1. A Proposed Scrambling Vector for the CCK Blockcode
doc.: IEEE /303
September 1998
September 16, 1998
A Proposed Scrambling Vector for the CCK Blockcode
Chris Heegard,
Matthew Shoemake
&
Stan Ling
Alantro
Chris Heegard, Alantro

2. CCK code (n=8, k=4) Z4 c = mG (over Z4) d = 4
September 16, 1998
CCK code (n=8, k=4) Z4
G = [ ] [ ] [ ] [ ]
c = mG (over Z4)
A linear code (mG)
d = 4
Number of Nearest Neighbors = 24
Alantro

3. CCK Scrambling c = b.*mG + a Q: Which choice of a & b is best?
September 16, 1998
CCK Scrambling
c = b.*mG + a
bi in {-1, +1}
ai in {0, 1, 2, 3}
Q: Which choice of a & b is best?
First proposal:
b = [ ]
a = [ ]
New proposal:
b = [ ]
a = [ ]
Alantro

4. 100ns Delay Spread September 16, 1998 Alantro -2 -1.5 -1 -0.5 0.5 1
0.5 1
1.5 2 50
100
150
200
250
Trms: 100
Number of Channels: 1000
versus
Alantro

5. 100ns Delay Spread September 16, 1998 Alantro 100 200 300 400 500 600
100
200
300
400
500
600
700
800
900
1000
-2.5 -2
-1.5 -1
-0.5
0.5
Trms: 100
Number of Channels: 1000
versus
Alantro

6. 200ns Delay Spread September 16, 1998 Alantro -2 -1.5 -1 -0.5 0.5 1
0.5 1
1.5 2 50
100
150
200
250
Trms: 200
Number of Channels: 1000
versus
Alantro

7. 200ns Delay Spread September 16, 1998 Alantro 100 200 300 400 500 600
100
200
300
400
500
600
700
800
900
1000 -3
-2.5 -2
-1.5 -1
-0.5
0.5 1
Trms: 200
Number of Channels: 1000
versus
Alantro

8. Key Points A “flexible” component of Harris/Lucent Proposal
September 16, 1998
Key Points
A “flexible” component of Harris/Lucent Proposal
Study of best solution was solicited in July meeting
The New Solution has more robust multipath tolerance
No Hardware Cost
The CCK decoder structure (e.g., FFT method) is independent of choice of scramble vector
Rotational Invariance
“Differential” precoding of 2 bits per codeword is maintained
Alantro