Viterbi differential detection for binary partial response continuous phase modulation with index 0.5

The complexity of the multiple-symbol detection structures for partial response continuous phase modulation (CPM) signals goes exponentially with the length of the pulse shaping filter and the observation length as well. Simple no coherent trellis receivers for partial response CPM signals are proposed in this paper. Parallel to the simple coherent detectors, where CPM signals are approximately represented by a sum of Phase Amplitude Modulation waveforms, Laurent decomposition is applied to reduce the complexity. The proposed no coherent receiver is structured with only fixed K matched filters in the front-end and a processor which uses Viterbi algorithm with a 2N-1 states trellis to perform the sequence estimation. It is attractive because the structure does not involve any matrix calculations. The good error performance is confirmed by simulation results.

This paper considers the performance of a speech transmission scheme with application to cellular digital mobile radio systems. The source coder is embedded DPCM and modulation scheme belongs to a class of Partial Response Continuous Phase Modulation Both quantizing noise and transmission errors contribute to the overall mean squared error. The performance measure is audio signal to noise ratio. It is seen that in a fading environment space diversity is very effective in bringing down the threshold of channel signal to noise ratio to maintain the required audio signal to noise ratio. The number of channels the system can support is evaluated under various conditions.

The performance of constant envelope digital partial response continuous phase modulation (PRCPM) with two-bit differential detection and offset receiver diversity is theoretically analyzed in fast Rayleigh fading AWGN (additive white Gaussian noise) channels. A simple closed-form expression for the probability of error is derived and evaluated for cases of practical interest to researchers and designers of land mobile radio systems. It is shown that the dynamic BER performance is considerably improved using the offset diversity scheme. Thus, many new PRCPM signals having compact power spectra can be used in future mobile radio systems. >

In this paper, we numerically demonstrate the advantage of utilizing continuous amplitude and phase modulation in super-oscillation focusing lens design. Numerical results show that compared with simple binary amplitude modulation, continuous amplitude and phase modulation can greatly improve the super-oscillation focusing performance by increasing the central lobe intensity and the ratio of its energy to the total energy, reducing the sidelobe intensity, and substantially extending the field of view. Our study also reveals the role of phase distribution in reducing the spatial frequency bandwidth of the super-oscillation optical field on the focal plane. Based on continuous amplitude and binary phase modulation, a lens was designed with double layer metal slit array for wavelength of 4.6 µm. COMSOL is used to carry out the 2D simulation. The lens focal length is 40.18λ and the focal spot FWHM is 0.308λ. Two largest sidelobes are located right next to the central lobe with intensity about 40% of the central lobe intensity. Except for the two sidelobes, other sidelobes have intensity less than 25% of the central lobe intensity, which leads to a clear field of view on the whole focal plane.

Recently, a symbol detection scheme based on the Viterbi algorithm was proposed for binary Two Dimensional Optical Storage (TwoDOS) in the presence of Additive White Gaussian noise (AWGN). In this paper, we extend the symbol detection scheme to allow for multilevel modulation. We demonstrate the proof of concept in a typical non-linear high density storage channel with intersymbol interference and AWGN. The relative performance, between multilevel and binary modulations is presented, where multilevel modulation provides better performance in higher capacities.

The joint optimization of partial response continuous phase modulation (CPM) parameters is addressed. For fixed modulation order and memory length, the modulation index, the symbol rate and the phase pulse shape are considered as degrees of freedom. In particular, we drop the restriction of “classical” phase pulses and we allow for custom shapes, which are parametrized through Bezier curves. In order to deal with the many variables involved, an evolutionary algorithm is employed for numerical optimization. The optimization metric is related to the extrinsic information transfer (EXIT), under the assumption that CPM is serially concatenated with an outer convolutional encoder, as it is the case for several practical systems. The presence of high adjacent channel interference (ACI) is explicitly accounted for in the optimization process. We show that the proposed optimization strategy can effectively exploit the power-bandwidth trade-off. Nevertheless, only moderate improvements are achievable in comparison to state-of-the-art serially concatenated systems.

Summary form only given. Future mobile radio systems are expected to provide high-quality voice and high-speed data transmission and to be integrated into the digital communication networks in several countries. The performance of some digital modulation techniques that are relevant for future mobile radio systems is studied. These techniques are characterized by having a constant envelope signal to reduce the effect of nonlinearity and fading and a compact RF power spectrum to reduce adjacent channel interference. Most digital partial-response continuous-phase modulation (PRCPM) techniques such as 2 RC, 2 SRC, 2 RC, 3 SRC, GMSK, and GTFM have the above properties. Discriminator detection of these techniques is analyzed in fast Rayleigh fading characterizing land mobile radio channels. Approximate closed-form expressions for the probability of error are derived and numerical results are presented for land mobile radio systems. >

