Vision and Task Assistance Using Modular Wireless In Vivo Surgical Robots

Minimally invasive abdominal surgery (laparoscopy) results in superior patient outcomes compared to conventional open surgery. However, the difficulty of manipulating traditional laparoscopic tools from outside the body of the patient generally limits these benefits to patients undergoing relatively low complexity procedures. The use of tools that fit entirely inside the peritoneal cavity represents a novel approach to laparoscopic surgery. Our previous work demonstrated that miniature mobile and fixed-based in vivo robots using tethers for power and data transmission can successfully operate within the abdominal cavity. This paper describes the development of a modular wireless mobile platform for in vivo sensing and manipulation applications. Design details and results of ex vivo and in vivo tests of robots with biopsy grasper, staple/clamp, video, and physiological sensor payloads are presented. These types of self-contained surgical devices are significantly more transportable and lower in cost than current robotic surgical assistants. They could ultimately be carried and deployed by nonmedical personnel at the site of an injury to allow a remotely located surgeon to provide critical first response medical intervention irrespective of the location of the patient.      

In Situ Interferometric Monitoring of Fiber Insertion in Fiber Connector Components

We present an interferometric setup for in situ monitoring of fiber tip positions when inserting optical fibers for fixation in fiber connector components. It ensures an accurate fiber tip position at the fiber connector's front facet and across the fiber array in cases where postinsertion polishing is not possible. We demonstrate our technique by populating a plastic fiber connector for optical interconnect applications, and compare the fiber tip position measured in situ using our setup with the position measured off-line using a commercial white light interferometer, showing a deviation smaller than 5%.      

Performance Analysis and Design Criteria of BICM-ID With Signal Space Diversity for Keyhole Nakagami-$m$ Fading Channels

This paper generalizes the application bit-interleaved coded modulation with iterative decoding (BICM-ID) using signal space diversity (SSD) over keyhole Nakagami-$m$ fading channels. The tight union bound on the asymptotic error performance is first analytically derived. The near-optimal rotation matrix with respect to both the asymptotic performance and the convergence behavior is then determined. In particular, it is demonstrated that the suitable rotation matrix is the one that has 1) all entries equal in magnitude, 2) a high diversity order, and 3) a large minimum product of the ratios between squared distances to the power $m$ and log-squared distances to the power $m$ of the rotated constellation scaled by factors of signal-to-noise ratio (SNR) and the parameter $m$ . Various analytical and simulation results show that by employing SSD with a sufficiently large dimension, the error performance can closely approach that over an additive white Gaussian noise (AWGN) channel, even in the worst case of keyhole fading.      

Universal Lossless Compression of Erased Symbols

A source ${mmb X}$ goes through an erasure channel whose output is ${mmb Z}$. The goal is to compress losslessly ${mmb X}$ when the compressor knows ${mmb X}$ and ${mmb Z}$ and the decompressor knows ${mmb Z}$. We propose a universal algorithm based on context-tree weighting (CTW), parameterized by a memory-length parameter $ell$. We show that if the erasure channel is stationary and memoryless, and ${mmb X}$ is stationary and ergodic, then the proposed algorithm achieves a compression rate of $H(X_0vert X_{-ell}^{-1}, Z^ell)$ bits per erasure.      

Extrapolation and Correlation (EXTRACT): A New Method for Motion Compensation in MRI

A postprocessing technique is proposed for the correction of both translational and rotational motion artifacts in magnetic resonance imaging (MRI). The method consists of two steps: 1) k-space extrapolation to generate a motion-free reference, followed by 2) correlation with actual data to estimate motion. In this paper, two different extrapolation methods were investigated for the purpose of motion estimation: edge enhancement and finite-support solution. It was found that finite-support solution performs better near the k-space center, while the edge enhancement method is superior in the outer k-space regions. Therefore, a combination of the two methods was employed to generate a motion-free reference, whose correlations with the acquired data can subsequently determine the object motion. Motion compensation was demonstrated in simulation and in vivo MR experiments. The technique is shown to be robust against noise and various types of motion.      

