PBCC-22

1. PBCC-22 Chris Heegard, Ph.D., Sean Coffey, Ph.D., Anuj Batra, Ph.D.,Srikanth Gummadi and Matthew Shoemake, Ph.D.Home and Wireless Networking Texas Instruments 141 Stony Circle, Suite 130 Santa Rosa California 95401 (707) 521-3060,heegard@ti.com Chris Heegard, Texas Instruments

2. Outline • History • Discovery of a New Code • PBCC-22 Properties and Performance • Conclusion Chris Heegard, Texas Instruments

3. Short History of PBCC • Alantro Communications incorporated, August 1997 Blending the Theory of Information with the Art of Silicon • PBCC-11 introduced in IEEE 802.11 • 64 State Binary Convolutional Code + Signal Scrambler • Introduced in March 1998 meeting • Adapted as “High Performance” option • Although it provided a more robust solution, +3dB C.G., it was deemed “too complex” • Time to market was a major factor in selection of CCK • Harris semiconductor had a working MBOK chip Chris Heegard, Texas Instruments

4. Movitation for Higher Performance Chris Heegard, Texas Instruments

5. History (cont) • PBCC-22 developed beginning in summer of 1998 • Constraints • Interoperability with IEEE 802.11b networks • Translate coding gain advantage to “double the data rate” • 22 Mbps • Compatibility with IEEE 802.11b radios • 8-PSK, 11 MHz symbol rate, short preamble • Operate in the same environment as CCK-11 • 64 state code --->> 256 state code • A good engineering solution: cost versus performance • Satisfy FCC Requirements Chris Heegard, Texas Instruments

6. Discovery of a New Code • Problem: Find optimal • (k=2, n = 3) 256 state code matched to 8PSK • Solution discovered in January 1999 • The new code has many interesting features • Optimal Distance Spectrum for 8-PSK • Optimal Free Distance in many scenarios • 8-PSK, Digital-8PSK • Hamming distance (Binary coding) • Underboeck 8-way partition (Trellis Coded QAM) Chris Heegard, Texas Instruments

7. Packet Binary Convolutional Coding • Combines Binary Convolutional Coding with Codeword Scrambling • PBCC-22Rate k=2, n=3 encoder • 256 state • Digital-8PSK modulation • Dfree^2/Es = 704/98 = 8.6 dB • Reference: 16QAM+Interleaved (k=1,n=2) 64 state BCC • Dfree^2/Es = 40/10 = 6.0 dB (-2.6 dB) Chris Heegard, Texas Instruments

8. PBCC Components Chris Heegard, Texas Instruments

9. BCC Encoder for 22Mbps • PBCC-22: Chris Heegard, Texas Instruments

10. The “s” Sequence • A length 256 sequence generated from a length 16 sequence • [c0,c1,…,c15] = [0011001110001011] • Periodically extended for >256 Chris Heegard, Texas Instruments

11. Digital 8-PSK Chris Heegard, Texas Instruments

12. Cumulative Distribution with Upper Bound 50 40 30 Number of States: 256 Average Number G: 21 2 12 20 10 25 12 10 0 350 360 370 380 390 400 Distance Cumulative Distribution with Upper Bound 600 500 400 Number of States: 256 Average Number G: 21 2 12 300 10 25 12 200 100 0 350 400 450 500 Distance Distance Bound Chris Heegard, Texas Instruments

13. Distance Spectrum with Cumulative Distribution 8 7 6 5 Number of States: 256 G: 21 2 12 Average Number 10 25 12 4 3 2 1 0 350 360 370 380 390 400 Distance Average Distance Spectrum Chris Heegard, Texas Instruments

14. AWGN Performance Chris Heegard, Texas Instruments

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17. Conclusions • PBCC is an innovative new code that solves a real problem • Backward compatible with IEEE 802.11b standard • Backward compatible with radio and regulatory requirements • “Doubles the Data Rate” in the same environment • Patent pending Chris Heegard, Texas Instruments