Methods for estimation of the uncoded symbol error rate at the receiver

In some communications systems, uncoded symbol error rate (SER) estimation is required to be performed "on-the-fly" at the receiver, in order to provide a measure of the quality of service or to aid in the power control process required for CDMA systems. An example is the 3GPP WCDMA UMTS standard, where transport channel and physical channel bit error rates have been required as metrics to be estimated by the receiver. In this paper, we analyze the performance of a number of uncoded SER estimation techniques, including a novel technique in which we use the soft information of the received symbols to obtain a fast and accurate estimate of the uncoded SER. The technique we introduce outperforms the commonly used decode/re-encode/compare technique, in terms of accuracy and required estimation interval. Our technique also outperforms the brute-force technique, which is to send a known test-pattern, demodulate it at the receiver, and count the observed discrepancies.