One-bit Information Research Articles

Sub-column pixel neural network scheme for modulation format shifting based optical camera communications.

In this Letter, a sub-column pixel neural network (SCPNN) scheme is proposed to label the pixel patterns in modulation format shifting based optical camera communication (MFS-OCC) systems. The MFS scheme, by identifying on-off keying (OOK) and Manchester signal formats, can additionally harvest one-bit information without sacrificing the pixel width per bit, resulting in a higher transmission rate for OCC without multi-level modulation. Compared with the conventional multi-threshold decision (MTD) scheme, the proposed SCPNN can effectively mitigate the impact of inter-symbol interference (ISI) and noise on signal decision by making full use of all pixels in one-bit period. The experimental results show that, in the case of the illuminance as low as 300 lux, the SCPNN scheme can attain a data rate of 8.16 Kbps with an average bit-error-rate (BER) of 2.2 × 10-3 below the HD-FEC limitation of 3.8 × 10-3. Meanwhile, the SCPNN scheme achieves remarkable BER performance improvement compared to both MFS-OCC with MTD scheme and conventional OOK-OCC system.

Computing One-Bit Compressive Sensing via Double-Sparsity Constrained Optimization

One-bit compressive sensing gains its popularity in signal processing and communications due to its low storage costs and low hardware complexity. However, it has been a challenging task to recover the signal only by exploiting the one-bit (the sign) information. In this paper, we appropriately formulate the one-bit compressive sensing into a double-sparsity constrained optimization problem. The first-order optimality conditions for this nonconvex and discontinuous problem are established via the newly introduced <inline-formula><tex-math notation="LaTeX">$\tau$</tex-math></inline-formula>-stationarity, based on which, a gradient projection subspace pursuit (GPSP) algorithm is developed. It is proven that GPSP can converge globally and terminate within finite steps. Numerical experiments have demonstrated its excellent performance in terms of a high order of accuracy with a high computational speed.

Spectrum Sensing for Optical Wireless Scattering Communications Over Málaga Fading—A Cooperative Approach With Hard Decision Fusion

This paper presents collaborative spectrum sensing for optical wireless scattering communications. The received signal is characterized by the conditional Poisson distribution, given the mean photon count following Málaga distributed correlated fading. We consider multi-scattered non-coplanar links and use the stochastic analytical method to model the channel. A system model is developed, utilizing the cooperative diversity drawn from the fact that the users are randomly distributed. A novel centralized cooperative spectrum sensing technique is developed that all the raw data available at each collaborative user are combined at the fusion center to make a decision. Another novel decentralized technique is also proposed where only one-bit information is required to be sent to the fusion center. For this decentralized technique, we propose a unique voting rule that leverages the location flexibility of randomly distributed users with each user experiencing correlated fading. Results demonstrate their effectiveness and provide insights into the proposed cooperative spectrum sensing system. Interestingly, it is also found that the use of the proposed voting rule requires fewer than the total number of collaborative users while satisfying a given error rate, and yields the Bernoulli distributed output of the fusion center.

Encoding Information into Polyethylene Glycol Using an Alcohol-Isocyanate "Click" Reaction.

In this article, the capability of encoding information using a homologous series of monodisperse monomethoxypolyethylene glycols (mPEG), with a number of ethylene oxide units ranging from nEO = 5 to 8, and monodisperse linear aliphatic isocyanates containing a number of CH2 units from 3 to 7, is demonstrated. The “click” reaction of the two corresponding homologous series yielded 20 different isocyanate end-capped polyethylene glycol derivatives (mPEG-OCONHR) whose sodiated adduct ion’s nominal m/z values spanned from 360 to 548, providing an average ca. 8 m/z unit for the storage of one-bit information. These mPEG-OCONHR oligomers were then used to encode information in binary sequences using a 384-well MALDI sample plate and employing the common dried-droplet sample preparation method capable of encoding 20 bit, i.e., 2.5 byte information in one spot, was employed. The information stored in the spots was read by MALDI-TOF MS using the m/z value of the corresponding mPEG-OCONHR oligomers. The capability of the method to store data was demonstrated by writing and reading a text file, visualizing a small picture and capturing a short audio file written in Musical Instrument Digital Interface (MIDI) sequence. Due to the very large similarities in the chemical structures of the encoding oligomers and their “easy to be ionized” property, as well as their very similar ionization efficiencies, the MALDI-TOF MS signal intensities from each compound was so strong and unambiguous that complete decoding could be performed in each case. In addition, the set of the proposed encoding oligomers can be further extended to attain higher bit “densities”.