Robust Precoder Adaptation for MIMO Links With Noisy Limited Feedback

In this paper, we propose two robust limited feedback designs for multiple-input multiple-output (MIMO) adaptation. The first scheme, namely, the combined design jointly optimizes the adaptation, CSIT (channel state information at the transmitter) feedback as well as index assignment strategies. The second scheme, namely, the decoupled design, focuses on the index assignment problem given an error-free limited feedback design. Simulation results show that the proposed framework has significant capacity gain compared to the naive design (designed assuming there is no feedback error). Furthermore, for large number of feedback bits $C_{rm fb}$, we show that under two-nearest constellation feedback channel assumption, the MIMO capacity loss (due to noisy feedback) of the proposed robust design scales like ${cal O}(P_e2^{-{{C_{rm fb}}over{t+1}}})$ for some positive integer $t$. Hence, the penalty due to noisy limited feedback in the proposed robust design approaches zero as $C_{rm fb}$ increases.      

A Note on Limited-Trial Chase-Like Algorithms Achieving Bounded-Distance Decoding

For the decoding of a binary linear block code of minimal Hamming distance $d$ over additive white Gaussian noise (AWGN) channels, a soft-decision decoder achieves bounded-distance (BD) decoding if its squared error-correction radius is equal to $d$. A Chase-like algorithm outputs the best (most likely) codeword in a list of candidates generated by a conventional algebraic binary decoder in a few trials. It is of interest to design Chase-like algorithms that achieve BD decoding with as least trials as possible. In this paper, we show that Chase-like algorithms can achieve BD decoding with only $O(d^{1/2+varepsilon })$ trials for any given positive number $varepsilon $.      

Integrating Phase-Change Memory Cell With Ge Nanowire Diode for Crosspoint Memory—Experimental Demonstration and Analysis

In this paper, we demonstrate a novel phase-change memory cell utilizing a low-temperature in situ doped single crystalline germanium nanowire diode as a bottom electrode as well as a memory-cell selection device. The integrated memory cell shows promising characteristics such as low programming current, large set/reset resistance ratio, and rectifying behavior, which is required for high-density 3-D crosspoint memory. The small contact area determined by the diameter of nanowires enables low programming current below 200 $muhbox{A}$ for reset and 50 $muhbox{A}$ for set. The average resistance ratio of set/reset state programmed by repetitive pulse programming is 82, which is large enough for large-array operation. The heterojunction formed between in situ doped Ge nanowires and Si substrate provides $hbox{100}times$ isolation for crosspoint-memory operation.      

Noncoherent Synchronization of UWB-IR Multiple-Antenna Multipath Channels

This paper deals with the maximum-likelihood (ML) noncoherent data-aided (e.g., no blind) synchronization of multiple-antenna ultrawideband impulse-radio (UWB-IR) terminals that operate over broadband channels and are affected by multipath fading with a priori unknown number of paths and path-gain statistics. The synchronizer that we developed achieves the ML data-aided joint estimate of the number of paths and their arrival times (e.g., time delays), without requiring any a priori knowledge and/or a posteriori estimate of the amplitude (e.g., module and sign) of the channel gains. The ultimate performance of the proposed synchronizer is evaluated (in closed form) by developing the corresponding CramÉr–Rao bound (CRB), and the analytical conditions for achieving this bound are provided. The performance gain for the synchronization accuracy of multipath-affected UWB-IR signals arising from the exploitation of the multiple-antenna paradigm is (analytically) evaluated. Furthermore, a low-cost sequential implementation of the proposed synchronizer is detailed. It requires an all-analog front-end circuitry composed of a bank of sliding-window correlators, whose number is fully independent from the number of paths comprising the underlying multiple-antenna channel. Finally, the actual performance of the proposed synchronizer is numerically tested under both the signal acquisition and tracking operating conditions.      

