Security Tradeoffs in Rate Splitting Multiple Access: Optimal Signal Splitting vs Revealing

This paper considers the secrecy performance of rate splitting (RS) scheme in multi-user multiple-input single-output (MU-MISO) systems. The split of the users' messages into common and private parts can enhance the sum-rate of the communication systems. However, this split of the messages reveals part of the users' messages making them prone to eavesdropping. Thus, to consider the tradeoff between the sum-rate and the secrecy of RS, new analytical expressions for the ergodic sum-rate and ergodic secrecy rate are derived. Then, based on the analytical expressions of the ergodic rates, novel power allocation strategy that maximizes the sum-rate subject to a target secrecy rate is proposed and investigated. Our Monte Carlo simulations show a close match with our theoretical derivations. They also reveal that, by tuning the portion of the split signals, our power allocation approach provides a scalable tradeoff between sum-rate benefits and secrecy

Rate-Splitting Multiple Access for Joint Radar-Communications with Low-Resolution DACs

In this paper, we introduce the design of a multi-antenna Joint Radar-Communication (JRC) system with Rate Splitting Multiple Access (RSMA) and low resolution Digital-to-Analog Converter (DAC) units. Using RSMA, the communication messages are split into private and common parts, then precoded and quantized before transmission. We use a problem formulation to design the JRC system with RSMA and low resolution DACs by maximizing communication sum-rate and the proximity of the resulting JRC waveform to an optimal radar beampattern under an average transmit power constraint. We solve the joint sum-rate maximization and beampattern error minimization problem using Alternating Direction Method of Multipliers (ADMM) method. The numerical results show that RSMA achieves a significantly higher sum-rate compared to Space Division Multiple Access (SDMA) while providing the same Normalized Mean Square Error (NMSE) for the designed radar beampattern

Testing Multiple Coordination Constraints with a Novel Bimanual Visuomotor Task

The acquisition of a new bimanual skill depends on several motor coordination constraints. To date, coordination constraints have often been tested relatively independently of one another, particularly with respect to isofrequency and multifrequency rhythms. Here, we used a new paradigm to test the interaction of multiple coordination constraints. Coordination constraints that were tested included temporal complexity, directionality, muscle grouping, and hand dominance. Twenty-two healthy young adults performed a bimanual dial rotation task that required left and right hand coordination to track a moving target on a computer monitor. Two groups were compared, either with or without four days of practice with augmented visual feedback. Four directional patterns were tested such that both hands moved either rightward (clockwise), leftward (counterclockwise), inward or outward relative to each other. Seven frequency ratios (3∶1, 2∶1, 3∶2, 1∶1, 2∶3. 1∶2, 1∶3) between the left and right hand were introduced. As expected, isofrequency patterns (1∶1) were performed more successfully than multifrequency patterns (non 1∶1). In addition, performance was more accurate when participants were required to move faster with the dominant right hand (1∶3, 1∶2 and 2∶3) than with the non-dominant left hand (3∶1, 2∶1, 3∶2). Interestingly, performance deteriorated as the relative angular velocity between the two hands increased, regardless of whether the required frequency ratio was an integer or non-integer. This contrasted with previous finger tapping research where the integer ratios generally led to less error than the non-integer ratios. We suggest that this is due to the different movement topologies that are required of each paradigm. Overall, we found that this visuomotor task was useful for testing the interaction of multiple coordination constraints as well as the release from these constraints with practice in the presence of augmented visual feedback