Capacity, fairness, and queueing performance analysis of opportunistic scheduling with one-bit feedback

In this paper, we consider opportunistic downlink scheduling in a cellular network that exploits multiuser diversity using one-bit feedback. To reduce the feedback overhead inherent in opportunistic scheduling, mobile stations are allowed to send one-bit information to the base station only when their channel quality exceeds a given threshold value. The objective of this paper is two-fold: (i) find the threshold value that can optimize queueing performance of the scheduler and (ii) investigate the relationship among capacity, fairness, and queueing performance. To this end, we first derive a formula for the sum-rate capacity as a function of the threshold. Next, we quantify the long-term and short-term fairness using Jain’s fairness index. Lastly, we develop a packet-level queueing model and derive QoS measures such as queueing delay and packet loss probability. Based on our analysis, we optimize the threshold value by considering both the traffic condition at the MAC layer and the temporal channel correlation at the PHY layer. Numerical results show that the optimized threshold can significantly reduce the average queueing delay and the packet loss probability. In addition, we find that there is a trade-off between short-term fairness and sum-rate capacity, whose control knob is the threshold. We show that, from a queueing performance perspective, supporting the sum-rate capacity (resp. the short-term fairness) is more important when the traffic is heavy (resp. light) or the wireless channel varies with low (resp. high) temporal correlation.

On Channel Selection for Carrier Aggregation Systems

In this paper, the problem of sub-channel selection for carrier aggregation (CA) systems is examined. CA enables the achievement of high data rate links via simultaneous transmissions over multiple component carriers. A CA system usually occupies only a limited number of sub-channels $M$ of these components due to limitations on the maximum permitted number of sub-channels per system. From an information theoretic point of view, a CA system should detect and employ the $M$ -best sub-channels out of the $N$ available ones. To that end, such a system probes a subset of sub-channels during each coherence time via pilot transmission. Then, for the best $M$ sub-channels, one-bit feedback information is transmitted in order to prohibit the transmission through sub-channels with gain below a threshold. The aim is to derive tractable forms via employing the extreme value theory for the sum rate (lower bound on ergodic capacity) achieved by the system under Rayleigh fading and then, to optimize jointly the training length and power, the number of the probed sub-channels (probing bandwidth size) and the feedback threshold such that the sum rate is maximized by considering the sub-channel estimation error. The accuracy of the theoretical analysis is verified by numerical results.

Undersampled differential phase shift on-off keying for optical camera communications

OCC (Optical Camera Communication) has been proposed in recent years as a new technique for visible light communications. This paper introduces the implementation and experimental demonstration of an OCC system. Phase uncertainty and phase slipping caused by camera sampling are the two major challenges for OCC. In this paper, we propose a novel modulation scheme called undersampled differential phase shift on-off keying to encode binary data bits without exhibiting any flicker to human eyes. The phase difference between two consecutive samples conveys one-bit information, which can be decoded by a low-frame-rate camera receiver. Error detection techniques are introduced to enhance the reliability of the system. We present the hardware and software design of the proposed system, which is implemented with a Xilinx FPGA and a Logitech commercial camera. Experimental results demonstrate that a bit-error rate of 10-5 can be achieved with 7.15 mW received signal power over a link distance of 15 cm.

Cooperative diversity scheme using SPC in MIMO‐OFDMA system

A method to obtain high diversity gain is proposed by spatial phase coding (SPC) in the cooperative multiple input multiple output-orthogonal frequency division multiple access (MIMO-OFDMA) system. SPC provides improved diversity gain dramatically in proportion to the number of received paths although the one-bit feedback information is used. Moreover, the cooperative MIMO-OFDMA system has received paths without additional antennas more than the conventional MIMO-OFDMA system. Therefore, SPC can improve reliability in the cooperative MIMO-OFDMA system effectively.

A quantum error-correction circuit based on cyclic code

In this paper, the cyclic code of the classic circuit is transformed and transplanted; then, the quantum encoding scheme based on cyclic code and quantum error-correction circuit is constructed. The proposed circuit can correct one-bit error, and the use of redundant bits to encode more than one-bit quantum information breaks the previous limitations of many bits encoding a quantum bit. Compared with the existing coding circuits (Shor code, Steane code and five stable subcode), it shows obvious superiority in the quantum coding efficiency and transmission efficiency.

