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The motivation behind this study is the essential need for survivability in the telecommunications networks. An optical signal should find its destination even if the network experiences an occasional fiber [...]

Aggressive technology scaling raises the need for efficient methods to characterize and model circuit variation at both the front and back end of line, where critical parameters such as threshold voltage and parasitic capacitance must be carefully modeled for accurate circuit performance. In this paper we address this need by contributing a test circuit methodology for the extraction of spatial, layout and size dependent variations at both device and interconnect levels. The test chip uses a scan chain approach combined with low-leakage and low-variation switches, and Kelvin sensing connections, providing access to detailed analog device characteristics in large arrays of test devices. Variation measurement using the designed test chip has proven successful for both device and interconnect test structures. The parameter extraction and variation analyses made possible by the variation test chip enable the identification of likely variation sources, quantification of circuit impact and sensitivity, and specification of layout practices for variation minimization. Index Terms--Design for manufacturability, statistical metrology, statistical modeling, variation.

Multiple-input multiple-output (MIMO) spatial multiplexing that needs to separate and detect transmitted signal streams by using processing at the receiver end can increase the data rates of transmissions on independent and identically distributed (i.i.d.) channels. Such channels have been considered to exist in nonline-of-sight (NLOS) environments. However, actual communications may also be conducted in line-of-sight (LOS) environments. While an LOS component can increase the received power level, it may also cause correlated channels that make it difficult to detect the transmitted streams. In this paper, we describe the performance of 4 x 4 MIMO spatial multiplexing based on LOS and NLOS channel measurements in an indoor environment. For eight configurations of uniform linear arrays (four antenna spacings and two array orientations), we evaluated the cumulative distribution function (CDF) of the channel capacity and bit error rate performance versus transmit power, and we analyzed them in terms of antenna pattern, fading correlation, CDFs of MIMO channel elements, and CDFs of eigenvalues. Results show that, despite higher fading correlations and non i.i.d, channel characteristics, the performance of MIMO spatial multiplexing in the LOS environment is better than that in the NLOS one. However, the performance in the measured LOS environment largely depends on the MIMO configuration. Index Terms--Array element pattern, bit error rate (BER), channel capacity, channel element distribution, eigenvalue distribution, fading correlation, indoor channel measurement, multiple-input multiple-output (MIMO), mutual coupling, spatial multiplexing.

Nowadays, techniques for education are based on the combination of theoretical formulas, experimental measurement and simulation approaches. Theoretical analysis, experimental and simulation approaches based educations allow developing simple and non expensive tools for the aim of studying complex problems in optical network communication. Theoretical formulas, used to describe the non linear effects on digital lightwave links, may by simplified with the use of simulation models so that real and industrial applications can be approached. In this study, we use theoretical model taking into account system parameters, physical penalty and transmission speed, for the purpose of developing simulation tools. Using these simulation techniques, it is possible to investigate various compensation techniques and demonstrate their effects on system performances. Key words: Theoretical analysis, simulation techniques, compensation techniques, transmission optical system, DWDM technology, INTRODUCTION Rapid growth of the global communication network is being made possible by the availability of new optical fiber technologies. Dense Wavelength Division Multiplexing system DWDM saves the network operators [...]

The performance of the type-based multiple access (TBMA) is analyzed by using large deviations theory (LDT), which has considered the medium access communication problem between sensor nodes and a fusion center. Numerical simulations have shown that the error exponents provide accurate estimates of the performance of TBMA.

Two distributed detection problems involving correlated sensor observations in the one-dimensional (1-D) sensor network are presented. The results have shown that although the lack of multiple access channels (MAC) synchronization causes degradation in error exponents, those degradations are negligible when the phase mismatch among sensors is sufficiently small.

A successive approximation method is proposed that is based on the conventional line-by-line-addressing. Many gray shades can be exhibited without flicker by using low-cost liquid crystal display drivers, which are designed to drive the pixels to either ON or OFF states in bilevel displays.

