Shu-Ming Tseng

Asynchronous multicarrier DS-CDMA using mutually orthogonal complementary sets of sequences

The use of sets of multiple spreading sequences per user in multicarrier code-division multiple-access (CDMA) is investigated. Each user is assumed to have a distinct set of spreading sequences, with a different spreading sequence for each carrier in each users set. We show that when these sets of sequences are chosen to be the mutually orthogonal (MO) complementary sets of sequences, multiple-access interference is minimal on a nonfading channel. As a result of the autocorrelation sidelobe cancellation properties of the MO complementary sequences, it is possible to pack symbols more closely together on the nonfading channel, resulting in a higher data rate than in multicarrier CDMA using the same spreading sequence for each carrier. The resulting communication system scheme results in an easily parallelized receiver architecture that may be useful in nonfading coherent channels, such as the optical fiber channel or the Rician channel with a strong line-of-sight component. On the Rayleigh fading channel, the performance of the system is identical to that of multicarrier CDMA employing a single spreading sequence per user, with only a minimal increase in receiver complexity.

Closed-form four-channel monopulse two-target resolution

A novel closed-form solution to resolve the directions of arrival (azimuth and elevation) of two sources using a single snapshot (monopulse) of four independent channels is presented. Both phase comparison monopulse and amplitude comparison monopulse are solved. Exceptions where the two targets cannot be resolved are also discussed. Numerical simulation result of a practical phased-array configuration validates the effectiveness of the new solution.

Sequential detection for multiuser MIMO CDMA systems with single spreading code per user

We consider multiuser MIMO CDMA systems where each user has multiple transmit antennas and different transmit antennas of the same user use the same spreading code. Because transmit antennas of the same user use the same spreading code, inter antenna interference would degrade the system performance. We propose a novel decision-window-based data detection (sequential detection) method to mitigate the inter antenna interference. We also modify the existing single-user single-antenna channel estimation algorithm for multiuser multiantenna systems. The simulation results show that, under the same channel estimation algorithm, the proposed sequential detection scheme with decision window of two symbols significantly outperforms the non-sequential one which is a special case of the proposed one when the decision window is of one symbol. It also outperforms the existing SIC-VBLAST, decorrelator-VBLAST, and MMSE-VBLAST schemes.

An adaptive partial parallel multistage detection for MIMO systems

The full parallel multistage detection for multiple-input multiple-output systems has less processing delay and better performance than the vertical Bell Laboratories layered space-time detection scheme. However, due to the disadvantage of full parallel interference cancellation, its performance degrades when the received power of the substreams at one receiving antenna is unbalanced and/or when the system is heavily loaded. Therefore, we introduce adaptive partial weighting coefficients into the parallel multistage detection. The weighting coefficients are evaluated using the average decision correct probabilities in the previous stage. The simulation results show that the uncoded error probability of the proposed method is lower than that of the recently proposed full parallel multistage detection scheme with perfect or imperfect channel estimation.

A novel ICI self-cancellation scheme for OFDM systems

We propose a novel intercarrier interference (ICI) self-cancellation scheme for orthogonal frequency division multiplexing (OFDM) systems. The symmetric scheme is the best among all ICI self-cancellation scheme in the literature. Its coefficient pair is (1, − 1), and the loading subcarriers are the kth and N−k − 1th subcarriers, where N is the number of subcarriers. We propose to modify the symmetric scheme and change the coefficient pair from (1, − 1) to (1, −µ) where µis between 0 and 1. The proposed modified symmetric scheme has better carrier-to-interference-ratio (CIR) than all previous ICI self-cancellation schemes by at least 1.7 dB when the normalized frequency offset is 0.5. Copyright

Software Viterbi Decoder with SSE4 Parallel Processing Instructions for Software DVB-T Receiver

In this paper, we discuss the procedures how to make Viterbi decoder faster. The implementation in Intel CPU with SSE4 parallel processing instruction sets and some other methods achieves the decoding speed 47.05 Mbps (0.64 Mbps originally). The DVB-T mode used in Taiwan needs 13.27 Mbps to achieve real-time reception, so our implementation of software Viterbi decoder takes only 28% CPU loading.

GPU-Accelerated Single Image Depth Estimation with Color-Filtered Aperture

There are two major ways to implement depth estimation, multiple image depth estimation and single image depth estimation, respectively. The former has a high hardware cost because it uses multiple cameras but it has a simple software algorithm. Conversely, the latter has a low hardware cost but the software algorithm is complex. One of the recent trends in this field is to make a system compact, or even portable, and to simplify the optical elements to be attached to the conventional camera. In this paper, we present an implementation of depth estimation with a single image using a graphics processing unit (GPU) in a desktop PC, and achieve real-time application via our evolutional algorithm and parallel processing technique, employing a compute shader. The methods greatly accelerate the compute-intensive implementation of depth estimation with a single view image from 0.003 frames per second (fps) (implemented in MATLAB) to 53 fps, which is almost twice the real-time standard of 30 fps. In the previous literature, to the best of our knowledge, no paper discusses the optimization of depth estimation using a single image, and the frame rate of our final result is better than that of previous studies using multiple images, whose frame rate is about 20fps.

A Wireless Based Sensor for Patient Monitoring System with Remote Diagnostic

In this paper, we propose a mobile patient system using common approach sensor platform called the wireless based patient sensor platform (WSP, sensor node) which has remote access capability. The goals of the WSP are to establish: standard sensor node (system on module), a common software .The proposed platform architecture (sensor node) offers flexibility, easy customization for different vital parameter collecting and sending . An prototype has been established based on wireless communication channel. Wireless LAN (IEEE802.11) and WMTS has been used as communication channel on our prototype (sensor node). Desire sensor information(vital parameter) can be viewed remotely, and also vital parameters can be adjusted to meet demand.

A Notebook PC Based Real-Time Software Radio DAB Receiver

This paper introduces a prototype portable software radio research platform for DAB developed by us which consist a USB RF receiver module ,USB interface and a PC based software for device controlling and signal processing. We also add turbo decoding and ICI cancellation to improve the performance due to mobility. In addition, the software radio research platform for DAB can plot the SNR, BER, and spectrum in real time for analysis.

Reed-Solomon decoder optimization for PC-based DVB-T software radio receiver

We use look up tables, SIMD parallel processing instruction sets and loop expansion to implement RS decoder in the Intel CPU platform. Our implementation of Reed-Solomon decoder takes only 1.89% CPU loading.