IEEE 802.15-10-0501-00-004g Submission Sangsung Choi & Cheolho Shin, ETRI Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

IEEE 802.15-10-0501-00-004g

Submission Sangsung Choi & Cheolho Shin, ETRI

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Submission Title: A proposal of Comment resolutions for Interleaver and Pad bits in OFDM Group.

Date Submitted: July, 2010

Source: Sangsung Choi & Cheolho Shin

Electronics and Telecommunications Research Institute(ETRI)

Voice: +82 42 860 6722, +82 42 860 6831 Fax: +82 42 860 5218

E-maill: [email protected], [email protected]

Re: TG4g comment resolution

Abstract: Working doc of OFDM Comment Resolutions

Purpose: Comment Resolutions for CID #1041, #1409,#1411 and #1064

Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.

Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

Slide 1

July, 2010


IEEE 802.15-10-0501-00-004g

Comment resolutions for CID #1041, #1409 and #1411

Slide 2

• Comments - CID #1041 : modify the Ncbps clearly - CID #1409 : Definition of Ncbps and Nbpsc are needed - CID #1411 : Definition of Ncbps and Nbpsc are needed

• Proposed Change - CID #1041 : for example, Ncbps = 96*{1,2} -> Ncbps = 96*Nbpsc - CID #1409 : Definition of Ncbps and Nbpsc are needed - CID #1411 : Provide the definitions

• Proposed Resolution - CID #1041 : proposed to modify accordingly. See also Document 15-10-0423-00-004g


IEEE 802.15-10-0501-00-004g


Slide 3

Nrow = 12;OFDM Option 1: Ncbps = 96 *NbpscOFDM Option 2: Ncbps = 48 *NbpscOFDM Option 3: Ncbps = 24 *NbpscOFDM Option 4: Ncbps = 12 *NbpscOFDM Option 5: Ncbps = 6 *Nbpsc


IEEE 802.15-10-0501-00-004g


Slide 4

• For example , in MCS 0 of OFDM Option 1 - Nbpsc = 1 (BPSK) , Ncbps = 96 * 1 = 96 - Interleaving size = 96• For example , in MCS 0 of OFDM Option 2 - Nbpsc = 1 (BPSK) , Ncbps = 48 * 1 = 48 - Interleaving size = 48• For example , in MCS 1 of OFDM Option 3 - Nbpsc = 1 (BPSK) , Ncbps = 24 * 1 = 24 - Interleaving size = 24• For example , in MCS 2 of OFDM Option 4 - Nbpsc = 2 (QPSK) , Ncbps = 12 * 2 = 24 - Interleaving size = 24• For example , in MCS 6 of OFDM Option 5 - Nbpsc = 2 (QPSK) , Ncbps = 6 * 2 = 12 - Interleaving size = 12


IEEE 802.15-10-0501-00-004g

Comment resolutions for CID #1064

Slide 5

• Comments - CID #1064 : OPFM symbol number for the PHY header of Option 1

and Option 2 should be modified considering the interleaver size

• Proposed Change - CID #1064 : 4 OFDM symbols for the PHY header of Option 1 and 8 OFDM symbols for the PHY header of Option 2

• Proposed Resolution - CID #1064 : Proposed resolution in document 15-10-0423-00-004g.


IEEE 802.15-10-0501-00-004g

PHY Header fields for OFDM

Slide 6

• PHY Header fields are 36 bits including HCS and tail bits

Rate(5 bits)

Reserved(1 bit)

Frame Length(11 bits)

Reserved(2 bits)

Scrambler(2 bits)

Reserved(1 bit)

6 bits 2 bytes

Header Check SequenceCalculation

Append HCS

HCS

Rate(5 bits)

Reserved(1 bit)

Frame Length(11 bits)

Reserved(2 bits)

Scrambler(2 bits)

Reserved(1 bit)

6 bits 2 bytes 1 byte

HCS(8 bits)

Tail(6 bits)

6 Zero Bits

Pad bits

Append PAD bits


IEEE 802.15-10-0501-00-004g

Construction of Symbol number and Pad bits

Slide 7

• The Symbol number and Pad bits can be constructed by the formulas (16), (17) and (18) in page 67 of draft standard.