Finite State Channels With Time-Invariant Deterministic Feedback

We consider capacity of discrete-time channels with feedback for the general case where the feedback is a time-invariant deterministic function of the output samples. Under the assumption that the channel states take values in a finite alphabet, we find a sequence of achievable rates and a sequence of upper bounds on the capacity. The achievable rates and the upper bounds are computable for any $N$, and the limits of the sequences exist. We show that when the probability of the initial state is positive for all the channel states, then the capacity is the limit of the achievable-rate sequence. We further show that when the channel is stationary, indecomposable, and has no intersymbol interference (ISI), its capacity is given by the limit of the maximum of the (normalized) directed information between the input $X^{N}$ and the output $Y^{N}$ , i.e., $$C = lim _{N rightarrow infty } {{ 1}over { N}} max I(X^{N} rightarrow Y^{N} )$$ where the maximization is taken over the causal conditioning probability $Q(x^{N}Vert z^{N-1})$ defined in this paper. The main idea for obtaining the results is to add causality into Gallager's results on finite state channels. The capacity results are used to show that the source–channel separation theorem holds for time-invariant determinist feedback, and if the state of the channel is known both at the encoder and the decoder, then feedback does not increase capacity.      

Efficient FPGA Realization of CORDIC With Application to Robotic Exploration

We present an area-efficient method and field-programmable gate array (FPGA) realization for two common operations in robotics, namely, the following: 1) rotating a vector in 2-D and 2) aligning a vector in the plane with a specific axis. It is based on a new coordinate rotation digital computer (CORDIC) algorithm that is designed to work with a small set of elementary angles. Unlike conventional CORDIC, the proposed algorithm does not require a ROM and a full-fledged barrel shifter. The proposed CORDIC algorithm is used to design hardware-efficient solutions for two mobile robotic tasks in an indoor environment without employing division and floating-point calculations. Experiments with a sole low-end FPGA-based robot in static as well as dynamic environments validate the power of the approach.      

OSNR Margin Brought by Nonlinear Regenerators in the Presence of PMD and Amplified Spontaneous Emission Noise

The behavior of a 2R optical regenerator in a link limited by amplified spontaneous emission (ASE) noise and polarization-mode dispersion (PMD) is investigated in detail in this paper. 2R regeneration techniques are well known for combating the accumulation ASE noise in an optical signal, but their behavior in the presence of PMD is mostly unknown. Here, we propose a general method to calculate the total outage probability in a link including a cascade of optical regenerators. Through the use of semianalytical models, we study the ability of 2R optical regenerators to combat at the same time PMD distortions and ASE noise accumulation in an optical signal, and show their interesting potential to counter independently both detrimental effects.      

Properties and Applications of Preimage Distributions of Perfect Nonlinear Functions

The preimage distributions of perfect nonlinear functions from an Abelian group of order $n$ to an Abelian group of order $3$ or $4$, respectively, are studied. Based on the properties of the preimage distributions of perfect nonlinear functions from an Abelian group of order $3^{r}$ to an Abelian group of order $3$, the weight distributions of the ternary linear codes $C_{Pi}$ from the perfect nonlinear functions $Pi (x)$ from $F_{3^{r}}$ to itself are determined. These results suggest that two open problems, proposed by Carlet, Ding, and Yuan in 2005 and 2006, respectively, are answered.      

On the Values of Kloosterman Sums

Given a prime $p$ and a positive integer $n$ , we show that the shifted Kloosterman sums $$sum _{x in BBF _{p^{n}}} psi (x + ax^{p^{n}-2}) = sum _{xin BBF _{p^{n}}^{ast }} psi(x + ax^{-1}) + 1, quad a inBBF _{p^{n}}^{ast }$$ where $psi$ is a nontrivial additive character of a finite field $BBF _{p^{n}}$ of $p^{n}$ elements, do not vanish if $a$ belongs to a small subfield $BBF_{p^{m}} subseteq BBF _{p^{n}}$. This complements recent results of P. Charpin and G. Gong which in turn were motivated by some applications to bent functions.      

