Peter F. Driessen

Simulation results for an interference-limited multiple-input multiple-output cellular system

We describe a simulation study of a cellular system using multiple-input multiple-output (MIMO) antenna techniques along with adaptive modulation and aggressive frequency reuse. We show for the case of 3 transmit and 3 receive antennas, how much MIMO systems outperform systems with receive-diversity-only when noise dominates. When co-channel interference from surrounding cells dominates, the differences shrink, as do the absolute numbers. We quantify these reductions for the specific cases studied, and discuss further areas of research.

Data throughputs using multiple-input multiple-output (MIMO) techniques in a noise-limited cellular environment

We present a general framework to quantify the data throughput capabilities of a wireless communication system when it combines: (1) multiple transmit signals; (2) adaptive modulation for each signal; and (3) adaptive array processing at the receiver. We assume a noise-limited environment, corresponding to either an isolated cell or a multicell system whose out-of-cell interference is small compared with the thermal noise. We focus on the user data throughput, in bits per second/Hertz (bps/Hz), and its average over multipath fading, which we call the user spectral efficiency. First, an analysis method is developed to find the probability distribution and mean value of the spectral efficiency over the user positions and shadow fadings, both as a function of user distance from its serving base station and averaged over the cell coverage area. We assume fading conditions and receiver processing that lend themselves to closed-form analysis. The resulting formulas are simple and straightforward to compute, and they provide a number of valuable insights. Next, we run Monte Carlo simulations, both to confirm the analysis and to treat cases less amenable to simple analysis. A key contribution of this paper is a simple formula for the mean spectral efficiency in terms of the propagation exponent, mean signal-to-noise ratio at the cell boundary, number of antennas, and type of coding. Under typical propagation conditions, the mean spectral efficiency using three transmit and three receive antennas ranges from 19.2 bps/Hz (uncoded) to 26.8 bps/Hz (ideally coded), highlighting the potential benefits of multiple transmissions combined with adaptive techniques. This is much higher than the spectral efficiencies for a link using a single transmitter and a threefold receive diversity under the same conditions, where the range is from 8.77 bps/Hz to 11.4 bps/Hz. Moreover, the latter results are not nearly as practical to achieve, as they can for large signal constellations that would be highly vulnerable to impairments.

Gesture-Based affective computing on motion capture data

This paper presents research using full body skeletal movements captured using video-based sensor technology developed by Vicon Motion Systems, to train a machine to identify different human emotions. The Vicon system uses a series of 6 cameras to capture lightweight markers placed on various points of the body in 3D space, and digitizes movement into x, y, and z displacement data. Gestural data from five subjects was collected depicting four emotions: sadness, joy, anger, and fear. Experimental results with different machine learning techniques show that automatic classification of this data ranges from 84% to 92% depending on how it is calculated. In order to put these automatic classification results into perspective a user study on the human perception of the same data was conducted with average classification accuracy of 93%.

Attainable throughput of an interference-limited multiple-input multiple-output (MIMO) cellular system

We investigate the high spectral efficiency capabilities of a cellular data system that combines the following: 1) multiple transmit signals, each using a separately adaptive modulation; 2) adaptive array processing at the receiver; and 3) aggressive frequency reuse (reuse in every cell). We focus on the link capacity between one user and its serving base station, for both uncoded and ideally coded transmissions. System performance is measured in terms of average data throughput, where the average is over user location, shadow fading, and fast fading. We normalize this average by the total bandwidth, call it the mean spectral efficiency, and show why this metric is a useful representation of system capability. We then quantify it, using simulations, to characterize multiple-input multiple-output systems performance for a wide variety of channel conditions and system design options.