Cognitive Radios for Preserving Primary Outage Performance over Two-Hop Relay Channels

We consider cognitive radio (CR) communications over two-hop relay channels. It is assumed that the secondary sender has only one-bit information indicating whether or not it is allowed to access, while the primary nodes still operate even without any prior knowledge on the secondary nodes. We propose three different two-hop relaying protocols according to how much the relay has prior knowledge on its outgoing channels, and show that the proposed relaying protocols make it possible for the secondary sender to transmit data without causing any loss at the primary outage probability. It is also shown that the proposed relaying protocols make the secondary outage probability as small as possible by increasing the signal-to-noise ratio (SNR) if the relay has prior knowledge on its outgoing channel to the primary receiver.

Distributed quantum entanglement sharing model for high-performance real-time system

Two processors jointly provide a real-time service which can be completed by exactly one processor. Assuming each processor is allowed to announce only a one-bit information in a distributed way to decide which one should process the job, inevitably some of the jobs will get lost if only classical resources are used. In this paper, we proposed the distributed quantum entanglement sharing (DQES) model to share quantum entanglement with processors. Assisted with DQES model, not only the system dependability can be enhanced, but the faulty processor can also be identified. We also presented some possible applications such like database consistency, job scheduling, system dependability, and reliable communication protocols.

Capacity and Fairness Trade-off in an Outage Situation over Multiuser Diversity Systems

Without an appropriate scheduling scheme for subscriber stations (SSs) in an outage situation, the opportunistic feedback protocol degrades the system performance and it does not achieve the desired capacity and fairness trade-off. In this paper, we propose a new downlink multiuser scheduling scheme to balance a trade-off between capacity and fairness with one-bit information. In particular, we propose a high successful-feedback SS selection (HSSS) scheme using one-bit information to provide the flexible trade-off in an outage situation. As a result, the proposed scheme not only reduces a significant feedback overload but also considers scheduling in the outage situation. Simulation results show that the proposed scheme achieves the flexible trade-off between capacity and fairness in the outage situation.

Distributed Consensus for Multiagent Systems with Communication Delays and Limited Data Rate

This paper considers the average consensus problem for multiagent networks with communication delays and limited data rate. On one hand, communication delays often exist in information acquisition and transmission; on the other hand, only limited state information of agents can be transmitted to their neighbors at each time step due to bandwidth constraints. The average consensus problem becomes much more complicated when both delays and data-rate constraints are to be considered. In this paper, a distributed consensus protocol is proposed based on dynamic encoding and decoding. It is shown that for a connected network, as long as the time delays are bounded, the average consensus can be achieved with a finite communication data rate. In particular, it is shown that merely a one-bit information exchange between each pair of adjacent agents at each time step suffices to guarantee the average consensus.

Quantum energy teleportation with an electromagnetic field: discrete versus continuous variables

It is well known that usual quantum teleportation protocols cannot transport energy. Recently, new protocols called quantum energy teleportation (QET) have been proposed, which transport energy by local operations and classical communication with the ground states of many-body quantum systems. In this paper, we compare two different QET protocols for transporting energy with the electromagnetic field. In the first protocol, a 1/2 spin (a qubit) is coupled with the quantum fluctuation in the vacuum state and measured in order to obtain one-bit information about the fluctuation for the teleportation. In the second protocol, a harmonic oscillator is coupled with the fluctuation and measured in order to obtain continuous-variable information about the fluctuation. In the spin protocol, the amount of teleported energy is suppressed by an exponential damping factor when the amount of input energy increases. This suppression factor becomes power damping in the case of the harmonic oscillator protocol. Therefore, it is concluded that obtaining more information about the quantum fluctuation leads to teleporting more energy. This result suggests a profound relationship between energy and quantum information.

A Scheme for Information Erasure in a Double-Well Potential

We design an experimental scheme to realize one-bit information erasure and restoring processes by considering an overdamped colloidal particle in a double-well optical trap, which is added by a controllable laser tweezer. Using the Monte Carlo method, we simulate numerically the Langevin equation to calculate the mean work spent during the entire process and validate the entropy production fluctuation theory. Our result shows that the distribution of entropy production becomes narrow with increasing temperature and becomes stationary, represents the diminishing extent of irreversibility.

