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11
Multilevel Codes: Theoretical Concepts and Practical Design Rules
, 1999
"... This paper deals with 2 ` ary transmission using multilevel coding (MLC) and multistage decoding (MSD). The known result that MLC and MSD suffice to approach capacity if the rates at each level are appropriately chosen is reviewed. Using multiuser information theory, it is shown that there is a ..."
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Cited by 206 (33 self)
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This paper deals with 2 ` ary transmission using multilevel coding (MLC) and multistage decoding (MSD). The known result that MLC and MSD suffice to approach capacity if the rates at each level are appropriately chosen is reviewed. Using multiuser information theory, it is shown that there is a large space of rate combinations such that MLC and full maximumlikelihood decoding (MLD) can approach capacity. It is noted that multilevel codes designed according to the traditional balanced distance rule tend to fall in the latter category and therefore require the huge complexity of MLD. The capacity rule, the balanced distances rules, and two other rules based on the random coding exponent and cutoff rate are compared and contrasted for practical design. Simulation results using multilevel binary turbo codes show that capacity can in fact be closely approached at high bandwidth efficiencies. Moreover, topics relevant in practical applications such as signal set labeling, dimensional...
The impact of constellation cardinality on Gaussian channel capacity
 in Proc. Allerton Conf. Commun., Control and Comp
, 2010
"... Abstract—Denote by Cm(snr) the Gaussian channel capacity with signaltonoise ratio snr and input cardinality m. We show that as m grows, Cm(snr) approaches C(snr) = 12 log(1 + snr) exponentially fast. Lower and upper bounds on the exponent are given as functions of snr. We propose a family of inpu ..."
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Cited by 15 (4 self)
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Abstract—Denote by Cm(snr) the Gaussian channel capacity with signaltonoise ratio snr and input cardinality m. We show that as m grows, Cm(snr) approaches C(snr) = 12 log(1 + snr) exponentially fast. Lower and upper bounds on the exponent are given as functions of snr. We propose a family of input constellations based on the roots of the Hermite polynomials which achieves exponential convergence. I.
On Gaussian Interference Channels with Mixed Gaussian and Discrete Inputs
"... Abstract—This paper studies the sumrate of a class of memoryless, realvalued additive white Gaussian noise interference channels (IC) achievable by treating interference as noise (TIN). We develop and analytically characterize the rates achievable by a new strategy that uses superpositions of Gau ..."
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Cited by 2 (2 self)
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Abstract—This paper studies the sumrate of a class of memoryless, realvalued additive white Gaussian noise interference channels (IC) achievable by treating interference as noise (TIN). We develop and analytically characterize the rates achievable by a new strategy that uses superpositions of Gaussian and discrete random variables as channel inputs. Surprisingly, we demonstrate that TIN is sumgeneralized degrees of freedom optimal and can achieve to within an additive gap of O(1) or O(log log(SNR)) to the symmetric sumcapacity of the classical IC. We also demonstrate connections to other channels such as the IC with partial codebook knowledge and the block asynchronous IC. I.
Near optimal energy control and approximate capacity of energy harvesting communication,” arXiv preprint arXiv:1405.1156
, 2014
"... ar ..."
The Capacity Loss of Dense Constellations
"... Abstract—We determine the loss in capacity incurred by using signal constellations with a bounded support over general complexvalued additivenoise channels for suitably high signaltonoise ratio. Our expression for the capacity loss recovers the power loss of 1.53dB for square signal constellatio ..."
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Cited by 1 (0 self)
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Abstract—We determine the loss in capacity incurred by using signal constellations with a bounded support over general complexvalued additivenoise channels for suitably high signaltonoise ratio. Our expression for the capacity loss recovers the power loss of 1.53dB for square signal constellations. I.
On the TwoUser Interference Channel With Lack of Knowledge of the Interference Codebook at One Receiver
"... Abstract — In multiuser information theory, it is often assumed that every node in the network possesses all codebooks used in the network. This assumption may be impractical in distributed ad hoc, cognitive, or heterogeneous networks. This paper considers the twouser interference channel with one ..."
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Abstract — In multiuser information theory, it is often assumed that every node in the network possesses all codebooks used in the network. This assumption may be impractical in distributed ad hoc, cognitive, or heterogeneous networks. This paper considers the twouser interference channel with one oblivious receiver (ICOR), i.e., one receiver lacks knowledge of the interfering cookbook, whereas the other receiver knows both codebooks. This paper asks whether, and if so how much, the channel capacity of the ICOR is reduced compared with that of the classical IC where both receivers know all codebooks. A novel outer bound is derived and shown to be achievable to within a gap for the class of injective semideterministic ICORs; the gap is shown to be zero for injective fully deterministic ICORs. An exact capacity result is shown for the general memoryless ICOR when the nonoblivious receiver experiences very strong interference. For the linear deterministic ICOR that models the Gaussian noise channel at high SNR, nonindependent identically distributed. Bernoulli(1/2) input bits are shown to achieve points not achievable by i.i.d. Bernoulli(1/2) input bits used in the same achievability scheme. For the realvalued Gaussian ICOR, the gap is shown to be at most 1/2 bit per channel use, even though the set of optimal input distributions for the derived outer bound could not be determined. Toward understanding the Gaussian ICOR, an achievability strategy is evaluated in which the input alphabets at the nonoblivious transmitter are a mixture of discrete and Gaussian random variables, where the cardinality of the discrete part is appropriately chosen as a function of the channel parameters. Surprisingly, as the oblivious receiver intuitively should not be able to jointly decode the intended and interfering messages (whose codebook is unavailable), it is shown that with this choice of input, the capacity region of the symmetric Gaussian ICOR is to within 1/2 log (12πe) ≈ 3.34 bits (per channel use per user) of an outer bound for the classical Gaussian IC with full codebook knowledge at both receivers.