• According to these formulas, the PHY header occupies 3 OFDM symbols for OFDM 1 and 6 OFDM symbols for Options 2,3,4 and 5.

• However, these formulas should be corrected considering the Interleaving size and FDS repetition because the Interleaving can’t be completed in several data rate modes using FDS if we use these formulas.


IEEE 802.15-10-0501-00-004g

Slide 8

- According to Formula (16), (17), and (18)

• Nsym=Ceiling((8xLENGTH+6)/NDBPS)

Nsym = ceiling(8x3.75+6)/12)=3

• NDATA=Nsym x NDBPS

MDATA=3 x 12 =36

• Npad=NDATA-(8XLENGTH+6),

Npad = 36-(8 X 3.75+6) = 0

For Example of Option 1

Optiondata rate

(Kbps)Modulation

Coding

rate

(R)

FDS

(NF)

Coded Bits

/OFDM symbol

at IFFT

NCBPS

DATA Bits

/OFDM symbol

at IFFT

NDBPS

NPAD NSYM

100 BPSK 0.5 4 24 12 0 3

50 BPSK 0.5 4 12 6 0 6

50 BPSK 0.5 2 12 6 0 6

50 QPSK 0.5 2 12 6 0 6

50 DCM 0.75 1 8 6 0 65

1

2

3

4


IEEE 802.15-10-0501-00-004g

Slide 9

For Example of Option 1(Continued)

DATAEncoder

(R=½)Interleaver

SubcarrierModulation

Mapper

FDS ( X4 )

IFFTCyclicPrefix

InsertionFiltering

DAC/RF Transceiver

/PA

Pad : 0 bits

Header : 36 bits

36 bits 72 bits 72 bits

72 carriers

24 carriers/OFDM

symbol

3 OFDM symbols

Interleaver size = 96

- According to the formula in page 67 of draft standard,

The bit number of PHY header fields is 36, and then it increases 72 bits

after Convolutional encoder.

<Block diagram of PHY Header Construction>


IEEE 802.15-10-0501-00-004g

Slide 10

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- In this case, the interleaving size is 96 .

- Thus, the interleaving of 96 can't be completed using 72 bits of PHY

header fields as shown below figure .

<Interleaving Procedure>


IEEE 802.15-10-0501-00-004g

Slide 11

- According to Formula (16), (17), and (18)

• Nsym=Ceiling((8xLENGTH+6)/NDBPS)

Nsym = ceiling(8x3.75+6)/6)=6

• NDATA=Nsym x NDBPS

MDATA=6 x 6 =36

• Npad=NDATA-(8XLENGTH+6),

Npad = 36-(8 X 3.75+6) = 0


Optiondata rate

(Kbps)Modulation

Coding

rate

(R)

FDS

(NF)

Coded Bits

/OFDM symbol

at IFFT

NCBPS

DATA Bits

/OFDM symbol

at IFFT

NDBPS

NPAD NSYM

100 BPSK 0.5 4 24 12 0 3

50 BPSK 0.5 4 12 6 0 6

50 BPSK 0.5 2 12 6 0 6

50 QPSK 0.5 2 12 6 0 6

50 DCM 0.75 1 8 6 0 65

1

2

3

4


IEEE 802.15-10-0501-00-004g

Slide 12


- According to the formulas in page 67 of draft standard,

The bit number of PHY header fields is 36, and then it increases 72 bits

after Convolutional encoder.


DATAEncoder

(R=½)Interleaver


Mapper

FDS ( X4 )

IFFTCyclicPrefix

InsertionFiltering

DAC/RF Transceiver

/PA

Pad : 0 bits

Header : 36 bits


72 carriers

12 carriers/OFDM

symbol

6 OFDM symbols



IEEE 802.15-10-0501-00-004g

Slide 13



- Thus, the interleaving of 48 can't be completed using 72 bits of PHY


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IEEE 802.15-10-0501-00-004g

PSDU fields for OFDM

Slide 14

• The maximum PSDU are 2047bytes

• For convenience of explanation, PSDU Length of 3 bytes is assumed.

• Although the formulas in page 67 of draft standard generate the Symbol number and Pad bits in PHY Header fields correctly, the Interleaving still can’t be completed in several data rate modes Using FDS of Option3 and 4.

