All Digital Multi-Gigabit Baseband P. Sandeep M. Seo M. Rodwell - - PowerPoint PPT Presentation

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All Digital Multi-Gigabit Baseband P. Sandeep M. Seo M. Rodwell - - PowerPoint PPT Presentation

Feb 21, 2024 224 likes •550 views

Joint Channel and Mismatch Correction for OFDM Reception with Time-interleaved ADCs All Digital Multi-Gigabit Baseband P. Sandeep M. Seo M. Rodwell U. Madhow ECE Dept, UCSB ECE Dept, UCSB All Digital Baseband Digital Baseband

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SLIDE 1

Joint Channel and Mismatch Correction for OFDM Reception with Time-interleaved ADCs

All Digital Multi-Gigabit Baseband

  • P. Sandeep
  • U. Madhow
  • M. Seo
  • M. Rodwell

ECE Dept, UCSB

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SLIDE 2

ECE Dept, UCSB

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SLIDE 3

All Digital Baseband

“Digital Baseband” Receiver

cos (wt ) ADC Synchronization Equalization Demodulation Decoding

ECE Dept, UCSB

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SLIDE 4

Signal Processing Issues

Analog –to-Digital Converter (ADC)

Analog In Digital Out Sampling rate & Output resolution

ECE Dept, UCSB

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SLIDE 5

Large bandwidth !

ECE Dept, UCSB

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SLIDE 6

Need for Resolution

REFLECTOR TRANSMITTER RECEIVER

ECE Dept, UCSB

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SLIDE 7

ADCs available

Speed 100 KHz 10MHz 100MHz 1 GHz Resolution 24 bit 18 bit 15 bit 8 bit Power 1-10mW 10-100mW 100mW-1W 1-10W

ADC Survey by Le et al, IEEE Sig. Proc. Mag. Nov’05

ECE Dept, UCSB

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SLIDE 8

High speed, moderate resolution ADCs ?

ECE Dept, UCSB

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SLIDE 9

Solution

Time-interleaving

ECE Dept, UCSB

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SLIDE 10

Issues ?

  • Mismatch between parallel channels

ECE Dept, UCSB

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SLIDE 11

Mismatch model

Munkyo Seo, Rodwell & Madhow, IEEE Tran. Mic. Tech. March 2005 Gain and timing mismatch

ECE Dept, UCSB

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SLIDE 12

TI ADCs for multi-Gigabit Communication

ECE Dept, UCSB

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SLIDE 13

Conventional approach

TI ADC : Status and Future Directions, by Vogel et al ISCAS 06

Make a better ADC Make a better ADC

ECE Dept, UCSB

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SLIDE 14

Our approach to mismatch

Adapt mismatch correction to Communication signal

ECE Dept, UCSB

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SLIDE 15

Example : TI-ADC in OFDM system

ECE Dept, UCSB

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SLIDE 16

OFDM transceiver

Training Data DAC cos (wt ) cos (wt ) TI ADC Training’ Training Data’

OFDM transceiver

ECE Dept, UCSB

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SLIDE 17

Structure of mismatch induced interference

ECE Dept, UCSB

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SLIDE 18

Signal at sub-carrier ‘0’

ECE Dept, UCSB

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SLIDE 19

Zero-forcing Equalization

# of ADCs = 8 # of interferers = 8

Orthogonal to interference space Signal vector Interference space

ECE Dept, UCSB

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SLIDE 20

Equalization performance

  • 16 QAM, OFDM
  • 8 parallel-ADCs
  • 10% mismatch

(~20ps, 5GSa/s)

ECE Dept, UCSB

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SLIDE 21

Estimation of mismatch

ECE Dept, UCSB

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SLIDE 22

Joint channel-mismatch estimation

Received Training Iterations

ECE Dept, UCSB

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SLIDE 23

Accuracy in estimates

ECE Dept, UCSB

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SLIDE 24

Hardware Experiment

ECE Dept, UCSB

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SLIDE 25

Setup

1 Received Baseband (2x)

4x100 MSa/s ADCs

14 bit sampled data

1 On TI ADC testbed of Dr. Munkyo Seo, Prof Rodwell’s Lab

ECE Dept, UCSB

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SLIDE 26

Results

ECE Dept, UCSB

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SLIDE 27

Conclusions

Gigabit Wireless Time-interleaved ADC Joint demodulation & mismatch correction Mismatch compensation

ECE Dept, UCSB

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SLIDE 28

THANKS THANKS

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SLIDE 29

Flash ADC

Comparators Digital logic Analog Input 00 01 11 10

Flash ADC 2N comparators Static power

2 bits

ECE Dept, UCSB

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SLIDE 30

SAR ADC

Successive Approximation Register

00 01 11 10

ECE Dept, UCSB

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SLIDE 31

MIMO Receiver

RECEIVER 2kT ADC 2 ADC 1 2kT ADC 4 ADC 3 (2k+1)T (2k+1)T

ECE Dept, UCSB