Browsing by Author "Moser, Stefan M."

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Asymptotic Capacity Results for MIMO Wireless Optical Communication
(2017-01-01)
Moser, Stefan M.
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Mylonakis, Michail
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Wang, Ligong
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Wigger, Michele
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電機工程學系
This paper provides several asymptotic capacity results for the multiple-input multiple-output free-space optical intensity channel in the regime of high signal-to-noise ratio (SNR). For the case where the channel matrix has full column rank, the asymptotic capacity is derived assuming a peak-power constraint on each transmit antenna, or an average-power constraint on the total power across all transmit antennas, or both. For multiple-input and single-output channels, the asymptotic high-SNR capacity is derived when either only the total average power is constrained, or only the per-antenna peak power is constrained, or both but with the average-power constraint being sufficiently loose.
Asymptotic High-SNR Capacity of MISO Optical Intensity Channels
(2017-01-01)
Moser, Stefan M.
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Wang, Ligong
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Wigger, Michdle
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電機工程學系
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Department of Electrical and Computer Engineering
This paper derives the asymptotic capacity for the multiple-input single-output free-space optical intensity channel in the regime of high signal-to-noise ratio (SNR). The asymptotic result is proven via upper and lower bounds on capacity at finite SNR.
Bounds on the Capacity of the Additive Inverse Gaussian Noise Channel
(2012)
Chang, Hui-Ting
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Moser, Stefan M.
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電機資訊學士班
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Undergraduate Honors Program of Electrical Engineering and Computer Science
A very recent and new model describing communication based on the exchange of chemical molecules in a drifting liquid medium is investigated and new analytical upper and lower bounds on the capacity are presented. The bounds are asymptotically tight, i.e., if the average-delay constraint is loosened to infinity or if the drift velocity of the liquid medium tends to infinity, the corresponding asymptotic capacities are derived precisely.
Capacity of the Memoryless Additive Inverse Gaussian Noise Channel
(2014-12-01)
Li, Hui
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Moser, Stefan M.
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Guo, Dongning
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交大名義發表
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National Chiao Tung University
The memoryless additive inverse Gaussian noise channel model describing communication based on the exchange of chemical molecules in a drifting liquid medium is investigated for the situation of simultaneously an average-delay and a peak-delay constraint. Analytical upper and lower bounds on its capacity in bits per molecule use are presented. These bounds are shown to be asymptotically tight, i.e., for the delay constraints tending to infinity with their ratio held constant (or for the drift velocity of the fluid tending to infinity), the asymptotic capacity is derived precisely. Moreover, characteristics of the capacity-achieving input distribution are derived that allow accurate numerical computation of capacity. The optimal input appears to be a mixed continuous and discrete distribution.
Capacity Results of an Optical Intensity Channel With Input-Dependent Gaussian Noise
(2012-01-01)
Moser, Stefan M.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
This paper investigates a channel model describing optical communication based on intensity modulation. It is assumed that the main distortion is caused by additive Gaussian noise, however, with a noise variance depending on the current signal strength. Both the high-power and low-power asymptotic capacities under simultaneously both a peak-power and an average-power constraint are derived. The high-power results are based on a new firm (nonasymptotic) lower bound and a new asymptotic upper bound. The upper bound relies on a dual expression for channel capacity and the notion of capacity-achieving input distributions that escape to infinity. The lower bound is based on a new lower bound on the differential entropy of the channel output in terms of the differential entropy of the channel input. The low-power results make use of a theorem by Prelov and van der Meulen.
Capacity Results of an Optical Intensity Channel With Input-Dependent Gaussian Noise
(2012-01-01)
Moser, Stefan M.