The inherent queuing delay introduced by the demultiplexing algorithm of the parallel packet switch (PPS) in commercial switches, responsible for dispatching cells to the middle-stage switches, relative to an optimal work-conserving switch, is investigated. The lower bounds of the inherent queuing delay of a symmetric and fault-tolerant PPS indicate that employing algorithms using slightly out-of-date information may greatly improve the PPS performance.

The linear prediction (LP) algorithm estimates a zero-forcing (ZF) equalizer from the channel output's second-order statistics (SOS). Careful examination shows that it allows determining a whole subspace of ZF equalizers and the one obtained by maximizing the single-to-noise ratio at the equalizer output not only outperforms the original LP equalizer, but also attain the lowest achievable mean-square error.

The time-domain equalizer (TEQ) design literature is surveyed for complexity reduction techniques, and the complexity requirement of the most popular algorithms are calculated for their original and reduced-complexity implementations. The results suggest that choosing the best equalizer design depends on the bit rate and complexity targets as the per-tone equalizer has the highest achievable bit rate with higher cost and Minimum Delay Spread TEQ has the lowest cost with average performance.

The codebook design problem associated with transmit beamforming in multiple-input multiple-output (MIMO) spatial multiplexing systems with finite-rate feedback is investigated and a multimode spatial multiplexing transmission strategy that allows for efficient utilization of the feedback bits by quantizing only relevant beamforming vectors is proposed. This scheme can be viewed as a rough and indirect implementation of water-filling power allocation over the multiple spatial channels.

A detailed derivation of the evolution equation of the amplitude of a cavity mode, coupled to a waveguide, starting from Maxwell's equations, is provided by using the reciprocity relations. Results confirm that detuning is estimated in the case of photonic crystal cavity, coupled to a photonic crystal waveguide, showing that it is significant especially, if the structure is used for filtering applications.

A novel design of a tap consisting of two functional stages, a mode exciter, which determines the tapping ratio and a modal demultiplexer for separating the tap signal from the main channel, is described. The introduction of the tap to an optical circuit has negligible effect on the main signal being tapped, while the tapped signal exhibits low wave-length-dependent loss and polarization-dependent loss over a very wide spectral range.

The popular wavelet framework for signal representation is extended to error control coding with a primary goal to use cyclic finite-field wavelets and filter banks to study arbitrary-rate L-circulant codes. It is shown that the wavelet representation leads to an efficient implementation of the block code encoder and the syndrome generator.

A study is conducted on the problem of communicating sensor readings over a Gaussian multi-access channel. It is shown that the type-based multiple access (TBMA) is asymptotically optimal in the limit of large number of sensors if the sensor channel gains are identical.

An analysis of the multiplexing process occurring in lenticular and parallax-barrier three dimensional (3-D) display using tools from multidimensional theory is described. It is suggested that anti-alias profiteering is essential for high-quality view multiplexing and should be incorporated by 3-D automultiscopic screen manufacturers into multiplexing software.

The simple closed-form solutions for Schur-concave/convex cost functions in a single multiple-input multiple-output (MIMO) communication system as well as in the multiple MIMO channels such as the multi-antenna multicarrier systems are discussed. By relating the work for a convex/concave system with another proposed method, the average bit error rate (BER) of the system can be minimized which can then be used for the non Schur-concave/convex functions.

The hard decision bit-level cancellation (BLC) is employed to reduce the dimension of the multiple-input multiple-output (MIMO) detection as it provides better performance than the symbol-level cancellation and also the extrinsic bit information can be directly used for the BLC. Two approaches, namely the projection based approach for a lower order modulation and the minimum mean square error filtering with soft-decision cancellation for the higher order, are used for the uncancelled bits.

The channel matrix is estimated using specific properties of orthogonal space-time block codes (OSTBCs), which is then used in the maximum-likelihood (ML) receiver for the blind decoding of the OSTBCs. The results show that the proposed technique is applicable to any OSTBC and is better than the other coding schemes, with reference to the computational costs, scalar ambiguities, performance and the need of a pilot system.

