Chen Kang-sheng

Analyzing the interference power of narrowband jamming signal on UWB system

This paper derives the closed form expression for the interference power of narrowband jamming signal on time-hopping ultra-wide bandwidth system with binary pulse position modulation, assuming the jamming signal as a continuous wide sense stationary zero mean random process and the time hopping codes as a pseudorandom sequence. When the bandwidth of the jamming signal is much smaller than the data rate of UWB system, the approximate expression is presented, based on which some design guides for UWB signal parameters selection are given to reduce the interference power when the jamming signal power and the UWB pulse are fixed. Simulations demonstrate all of the analysis.

Using interacting multiple model particle filter to track airborne targets hidden in blind Doppler

In airborne tracking, the blind Doppler makes the target undetectable, resulting in tracking difficulties. In this paper, we studied most possible blind-Doppler cases and summed them up into two types: targets’ intentional tangential flying to radar and unintentional flying with large tangential speed. We proposed an interacting multiple model (IMM) particle filter which combines a constant velocity model and an acceleration model to handle maneuvering motions. We compared the IMM particle filter with a previous particle filter solution. Simulation results showed that the IMM particle filter outperforms the method in previous works in terms of tracking accuracy and continuity.

Multiplexing Chaotic Signals Generated by Colpitts Oscillator and Chua Circuit Using Dual Synchronization

We demonstrate multiplexing chaotic signals generated by two totally different dynamic systems (one is a Colpitts oscillator and the other is a Chua circuit) using dual synchronization and propose a method to select the proper coupling parameters. In the response systems, the cross coupling method is used, in which the voltage difference between the sum of two master oscillators and one slave oscillator is converted to current and then feed into the other slave oscillator. The result in this letter offers a potential multiuser coherent chaotic communication scheme where different chaotic oscillators can be used in one system.

A random sequence generator based on chaotic circuits

In this paper, a random sequence generator based on chaotic circuits is presented. Fundamental principle and experimental circuit have been carried out in case of Chua’s circuit. The statistical results are in good agreement with probability characteristics of random sequence.

A novel technique fast optimizing the layout parameters of planar spiral inductor

Based on the physical model of planar spiral inductor and the closed-form inductance expression proposed by Jenei etc., this paper develops a novel technique fast optimizing the layout parameters of spiral inductor. It has been shown Jeneis formula is more accurate than the closed-form formulas presented before, and this paper further demonstrates that Jeneis formula can yield a speed about two magnitude order faster than GreenHouse method with a comparable accuracy. Mathematical analysis of Jeneis formula immediately leads to the derivation of BSA to search out all layout parameters satisfying constraints quickly, then the set with the highest Q can be identified. Experiments show that BSAs searching speed is about three magnitude order faster than the incremental searching algorithm based on GreenHouse method, while the accuracy of both algorithms are similar. The efficiency and accuracy of the optimizing technique are demonstrated by experiments.Based on the physical model of planar spiral inductor and the closed-form inductance expression proposed by Jenei etc., this paper develops a novel technique fast optimizing the layout parameters of spiral inductor. It has been shown Jeneis formula is more accurate than the closed-form formulas presented before, and this paper further demonstrates that Jeneis formula can yield a speed about two magnitude order faster than GreenHouse method with a comparable accuracy. Mathematical analysis of Jeneis formula immediately leads to the derivation of BSA to search out all layout parameters satisfying constraints quickly, then the set with the highest Q can be identified. Experiments show that BSAs searching speed is about three magnitude order faster than the incremental searching algorithm based on GreenHouse method, while the accuracy of both algorithms are similar. The efficiency and accuracy of the optimizing technique are demonstrated by experiments.

The encoder/decoder based on parallel FBGs in optical CDMA system

The authors put forward the encoder/decoder based on parallel fiber Bragg gratings (FBGs) in an optical code division multiple access (OCDMA) system, and their principles are analyzed by transfer function theory. With these devices, we design a direct sequence (DS) version of the OCDMA system. The simulation result is given, as well as the power efficiency of the system, maximum data bit rate and bit error rate (BER) are investigated.

Robust Time Synchronization Scheme Combating Frequency Offset for IEEE 802.16a OFDM Systems

Orthogonal frequency division multiplexing (OFDM) is a promising technology for the next generation high-speed wireless communication. However, carrier frequency offset (CFO) induced by Doppler frequency drift and mismatch of the transceivers oscillators influences the time synchronization for OFDM systems. In this paper a robust time synchronization scheme compatible to IEEE 802.16a specification is proposed. It uses the symmetrical cross-correlation structure to eliminate the impact of frequency offset totally and to capture the accurate starting position of the FFT windows rapidly. Computer simulations demonstrate that the synchronization scheme is very efficient in combating large CFO

Hybrid direct sequence/frequency hopping encoding/decoding for optical CDMA system using FBGs

A hybrid direct sequence/frequency hopping (DS/FH) scheme is proposed for an optical code division multiple access (OCDMA) system. The optical encoder/decoder with prime-hop codes is based on fiber Bragg gratings (FBGs), and double optical hard-limiters are placed on both sides of decoder respectively. With such a design, the OCDMA system has large number of simultaneous user, high power efficiency and low bit error rate (BER). Furthermore, we apply a new method to calculate the precise BER of the system.

Rotary traveling-wave oscillator design using 0.18 μm CMOS

A rotary traveling-wave oscillator (RTWO) targeted at 5.8 GHz band operation is designed and fabricated using standard 0.18 μm CMOS technology. Both simulation and measurement results are presented. The chip size including pads is 1.5 × 1.5 mm2. The measured output power at a frequency of 5.285 GHz is 6.68 dBm, with a phase noise of −102 dBc/Hz at 1 MHz offset from the carrier.

Theoretical study on THz components and systems

The photonic bands and gaps in photonic crystal make possible to fabricate several applications in THz components and systems. The dispersion relations, transmission relations, and electromagnetic field distribution have been studied for several photonic crystal structures, such as waveguide, resonance cavity, splitter, filter, switch and so on. The main characteristics of these components and systems are discussed and the computer simulation results are given. THz components based on photonic crystal with these structures are presented.