PSDU : 3 Bytes Tail bits Pad bits

6 Zero Bits(Tail Bits)

Pad Bits


IEEE 802.15-10-0501-00-004g

Slide 15

- If the PSDU Length of 3bytes is assumed in 50Kbps mode of Option 3

and 4, the number of Symbol and Pads bits can be calculated by the

formula (16), (17), and (18) in page 67 of draft standard.

• Nsym = Ceiling((8xLENGTH+6)/NDBPS)

Nsym = ceiling(8x3+6)/6)=5

• NDATA = Nsym x NDBPS

MDATA=5 x 6 =30

• Npad = NDATA-(8XLENGTH+6),

Npad = 30-(8 X 3+6) = 0

For Example of Option 3 & 4

Optiondata rate

(Kbps)Modulation

Coding

rate

(R)

FDS

(NF)

Coded Bits

/OFDM symbol

at IFFT

NCBPS

DATA Bits

/OFDM symbol

at IFFT

NDBPS

NPAD NSYM

50 BPSK 0.5 2 12 6 0 5

50 QPSK 0.5 2 12 6 0 5

3

4


IEEE 802.15-10-0501-00-004g

Slide 16

- PHY Payload of 30 bits including PSDU and tail bits increase (3*8 + 6)*2 = 60 bits after Convolutional encoder.

<Block diagram of PSDU Construction>

For Example of Option 3 & 4(Continued)

DATA ScramblerEncoder

(R=½)Puncturer Interleaver


Mapper

FDS ( X2 )

IFFTCyclicPrefix

InsertionFiltering

DAC/RF Transceiver

/PA

If R=1/2

PSDU 3byte + tail bits

3*8+6 = 30 bits Pad : 0 bits


12 carriers/OFDM symbol in Option 36 carriers/OFDM symbol in Option 4

60 carriers in Option 330 carriers in Option 4


5 OFDM symbols


IEEE 802.15-10-0501-00-004g

Slide 17

- In this case, the interleaving size is 24.

- Thus, the interleaving of 24 can't be completed using 60 bits as shown below figure.

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IEEE 802.15-10-0501-00-004g

Propose new formulas for Construction of Symbol number and Pad bits

Slide 18

• We propose new formulas for PAD bits and the number of symbols considering the Interleaving size and FDS repetition.

- refer the document #15-10-0423

NCBPS = Ncbps

NDBPS = NCBPS * R

NPAD = NDBPS * ceiling ((8*LENGTH + 6)/NDBPS) - (8*LENGTH +

6)

NSYM = NsF * ceiling ((8*LENGTH + 6)/NDBPS)

-R: Coding rate

-NsF: Spreading Factor of FDS

-Ncbps: Coded Bits per OFDM symbol at interleaver

-NCBPS : Coded Bits per NsF OFDM symbols at IFFT

-NDBPS : DATA Bits per NsF OFDM symbols at IFFT


IEEE 802.15-10-0501-00-004g

Symbol Number and Pad bits in PHY Header fields by the new proposed formulas

Slide 19

• Construction of Symbol number and Pad bits of PHY Header using the new proposed formulas

Optiondata rate

(Kbps)Modulation

Coding

rate

(R)

FDS

(NSF)

Coded Bits

/OFDM symbol

at interleaver

Ncbps

Coded Bits

/NSF OFDM symbol

at IFFT

NCBPS

DATA Bits

/NSF OFDM symbol

at IFFT

NDBPS

NPAD NSYM

100 BPSK 0.5 4 96 96 48 12 4

50 BPSK 0.5 4 48 48 24 12 8

50 BPSK 0.5 2 24 24 12 0 6

50 QPSK 0.5 2 24 24 12 0 6

50 DCM 0.75 1 8 8 6 0 65

1

2

3

4

Option 1

NCBPS= 96

NDBPS= 48

NPAD = 48 * ceil (36/48) - (36) = 12

NSYM = 4 * ceil (36/48) = 4

Option 2

NCBPS= 48

NDBPS= 24

NPAD = 24 * ceil (36/24) - (36) = 12

NSYM = 4 * ceil (36/24) = 4 *2 = 8


IEEE 802.15-10-0501-00-004g

Slide 20


- According to the new proposed formulas,

The bit number of PHY header fields including pad bits is 48, and then it

increases 96 bits after Convolutional encoder.