Multiple-input-multiple-output (MIMO) antenna selection algorithms where the set of possible solutions is large and only noisy estimate of the channel is available, is examined, and also proposed a simulation based discrete stochastic optimization algorithms to adaptively select a better antenna subset using criteria such as maximum mutual information, boundaries on error rate. Results reveal that no closed-form expression for the objective function is needed and only an estimate of it is sufficient.

The uniform channel decomposition (UCD) scheme for multiple-input-multiple-output (MIMO) communications that can decompose a MIMO channel into multiple subchannels with identical capacities in a capacity losses manner is introduced. The UCD scheme can provide much convenience for the subsequent modulation/demodulation and coding/decoding procedure due to obviating the need for bit allocation and also it can achieve the maximal diversity gain.

New approach for the blind identification of a multi-input-multi-output (MIMO) system is proposed with identifying and unknown linear, time-invariant mixing system, driven by and unobserved source, based on the system's observed output, and on the presumed independent, identically distributed time-structure of the source. Although, performance of the algorithm depends on the choice of processing-points, it compares favorably with other algorithms, especially at moderate signal-to-noise ratio conditions, as it is demonstrated in simulation results.

A joint transceiver design that combines the geometric mean decomposition (GMD) with either the conventional zero-forcing VBLAST decoder or the zero-forcing dirty paper precoder (ZFDP) is proposed. The scheme decomposes a multi-input multi-output (MIMO) channel into multiple identical parallel subchannels, which could make it rather convenient to design modulation/demodulation and coding/decoding schemes.

A low-complexity soft-decision equalization approach for frequency selective multi-input multi-output (MIMO) communication systems is developed. The proposed Kalman-Probabilistic Data Association (PDA) detector performs local multiuser detection (MUD) within a subblock of the received data instead of over the entire data set to reduce the computational load.

The problem of blindly identifying multiple input multiple output (MIMO) finite impulse response (FIR) channels without the conventional assumption of identical column degrees is addressed. A subspace-based algorithm is developed that identifies the channel's columns sequentially from the lowest degree columns to the highest degree ones.

The design of a multiple-input multiple-output (MIMO) communication system with channel knowledge at the transmitter and receiver is considered. A global view of the problem by bridging the gap between the existing results on the selection of the constellations and on the design of the signal processing in the form of a linear transceiver is provided.

Limited feedback multimode precoding for the spatial multiplexing multiple-input multiple-output (MIMO) wireless systems is presented. This allows the MIMO system to adaptively vary both the number of substreams and the precoder using current channel conditions.

The application of III-nitride semiconductor materials in infrared wavelength regions for fiber-optic communications is proposed. The feasibility of making functional waveguide optical devices using GaN-AlGaN heterostructures, such as straight waveguides, 3-dB optical waveguide couplers and AWG wavelength routers is demonstrated.

A method based on tilted distributed feedback (DFB) gratings is presented to be used in combination with specially bent or tilted straight waveguides for the low-cost and ultraprecise definition of different wavelength channels in lasers for Dense wave-length division multiplexing (DWDM) fiberoptic communication systems.

The use of space-division multiple access (SDMA) in the downlink of a multi-user multiple-input, multiple-output (MIMO) wireless communications network can provide a substantial gain in system throughput. Two constrained solutions such as 'block-diagonalization' and 'successive optimization' are presented.

The advantages of multiple-input multiple-output (MIMO) technology in ultrawideband (UWB) communication systems are investigated evaluating the channel capacity from measurements taken in indoor environments. The results suggest that in practical instances spatial diversity is more attractive than spatial multiplexing for ultrawideband systems. Index Terms--Multiple-input multiple-output (MIMO), spatial diversity gain, spatial multiplexing gain, ultrawideband (UWB).

Various taper functions are well known to suppress side lobes in antenna array factors. These tapers are limited to either transmit or receive arrays and are mostly restricted to arrays with a high number of elements. This paper presents an approach for applying taper functions also to digital beamforming (DBF) arrays with transmitter multiplexing. For such DBF configurations, taper functions have not been known yet. An example for a multiple transmit DBF taper will be given which is dedicated for low number of elements. Index Terms--Digital beamforming (DBF), multitransmit digital beamforming, taper function.