A Dependable SRAM with 7T/14T Memory Cells

SUMMARY This paper proposes a novel dependable SRAM with 7T/14T memory cells, and introduces a new concept, “quality of a bit (QoB)” for it. The proposed SRAM has three modes: a normal mode, highspeed mode, and dependable mode, and dynamically scales its reliability, power and speed by combining two memory cells for one-bit information (i.e. 14 T/bit). By carrying out Monte Carlo simulation in a 65-nm process technology, the minimum voltages in read and write operations are improved by 0.21 V and 0.26 V, respectively, with a bit error rate of 10 −8 kept. In addition, we confirm that the dependable mode achieves a lower bit error rate than the error correction code (ECC) and multi module redundancy (MMR). Furthermore, we propose a new memory array structure to avoid the half-selection problem in a write operation. The respective cell area overheads in the normal mode are 26% and 11% in the cases where additional transistors are pMOSes and nMOSes, compared to the conventional 6T memory cell.

Design of a fair scheduler exploiting multiuser diversity with feedback information reduction

In this letter, we propose a new downlink fair scheduling scheme exploiting the multiuser diversity to enhance the transmission capacity. In the proposed scheme, only the MSs (mobile stations) whose normalized SNR (signal-to-noise ratio) values are larger than a given threshold feedback one-bit information to the BS (base station). As a result, while achieving the strict fairness, the proposed scheme can efficiently utilize the spectrum by reducing the considerable amount of the feedback information, compared to the proportional fair scheduling scheme where all the MSs feed back the normalized SNR values to the BS. Numerical studies show that the transmission capacity in the proposed scheme with a suitable value of the threshold is very close to that in the proportional fair scheduling scheme.

Exploiting Multiuser Diversity With Imperfect One-Bit Channel State Feedback

It has been well recognized that significant throughput gains can be leveraged in multiuser wireless communication systems by exploiting multiuser diversity with a smart scheduler. This scheduler collects channel state information (CSI) from all users and allocates the resources to the user(s) experiencing favorable channel conditions. However, for a frequency-division-duplex system with a large number of users, how to efficiently collect the required CSI will be a challenging task, especially when the feedback links are of limited capacity. In this paper, we propose a scheduling algorithm to exploit multiuser diversity with possibly imperfect one-bit channel state feedback. The basic idea is to define a threshold lambda and let each user report one-bit information to the scheduler about the comparison between its measured channel fading level and lambda. Correspondingly, the scheduler uses these feedback bits to classify all users into two sets and assigns the channel to one user belonging to the set experiencing favorable channel conditions. Several implementation schemes are developed by attacking the optimization of lambda under different system configurations, covering both the case when the one-bit feedback is perfect and those when the one-bit feedback is imperfect. Computer simulations show that when the user number is large, say, more than ten users, the proposed scheduling supports significantly larger data rate over the round-robin scheduling, while in comparison with the optimum scheduling with complete CSI, the performance loss is limited if the one-bit feedback is of high reliability. In addition, our studies show that we can effectively enhance the robustness against feedback imperfectness by incorporating the feedback reliability into optimization of lambda

Robust and high-quality time-domain audio watermarking based on low-frequency amplitude modification

This work proposes a method of embedding digital watermarks into audio signals in the time domain. The proposed algorithm exploits differential average-of-absolute-amplitude relations within each group of audio samples to represent one-bit information. The principle of low-frequency amplitude modification is employed to scale amplitudes in a group manner (unlike the sample-by-sample manner as used in pseudonoise or spread-spectrum techniques) in selected sections of samples so that the time-domain waveform envelope can be almost preserved. Besides, when the frequency-domain characteristics of the watermark signal are controlled by applying absolute hearing thresholds in the psychoacoustic model, the distortion associated with watermarking is hardly perceivable by human ears. The watermark can be blindly extracted without knowledge of the original signal. Subjective and objective tests reveal that the proposed watermarking scheme maintains high audio quality and is simultaneously highly robust to pirate attacks, including MP3 compression, low-pass filtering, amplitude scaling, time scaling, digital-to-analog/analog-to-digital reacquisition, cropping, sampling rate change, and bit resolution transformation. Security of embedded watermarks is enhanced by adopting unequal section lengths determined by a secret key.

Quantum Cryptography Based on Split Transmission of One-Bit Information in Two Steps

We propose a simple quantum cryptographic scheme involving truly two orthogonal states. The security of the protocol is based on splitting the transfer of one-bit information into two steps, ensuring that only a fraction of the bit information is transmitted at a time. A particular implementation with an asymmetric interferometer is presented, which does not require the random timing of the packet sending as was used by Goldenberg and Vaidman [Phys. Rev. Lett. 75, 1239 (1995)].