正交分頻多工編碼雙向放大轉送中繼系統之通道盲估測

Abstract

Orthogonal frequency division multiplexing (OFDM) has recently received considerable interest for its advantages in high-bit-rate transmissions over frequency-selective fading channels. Recently, research on wireless relay networks becomes popular because of the following reasons. When a transmitter and a receiver are unable to communicate with each other because of the distance between them or fading of the channel, they can be connected by one or multiple relay nodes to create an alternate route. Relay transmission can enhance the reliability, increase the rate in wireless networks. Relay transmission provides an effective means of improving spectral and power efficiency. In addition, the use of multiple antennas to achieve transmit diversity in the cellular uplink is impractical due to the size constraints at each mobile. Cooperative communication can overcome this constraint problem. Relay nodes cooperate with terminals of the users when each relay nodes transmit its own information to destination by processing the information from source. This thesis studies the blind channel estimation for amplify-and-forward(AF) TWRN ZP-OFDM systems. We will show how to apply the subspace-based blind channel estimation algorithm for the case of TWRN ZP-OFDM systems. Pilots for estimating the scalar ambiguity in blind channel estimation are also derived. Simulations are carried out to verify the performance of the proposed method. Compared with the existing blind channel estimation method in TWRN, our proposed method has a better performance.