OFDM transmitter diversity systems that do not required a cyclic prefix have recently been proposed as means to improve bandwidth efficiency. For these systems, knowledge of the channel parameters is required at the r...
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OFDM transmitter diversity systems that do not required a cyclic prefix have recently been proposed as means to improve bandwidth efficiency. For these systems, knowledge of the channel parameters is required at the receivers for interference cancellation, diversity combining, and decoding, In this paper, we propose a low complexity pilot-symbol-assisted channel estimator for OFDM transmitter diversity systems without a cyclic prefix. The pilot symbols are constructed to be periodic within an OFDM symbol interval in order to avoid ISI and ICI and to be non-overlapping in frequency to allow for the simultaneous sounding of the multiple diversity channels. The time-varying channel responses are then tracked by interpolating a set of estimates obtained through periodically transmitted pilot symbols. The effectiveness and limitations of the proposed estimator are verified by computer simulations.
In this paper we will develop a method to determine cross sections of arbitrary two-dimensional tubular structures, which are allowed to branch, by means of a Stokes flow based boundary integral formulation. The measu...
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In this paper we will develop a method to determine cross sections of arbitrary two-dimensional tubular structures, which are allowed to branch, by means of a Stokes flow based boundary integral formulation. The measure for the cross sections for a point on the boundary of a given structure will be the path obtained by integrating perpendicularly to the flow lines from one side of the boundary to the other. Special emphasis will be put on the behavior at branching points, the behavior at vortices, and the necessary boundary conditions. The method can be extended to three dimensional problems.
In this paper, we use an alternative approach to derive the minimum mean-square error decision feedback equalizer. This derivation yields insight which allows the equalizer to be designed so that its SINR performance ...
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In this paper, we use an alternative approach to derive the minimum mean-square error decision feedback equalizer. This derivation yields insight which allows the equalizer to be designed so that its SINR performance is relatively insensitive to variations in the decision delay (also known as the cursor). The design, while generally applicable to the DFE, is illustrated using 8-level vestigial sideband modulation as used in the ATSC digital television standard. We simulate several channels and show that the SINR varies little across a relatively wide band of decision delays.
The operational six-transistor SRAM cell was experimentally demonstrated using bulk FinFET CMOS technology. A cell size of 0.79 mum(2) was achieved by 90 nm node technology, with stable operation at 1.2 V using 4 leve...
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ISBN:
(纸本)0780378725
The operational six-transistor SRAM cell was experimentally demonstrated using bulk FinFET CMOS technology. A cell size of 0.79 mum(2) was achieved by 90 nm node technology, with stable operation at 1.2 V using 4 levels of W and Al interconnects. Static noise margin of 280 mV was obtained. at V-CC of 1.2 V To our knowledge, this represents the first experimental demonstration of a fully integrated bulk FinFET SRAM cell.
We investigated the effect of rapid thermal annealing (RTA) on the photoluminescence (PL) and elec.roluminescence of the In0.53Ga0.47As/In0.53 (Ga0.6 Al0.4)0.47 As multiple quantum well (MQW) laser structure with InGa...
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We investigated the effect of rapid thermal annealing (RTA) on the photoluminescence (PL) and elec.roluminescence of the In0.53Ga0.47As/In0.53 (Ga0.6 Al0.4)0.47 As multiple quantum well (MQW) laser structure with InGaAlAs barrier layers provided by the digital-alloy technique. The SiO2-(Si3N4-) capped samples followed by the RTA exhibited a significant improvement of PL intensity without any appreciable shifts in PL peak energy for settings of up to 750 °C (800 °C) for 45 s. This improvement is attributed to the annealing of nonradiative defects in InAlAs layers of digital-alloy InGaAlAs and partially those near the heterointerfaces of the digital-alloy layers. The InGaAs/InGaAlAs MQW laser diodes fabricated on the samples annealed at 850 °C show a hugely improved lasing performance.
The problems associated with Linda predicate operations inp() and rdp() are well known but not always well understood. One problem, from a purely academic standpoint, is that of semantic ambiguity in the case of failu...
