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Doc.: IEEE 802.11-00/202 Submission July 2000 Mark Webster, IntersilSlide 1 of 21 Frequency Domain Modulators for 802.11b Mark Webster Intersil Corporation.

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Presentation on theme: "Doc.: IEEE 802.11-00/202 Submission July 2000 Mark Webster, IntersilSlide 1 of 21 Frequency Domain Modulators for 802.11b Mark Webster Intersil Corporation."— Presentation transcript:

1 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 1 of 21 Frequency Domain Modulators for b Mark Webster Intersil Corporation July 2000

2 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 2 of 21 Overview Examine frequency domain modulator for and 2 Mbps Barker signaling. Examine frequency domain modulator for 5.5 and 11 Mbps CCK signaling. Examine frequency domain modulator for 5.5 and 11 Mbps PBCC signaling. Compare b frequency domain modulators to OFDM modulator. Cyclic extensions for Barker or CCK transmissions (non b variant).

3 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 3 of 21 1 and 2 Mbps BARKER Mode: Time Domain Modulator 1 Mbps: BPSK 2 Mbps: QPSK time Time Domain Multiply Narrow Sinc Spectrum Wide Sinc Spectrum

4 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 4 of Barker Code Viewed in Discrete Domain 11 Chip BARKER Code DFT SPECTRUM

5 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 5 of Chip Pulse time Periodically Extended Barker Samples Periodically Extended Barker Chips convolution Barker Code Spreading Detail Pulse Shape Envelop

6 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 6 of 21 Barker Mode Signaling Revisited 1 Mbps: BPSK 2 Mbps: QPSK time Time Domain Multiply Equals Frequency Domain Convolution time Composite

7 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 7 of 21 Pulse Shape Envelop Constituent Stacked Carriers Spread Spectrum: Stacked Carriers Composite

8 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 8 of 21 phzFreqRespDeg ampFreqResp freqMHz Sub-Carrier Amplitude/Phase

9 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 9 of pt. IFFT Compute Amp/Phz of each Subcarrier P/S Barker Spectrum BPSK/QPSK Rotation Info Bit(s) 1 and 2 Mbps BARKER Mode: Frequency Domain Modulator Constellation Mapper Freq (MHz) A 1 e j 1 A 2 e j 2 A 3 e j 3 A 5 e j 5 A 4 e j 4 A 6 e j 6 A 11 e j 11 A 7 e j 7 A 8 e j 8 A 10 e j 10 A 9 e j

10 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 10 of 21 2 Mbps Subcarrier Constellations

11 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 11 of Mbps CCK Mode: Time Domain Modulator QPSK time Time Domain Multiply time 4 Spreading Codes

12 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 12 of 21 8 pt. IFFT Compute Amp/Phz of each Subcarrier P/S 4 Codeword Spectrums QPSK Rotation 2 Info Bits 5.5 Mbps CCK Mode: Frequency Domain Modulator Constellation Mapper Info Bits A 1 e j 1 A 2 e j 2 A 3 e j 3 A 5 e j 5 A 4 e j 4 A 6 e j 6 A 7 e j 7 A 8 e j

13 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 13 of Mbps Codeword Subcarrier Spectrums

14 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 14 of Mbps Subcarrier Constellations QAM Constellations

15 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 15 of Mbps CCK Mode: Time Domain Modulator QPSK time Time Domain Multiply time 64 Spreading Codes

16 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 16 of 21 8 pt. IFFT Compute Amp/Phz of each Subcarrier P/S 64 Codeword Spectrums QPSK Rotation 2 Info Bits 11 Mbps CCK Mode: Frequency Domain Modulator Constellation Mapper Info Bits A 1 e j 1 A 2 e j 2 A 3 e j 3 A 5 e j 5 A 4 e j 4 A 6 e j 6 A 7 e j 7 A 8 e j

17 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 17 of Mbps Subcarrier Constellations Sub-Carriers 1, 3, 5, 7 Sub-Carriers 2, 4, 6, 8 QAM Constellations

18 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 18 of 21 8 pt. IFFT Compute Amp/Phz of each Subcarrier P/S 8 Info Bits 11 Mbps PBCC Mode: Frequency Domain Modulator Constellation Mapper Exists, but is Complicated 8 A 1 e j 1 A 2 e j 2 A 3 e j 3 A 5 e j 5 A 4 e j 4 A 6 e j 6 A 7 e j 7 A 8 e j

19 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 19 of 21 Scrambler Viterbi Encoder Interleaver Constellation Mapper IFFT Add Cyclic Extension A OFDM MODULATOR BLOCK DIAGRAM Data Sub-Carrier Constellations BPSK: 6, 9 Mbps QPSK: 12, 18 Mbps 16 QAM: 24, 36 Mbps 64 QAM: 48, 54 Mbps OFDM DIRECTLY EMBRACES FREQUENCY DOMAIN SIGNALING Used to Eliminate the Need for IBI Equalizer BPSK Pilot Subcarriers Cyclically Extends Sub-Carriers

20 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 20 of Samples 64 Samples IFFT/FFT SPAN Cyclic Extend 4 usecs OFDM Symbol KHz Tone Spacing 52 Subcarriers... frequency time a OFDM Symbol 20 MHz x 4 usecs = 80 samples ~16.25 MHz Equivalent to 64 Chip Codewords

21 doc.: IEEE /202 Submission July 2000 Mark Webster, IntersilSlide 21 of 21 Cyclic Extensions Can Be Used on Any Codeword Original Codeword Cyclically- Extended Codeword Smoothly Extends Sub-Carriers in Time


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