Gary E. Kopec, Member, IEEE, and Mauricio Lomelin, Member, IEEE July 20, 1997 Abstract An approach to supervised training of character templates from page images and unaligned transcriptions is proposed. The template training problem is formulated as one of constrained maximum likelihood parameter estimation within the document image decoding framework. This leads to a three-phase iterative tra...

Coded modulation systems based on low density parity check (LDPC) codes of finite lengths are considered. The union bounds on the bit error probabilities of the maximum likelihood (ML) decoding are presented for both additive white Gaussian noise (AWGN) and flat Rayleigh fading channels. The tightness of the derived bound is verified by simulating the ML decoding of a very short LDPC code. For ...

information patterns giving low weight words for the first The turbo decoding is a sub-optimal decoding, i.e. it is not a maximum likelihood decoding. It is important to be aware of this fact when the parameters for the scheme are chosen. This goes especially for the selection of component codes, where the selection often has been based solely on the performance at high SNR’s. We will show that...

In this paper, a serial concatenation scheme and its iterative decoding algorithm between Low Density Parity Check codes (LDPC) and Reed-Solomon codes are proposed. For the decoder, the soft output values delivered by LDPC are used as reliability values to perform the Chase decoding of Reed-Solomon (RS) codes which return soft information to LDPC decoder. This approach presents an option scheme...

In this paper, the performance of punctured convolutional codes of short constraint lengths is discussed. The punctured codes are used to provide error protection to a particular user in an asynchronous CDMA system. A perfect phase reference is assumed to be available throughout this paper. A slow fading Rician channel is assumed. Maximum likelihood decoding through a Viterbi algorithm is used ...

This paper addresses the asymptotic diversity performance of Alamouti transmit diversity technique especially in time-selective fading channels. In particular, a linear quasi-maximum-likelihood (QML) decoding method is employed for the Alamouti transmit diversity system to solve the error floor problem induced by the conventional linear ML decoding method. By judiciously utilizing the derived a...

Turbo decoding is based on the concept of maximum likelihood decision on blocks of data. The decision on a bit affects the decoding of subsequent bits. Fading is a type of corruption whose effect can be extended over a period of multiple bits, resulting in significant performance degradation for turbo code. In this paper, a Markov process is utilized to model a fading channel, and bit error rat...

The sphere decoding algorithm (SDA) has been widely used for maximum likelihood (ML) detection in MIMO systems. However, the conventional SDA is very complex for hardware implementation, and the throughput of current SDA implementation is below the requirement of next generation high-speed wireless communications. In this paper, we introduce an efficient pipeline interleaved (PL) sphere decodin...

Multiple input multiple output (MIMO) supports greater data rate and higher reliability in wireless communication. MIMO technique uses the multiple antennas to achieve high transmission rate. The receiver end of the MIMO consists of linear and non-linear decoding techniques. In this paper we are discussing about the linear and non-linear decoding techniques used at the receiver. Zero forcing (Z...