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.

Carrier Phase Estimation in Multi-Subcarrier Coherent Optical Systems

Abstract: In this letter, we analyze three different carrier phase estimation approaches for coherent optical systems based on multi-subcarrier modulation, comparing them in terms of both performance and complexity. Averaging the estimated values on the subcarriers (SCs) significantly increases the laser linewidth tolerance at the expense of additional complexity, while using a single SC for carrier phase estimation yields a complexity reduction without any substantial performance loss with respect to performing a separate phase estimation on all SCs

System and method for adaptive bit loading source coding via vector quantization

Abstract: A communication system includes a data transmitter and a data receiver in which the data transmitter transmits data using a multicarrier modulation, such as an OFDM modulation technique. The data receiver determines a predetermined level of modulation for at least one carrier of the multicarrier modulation corresponding to a received signal-to-noise ratio for the carrier using a vector quantization technique. The predetermined level of modulation for each carrier is based on an index to a codeword in a codebook corresponding to the signal-to-noise ratio for the carrier. The index to the codeword is a nearest neighbor to a vector corresponding to the signal-to-noise ratio for the carrier, and the codeword for each predetermined level of modulation is determined based on an adaptive-bit-loading technique. The data receiver transmits the index to the codeword for each carrier to the data transmitter in order to update the modulation at the data transmitter.

Carrier frequency estimator for a signal receiver

Abstract: A method and apparatus for estimating a carrier frequency of an incoming signal. The carrier frequency estimator determines the phase difference between the phases for two successive modulation symbols when the two successive modulation symbols are within a particular magnitude range having at least two evenly spaced modulation phase states. The carrier frequency estimator includes a magnitude selector for selecting modulation symbols within the particular magnitude range and a phase subtractor coupled to the magnitude selector for determining phase differences between the successive modulation symbol phases. A signal receiver of the present invention uses the phase differences for tuning a locally generated frequency for tracking a carrier frequency of an incoming radio frequency (RF) signal.

Trellis codes for 4-ary continuous phase frequency shift keying

Abstract: The approach of Morales-Moreno and Pasupathy (1988) is extended for the design of trellis codes for 4-ary continuous phase frequency shift keying (CPFSK) with modulation index h=1/2. The criterion for comparison of codes is the maximum free Euclidean distance for a given rate and the number of states of the signal space code. For the same number of states of the signal space code, these codes improve the free Euclidean distance by up to 1.25 dB over previously published results. Finally, the implementation of the combined coding and modulation system is discussed. >