Low-density parity-check codes with rates very close to the capacity of the q-ary symmetric channel for large q

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Balanced bipolar codes consist of sequences in which the symbols ‘−1’ and ‘+1’ appear equally often. Several generalizations to larger alphabets have been considered in literature. For example, for the q-ary alphabet {−q+1,−q+3, . . . , q−1}, known concepts are symbol balancing, i.e., all alphabet symbols appear equally often in each codeword, and charge balancing, i.e., the symbol sum in each codeword equals zero. These notions are equivalent for the bipolar case, but not for q > 2. In this paper, a third

Unlike in the traditional half-duplex (HD) mode of transmission over a wireless link, in the full-duplex (FD) mode both terminals receive and transmit on the same frequency band, simultaneously. Hence, FD gives us up to twice the spectral efﬁciency of HD, has the potential to resolve the hidden terminal problem, and makes relaying much more efﬁcient. As such, FD is one of the most promising new physical layer techniques being developed at the moment. However, a major difﬁculty in achieving FD operation is t

Simulations of edge turbulence are particularly challenging due to the presence of large amplitude fluctuations and to the coupling of equilibrium and fluctuating scales. While validating edge simulations is necessary to assess the accuracy of our understanding, difficulties in experimental diagnostics and the lack of a precise validation methodology have, to date, severely limited the process. The Global Braginskii Solver (GBS) code has been developed to simulate plasma turbulence in edge-relevant conditio

In this paper, we give a characterization of the rate region for the degraded two message set problem, applied to a combination network with erasure channels. We also provide an algorithm that uses topological information in order to deliver the two messages to the receivers, and we show that our algorithm is optimal, in the sense that it achieves any rate pair in the region. We compare our algorithm analytically with a naive approach oblivious to the network structure, and we give an insight on what benefi

We present the AMIDA 2009 system for participation in the NIST RT’2009 STT evaluations. Systems for close-talking, far field and speaker attributed STT conditions are described. Im- provements to our previous systems are: segmentation and diar- isation; stacked bottle-neck posterior feature extraction; fMPE training of acoustic models; adaptation on complete meetings; improvements to WFST decoding; automatic optimisation of decoders and system graphs. Overall these changes gave a 6- 13% relative reduction i

In this paper lossless compression with polar codes is considered. A polar encoding algorithm is developed and a method to design the code and compute the average compression rate for finite lengths is given. It is shown that the scheme achieves the optimal compression rate asymptotically. Furthermore, the proposed scheme has a very good performance at finite lengths. Both the encoding and decoding operations can be accomplished with complexity O(N logN) where N denotes the length of the code.

Presented is a novel approach for enhancing the signal-to-noise ratio (SNR) of optical fibre distributed temperature sensors. The proposed method is based on cyclic codes and it can be implemented by high-power lasers, which are required for long-range applications but are unsuitable for conventional coding techniques. The expected performance improvement, in terms of temperature resolution, sensing range and measurement time, is confirmed by simulations.

We consider the problem of minimizing delay when broadcasting over erasure channels with feedback. A sender wishes to communicate the same set of m messages to several receivers. The sender can broadcast a single message or a combination (encoding) of messages to all receivers at each timestep, through separate erasure channels. Receivers provide feedback as to whether the transmission was received. If, at some time step, a receiver cannot identify a new message, delay is incurred. Our notion of delay is mo

Providing real-time multimedia services over a best-effort network is challenging due to the stringent delay requirements in the presence of complex network dynamics. Multiple description (MD) coding is one approach to transmit the media over diverse (multiple) paths to reduce the detrimental effects caused by path failures or delay. The novelty of this work is to investigate the resource allocation in a network, where there are several competing MD coded streams. This is done by considering a framework tha

We propose a new auditory inspired feature extraction technique for automatic speech recognition (ASR). Features are extracted by filtering the temporal trajectory of spectral energies in each critical band of speech by a bank of finite impulse response (FIR) filters. Impulse responses of these filters are derived from a modified Gabor envelope in order to emulate asymmetries of the temporal receptive field (TRF) profiles observed in higher level auditory neurons. We obtain

