| Summary: | 碩士 === 國立中興大學 === 電機工程學系 === 90 === In recent years, with technology progress, data transmission used wireless interface has become popular. The IEEE 802.11 standard for wireless LAN was proposed for this propose. In this thesis, we introduce channel model, modulation formats, spread spectrum techniques and modulation techniques for 802.11.b. The wireless network systems would be degraded by numerous factors including channel fading, channel noise, frequency offset, and phase offset… etc. We discuss the carrier recovery loop to resolve the problem of frequency offset and phase offset between transmitter and receiver in this thesis.
The frequency offset is converged and compensated by the carrier recovery loop, but the residual phase error can’t be recovered. A new structure and algorithm are proposed for carrier recovery. The algorithms use the information of received signal to compensate the frequency offset and residual phase error without using the loop filter and NCO (Numerically Controlled Oscillator). In other words, the recovered signal is on the I and Q correctly. Compare with traditional carrier recovery loop, the new structure have the advantage of easy to implement and a shorter convergent time.
|
|---|
