Abstract: Data transmission is disclosed over a transmission channel that is subject to narrowband interferers. An increased overall bit or data transmission rate is achieved by an exemplary method of determining a channel capacity of plural sub-channels of the transmission channel based on a net background noise power estimation. The net background noise power contains only white noise-like contributions and excludes, to a reasonable extent, noise contributions or signal power from narrowband interferers. Hence, the net background noise power can be reduced. For example, an Orthogonal Frequency Division Multiplex (OFDM) signal code construction or bit allocation scheme can be chosen that provides for optimized data transmission at a data rate that approximates or approaches the more realistic channel capacity of an individual sub-channel, resulting in an increased overall bit or data transmission rate.

Abstract: Data transmission is disclosed over a transmission channel that is subject to narrowband interferers. An increased overall bit or data transmission rate is achieved by an exemplary method of determining a channel capacity of plural sub-channels of the transmission channel based on a net background noise power estimation. The net background noise power contains only white noise-like contributions and excludes, to a reasonable extent, noise contributions or signal power from narrowband interferers. Hence, the net background noise power can be reduced. For example, an Orthogonal Frequency Division Multiplex (OFDM) signal code construction or bit allocation scheme can be chosen that provides for optimized data transmission at a data rate that approximates or approaches the more realistic channel capacity of an individual sub-channel, resulting in an increased overall bit or data transmission rate.

Abstract: The present invention relates to a method for encrypting digital information using communication devices, which have an interface for a replaceable or writable storage medium, whose content may be read out and duplicated, having a storage medium which is connected to the interface, a supply of symbols for encryption being stored on the digital storage medium, which may be read out on the basis of an address, having an encryption unit which employs the supply of symbols for encrypting and/or decrypting the digital data stream of the communication device on the basis of at least one address.

Abstract: A method for frequency and time synchronization of a receiver for receiving Orthogonal Frequency Division Multiplexing (OFDM) signals is described. A quality criterion of a OFDM signal is determined during one of the frequency intervals (hops) for each point of one of the two-dimensional frequency and time search areas. The area point having the optimum quality criterion (?x, fx) of the OFDM signal is then determined on the basis of said quality criterion, and the receiver is synchronized on the nominal frequency in view of the different between the nominal frequency (f0) and the frequency value (fx) corresponding to the optimum quality criterion. The OFDM signal may be demodulated and decoded starting with the time value (?x) corresponding to the optimum quality criterion.

Abstract: The invention relates to a system for transmitting data according to the frequency hopping method. The digital data, which is transmitted in suddenly changing transmission frequency hops, is encoded according to a woven code consisting of an interlinked external and internal convolution code. The data to be transmitted by hop is preferably distributed over several parallel hops sent with different frequencies.

Abstract: The invention relates to a frequency and time synchronization of a receiver (E) for receiving OFDM signals on a fixed carrier frequency. The inventive method is characterized by determining in a first step the approximate nominal value of the frequency and of the time origin of the OFDM signal via a two-dimensional frequency-time search mode and the determination of the area point with the optimum quality criterion of the OFDM signal or via the evaluation of a synchronization sequence transmitted by the transmitter. In a subsequent second step the phase of at least one of the pilot signals transmitted together with the OFDM signal is determined in the receiver (E) and is averaged across several OFDM signal blocks; and a more exact nominal value of the frequency and of the time origin of the OFDM signal is determined therefrom. The receiver (E) is then synchronized to the frequency so determined and the OFDM signal is demodulated with the time origin value so determined.

Abstract: The invention relates to a method for the frequency and time synchronisation of a receiving OFDM signals. A quality criterion of the OFDM signal is determined during one of the frequency intervals (hops) for each point of one of the two-dimensional frequency and time search areas. The area point having the optimum quality criterion (&tgr;x,x) of the OFDM signal is then determined on the basis of said quality criterion, and the receiver is synchronised on the nominal frequency in view of the difference between the nominal frequency (fo) and the frequency value (fx) corresponding to the optimum quality criterion. The OFDM signal is demodulated and decoded starting with the time value (&tgr;x) corresponding to the optimum quality criterion.

Abstract: The invention relates to a system for transmitting data according to the frequency hopping method. The digital data, which is transmitted in suddenly changing transmission frequency hops, is encoded according to a woven code consisting of an interlinked external and internal convolution code. The data to be transmitted by hop is preferably distributed over several parallel hops sent with different frequencies.