1. A more efficient DL-MAP IE for MAPs
Document Number:
IEEE S802.16m-08/099r1
Date Submitted:
Source:
Kanchei (Ken) Loa, Tsung-Yu Tsai, Yi-Hsueh Tsai, Yung-Ting Lee, Hua-Chiang Yin Voice:
Institute for Information Industry (III)
7F, No. 133, Sec. 4, Minsheng E. Rd., Taipei City 105, Taiwan
Re:
IEEE j-08/020: “IEEE Working Group Letter Ballot Recirc #28c: Announcement”
Abstract:
This contribution proposes the compressed DL-MAP IE
Purpose:
Text proposal for j Draft Document.
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2. A More Efficient DL-MAP IE for MAPs
Institute of Information Industry (III)

3. Introduction
Four parameters are included in the DL-MAP IE to describe a 2D allocation
“OFDMA symbol offset”, “OFDMA sub-channel offset”, “number of OFDMA symbols”, and “number of OFDMA sub-channels”
The above approach is intuitive but not efficient since the MAP overhead is high
This contribution proposes a Compressed DL-MAP IE
Only two parameters: “number of OFDMA symbols” and “number of subchannels” are used to describe the 2D allocation
The receiver can uniquely re-construct the 2D allocations
The Compressed DL-MAP IE replace the original DL-MAP IE in RS_Access-MAP, RS_Relay-MAP, and R-MAP to reduce the MAP overheads on the relay link
Reduce the DL-MAP IE overhead of DL data burst description from 27 bits to 13 bits

4. Concept of Compressed DL-MAP IE (1)
Specifically, we index the DL zone as a 2-D time-frequency (OFDMA symbols-subchannels) table
Every slots of the DL zone are indexed (1 ~ 38) as shown in right-hand side of the below figure
The index of the left top slot of a burst is the “start index” of that burst
In the figure below, the start indices of the data bursts, shown in left hand side of the following figure, are 6, 7, 9, 21, 26, and 35, respectively

5. Concept of Compressed DL-MAP IE (2)
The data burst are further indexed as Burst 1, Burst 2, and so on, sorted in a increasing order as shown in the below figure
With the burst sequence and given the corresponding “length” (number of OFDMA symbols) and “width” (number of subchannels) of every burst, the 2D allocations of the DL zone can be re-constructed uniquely
The allocations of FCH and MAPs are known already
The start index of the first burst can be uniquely identified. Moreover, the allocation of the first burst can be identified by the given “length” and “width”
Similarly, knowing the allocations of FCH, DL-MAP, and the first burst, the start index of the second burst can be uniquely identified

6. Example 1: Full Allocation Every slot is allocated

7. Example 2: Partial Allocation Not all slots are allocated
Since the DL data burst is rectangular, we can use one or more “null rectangular bursts” for those slots which are not allocated
Null Burst

8. Proposed Compressed DL-MAP IE

9. RS_Access-MAP with Proposed Compressed DL-MAP IE

10. R-MAP with Proposed Compressed DL-MAP IE

11. Conclusions
In this contribution, a Compressed DL-MAP IE is proposed to reduce the overheads of R-MAP, RS_Access-MAP, and RS_Relay-MAP
The complexity is , where N , S, and C are the number of IEs, the number of symbols, and the number of subchannels, respectively
Adopt the proposed text changes in C80216j-08/099r1 or later version