Blind SNR Estimation on WCDMA system with Unequal Power Signals and without any Prior Knowledge
Siavash Ghavami, Vahid Tabataba Vakili · 2007
In this paper we have estimated signal to noise ratio (SNR) of active users in uplink scenario of CDMA systems blindly. We have not any knowledge about PN (pseudo noise) code, frequency, and timing of received signals. In this way first we synchronized received signal of desired user and then we use subspace method for SNR estimation of synchronized user. This type of SNR estimation is classified as non data aided (NDA) methods. Our synchronization is based on maximizing of covariance matrix Frobenius norm. After that by estimating PN code of strongest signal we are able to estimate transmitted signal data, and by using estimated SNR, we can eliminate this signal from received signal by using SIC (serial interference canceller). By repetition this cycle for each user we can estimate SNR of active users in uplink scenario. Also, in this paper we use minimum description length (MDL) criteria for estimating signal subspace dimension. Standard divisions of estimated SNR show that good agreement with exact SNR for all users.