Demodulation method for continuous phase modulation signals based on least-squares method

Vasyl Yu. Semenov

doi:10.3103/S0735272718040027

Authors

Vasyl Yu. Semenov Limited Liability Company "Delta SPE", Ukraine

DOI:

https://doi.org/10.3103/S0735272718040027

Keywords:

CPM, LMS, continuous phase modulation, least-squares method

Abstract

Continuous phase modulation (CPM) schemes are attractive for telecommunication systems, which are limited in terms of the bandwidth and signal power due to their high spectral efficiency. In this paper we present a method for the demodulation of continuous phase modulation signals based on least-squares method (LSM). This method (CPM-LSM) is based on the optimal linear estimation of information symbols from the phase of the received signal by solving the overdetermined system of equations using the least squares method. Mathematical substantiation for the application of the proposed CPM-LSM method is presented. Preliminary experimental results of modeling using Geo-Mobile Radio (GMR-2) signals indicate that the method is robust with respect to carrier phase errors. Another feature of CPM-LSM method is that it does not use unique words (symbol patterns for amplitude/phase alignment). The latter fact is very important since unique words usually occupy up to twenty percent of transmitted packet size. The absence of unique words can substantially increase the information throughput.

References

LAURENT, P. “Exact and approximate construction of digital phase modulations by superposition of amplitude modulated pulses (AMP),” IEEE Trans. Commun., v.34, n.2, p.150-160, 1986. DOI: https://doi.org/10.1109/TCOM.1986.1096504.

BJERKE, B.A.; PROAKIS, J.G.; LEE, K.Y.M.; ZVONAR, Z. “A comparison of GSM receivers for fading multipath channels with adjacent and co-channel interference,” IEEE J. Select. Areas Commun., v.18, n.11, p.2211-2219, 2000. DOI: https://doi.org/10.1109/49.895026.

KUMAR, L.; MITTAL, D.K.; SHRESTHA, R. “VLSI-design and FPGA-implementation of GMSK-demodulator architecture using CORDIC engine for low-power application,” Proc. IEEE Annual India Conf., INDICON, 16-18 Dec. 2016, Bangalore, India. IEEE, 2016. DOI: https://doi.org/10.1109/INDICON.2016.7838954.

SEN, D.; YUHONG, Y.; PENGHUI, C.; BIN, G. “Research on separability of GMSK mixed signals based on modulation parameters,” Proc. of 5th Int. Conf. on Electronics Information and Emergency Communication, ICEIEC, 14-16 May 2015, Beijing, China. IEEE, 2015. DOI: https://doi.org/10.1109/ICEIEC.2015.7284514.