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We consider a multiple access relay channel (MARC) network consisting of two sources, one relay, and one common destination applying compute-and-forward (CF) strategy. We show that the direct application of CF to the MARC network results in poor error performance bounded by (p + 1)−1, the probability of rank deficiency of the coefficient matrix over Fp. To solve this problem, we propose two practical...
Word units are a popular choice in statistical language modelling. For inflective and agglutinative languages this choice may result in a high out of vocabulary rate. Subword units, such as morphs, provide an interesting alternative to words. These units can be derived in an unsupervised fashion and empirically show lower out of vocabulary rates. This paper proposes a morph-to-word transduction to...
A multi-stream framework with deep neural network (DNN) classifiers is applied to improve automatic speech recognition (ASR) in environments with different reverberation characteristics. We propose a room parameter estimation model to establish a reliable combination strategy which performs on either DNN posterior probabilities or word lattices. The model is implemented by training a multilayer perceptron...
Spoken term detection, especially of out-of-vocabulary (OOV) keywords, benefits from the use of sub-word systems. We experiment with different language-independent approaches to sub-word unit generation, generating both syllable-like and morpheme-like units, and demonstrate how the performance of syllable-like units can be improved by artificially increasing the number of unique units. The effect...
When using connectionist temporal classification (CTC) based acoustic models (AMs) for large vocabulary continuous speech recognition (LVCSR), most previous studies have used a naive interpolation of the CTC-AM score and an additional language model score, although there is no theoretical justification for such an approach. On the other hand, we recently proposed a theoretically more sound decoding...
Connectionist Temporal Classification (CTC) model has achieved state-of-the-art LVCSR performance. However, due to the introduction of the blank symbol, word-level confidence measures (CM) based on CTC model can not be easily calculated by directly using the traditional phone posterior normalization or confusion network (CN) approaches. Recently, a phone synchronous decoding (PSD) framework has been...
In this paper we aim to enhance keyword search for conversational telephone speech under low-resourced conditions. Two techniques to improve the detection of out-of-vocabulary keywords are assessed in this study: using extra text resources to augment the lexicon and language model, and via subword units for keyword search. Two approaches for data augmentation are explored to extend the limited amount...
We study the transmission of confidential messages across a wireless broadcast channel with K > 2 receivers and K helpers. The goal is to transmit all messages reliably to their intended receivers while keeping them confidential from the unintended receivers. We design a codebook based on nested lattice structure, cooperative jamming, lattice alignment, and i.i.d. coding. Moreover, we exploit the...
In this paper, we propose a construction of non-binary WOM (Write-Once-Memory) codes for q-level WOM storages based on integer programming. The WOM codes discussed in this paper are fixed rate (n, q, M, t∗)-WOM codes where messages in an alphabet of size M can be sequentially written in n-cells at least t∗-times. The proposed construction has the two features. First, it possesses a systematic method...
The performance of lattice coding and decoding for the ergodic fading point-to-point channel is studied in the presence of channel estimation errors at the receiver. We show that lattice codes achieve rates within a constant gap to that of Medard's scheme with Gaussian input. Interestingly, the gap does not depend on the channel estimation error variance nor the signal-to-noise ratio (SNR), for a...
This paper considers communication over the point-to-point Gaussian channel with stationary and ergodic channel gain and full channel state information. The capacity of this channel can be achieved in a straightforward manner via any capacity-achieving codebook for the non-fading Gaussian channel, in conjunction with separable coding, i.e., coding independently over each fading state. Despite its...
Sphere decoding(SD)is an efficient algorithm which has been proposed in Multiple input Multiple output (MIMO) digital communication. Sphere decoding algorithm is based on the rule of maximum likelihood decoding algorithm, But SD algorithm does not like ML algorithm to retrieve all of the lattice. However, SD in some environment complexity is very high. The complexity of the SD is controlled by radius...
In this paper, we introduce a multimodal speech recognition scenario, in which an image provides contextual information for a spoken caption to be decoded. We investigate a lattice rescoring algorithm that integrates information from the image at two different points: the image is used to augment the language model with the most likely words, and to rescore the top hypotheses using a word-level RNN...
In this paper, we explore the usage of automated hyper-parameter optimization techniques with scalarization of multiple objectives to find decoder hyper-parameters suitable for a given acoustic and language model for an LVCSR task. We compare manual optimization, random sampling, tree of Parzen estimators, Bayesian Optimization, and genetic algorithm to find a technique that yields better performance...
In this paper, we propose a new downlink non-orthogonal multiuser superposition transmission scheme for future 5G cellular networks, which we refer to as the lattice partition multiple access (LPMA). In this proposed design, the base station transmits multilevel lattice codes for multiple users. Each user's code level corresponds to a distinct prime and is weighted by a product of all distinct primes...
Many aspects of lattice coding and decoding under time-varying multiple-antenna systems remain unexplored. This paper studies the achievable rates using lattice codes for the multiple-input- multiple-output (MIMO) point-to-point channel with ergodic fading and channel state information at the receiver. The proposed lattice coding scheme involves the use of decision regions that are universal for almost...
We propose and design a lattice coded physical- layer network coding (PNC) over a finite complex number field Z[ω]/ξZ[ω] in a two-way relay channel (TWRC). In our design, we construct the lattice codes from an irregular repeat- accumulate (IRA) code over GF(q). A randomly generated coset is employed to our scheme to ensure that the codes exhibit permutation invariance and...
A multiple-input-multiple-output (MIMO) version of Costa's dirty paper channel is studied, where both the input signal and the state experience ergodic fading with channel state information at the receiver. An inner bound using lattice coding and decoding is derived and its gap to the point-to- point ergodic capacity is computed. Under Rayleigh fading, the gap is a constant that vanishes as the number...
Compute-and-Forward relaying schemes exploit the additive nature of the wireless channel for decoding linear equations/combinations of transmitted messages. However, decoding equations that maximize the computation rate at each relay is in general not optimal from the network perspective. In fact, the (destination) receiver may fail to recover the individual messages even when the relays have successfully...
Real convolutional lattices over the ring of integers Z are considered in this paper. We study the stability of convolutional lattices under sphere decoding. A new stable family of time-alternating convolutional lattices is proposed. The structure, the parameters, and a performance example are shown for time-alternating convolutional lattices. These lattices can be used as constituent blocks in concatenated...
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