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.

Reduced complexity receivers for layered space-time CPM

Abstract: Layered space-time (LST) transmissions employing continuous phase modulations (CPM) are well motivated for both bandwidth- and power-limited multiantenna communications. However, one of the major challenges for LST-CPM is the high complexity it incurs with maximum likelihood (ML) detection. In this paper, we develop reduced complexity LST-CPM receivers. First, we consider single antenna systems. Specifically, we study a reduced complexity Viterbi receiver for binary CPM. Based on this design, we introduce differential encoding for a class of CPM signals and analyze its performance gain both theoretically and with simulations. Second, we focus on multiantenna LST systems with minimum shift-keying (MSK)-type modulations. With group nulling-canceling (NC) and low-complexity linear equalization, we convert a coded multiuser detection problem into an uncoded one with small equalization loss. We also find that the combination of sphere decoding with hard-decision iterative processing is effective in boosting performance with a controllable complexity increase. Both analytical and simulated performance confirm that the novel LST-MSK receiver exhibits markedly improved performance relative to conventional NC detectors with moderate complexity increase.

Non-coherent spread-spectrum continuous-phase modulation communication system

Abstract: A technique for modulating and demodulating CPM spread spectrum signals and variations of CPM spread spectrum signals. A spread spectrum transmitter includes a chip sequence generator for generating a chip sequence from a data stream, a switch for dividing said chip sequence into an odd chip sequence and an even chip sequence, and a modulator for generating and transmitting a continuous phase modulated signal from said odd chip sequence and said even chip sequence. A spread spectrum receiver comprises a plurality of non-coherent serial CPM correlators, each generating a correlation signal. In a preferred embodiment, the chip sequence generator of the transmitter comprises a table of symbol codes, each symbol code comprising a series of chips corresponding to a unique series of bits in said data stream, and each non-coherent serial CPM correlator is configured to detect one of the symbol codes. The spread spectrum receiver selects a data symbol based on said correlation signals output from the non-coherent serial CPM correlators. A spread spectrum preamble may be used to set initial timing for the non-coherent serial CPM correlators.

Multiple-bit differential detection of offset QPSK

Abstract: Analogous to multiple-symbol differential detection of quadrature phase-shift keying (QPSK), a multiple-bit differential detection scheme is described for offset QPSK that also exhibits continuous improvement in performance with increasing observation interval. Being derived from maximum-likelihood considerations together with the representation of differentially encoded offset QPSK as a continuous phase modulation, the proposed scheme is purported to be the most power-efficient scheme for such a modulation and detection method.

Joint phase and timing recovery with CPM signals

Abstract: We describe an algorithm for joint timing and carrier phase recovery with CPM signaling. The proposed method may be employed with any CPM format and with either full or reduced state detectors. It can be implemented in digital form with a limited computational complexity. Simulation results show that its tracking performance is excellent. However, when operated in its simplest form, it may exhibit false locks during acquisition. In particular, this happens with multilevel partial response formats. A simple solution to false locks is proposed.