Block demodulation method for psk signal by sequential regression estimator

Abstract

AbstractThis paper considers the block demodulation method with carrier phase synchronization without preamble, and presents a proposal and evaluation for the new carrier phase synchronization method based on the sequential regression estimator. The block demodulation has a feature in that the traditional way of real‐time demodulation is not adhered to, and the preamble is not required. This improves greatly the throughput especially in a short packet communication.The traditional system is based on the least‐square scheme, noting that the cumulative carrier phase variation between data symbols is represented in a linear form. It has a problem in that the linearity is lost due to noise in deriving the cumulative value for the phase variation, which may greatly deteriorate the demodulation performance.The sequential regression estimator proposed in this paper is based essentially on the least‐square principle. However, the cumulative value is not determined for each time as in the traditional method but the estimation is updated based on the difference between the observed value and the value estimated from the data up to the previous sample. Consequently, the problem in the traditional system essentially is eliminated.Because of this elaboration, the computation in the proposed system is very small compared with traditional systems. It is seen as a result of simulation that the tolerable noise margin for 80 percent synchronizing probability, which has been used as the evaluation criterion, is improved by 11 dB for BPSK.In the satellite packet communications network such as VSAT (very small aperture terminal), the throughput is improved remarkably. Applying the proposed principle to the design of the present link, the time‐ratio, where the burst synchronization error is 1 percent or less in the Ku band, is 0.03 percent. In VSAT, a random access scheme is employed. Considering the burst collision probability of the access, it follows that the burst synchronization error probability of 1 percent does not affect the overall performance, and the proposal in this paper can be considered as sufficiently practical.