λ–MIMO: massive MIMO via modulo sampling

Massive multiple-input multiple-output (M-MIMO) architecture is the workhorse of modern communication systems. Currently, two fundamental bottlenecks, namely, power consumption and receiver saturation, limit the full potential achievement of this technology. These bottlenecks are intricately linked with the analog-to-digital converter (ADC) used in each radio frequency (RF) chain. The power consumption in M–MIMO systems grows exponentially with the ADC’s bit budget while ADC saturation causes permanent loss of information. This motivates the need for a solution that can simultaneously tackle the above-mentioned bottlenecks while offering advantages over existing alternatives such as low-resolution ADCs. Taking a radically different approach to this problem, we propose λ–MIMO architecture which uses modulo ADCs (Mλ–ADC) instead of a conventional ADC. Our work is inspired by the Unlimited Sampling Framework. Mλ–ADC in the RF chain folds high dynamic range signals into low dynamic range modulo samples, thus alleviating the ADC saturation problem. At the same time, digitization of modulo signal results in high resolution quantization. In the novel λ–MIMO context, we discuss baseband signal reconstruction, detection and uplink achievable sum-rate performance. The key takeaways of our work include, (a) leveraging higher signal-to-quantization noise ratio (SQNR), (b) detection and average uplink sum-rate performances comparable to a conventional, infinite-resolution ADC when using a 1-2 bit Mλ–ADC. This enables higher order modulation schemes e.g. 1024 QAM that seemed previously impossible, (c) superior trade-off between energy efficiency and bit budget, thus resulting in higher power efficiency. Numerical simulations and modulo ADC based hardware experiments corroborate our theory and reinforce the clear benefits of λ–MIMO approach

Hearing loss is part of the clinical picture of ENPP1 loss of function mutation

Background: Ecto/nucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1) loss-of-function mutations have been described in patients with autosomal recessive hypophosphatemic rickets (HR), in patients with generalized arterial calcification of infancy (GACI) and in several patients with both conditions. Out of more than 50 cases of homozygous or compound heterozygous ENPP1 loss-of-function mutations published so far, 1 case with labyrinthine deafness probably due to occlusion of inner ear supplying arteries and 2 cases of conductive hearing loss due to stapedovestibular calcification diagnosed in childhood have been reported. Aims: To report a case of ENPP1 loss-of-function novel mutation presenting with HR and very early onset and severe hearing loss. Methods: Case report and review of the literature. Results: We report on a patient homozygous for a novel 1-bp deletion in ENPP1 that presented with GACI evolving towards HR associated with a mixed hearing loss (both labyrinthine and conductive) diagnosed at 9 days of life that evolved towards profound labyrinthine deafness. Conclusion: Hearing loss is a rare finding in patients with ENPP1 loss-of-function mutations. Interestingly, it has already been described in other affected patients, in ENPP1 knock-out mice and in other diseases of pyrophosphate metabolism. Conversely it seems to be absent in children with the X-linked form of HR. © 2013 S. Karger AG, Basel.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Dynamic RF combining for multi-antenna ambient energy harvesting

Abstract Ambient radio frequency (RF) energy harvesting (EH) technology is key to realize self-sustainable, always-on, low-power, massive Internet of Things networks. Typically, rigid (non-adaptable to channel fluctuations) multi-antenna receive architectures are proposed to support reliable EH operation. Herein, we introduce a dynamic RF combining architecture for ambient RF EH use cases, and exemplify the attainable performance gains via three simple phase shifts’ exploration mechanisms, namely, brute force (BF), sequential testing (ST) and codebook based (CB). Among the proposed mechanisms, BF demands the highest power consumption, while CB requires the highest-resolution phase shifters, thus tipping the scales in favor of ST. Finally, we show that the performance gains of ST over a rigid RF combining scheme increase with the number of receive antennas and energy transmitters’ deployment density

A comparative study of scalable video coding schemes utilizing wavelet technology

Video transmission over variable-bandwidth networks requires instantaneous bit-rate adaptation at the server site to provide an acceptable decoding quality. For this purpose, recent developments in video coding aim at providing a fully embedded bit-stream with seamless adaptation capabilities in bit-rate, frame-rate and resolution. A new promising technology in this context is wavelet-based video coding. Wavelets have already demonstrated their potential for quality and resolution scalability in still-image coding. This led to the investigation of various schemes for the compression of video, exploiting similar principles to generate embedded bit-streams. In this paper we present scalable wavelet-based video-coding technology with competitive rate-distortion behavior compared to standardized non-scalable technology