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A Proposed Scrambling Vector for the CCK Blockcode

A Proposed Scrambling Vector for the CCK Blockcode. Chris Heegard, Matthew Shoemake & Stan Ling. CCK code (n=8, k=4) Z 4. G = [1 1 1 1 1 1 1 1] [1 1 1 1 0 0 0 0] [1 1 0 0 1 1 0 0] [1 0 1 0 1 0 1 0] c = m G (over Z 4 ) A linear code ( m G) d = 4

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A Proposed Scrambling Vector for the CCK Blockcode

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  1. A Proposed ScramblingVector for the CCK Blockcode Chris Heegard, Matthew Shoemake & Stan Ling Alantro

  2. CCK code(n=8, k=4) Z4 • G = [1 1 1 1 1 1 1 1] [1 1 1 1 0 0 0 0] [1 1 0 0 1 1 0 0] [1 0 1 0 1 0 1 0] • c = mG (over Z4) • A linear code (mG) • d = 4 • Number of Nearest Neighbors = 24 Alantro

  3. 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 = [+1 +1 +1 +1 +1 +1 +1 +1] • a = [ 0 0 0 2 0 0 2 0] • New proposal: • b = [-1 -1 -1 -1 +1 +1 +1 +1] • a = [ 1 0 3 0 0 2 3 3] Alantro

  4. 250 200 0 0 0 2 0 0 2 0 Trms: 100 versus Number of Channels: 1000 5 4 7 4 0 2 3 3 150 100 50 0 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 100ns Delay Spread Alantro

  5. 0.5 0 0 0 0 2 0 0 2 0 Trms: 100 versus Number of Channels: 1000 -0.5 5 4 7 4 0 2 3 3 -1 -1.5 -2 -2.5 0 100 200 300 400 500 600 700 800 900 1000 100ns Delay Spread Alantro

  6. 250 200 0 0 0 2 0 0 2 0 Trms: 200 versus Number of Channels: 1000 5 4 7 4 0 2 3 3 150 100 50 0 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 200ns Delay Spread Alantro

  7. 1 0.5 0 0 0 0 2 0 0 2 0 Trms: 200 versus Number of Channels: 1000 -0.5 5 4 7 4 0 2 3 3 -1 -1.5 -2 -2.5 -3 0 100 200 300 400 500 600 700 800 900 1000 200ns Delay Spread Alantro

  8. 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

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