1. MCS signaling for reducing MAP overhead
IEEE Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-09/0554
Date Submitted:
Source:
Seunghoon Choi, Sung-Eun Park, Chiwoo Lim, Songnam Hong, Jaeweon Cho, Jaehee Cho, Heewon Kang, Hokyu Choi
{seunghoon.choi, se.park, chiwoo.lim, sn7955.hong, jaeweon.cho, jaehee1.cho, hkang,
Samsung Electronics, Co., Ltd.
416 Maetan-3, Suwon, , Korea
Venue:
IEEE m-09/0012, “Call for Contributions on Project m Amendment Working Document (AWD) Content”,
Target Topic: “Channel coding and HARQ”
Base Contribution:
None
Purpose:
To be discussed and adopted by TGm for m amendment
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2. MCS signaling for Reducing MAP Overhead
Seunghoon Choi, Sung-Eun Park, Chiwoo Lim, Songnam Hong,
Jaeweon Cho, Jaehee Cho, Heewon Kang, Hokyu Choi
Samsung Electronics Co., Ltd. 2

3. About This Contribution
Goal and scope of this contribution
Propose schemes for reducing MAP overhead for m
Issue to be addressed in this contribution
MAP information in m
New scheme for reducing overhead in m 3

4. MAP information in 802.16m MAP information can include the followings:
Resource allocation information
MCS index
AI-SN
SPID (SubPacket ID)
CoRe version
ACID (HARQ channel ID)
Etc.
In conventional MAP transmission, the above information are transmitted at every transmission. 4

5. Consideration on MAP information
There are three types of information in MAP.
Information necessary for every transmission
Resource allocation information (except persistent allocation)
AI-SN
ACID
Information only necessary for initial transmission
The information for calculation of burst size (Nep)
For example, modulation and code rate (or spectral efficiency)
Information only necessary for retransmission
The information can be fixed in initial transmission without any penalty.
SPID
CoRe version 5 5

6. New schemes for m
Proposed scheme multiplexes different types of information.
Modulation and Code rate
The information for calculation of burst size is very important, but burst size should not be changed during one HARQ transmission. So, this information is only necessary for initial transmission.
In MCS table, MCS index indicates modulation and code rate.
Modulation can be changed under adaptive HARQ.
Code rate is used for calculating burst size in initial transmission, but doesn’t have any information in retransmission.
SPID and CoRe version
SPID and CoRe version are the information that can be fixed in initial transmission without any penalty.
CoRe may not operate in case that modulation is changed in retransmission. 6 6

7. New schemes for m
In proposed scheme, MCS index in MCS table have different information for initial and retransmission.
Initial transmission : MCS index indicates modulation and code rate.
Retransmission : MCS index indicates modulation, SPID and CoRe version.
Proposed scheme assumes the 4-bit MCS index, 2-bit SPID and 1 bit CoRe version.
Additional bits for SPID and CoRe version are possible if the gain is guaranteed.
Even if additional bits are used, the bit in current table indicates a part of whole bits and other bits can be included in other MAP field.

8. New schemes for m
In proposed scheme, the bits for signaling SPID and CoRe version can be removed or reduced.
There is no drawback for conventional operation.
Only one restriction is that there is no CoRe operation in case that modulation is changed in retransmission. But, this restriction is reasonable.
In MCS table for retransmission
“+” and “-” are utilized when modulation at retransmission is not same to that at initial transmission as follows.
When modulation is QPSK at initial transmission, “-” and “+” represent 64QAM and 16QAM at retransmission, respectively.
When modulation is 16QAM at initial transmission, “-” and “+” represent QPSK and 64QAM at retransmission, respectively.
When modulation is 64QAM at initial transmission, “-” and “+” represent 16QAM and QPSK at retransmission, respectively.

9. MCS for initial transmission MCS for retransmission
New schemes for m
MCS for initial transmission
MCS for retransmission
MCS index
Modulation
Code rate
QPSK
31/256 1
47/256 2
70/256 3
98/256 4
131/256 5
166/256 6
199/256 7
16QAM
123/256 8
149/256 9
176/256 10
204/256 11
229/256 12
64QAM
173/256 13
196/256 14
218/256 15
234/256
MCS index
Modulation
SPID
CoRe version
Modulation is same as initial transmission. 1 2 3 4 5 6 7 8 - 9 10 11 12 +　 13 14 15
Modulation at initial transmission. - +
QPSK
64QAM
16QAM
MCS for initial transmission is just an example, so modulation and coderate details are not the scope of this proposal

10. Example In initial transmission, In retransmission,
MCS index ‘7’ is indicated : Modulation is 16QAM, SPID is 0 and CoRe version is 0.
In retransmission,
MCS index ‘2’ is indicated : Modulation is same as initial transmission (16QAM), SPID is 1 and CoRe version is 0.
MCS index ‘3’ is indicated : Modulation is same as initial transmission (16QAM), SPID is 1 and CoRe version is 1.
MCS index ‘9’ is indicated : Modulation is changed by QPSK, SPID is 1 and CoRe version is 0.
MCS index ’13’ is indicated : Modulation is changed by 64QAM, SPID is 1 and CoRe version is 0.

11. Text Proposal to 802.16m amendment
Start of Proposed Text Insert the following subsection at a new section 15: 15.x.1.1. MCS table To determine the modulation and code rate for current transmission, the AMS shall read the 4-bit ’MCS index’ field and 1-bit ‘AI-SN’ in MAP. The MCS index represent the different information according to AI-SN. For AI-SN=0 (initial transmission), it denotes the modulation and code rate as shown in Table xxx, and for AI-SN=1 (retransmission), it denotes the modulation, CoRe version, and SPID as shown in Table yyy. In Table yyy, “+” and “-” are utilized when modulation at retransmission is not same to that at initial transmission as follows. - When modulation is QPSK at initial transmission, “-” and “+” represent 64QAM and 16QAM at retransmission, respectively. - When modulation is 16QAM at initial transmission, “-” and “+” represent QPSK and 64QAM at retransmission, respectively. - When modulation is 64QAM at initial transmission, “-” and “+” represent 16QAM and QPSK at retransmission, respectively. 11 11

12. Text Proposal to 802.16m amendment
Table xxx ― MCS for initial transmission (AI-SN=0)
Table yyy ― MCS for retransmission (AI-SN=1)
End of Proposed Text
MCS index
Modulation
Code rate
QPSK
31/256 1
47/256 2
70/256 3
98/256 4
131/256 5
166/256 6
199/256 7
16QAM
123/256 8
149/256 9
176/256 10
204/256 11
229/256 12
64QAM
173/256 13
196/256 14
218/256 15
234/256
MCS index
Modulation
SPID
CoRe version
Modulation is the same as that of initial transmission. 1 2 3 4 5 6 7 8 - 9 10 11 12 +　 13 14 15 12 12