Continuous phase modulation

About: Continuous phase modulation is a research topic. Over the lifetime, 3199 publications have been published within this topic receiving 37245 citations. The topic is also known as: CPM.

MSK-Type Reception of Continuous Phase Modulation: Cochannel and Adjacent Channel Interference

Abstract: For binary continuous-phase modulation with modulation index h = 1/2 (MSK being a rather familiar example), quadrature matched-filter reception is possible with only minor degradation relative to the maximum likelihood (trellis-based) receiver. Thus this class of modulations provides good spectral attributes together with reception techniques capable of being implemented simply at high speeds. As usual, the constant-envelope property is also present. We study here the effects of interfering signals with the same modulation format, located at the same frequency (cochannel interference), or at a nearby frequency (adjacent channel interference). Coherent reception is assumed, and we analyze two channel situations: both signals nonfading with additive Gaussian noise; and both signals independently Rayleigh fading, with additive Gaussian noise. As one would expect, the smoothed phase modulation schemes have larger tolerable adjacent channel levels, while there is little differentiation in the cochannel case. We also find that MSK filters are usable for other formats with negligible loss in performance relative to the optimal linear filters, provided the filter parameters are rescaled appropriately.

Unified modulator for continuous phase modulation and phase-shift keying

Abstract: A “unified” modulator for multiple modulation schemes (e.g., GMSK and 8PSK) is described. The waveform for each modulation scheme is generated based on a set of one or more pulse shaping functions. The waveforms for all supported modulation schemes may be generated based on a composite set of all the different pulse shaping functions. The unified modulator includes a filter for each pulse shaping function in the composite set. To generate the waveform for a selected modulation scheme, the set of one or more filters for this modulation scheme is enabled and all other filters are disabled. The outputs from all enabled filters are summed to generate a modulator output. When switching between modulation schemes, a smooth transition may be obtained by (1) providing a suitable data pattern for each filter to be enabled or disabled and (2) generating symbols for the new modulation scheme with an appropriate initial phase.

Optimum Coherent Phase and Frequency Demodulation of a Class of Modulating Spectra

Abstract: The optimum phase-locked loop demodulator is obtained for a carrier, phase modulated by a stationary Gaussian modulating process whose spectrum is proportional to 1/1 + (f/B)2n where n is any positive integer. Results are obtained also when the carrier is frequency modulated by the process for the limiting cases n = 1 and as n approaches infinity. It is shown that for phase modulation the output SNR as a function of the channel SNR in the bandwidth B varies from linear to exponential behavior as n increases from 1 to ?. For the limiting cases the performance of frequency modulation is slightly inferior to that for phase modulation.

DCT-OFDM With Index Modulation

Abstract: In this letter, index modulation (IM) is proposed for OFDM systems based on a discrete cosine transform (DCT) implementation. The new DCT-OFDM-IM scheme is shown to yield spectral efficiency improvements of up to 38% relative to OFDM-IM and up to 55% relative to OFDM while occupying the same bandwidth and maintaining similar robustness against the frequency selective fading channels for low modulation orders.

Sequential quasi-convex-based algorithm for waveform design in colocated multiple-input multiple-output radars

Abstract: This study considers the problem of waveform design for colocated multiple-input multiple-output (MIMO) radars for multiple targets in the presence of multiple interferences in white Gaussian noise. Here, the authors jointly design the transmit waveform and receive beamforming by a sequential algorithm. The proposed sequential algorithm maximises the minimum signal-to-interference-plus-noise ratio (SINR) to design both continuous and finite alphabet phase waveforms. In the case of continuous phase, all phases can be chosen in the waveform space, while in finite alphabet case, phases are only chosen from a confine set. Two important practical constraints of ‘constant envelope’ and ‘similarity’ are considered as well. The authors also have converted the waveform design problem into a quasi-convex optimisation problem which can be effectively solved by using convex optimisation toolbox (CVX). They have evaluated the performance of the matched filter output, beampattern and peak-to-average power ratio via numerical simulations and shown that the proposed sequential method achieves better SINR performance compared with existing MIMO radar transmit waveform design methods, for both single and multiple target scenarios.