1. An interference mitigation framework in femtocell
(P80216m/D )
Document Number: IEEE C802.16m-09_2679
Date Submitted:
Source:
Kanchei(Ken) Loa, Yi-Ting Lin, Tsung-Yu Tsai, Yung-Lan Tseng, Chun-Yen Hsu, Chiu-Wen Chen
Institute for Information Industry (III)
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Base Contribution: N/A
Re : P802.16m/D3
Purpose: Discussion and approval of the proposal into the IEEE P802.16m/D3
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2. Introduction
In this contribution, we propose an interference mitigation (IM) framework with the following features:
Could operate under current PHY structure of m
Limit the additional modification and complexity of the PHY structure of femtocell.
Flexibility to accommodate different interference mitigation schemes or algorithms
The choosing and operating of interference mitigation schemes in femtocells have limited effect to the operation of AMSs.

3. Proposed Interference Mitigation Framework
The proposed IM framework considers two main categories of interference in femtocells
The interference between femtocells and overlapping macrocells
The interference between femtocells

4. IM between macrocell and femteocell
If the DFPC of overlapping macrocell(s) is not equal to 0
the Femto ABS is able to obtain the frequency partitions information of the overlapping macro ABS via either the SFH transmitted by the overlapping macro ABS or wireline backhaul.
Femto ABS can avoid scheduling data or control messages (e.g. A-MAP) in the occupied frequency partitions of the macro ABS (i.e. frequency partition with high power) to evade the interference.
For the case that macrocell’s DFPC is 1~6, there is always two frequency partitions which have lower interference from the overlapping macrocells.

5. IM between femtocells
Regardless the actual interference mitigation scheme performed in the backhaul, the Femto AMS receives/transmits data or control messages according to the received A-MAP.
The interference of data could be evaded by scheduling.
The signaling overhead for IM in the air link is minimized.
The location of A-MAP region of femtocell is in the first DRUs of one of the frequency partition
The Femto ABS transmits A-MAP in chosen frequency partition
The location of A-MAP region may be semi-static and switched to different frequency partitions.
The femto AMS could blindly decode the non-user-specific A-MAP in each frequency partition and detect the existence of A-MAP via the CRC in the non-user-specific A-MAP.
Since DRU is permutated in a cell-specific manner, when the non-user-specific A-MAP is detected (via CRC) in a frequency partition, the cell which transmits the A-MAP is also identified.
After non-user-specific A-MAP is detected, the Femto AMS continues to decode remaining part of the A-MAP region to obtain the scheduling information of this subframe.

6. Proposed text
[Add the following text in the section on page 604 (line 11) as shown below]
The Femto ABS transmits A-MAP in selected DL subframes and frequency partitions. When the A-MAP is transmitted by a Femto ABS in a DL subframe, it appears in the first DRUs of the selected frequency partition.