodings in AAI-SCD.
AMS can notice the ABS type of the T-ABS
SA-Preamble is partitioned in accordance with ABS type

7. Text Proposal
Insert and modify the following text in section in P802.16m/D1
The ABS may specify the different values of Trigger TLV encodings based on the target ABSs or ABS types the AMS shall scan and/or averaging parameters that override the default value defined in DCD (TBD) the AAI_SCD message.
Insert and modify the following text in section in P802.16m/D1
The trigger TLV (type xx) in Table xxx is encoded using the description in Table 702. It defines the trigger conditions for triggering S-ABS to T-ABS which is same ABS type with S-ABS. The ABS may define trigger conditions for triggering to ABS which has another ABS type by including trigger TLV for another ABS type. The trigger TLV for another ABS type (which includes ABS type parameter: such as macro, macro hot-zone, femto and relay, etc) is encoding using the description in Table XY.
Table 702-Trigger TLV Description
Name
Type
Length (Bytes)
Value
Type/Function/Action
xx.1 1
See Table YY-for description
Trigger Value
xx.2
Trigger value is the value used in comparing measured metric for determining a trigger condition
Trigger averaging duration
xx.3
Trigger averaging duration is the time measured in number of frames over which the metric measurements are averaged.

8. Text Proposal
Insert and modify the following text in section in P802.16m/D1
Table XY – Trigger TLV for another ABS type Description
Name
Type
Length (Bytes)
Value
ABS type
xx.1 1
ABS type of target ABS for this Trigger TLV: (Macro ABS, Macro Hot-zone ABS, Femto ABS, etc)
Type/Function/Action
xx.2
See Table YY-for description
Trigger Value
xx.3
Trigger value is the value used in comparing measured metric for determining a trigger condition from serving ABS to target ABS (which is defined in ABS type)
Trigger averaging duration
xx.4
Trigger averaging duration for target ABS (which is defined in ABS type) is the time measured in number of frames over which the metric measurements are averaged.