應用於影音多媒體無線傳輸中的自動增益控制和訊框同步器

Abstract

在這篇論文中，我們介紹了應用在IEEE 802.15.3c 系統中的自動增益控制器和訊框同步器。由於經過通道後訊號能量將會產生劇烈變化，為了對抗通道所造成的訊號能量衰竭，自動增益控制器必須週期性的對可變增益放大器作控制。我們偵測類比數位轉換器的最大可接受範圍去避免飽和錯誤和降低量化錯誤並且利用可適性加權值去對抗通道所造成的能量衰竭，以確保類比數位轉換器的輸入訊號能量能保持適當且穩定。 由於序文序列已在傳送端被重新取樣，使得交錯相關特性太差無法來作符元邊界偵測。在此提出了一個新的交錯相關方法和一些加強效能的機制，例如格狀搜尋和最大相似來作符元邊界偵測。在IEEE 802.15.3c 通道模型和載波頻率偏移200 ppm下的模擬結果指出當雜訊比大於6分貝時偵測錯誤率可以小於千分之一。

In this thesis, we introduce automatic gain control and frame synchronization algorithm for 802.15.3c systems. Due to the big variation of received signal power under path loss and shadowing effects the AGC must periodic control the VGA for whole packet with different control scheme. We are tracking the rest range of ADC to reduce quantization noise without ADC saturation and adaptive weight to defend shadowing effects. In frame synchronizer, the training sequence has been re-sampled at transmitter such that the correlation property of conventional cross-correlation metric gets too worse to estimate the symbol boundary. A new cross-correlation metric and several enhance performance schemes such as trellis search and Maximum likelihood is applying for boundary detection. Simulations in IEEE802.15.3c channel model with a carrier frequency offset (CFO) of ±200 ppm indicate that the detection error can be less than 0.1% at SNR ≧ 6 dB.