11.4\%

relative improvement in

When using random utility models for a route choice problem, choice set generation and correlation among alternatives are two issues that make the modeling complex. In this paper we discuss different models capturing path overlap. First, we analyze several formulations of the Path Size Logit model proposed in the literature and show that the original formulation should be used. Second, we propose a modeling approach where the path overlap is captured with a subnetwork. A subnetwork is a simplification of th

We consider streaming of pre-encoded and packetized media over best-effort networks in presence of acknowledgment feedbacks. We first review the rate-distortion optimization framework in such scenarios. Given an estimation of future transmission resources, and knowing about past transmissions and received acknowledgments, a scheduling algorithm is defined as a mechanism that selects the data to send over the network at any given time, so as to minimize the end-to-end distortion for the given communication r

We show that network coding allows to realize significant energy savings in a wireless ad-hoc network, when each node of the network is a source that wants to transmit information to all other nodes. Energy efficiency directly affects battery life and thus is a critical design parameter for wireless ad-hoc networks. We propose an implementable method for performing network coding in such a setting. We analyze theoretical cases in detail, and use the insights gained to propose a practical, fully distributed

Due to environmental concerns and strict constraints on interference imposed on other networks, the radiated power of emerging pervasive wireless networks needs to be strictly limited, yet without sacrificing acceptable data rates. Pulsed Time-Hopping Ultra-Wide Band (TH-UWB) is a radio technology that has the potential to satisfy this requirement. Although TH-UWB is a multi-user radio technology, non-zero cross-correlation between time-hopping sequences, time-asynchronicity between sources and a multipath

This paper proposes deterministic algorithms for decentralized network coding. Decentralized coding allows to locally specify the coding operations at network nodes without knowledge of the overall network topology, and to accommodate future changes in the network such as addition of receivers. To the best of our knowledge, these are the first deterministic decentralized algorithms proposed for network coding.

The Joint Photographic Experts Group (JPEG) has recently rolled out a new still image coding standard called JPEG 2000. This standard integrates an efficient image compression scheme with functionalities required by multimedia applications, such as progressiveness up to lossless coding, region of interest coding, and error resiliency. Security is a concern in many applications, and therefore also a desired functionality. This paper provides readers with insights and examples of how to combine security solut

This paper proposes a multiresolution Matching Pursuit decomposition of natural images. Matching Pursuit is a greedy algorithm that decomposes any signal into a linear expansion of waveforms taken from a redundant dictionary, by iteratively picking the waveform that best matches the input signal. Since the computational cost rapidly grows with the size of the signal, we propose a multiresolution strategy that, together with a dictionary training, significantly reduces the encoding complexity while still pro

Forward Error Correction copes with packet losses, but at the expense of an increase of the end-to-end delay. By failing to take this into account, existing error control schemes for audio often lead to end-to-end delays larger than 150 ms, which has an impact on the perceived audio quality. In this paper, we develop an adaptive error control scheme for audio which is delay aware, i.e. which incorporates the impact on the end-to-end delay in the choice of FEC. To this end, we model the perceived audio quali

Real-time audio over the best effort Internet often suffers from packet loss. So far, Forward Error Correction (FEC) seems to be an efficient way to attenuate the impact of loss. Nevertheless to ensure efficiency of FEC, the source rate must be continuously controlled to avoid congestion. In this paper, we describe a realisation of adaptive FEC subdued to a TCP-friendly rate control.

The theory and practice of digital communication during the past 50 years has been strongly influenced by Shannon's separation theorem. While it is conceptually and practically appealing to separate source from channel coding, either step requires infinite delay in general for optimal performance. On the other extreme is uncoded transmission, which has no delay but is suboptimal in general. In this paper, necessary and sufficient conditions for the optimality of uncoded transmission are shown. These conditi

Low-density parity-check codes with rates very close to the capacity of the q-ary symmetric channel for large q

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