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A frequency reconfigurable patch antenna is dynamically tuned to transmit frequency-shift keying (FSK) signals over a range of frequencies much broader than the static impedance bandwidth of the antenna. Experiments are conducted for two binary FSK schemes having different carrier spacing. In both cases, dynamic tuning of the antenna is shown to increase the amplitude of the radiated signal by providing a better match than the static antenna. However, the average energy of the radiated bit at each carrier frequency decreases as the symbol rate increases beyond the 3 dB bandwidth of the antenna. Therefore, the bandwidth of the antenna is found to be a limiting factor for the maximum achievable data rate in this scheme. As an alternative to shorter bit durations, the authors show that a higher level FSK scheme using dynamic tuning is able to increase throughput beyond what is possible with a static antenna. [ABSTRACT FROM AUTHOR]

A frequency reconfigurable patch antenna is dynamically tuned to transmit frequency‐shift keying (FSK) signals over a range of frequencies much broader than the static impedance bandwidth of the antenna. Experiments are conducted for two binary FSK schemes having different carrier spacing. In both cases, dynamic tuning of the antenna is shown to increase the amplitude of the radiated signal by providing a better match than the static antenna. However, the average energy of the radiated bit at each carrier frequency decreases as the symbol rate increases beyond the 3 dB bandwidth of the antenna. Therefore, the bandwidth of the antenna is found to be a limiting factor for the maximum achievable data rate in this scheme. As an alternative to shorter bit durations, the authors show that a higher level FSK scheme using dynamic tuning is able to increase throughput beyond what is possible with a static antenna. [ABSTRACT FROM AUTHOR]

The working frequency of wireless communication systems will inevitably be developed for the higher‐frequency terahertz (THz) band. An effective way to improve data transmission rates in this band is to adopt higher‐order modulation. However, existing THz wireless communication systems struggle to realise higher‐order modulation and demodulation at high speeds. Baseband digital modulation mixes signals with the same modulation and symbol rate. Different bit streams are sent on the 0.34 THz band and the receiver uses a per‐survivor processing algorithm to separate and demodulate the mixed signal. This doubles the transmission rate of THz data whilst avoiding the problem of modulation and demodulation at high speeds resulting from higher‐order modulation. Both simulation and measured data is used to verify the feasibility of the method. [ABSTRACT FROM AUTHOR]

In many communication channels the noise is non-Gaussian and usually exhibits impulsive characteristics. The symbol rate estimation problem of phase-shift keying (PSK) signals in this kind of impulsive noise environment is addressed. Since the performance of the cyclic statistics-based symbol rate estimation methods, which are very effective in Gaussian noise, may deteriorate significantly in the presence of impulsive noise, a robust method under the cyclostationary framework is proposed. Specifically, a robust form of cyclic autocorrelation based on the M-estimate concept is developed. Simulation results show that the proposed robust technique offers a significant performance gain over the cyclic autocorrelation method in impulsive noise. [ABSTRACT FROM AUTHOR]

Spreading factor (SF) in code-division multiple-access (COMA) systems depends on the data rate of the user, and is, there. fore, unknown a priori for a communication receiver. In this letter, the blind SF-detection problem in an additive while Gaussian noise channel is studied, and a novel one-step autocorrelation-based SF detector is proposed. Three decision rules are derived to find simple and robust SF detectors for practical communication receivers. Performance of the detectors is studied and compared with the optimal detector via Monte Carlo computer simulations. The auto- correlation-based SF detector appears to give performance close to the optimal detector, assuming perfect knowledge of signal-to-noise ratio (SNR). It is also found to be significantly more robust to SNR estimation errors than the optimal detector. [ABSTRACT FROM AUTHOR]

Based on the Monte-Carlo simulation of frequency tolerance and drift parameters in the microwave local multipoint distribution service (LMDS) systems, the relationships among symbol rate, temperature variation, and signal capture probability are investigated. To guarantee 100% probability of signal capture, symbol rate limitations are presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 418–420, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11397 [ABSTRACT FROM AUTHOR]