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ISBN:
(纸本)1892512416
The problems associated with Linda predicate operations inp() and rdp() are well known but not always well understood. One problem, from a purely academic standpoint, is that of semantic ambiguity in the case of failure. Despite this problem, commercial tuple space implementations all provide some version of the Linda predicate operations, and thus, problems concerning safety and liveness arise. Solutions to address these problems range from proposing extensions to an existing model of computation (CSP) to proposing alternative definitions for the Linda predicate operations themselves. While these solutions may at first appear unrelated, it is possible to relate these two disparate approaches in the context of lazy and eager semantics. The benefits of this characterization include a clearer understanding of the Linda predicates ambiguity problem, two respective solutions to this problem, and the importance of considering both lazy and eager semantic perspectives as techniques for problem solving in parallel and distributed systems.
During initialization, discrete multitone receivers train a time domain equalizer (TEQ) to shorten the channel impulse response to a preset length, v + 1. Arslan, Kiaei, and Evans report a Minimum Intersymbol Interfer...
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During initialization, discrete multitone receivers train a time domain equalizer (TEQ) to shorten the channel impulse response to a preset length, v + 1. Arslan, Kiaei, and Evans report a Minimum Intersymbol Interference (Min-ISI) method for TEQ design. Min-ISI TEQs give the highest bit rates among single-FIR TEQs amenable to real-time implementation on programmable fixed-point digital signal processors (DSPs). The Min-ISI method, however, has several disadvantages: (1) sensitivity to transmission delay, (2) inability to design TEQs longer than v + 1 taps, and (3) sensitivity to the fixed-point computation in the Cholesky decomposition. In this paper, we develop an alternate Min-ISI cost function, from which we derive (1) a fast search method for the optimal transmission delay, (2) extensions to design arbitrary-length Min-ISI TEQs, and (3) an iterative Min-ISI method. The iterative Min-ISI method avoids Cholesky decomposition, designs arbitrary length TEQs, and achieves the bit rate performance of the original Min-ISI method.
Sequential patterns discovery is a very important research topic in data mining and knowledge discovery, and it has been widely applied in business analysis. Previous works were focused on mining sequential patterns a...
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ISBN:
(纸本)905809622X
Sequential patterns discovery is a very important research topic in data mining and knowledge discovery, and it has been widely applied in business analysis. Previous works were focused on mining sequential patterns at a single concept level based on definite and accurate concept which may not be concise and meaningful enough for human experts to easily obtain nontrivial knowledge from the rules discovered. In this paper, we introduce concept hierarchies firstly, and then discuss a mining algorithm F-MLSPDA for discovering multiple-level sequential patterns with quantitative attribute based on fuzzy partitions.
In power elec.ronics systems the management of power loss and temperature of switching devices is indispensable for the reliability of the whole system. In this paper, a simple elec.ro-thermal simulation model is pres...
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In power elec.ronics systems the management of power loss and temperature of switching devices is indispensable for the reliability of the whole system. In this paper, a simple elec.ro-thermal simulation model is presented. This simulation model is capable of predicting the power loss and estimating the junction temperature of power device in various environmental conditions. The elec.ro-thermal model is composed of elec.rical network model, semiconductor device model and thermal network model. These parts Interact with each other to calculate the loss and temperature of device and parameters of each model. By focusing on the slow dynamics of heat sink temperature, the proposed model can be employed for the large time-scale simulations. A 200W boost converter using a power MOSFET as an active switch and adopting a natural convection cooling aluminum heat sink as a cooling device was taken as an example system. The experimental results are compared with the predicted values of the simulation model.
This paper presents a new ocean wind vector measurement technique that uses the combined passive and active microwave measurements respectively from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI...
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This paper presents a new ocean wind vector measurement technique that uses the combined passive and active microwave measurements respectively from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and the Precipitation Radar (PR). The wind speed is inferred by TMI over a wide swath that includes the narrower PR swath. The PR scans cross-track ± 18°;and near the swath edges, where the radar backscatter responds to both the magnitude and direction of the surface wind, we use the microwave radiometer estimate of wind speed and the measured sigma-0 at incidence angles greater than 15 degrees to derive wind direction. Because the PR provides only a single azimuth look, multiple possible wind direction solutions exist. The ability to selec. the proper (single) direction is beyond the scope of this paper;but comparisons are presented between the "closest" retrieved TRMM wind vectors and near-simultaneous wind vectors measured by the QuikSCAT satellite scatterometer to demonstrate the potential for measuring ocean surface vector winds.
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