Abstract: In the invention, a simple and robust method for clock offset compensation is proposed using an equalizer with time-varying signal windowing for which the timing information needed is obtained by an existing non-data-aided (NDA) timing estimator. Instead of interpolating the received signal, the proposed method compensates clock offset by using a moving signal window for equalizer. Since no interpolation is needed, the timing information required for the proposed method need not be so accurate as required for interpolation methods. Rather than the exact time drift due to clock offset, the proposed method requires only the timing points where the time drift accumulates to a pre-defined threshold. By applying an existing non-data-aided (NDA) timing estimator, the needed timing information can be obtained easily. Moreover, thanks to robustness of the NDA timing estimator, the proposed method is inherently robust and simple in implementation.

Abstract: A signal detection method with high detection probability and low false alarm rate is provided for spread spectrum communication systems. The method includes steps of a) receiving discrete-time input signal, b) converting the input signal into a correlator output signal with finite number of values, c) selecting a maximum value and a minimum value from the magnitude of values, respectively, d) dividing the maximum value by the minimum value for obtaining an enhanced peak value of the correlator output signal, and e) comparing the enhanced peak value of the correlator output signal with a predetermined threshold, wherein the input signal is detected as a spread spectrum signal if the enhanced peak value of the correlator output signal is greater than or equal to the predetermined threshold, whereas the input signal is not detected as a spread spectrum signal if the enhanced peak value of the correlator output signal is less than the predetermined threshold.

Abstract: The encryption/decryption device of the present invention comprises a first encryption/decryption table, and electrically connects a host with a second encryption/decryption table. The content of the first and the second encryption/decryption table comprises a station identifier field, an encryption/decryption algorithm identifier field and a key field for encrypting/decrypting the frames transmitted from or to the station. The encryption/decryption device comprises a data receiving unit, a data transmitting unit, a hardware encryption/decryption unit, a first checking unit and a second checking unit. The hardware encryption/decryption unit will encrypt/decrypt a frame if it can do so, or the encryption/decryption of the frame will be performed by the host.