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電機工程學系
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Department of Electrical and Computer Engineering
This paper investigates a channel model describing optical communication based on intensity modulation. It is assumed that the main distortion is caused by additive Gaussian noise, however, with a noise variance depending on the current signal strength. Both the high-power and low-power asymptotic capacities under simultaneously both a peak-power and an average-power constraint are derived. The high-power results are based on a new firm (nonasymptotic) lower bound and a new asymptotic upper bound. The upper bound relies on a dual expression for channel capacity and the notion of capacity-achieving input distributions that escape to infinity. The lower bound is based on a new lower bound on the differential entropy of the channel output in terms of the differential entropy of the channel input. The low-power results make use of a theorem by Prelov and van der Meulen.
Capacity Results on Multiple-Input Single-Output Wireless Optical Channels
(2018-11-01)
Moser, Stefan M.
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Wang, Ligong
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Wigger, Michele
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電信工程研究所
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Institute of Communications Engineering
This paper derives upper and lower bounds on the capacity of the multiple-input single-output free-space optical intensity channel with signal-independent additive Gaussian noise subject to both an average-intensity and a peak-intensity constraint. In the limit where the signal-to-noise ratio (SNR) tends to infinity, the asymptotic capacity is specified, while in the limit where the SNR tends to zero, the exact slope of the capacity is given.
Connections Between the Error Probability and the r-wise Hamming Distances
(2018-01-01)
Lin, Hsuan-Yin
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Moser, Stefan M.
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Chen, Po-Ning
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電信工程研究所
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Institute of Communications Engineering
An extension from the pairwise Hamming distance to the r-wise Hamming distance is presented. It can be used to fully characterize the maximum-likelihood decoding (MLD) error of an arbitrary code over the binary erasure channel (BEC). By noting that good codes always have large minimum r-wise Hamming distances for all r, a new design criterion for a code is introduced: the minimum r-wise Hamming distance. We then prove an upper bound for the minimum r-wise Hamming distance of an arbitrary code, called the generalized Plotkin bound, and provide a class of (nonlinear) codes that achieve the bound for every r.
Equidistant Codes Meeting the Plotkin Bound are Not Optimal on the Binary Symmetric Channel
(2013-01-01)
Chen, Po-Ning
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Lin, Hsuan-Yin
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Moser, Stefan M.
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電機資訊學士班
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Undergraduate Honors Program of Electrical Engineering and Computer Science
In this paper, we re-introduce from our previous work [1] a new family of nonlinear codes, called weak flip codes, and show that its subfamily fair weak flip codes belongs to the class of equidistant codes, satisfying that any two distinct codewords have identical Hamming distance. It is then noted that the fair weak flip codes are related to the binary nonlinear Hadamard codes as both code families maximize the minimum Hamming distance and meet the Plotkin upper bound under certain blocklengths. Although the fair weak flip codes have the largest minimum Hamming distance and achieve the Plotkin bound, we find that these codes are by no means optimal in the sense of average error probability over binary symmetric channels (BSC). In parallel, this result implies that the equidistant Hadamard codes are also nonoptimal over BSCs. Such finding is in contrast to the conventional code design that aims at the maximization of the minimum Hamming distance. The results in this paper are proved by examining the exact error probabilities of these codes on BSCs, using the column-wise analysis on the codebook matrix.
Expectations of a Noncentral Chi-Square Distribution With Application to IID MIMO Gaussian Fading
(2008)
Moser, Stefan M.
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電信工程研究所
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Institute of Communications Engineering
In this paper closed-form expressions are derived for the expectation of the logarithm and for the expectation of the n-th power of the reciprocal value (inverse moments) of a noncentral chi-square random variable of even degree of freedom. It is shown that these expectations can be expressed by a family of continuous functions g(m) (.) and that these families have nice properties (monotonicity, convexity, etc.). Moreover, some tight upper and lower bounds axe derived that are helpful in situations where the closed-form expression of g(m) (.) is too complex for further analysis. As an example of the applicability of these results, in the second part of this paper an independent and identically distributed (IID) Gaussian multiple-input-multiple-output (MIMO) fading channel with a scalar line-of-sight component is analyzed. Some new expressions axe derived for the fading number that describes the asymptotic channel capacity at high signal-to-noise ratios (SNR).