The generalized stack algorithm GSA (L, K), where L denotes the number of branches per state and K the number of extended paths, is a tree or trellis search algorithm combining a metric-first and a breadth-first strategy. The GSA is applied in the equalization of signals disturbed by noise and intersymbol interference (ISI) and in the decoding of convolutional codes. For wide trellises it is not useful to implement a Viterbi algorithm (VA), as the complexity of the VA raises exponentially to the width of the trellis. The GSA follows only C paths (with normally C/spl Gt/K), where C is the capacity of the path memory and the complexity of the GSA increases much less than that of the VA. Instead of it, the GSA requires a sorting device, which is rather expensive. Additionally the number of paths varies during the detection process and the paths have different time indices. Extracting and inserting few paths from a more or less sorted path memory disturbs the order only slightly. So we need only little rearranging effort for the path memory. This paper presents a suitable sorting structure for the GSA for a large path number. The structure exploits the inherent parallelism by a new sorting scheme called extended systolic priority queue (ESPQ). It provides a faster sorting than previous designs.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

One of the 3D display systems for full-color reconstruction by using binary phase modulation is presented. The improvement of reconstructed objects is achieved by optimizing the binary phase modulation and accumulating the speckle patterns by changing the random phase distributions. The binary phase pattern is optimized by the modified Frenel ping-pong algorithm. Numerical and experimental demonstrations of full color reconstruction are presented.

A low complexity carrier phase estimation (CPE) algorithm for M-ary quadrature amplitude modulation (m-QAM) optical communication systems is investigated in this paper. In the proposed CPE algorithm, a two-stage CPE method is adopted. In the first stage, the QPSK points of the constellation are picked out to achieve a coarse phase estimation using the traditional Viterbi and Viterbi algorithm. In the second stage, all the points of the constellation are used for a fine phase estimation. In addition, the fourth-power operation is replaced by the 4-level absolute operation for the removal of modulated data phase, which greatly reduced the complexity. The proposed method was investigated through simulation, with 16-QAM, 32-QAM and 64-QAM modulation formats, respectively. The simulation results show that the proposed algorithm has both good linewidth tolerance and amplified spontaneous emission noise tolerance as well as low complexity. Moreover, when the equalization enhanced phase noise is considered, the proposed method also has better performance than traditional algorithm.

Unified low-complexity decision feedback equalizer with adjustable double radius constraint

In this paper, use of recurrent neural network equalizer (RNNE) in place of linear equalizer (LE) to combat both linear and nonlinear distortions corrupting the Magneto-optical (MO) readback signal is discussed. It is shown that RNNE can outperform LE without introducing significant complexity. RNNE is used to equalize the MO recording readback signal corrupted by transition jitter, intersymbol interference (ISI) and additive white Gaussian Noise (AWGN) at a density of 50 kbpi. The MO signal is equalized to a partial response (PR) (1 + D) using either the RNNE or the LE and the equalizer's mean- squared-error (MSE) performance is compared. Then, the equalized signal is passed through a detector and it is shown that a signal equalized to a PR (1 + D) shape can be detected using either a bit-by-bit type of detector (BD) or a sequence detector implemented via Viterbi Algorithm (VA). The bit-error-rate (BER) performance of BD is compared to that of the Viterbi detector and it is shown that PR equalization of MO readback signals using RNNE improves MSE performance over linear equalizer, allowing use of BD rather than LE + Viterbi Algorithm with comparable BERs.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A novel high-precision decomposition algorithm for EMG (electromyography) signals based on the Viterbi algorithm is described. Under certain assumptions this algorithm yields the least squares solution in the time domain. It is shown that the EMG signal source can be modeled as a (M+1)-ary signaling system with intersymbol interference. Direct application of the Viterbi algorithm would lead to a decoder with approximately=10/sup 20/ states, which cannot be implemented. It is shown that according to the special nature of the EMG signal essential simplifications can be done. The resulting algorithm requires only on the order of 10/sup 4/ states. The test of the implemented algorithm shows that, in the mean, over 90% correctly detected innervation time points and only about 5% additional time points can be expected.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Sequence detection is studied for communication channels with intersymbol interference and non-Gaussian noise using a novel adaptive receiver structure. The receiver adapts itself to the noise environment using an algorithm which employs a Gaussian mixture distribution model and the expectation maximization algorithm. Two alternate procedures are studied for sequence detection. These are a procedure based on the Viterbi algorithm and a symbol-by-symbol detection procedure. The Viterbi algorithm minimizes the probability the sequence is in error and the symbol-by-symbol detector minimizes symbol error rate, which are different.

A channel with inter-symbol interference and random perturbations to timing is approximated using a finite-state Markov model. The inter-symbol interference is approximated by a finite-impulse response and the timing perturbations are approximated by a first-order random walk. A Viterbi algorithm is then applied to find the maximum-likelihood sequence of states on this model. The resulting state sequence defines the data sequence and timing trajectory which jointly maximize a likelihood function on the observed signal. This approach provides a means of detecting data with rapidly fluctuating timing perturbations at low signal-to-noise ratio. This is particularly relevant to data storage applications where mechanical fluctuations are translated into timing perturbations. Codes can be incorporated into the detector. The coding gain improves the reliability of both data detection and timing recovery. Codes which can be represented using a reasonably small state machine, such as trellis codes and high rate block parity codes, can be incorporated directly into the finite state model. For iterative decoders a BCJR algorithm can also be applied to this state machine to yield a posteriori probabilities on the data bits.