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 PBCC-22

Outline History Discovery of a New Code PBCC-22 Properties and Performance Conclusion PBCC-22

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 PBCC-22

Movitation for Higher Performance PBCC-22

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 PBCC-22

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) PBCC-22

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) PBCC-22

PBCC Components PBCC-22

BCC Encoder for 22Mbps PBCC-22: PBCC-22

The “s” Sequence A length 256 sequence generated from a length 16 sequence [c0,c1,…,c15] = [0011001110001011] Periodically extended for >256 PBCC-22

Digital 8-PSK PBCC-22

Distance Bound 350 360 370 380 390 400 10 20 30 40 50 Distance 10 20 30 40 50 Distance Average Number Cumulative Distribution with Upper Bound Number of States: 256 G: 21 2 12 10 25 12 450 500 100 200 300 600 PBCC-22

Average Distance Spectrum 350 360 370 380 390 400 1 2 3 4 5 6 7 8 Distance Average Number Distance Spectrum with Cumulative Distribution Number of States: 256 G: 21 2 12 10 25 12 PBCC-22

AWGN Performance PBCC-22

PBCC-22

PBCC-22

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 PBCC-22