Laplacian filtered minimum shift keying modulation

Abstract

Gaussian minimum shift keying (GMSK) is a continuous-phase frequency-shift keying modulation scheme. It is similar to standard minimum-shift keying (MSK); however the digital data stream is first shaped with a Gaussian filter before being applied to a frequency modulator. This has the advantage of reducing sideband power, which in turn reduces out-of- band interference between signal carriers in adjacent frequency channels. In this paper a new method of premodulation filtered MSK called Laplacian minimum shift keying (LMSK) is proposed. LMSK is proposed as a method for achieving good spectral efficiency over regular MSK, and it turns out to achieve improvement in error rate performance over the known GMSK. To compare the behavior of the system under the proposed method, bandwidth efficiency (i.e., bps/Hz), fractional out-of-band power and error rate performance in such systems are used. Results show that the proposed LMSK attains good improvement in spectral efficiency over MSK; and in using LMSK we have also good improvement in power efficiency over GMSK.