Impact of Feedback and Side-Information on the Asymptotic Capacity of Single-Input Multiple-Output Fading Channels With Memory
(2014-06-01)
Moser, Stefan M.
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交大名義發表
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National Chiao Tung University
An analytic expression for the asymptotic capacity of noncoherent single-input multiple-output regular fading channels with memory and with partial receiver side information is derived and is shown to remain unchanged by causal or acausal side information at the transmitter and by a noiseless feedback link. In particular, the corresponding fading numbers are identical. Furthermore, the asymptotic capacity of a single-input single-output nonregular Gaussian fading channel with memory is investigated, and it is shown that the prelog is unaffected by noiseless feedback.
Minimal-Rate Description for Multiple-Access Channels
(2012)
Huang, Sue-May
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Lu, Hsiao-Feng (Francis)
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Moser, Stefan M.
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傳播研究所
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Institute of Communication Studies
In this paper we consider the problem of a two-user multiple-access channel that is different from the conventional one. We require the receiver to provide only a reliable information-mixture of the incoming messages from the two users, not the exact contents. The minimum rate of such mixture is termed the minimal description rate of the channel output. Answers to this problem have many potential applications to the latest network-coding-based wireless communication networks. Exact capacity regions of a class of fading multiple-access channels are determined, along with the corresponding deterministic capacity-achieving coding schemes.
Nonlinear Codes Outperform the Best Linear Codes on the Binary Erasure Channel
(2015)
Chen, Po-Ning
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Lin, Hsuan-Yin
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Moser, Stefan M.
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電機學院
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College of Electrical and Computer Engineering
The exact value of the average error probability of an arbitrary code (linear or nonlinear) using maximum likelihood decoding is studied on binary erasure channels (BECs) with arbitrary erasure probability 0 < delta < 1. The family of the fair linear codes, which are equivalent to a concatenation of several Hadamard linear codes, is proven to perform better (in the sense of average error probability with respect to maximum-likelihood decoding) than all other linear codes for many values of the blocklength n and for a dimension k = 3. It is then noted that the family of fair linear codes and the family of fair nonlinear weak fit\'\', codes both maximize the minimum Hamming distance under certain blocklengths. However, the fair nonlinear weak flip codes actually outperform the fair linear codes, i.e., linearity and global optimality cannot be simultaneously achieved for the number of codewords being M - 2(3).
On the Capacity of Block Fading Optical Wireless Channels
(2019-01-01)
Li, Longguang
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Moser, Stefan M.
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Wang, Ligong
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Wigger, Michele
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電信工程研究所
This paper investigates the capacity of block fading optical intensity channels with more transmit than receive antennas under different assumptions on the transmitter's channel state information (CSI). Lower and upper bounds on the capacities are derived using the entropy power inequality (EPI) and a dual expression for capacity. Our lower bounds for perfect and partial CSI utilize a transmit-antenna cooperation strategy based on minimum-energy signaling, which we proposed recently. For perfect CSI, this lower bound matches the upper bound asymptotically in the high signal-to-noise ratio (SNR) regime. For imperfect CSI, our lower bound is close to its perfect-CSI counterpart.
On the Capacity of Free-Space Optical Intensity Channels
(2008)
Lapidoth, Amos
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Moser, Stefan M.
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Wigger, Michele A.
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電機工程學系
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Department of Electrical and Computer Engineering
New upper and lower bounds are presented on the capacity of the free-space optical intensity channel. This channel is characterized by inputs that are nonnegative (representing the transmitted optical intensity) and by outputs that are corrupted by additive white Gaussian noise (because in free space the disturbances arise from many independent sources). Due to battery and safety reasons the inputs are simultaneously constrained in both their average and peak power. For a fixed ratio of the average power to the peak power the difference between the upper and the lower bounds tends to zero as the average power tends to infinity, and the ratio of the upper and lower bounds tends to one as the average power tends to zero. The case where only an average-power constraint is imposed on the input is treated separately. In this case, the difference of the upper and lower bound tends to 0 as the average power tends to infinity, and their ratio tends to a constant as the power tends to zero.