Quantifying the Loss of Compress–Forward Relaying Without Wyner–Ziv Coding

The compress-and-forward (CF) strategy achieves the optimal diversity–multiplexing tradeoff (DMT) of a three-node half-duplex relay network in slow fading, under the assumption that the relay has perfect knowledge of all three channel coefficients and that the relay makes use of Wyner–Ziv (WZ) source coding with side information. This paper studies the achievable DMT of the same network when the relay is constrained to make use of standard (non-WZ) source coding. Under a short-term power constraint at the relay, using source coding without side information results in a significant loss in terms of the DMT. For multiplexing gains $r leq {2over 3}$, this loss can be fully compensated for by using power control at the relay. On the contrary, for $r in ({2over 3},1)$, the loss with respect to WZ coding remains significant.      

Single-Exclusion Number and the Stopping Redundancy of MDS Codes

For a linear block code ${cal C}$, its stopping redundancy is defined as the smallest number of check nodes in a Tanner graph for ${cal C}$, such that there exist no stopping sets of size smaller than the minimum distance of ${cal C}{bf .},$ Schwartz and Vardy conjectured that the stopping redundancy of a maximum-distance separable (MDS) code should only depend on its length and minimum distance.      

High-Temperature High-Power Operation of GaInNAs Laser Diodes in the 1220–1240-nm Wavelength Range

We report on the high-temperature performance of high-power GaInNAs broad area laser diodes with different waveguide designs emitting in the 1220–1240-nm wavelength range. Large optical cavity laser structures enable a maximum continuous-wave output power of $>$8.9 W at ${T}=20 ^{circ}$C with emission at 1220 nm and are characterized by low internal losses of 0.5 cm$^{-1}$ compared to 2.9 cm$^{-1}$ for the conventional waveguide structures. High-power operation up to temperatures of 120 $^{circ}$C is observed with output powers of $>$4 W at ${T}=90 ^{circ}$C. This laser diode showed characteristic temperatures of ${T}_{0} =112$ K and ${T}_{1}=378$ K.      

On the Achievable Rate Regions for Interference Channels With Degraded Message Sets

The interference channel with degraded message sets (IC-DMS) refers to a communication model, in which two senders attempt to communicate with their respective receivers simultaneously through a common medium, and one sender has complete and a priori (noncausal) knowledge about the message being transmitted by the other. A coding scheme that collectively has advantages of cooperative coding, collaborative coding, and dirty paper coding, is developed for such a channel. With resorting to this coding scheme, achievable rate regions of the IC-DMS in both discrete memoryless and Gaussian cases are derived. The derived achievable rate regions generally include several previously known rate regions as special cases. A numerical example for the Gaussian case further demonstrates that the derived achievable rate region offers considerable improvements over these existing results in the high-interference-gain regime.      

On the Cusick–Cheon Conjecture About Balanced Boolean Functions in the Cosets of the Binary Reed–Muller Code

In this paper, an amplification of the Cusick–Cheon conjecture on balanced Boolean functions in the cosets of the binary Reed–Muller code $RM(k,m)$ of order $k$ and length $2^m$, in the cases where $k = 1$ or $k geq (m-1)/2$, is proved.      

Logarithmic Sobolev Inequalities for Information Measures

For $alphageq 1$, the new Vajda-type information measure ${bf J}_{alpha}(X)$ is a quantity generalizing Fisher's information (FI), to which it is reduced for $alpha=2$ . In this paper, a corresponding generalized entropy power ${bf N}_{alpha}(X)$ is introduced, and the inequality ${bf N}_{alpha}(X) {bf J}_{alpha}(X)geq n$ is proved, which is reduced to the well-known inequality of Stam for $alpha=2$. The cases of equality are also determined. Furthermore, the Blachman–Stam inequality for the FI of convolutions is generalized for the Vajda information ${bf J}_{alpha}(X)$ and both families of results in the context of measure of information are discussed. That is, logarithmic Sobolev inequalities (LSIs) are written in terms of new more general entropy-type information measure, and therefore, new information inequalities are arisen. This generalization for special cases yields to the well known information measures and relative bounds.