Design of Space Time Spreading Matrices
"... In this paper, we study the design of space time spreading matrices that are modulation matrices for communications over multipleantenna block fading channels. We assume the channel is known to the receiver only and find necessary and su#cient conditions on the space time spreading matrices for ..."
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In this paper, we study the design of space time spreading matrices that are modulation matrices for communications over multipleantenna block fading channels. We assume the channel is known to the receiver only and find necessary and su#cient conditions on the space time spreading matrices for the separation of demodulation and decoding at the receivers without loss of optimality. From the perspective of information theory, we design the space time spreading matrices to maximize the mutual information between the transmitted information vector and the channel output. We apply the designed space time spreading code as an inner code in a bitinterleaved serially concatenated coding scheme, and find the connection between the endpoints of the extrinsic information transfer curves and certain mutual information quantities.
Some Simple Bounds on the Symmetric Capacity and Outage Probability for QAM Wireless Channels with Rice and Nakagami Fadings
, 2000
"... In this short contribution, quickly computable upper and lower bounds are presented on the symmetric capacity of flatfaded Rice and Nakagami channels with side information (SI) for datatransmissions via finitesize quadrature amplitude modulation (QAM) constellations. The proposed bounds exhibit th ..."
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In this short contribution, quickly computable upper and lower bounds are presented on the symmetric capacity of flatfaded Rice and Nakagami channels with side information (SI) for datatransmissions via finitesize quadrature amplitude modulation (QAM) constellations. The proposed bounds exhibit the appealing feature to be tight and asymptotically exact both for high and low signaltonoise ratios (SNR's). Furthermore, exponentially tight Chernofflike formulas are also presented for an analytical evaluation of the resulting system outage probabilities when interleaved packet transmissions are carried out.
Research Article Achieving Maximum Possible Speed on Constrained Block Transmission Systems
"... We develop a theoretical framework for achieving the maximum possible speed on constrained digital channels with a finite alphabet. A common inaccuracy that is made when computing the capacity of digital channels is to assume that the inputs and outputs of the channel are analog Gaussian random vari ..."
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We develop a theoretical framework for achieving the maximum possible speed on constrained digital channels with a finite alphabet. A common inaccuracy that is made when computing the capacity of digital channels is to assume that the inputs and outputs of the channel are analog Gaussian random variables, and then based upon that assumption, invoke the Shannon capacity bound for an additive white Gaussian noise (AWGN) channel. In a channel utilizing a finite set of inputs and outputs, clearly the inputs are not Gaussian distributed and Shannon bound is not exact. We study the capacity of a block transmission AWGN channel with quantized inputs and outputs, given the simultaneous constraints that the channel is frequency selective, there exists an average power constraint P at the transmitter and the inputs of the channel are quantized. The channel is assumed known at the transmitter. We obtain the capacity of the channel numerically, using a constrained BlahutArimoto algorithm which incorporates an average power constraint P at the transmitter. Our simulations show that under certain conditions the capacity approaches very closely the Shannon bound. We also show the maximizing input distributions. The theoretical framework developed in this paper is applied to a practical example: the downlink channel of a dialup PCM modem connection where the inputs to the channel are quantized and the outputs are real. We test how accurate is the bound 53.3 kbps for this channel. Our results show that this bound can be improved upon. Copyright © 2007 Hindawi Publishing Corporation. All rights reserved. 1.
Probabilistic Signal Shaping for BitInterleaved Coded Modulation
"... Abstract—A scheme is proposed that combines probabilistic signal shaping with bitinterleaved coded modulation (BICM). The transmitter generates symbols according to a distribution on the channel input alphabet. The symbols are labeled by bit strings. At the receiver, the channel output is decoded w ..."
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Abstract—A scheme is proposed that combines probabilistic signal shaping with bitinterleaved coded modulation (BICM). The transmitter generates symbols according to a distribution on the channel input alphabet. The symbols are labeled by bit strings. At the receiver, the channel output is decoded with respect to a bit metric. An achievable rate is derived using random coding arguments. For the 8ASK AWGN channel, numerical results show that at a spectral efficiency of 2 bits/s/Hz, the new scheme improves BICM without shaping and BICM with bit shaping (i Fabregas and Martinez, 2010) by 0.87 dB and 0.15 dB, respectively, and is within 0.0094 dB of the coded modulation capacity. The new scheme is implemented by combining a distribution matcher with a systematic binary lowdensity paritycheck code. The measured finitelength gains are very close to the gains predicted by the asymptotic theory. I.