On the Capacity of Free-Space Optical Intensity Channels
(2009-10-01)
Lapidoth, Amos
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Moser, Stefan M.
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Wigger, Michele A.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Upper and lower bounds are derived on the capacity of the free-space optical intensity channel. This channel has a nonnegative input (representing the transmitted optical intensity), which is corrupted by additive white Gaussian noise. To preserve the battery and for safety reasons, the input is constrained in both its average and its peak power. For a fixed ratio of the allowed average power to the allowed peak power, the difference between the upper and the lower bound tends to zero as the average power tends to infinity and their ratio tends to one as the average power tends to zero. When only an average power constraint is imposed on the input, the difference between the bounds tends to zero as the allowed average power tends to infinity, and their ratio tends to a constant as the allowed average power tends to zero.
On the Capacity of MIMO Optical Wireless Channels
(2020-09-01)
Li, Longguang
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Moser, Stefan M.
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Wang, Ligong
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Wigger, Michele
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電信工程研究所
This paper studies the capacity of a general multiple-input multiple-output (MIMO) free-space optical intensity channel under a per-input-antenna peak-power constraint and a total average-power constraint over all input antennas. The focus is on the scenario with more transmit than receive antennas. In this scenario, different input vectors can yield identical distributions at the output, when they result in the same image vector under multiplication by the channel matrix. We first determine the most energy-efficient input vectors that attain each of these image vectors. Based on this, we derive an equivalent capacity expression in terms of the image vector, and establish new lower and upper bounds on the capacity of this channel. The bounds match when the signal-to-noise ratio (SNR) tends to infinity, establishing the high-SNR asymptotic capacity. We also characterize the low-SNR slope of the capacity of this channel.
On the Capacity of MIMO Optical Wireless Channels
(2018-01-01)
Li, Longguang
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Moser, Stefan M.
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Wang, Ligong
;
Wigger, Michele
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電信工程研究所
This paper investigates the capacity of the multiple-input multiple-output free-space optical intensity channel under a per-input-antenna peak-power constraint and a total average-power constraint over all input antennas. Our work considers the setup with more transmit than receive antennas, and characterizes capacity as an alternative optimization problem over the distribution of the input vector times the channel matrix. This alternative capacity expression is then used to obtain upper and lower bounds on the capacity, which match asymptotically in the high signal-to-noise ratio regime.
On the Capacity of the Discrete-Time Poisson Channel
(2009-01-01)
Lapidoth, Amos
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Moser, Stefan M.
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電信工程研究所
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Institute of Communications Engineering
The large-inputs asymptotic capacity of a peak-power and average-power limited discrete-time Poisson channel is derived using a new firm (nonasymptotic) lower bound and an asymptotic upper bound. The upper bound is based on the dual expression for channel capacity and the notion of capacity-achieving input distributions that escape to infinity. The lower bound is based on a lower bound on the entropy of a conditionally Poisson random variable in terms of the differential entropy of its conditional mean.
On the fading number of multiple-input single-output fading channels with memory
(2006)
Moser, Stefan M.
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電信工程研究所
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Institute of Communications Engineering
We derive new upper and lower bounds on the fading number of non-coherent multiple-input single-output (MISO) fading channels of general (not necessarily Gaussian) regular law with spatial and temporal memory. The fading number is the second term, after the double-logarithmic term, of the high signal-to-noise ratio (SNR) expansion of channel capacity. In case of an isotropically distributed fading vector it is proven that the upper and lower bound coincide, Le., the general MISO fading number with memory is known precisely. The upper and lower bounds show that a type of beam-forming is asymptotically optimal.