1 / 16

On the Single-Chip Implementation of IEEE802.11a

On the Single-Chip Implementation of IEEE802.11a. 長庚電機通訊組 碩一 張晉銓 指導教授 : 黃文傑博士. Outline . Software simulation of the C-code The system concept and main parameters Analog Front-End introduction A scheme of synchronization blocks SAW filter. IEEE 802.11a structure.

lewis-olsen
Download Presentation

On the Single-Chip Implementation of IEEE802.11a

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. On the Single-Chip Implementation of IEEE802.11a 長庚電機通訊組 碩一 張晉銓 指導教授:黃文傑博士

  2. Outline • Software simulation of the C-code • The system concept and main parameters • Analog Front-End introduction • A scheme of synchronization blocks • SAW filter

  3. IEEE 802.11a structure • Data rate ranging from 6-54 Mb/s • Bandwidth 20MHz • Modulation: BPSK, QPSK ,QAM. • Symbol duration : 4us including 0.8us guard interval • Why we use single-chip?

  4. Computational Requirements of the Baseband Processor ●Software of the model (C-code) on a SUN Sparcstatsion 10 transmitted 1024 bytes 500 times at different bit rates from 6-54 Mb/s

  5. Computational Requirements of the Baseband Processor 99.9% ●In the receiver, the Viterbi decoder consumes most of the calculation power ●Processing power of the 802.11a system is distributed in an asymmetric fashion between transmit and receive operations. The OFDM synchronization unit was not modeled

  6. The system concept and mainparameters • The complete modem have three main blocks • Analog front- end • Digital baseband processor • DLC layer

  7. The system concept and mainparameters (conventional)

  8. Super-heterodyne transceiver • Require a narrowband filter (SAW surface acoustic wave). • The I/Q separation be done in the analog domain, which mean that two A/D converters with an analog BW of 10 MHz. • The IF chosen is 810 MHz. • Need to be routed off-chip which lead to an increase in power dissipation. • Two A/D converter resolution is 10 Bits. • Oversampling of 80 MHz. (A/D & D/A)

  9. Super-heterodyne transceiver

  10. Digital IF Receiver • Advantage: • Gain is distributed over several amplifiers • Good selectivity (due to the presence of preselect and channel filter • Conversion from a real to complex signal is done at one fixed freq. ●Disadvantage: ●A/D has to be least 20 MHz ●Numerically NCO ●The linearity of receiver hardware need be maintained

  11. Homodyne (Zero IF) receiver • LO will translate the desired channel to 0 Hz • IF SAW filter are placed with low-pass filter • Research Issue: • DC offset • Maintenance of I/Q balance • Maintenance of low second order distortion

  12. A scheme of synchronization blocks

  13. SPW Model of baseband with synchronization • The estimator is mainly based on autocorrelation and crosscorrelation, and the preamble structure has to be optimized in order to minimize the estimator varience. • Symbol/frame timing offset • Carrier frequency offset • Sampling clock frequency offset

  14. Approach for synchronization • Sampling clock freq. offset use a fixed clock and an interpolator filter and the filter factor that depend on some error signal. • Use pilot for channel estimation • A Gaussian or Lagrange interpolator filter • Due to the nearly independent behavior of correlation functions in time and freq. ,the problem is simplified by using two-dimension Wiener Filters

  15. This SAW filter for the receiving RF circuit of GSM mobile communication equipment operating at 935 MHz ~ 960 MHz.

  16. End • Thank you for your attention

More Related