DATAEncoder

(R=½)Interleaver


Mapper

FDS ( X4 )

IFFTCyclicPrefix

InsertionFiltering

DAC/RF Transceiver

/PA

Pad : 12 bits

Header : 36 bits


96 carriers

24 carriers/OFDM

symbol

4 OFDM symbols



IEEE 802.15-10-0501-00-004g

Slide 21



- Thus, the interleaving of 96 can be completed using 96 bits of PHY




IEEE 802.15-10-0501-00-004g

Slide 22


- According to the new proposed formulas,

The bit number of PHY header fields including pad bits is 48, and then it

increases 96 bits after Convolutional encoder.


DATAEncoder

(R=½)Interleaver


Mapper

FDS ( X4 )

IFFTCyclicPrefix

InsertionFiltering

DAC/RF Transceiver

/PA

Pad : 12 bits

Header : 36 bits


96 carriers

12 carriers/OFDM

symbol

8 OFDM symbols


IEEE 802.15-10-0501-00-004g

Slide 23



- Thus, the interleaving of 48 can be completed using 96 bits of PHY



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IEEE 802.15-10-0501-00-004g

PSDU fields for OFDM

Slide 24

• The maximum PSDU are 2047bytes

• For convenience of explanation, PSDU Length of 3 bytes is assumed.

PSDU : 3 Bytes Tail bits Pad bits

6 Zero Bits(Tail Bits)

Pad Bits


IEEE 802.15-10-0501-00-004g

Slide 25

- If the PSDU Length of 3bytes is assumed in 50Kbps mode of Option 3

and 4, the number of Symbol and Pads bits can be calculated by the

new proposed formulas.

NCBPS = 24 NDBPS = 24 * ½ = 12 NPAD = 12 * ceiling ((8*3 + 6)/12) - (8*3 + 6) = 6 NSYM = 2 * ceiling ((8*3 + 6)/12) = 6

For Example of Option 3 & 4

Optiondata rate

(Kbps)Modulation

Coding

rate

(R)

FDS

(NSF)

Coded Bits

/OFDM symbol

at interleaver

Ncbps

Coded Bits

/NSF OFDM symbol

at IFFT

NCBPS

DATA Bits

/NSF OFDM

symbol

at IFFT

NDBPS

NPAD NSYM

50 BPSK 0.5 2 24 24 12 6 6

50 QPSK 0.5 2 24 24 12 6 6

3

4


IEEE 802.15-10-0501-00-004g

Slide 26

- PHY Payload of 36 bits including PSDU, tail bits and Pad bits increase (3*8 + 6 +6)*2 = 72 bits after Convolutional encoder.

<Block diagram of PSDU Construction>


DATA ScramblerEncoder

(R=½)Puncturer Interleaver


Mapper

FDS ( X2 )

IFFTCyclicPrefix

InsertionFiltering

DAC/RF Transceiver

/PA

If R=1/2

PSDU 3byte + tail bits

3*8+6 = 30 bits Pad : 6 bits


12 carriers/OFDM symbol in Option 36 carriers/OFDM symbol in Option 4

72 carriers in Option 336 carriers in Option 4


6 OFDM symbols


IEEE 802.15-10-0501-00-004g

Slide 27

- In this case, the interleaving size is 24.

- Thus, the interleaving of 24 can be completed using 72 bits as shown below figure.



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IEEE 802.15-10-0501-00-004g

Conclusion

Slide 28

July, 2010

• The generation formulas for the number of symbol and PAD bits

in page 67 of draft standard can not consider the Interleaver

size and FDS repetition.

- In several data rate modes using FDS, Interleaving can’t be completed.

• Then, we propose new generation formulas for PAD bits and the

number of symbol considering the Interleaver size and FDS

repetition.

- The proposed formulas can be good solution for all data rate modes of

all Options.

Documents

IEEE 802.15-10-0501-00-004g Submission Sangsung Choi & Cheolho Shin, ETRI Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)