Simulation results for an interference-limited multiple input multiple output cellular system

We describe a simulation study of a cellular system using multiple-input multiple-output (MIMO) antenna techniques along with adaptive modulation and aggressive frequency reuse. We show for the case of 3 transmit and 3 receive antennas, how much MIMO systems outperform systems with receive-diversity-only when noise dominates. When co-channel interference from surrounding cells dominates, the differences shrink, as do the absolute numbers. We quantify these reductions for the specific cases studied, and discuss further areas of research.We describe a simulation study of a cellular system using multiple-input multiple-output (MIMO) antenna techniques along with adaptive modulation and aggressive frequency reuse. We show, for the case of 3 transmit and 3 receive antennas, how much MIMO systems outperform systems with receive-diversity-only when noise dominates. When co-channel interference from surrounding cells dominates, the differences shrink, as do the absolute numbers. We quantify these reductions for the specific cases studied, and discuss further areas of research.

DPLL bit synchronizer with rapid acquisition using adaptive Kalman filtering techniques

A second-order DPLL with time-varying loop gains is applied to the symbol synchronization of burst mode data signals. An algorithm to control the DPLL loop gains is derived from adaptive Kalman filtering theory. Simulation results for the variable gain DPLL compared to a fixed gain DPLL demonstrate the improved acquisition performance. >

Class-B Microwave-Photonic Link Using Optical Frequency Modulation and Linear Frequency Discriminators

A class-B optical link is demonstrated as a means to provide high spur-free dynamic-range (110.4 dBmiddotHz2/3) with a minimum average received power associated with the optical carrier. The link uses optical frequency modulation, linear fiber-Bragg-grating frequency discriminators, and balanced detection to provide high linearity and maximum signal power. Shot and intensity noises are minimized by the low total average received photocurrent (0.88 mA) that results from class-B operation

Link adaptation and power control for streaming services in EGPRS wireless networks

Using the MPEG-4 advanced audio coder (AAC) music as an example of streaming applications, we investigate the improvement of error performance for the streaming service by link adaptation and power control techniques in an enhanced general packet radio services (EGPRS) cellular network. A low packet error rate and variability are essential in providing a short error-burst length so that error concealment techniques can be effectively applied to music packets. We study the effects of a combined link adaptation and power control scheme (referred to as the error-based scheme) for achieving a target error rate and reducing error variability. By simulation, we compare the error performance of the error-based scheme at both the EGPRS block and AAC frame level with another adaptation algorithm (referred to as the throughput-based scheme) with a goal of maximizing overall network throughput. It is found that when offered with a similar traffic load, the former scheme can provide noticeable improvement of music quality over the throughput-based scheme. To achieve a similar AAC frame error rate, our results also show that the error-based scheme can increase the link throughput over the throughput-based scheme by 66.7% in one of our examples. These results reveal that by aiming at required error targets and thus reducing error variability, the error-based scheme for link adaptation and power control are helpful in improving quality and capacity for streaming applications.

Class-AB techniques for high-dynamic-range microwave-photonic links

Class-AB techniques are analyzed as a means to minimize the noise associated with the residual carrier in analog optical links. A bound for shot and intensity noise is derived and compared to previously reported measurements. It is found that for an ideal modulator transfer function (Class B), a substantial improvement in shot-noise limited spur-free dynamic range (e.g., 11.7 dB at 10% modulation) can be realized.

Prediction of multipath delay profiles in mountainous terrain

Measurements of the complex impulse response of 900 MHz radio channels in mountainous terrain in British Columbia, Canada, are used to quantify values for the normalized scattering cross section /spl sigma//sup 0/ for mountains covered with evergreen trees. The bistatic radar equation is then used in a propagation model to predict characteristics of the impulse response in similar terrain from topographical data. Three-dimensional (3-D) propagation models for mountainous areas are important, because such areas stress to the limit the multipath handling capabilities of most air interfaces. /spl sigma//sup 0/ is related to a more fundamental characteristic /spl gamma/ of the surface via Lamberts law. The measured value of /spl gamma/ is -21.1 /spl plusmn/2.9 dB, which is similar to some of the very few other values found in the literature. Using this value of /spl gamma/, the predicted multipath delay profiles correspond well with measurements. The results can be used to predict complex impulse responses in mountainous terrain which may be convolved with a simulated data stream to predict error rate, outage or other aspects of wireless system performance.