The Titan Corporation

Young M Kim

William C Lindsey

Successive packets of signals representing data are transmitted at progressive (hopping) frequencies from a controlled (e.g. transmitting) station to a controlling (e.g. receiving) station which processes the signals to recover the data. The frequencies of the signals are selected at the controlling station from a group of frequencies by determining the frequencies in which signals are received by the controlling station from the controlled station at each of the selected frequencies with the highest signal-to-noise ratios. The selection of the frequencies and the prioritization of the selected frequencies for use as the hopping frequencies may be provided once at the beginning of the transmission of data in packets from the controlled station to the controlling station, particularly when the channel conditions are relatively stable. Alternatively, the prioritization may be provided periodically during the transmission of data from the controlled station to the controlling station. The measured rate of errors in each packet at the different selected frequencies can also be used to select particular types of modulations and codings to be provided for the prioritized frequencies. Information relating to the hopping frequencies and the types of the modulations and codes selected by the controlling station are transmitted by the controlling station to the controlled station for use by the controlled station in transmitting data to the controlling station.

System for, and method of, providing frequency hopping

Data at a transmitter is modulated, in accordance with instructions from a receiver, to provide M different modulations in successive sequences. N spreading codes are also provided in successive sequences at the transmitter, in accordance with instructions from the receiver, alternately with the M data modulations. The alternate sequences of the M data modulations and the N spreading codes are paired and individual ones of the M data modulations and the N spreading codes in the paired sequences are combined (e.g. multiplied). Alternatively, an individual one of the M data modulations is combined (e.g. multiplied) with an individual one of the N spreading codes in the adjacent sequence. The modulator and the spreader may be included at the transmitter with (a) a channel encoder which provides channel coding in accordance with instructions from the receiver, (b) a puncturer which removes particular data in accordance with instructions from the receiver and (c) an interleaver. The paired combinations of the individual ones of the M data modulations and the N spreading codes are transmitted to the receiver, which uses correlation or matched filter techniques to recover each combination of the individual one of the data modulations and the individual one of the spreading codes. The recovered data is de-spread in accordance with instructions from the receiver, demodulated in accordance with instructions from the receiver and de-interleaved. The particular data punctured from the sequence is re-inserted and the data is then decoded in accordance with the instructions from the receiver.

System for, method of, transmitting data from a transmitter to a receiver and recovering the data at the receiver

Data at a transmitter is modulated, in accordance with instructions from a receiver, to provide M different modulations in successive sequences. N spreading codes are also provided in successive sequences at the transmitter, in accordance with instructions from the receiver, alternately with the M data modulations. The alternate sequences of the M data modulations and the N spreading codes are paired and individual ones of the M data modulations and the N spreading codes in the paired sequences are combined (e.g. multiplied). The paired combinations of the individual ones of the M data modulations and the N spreading codes are transmitted to the receiver, which uses correlation or matched filter techniques to recover each combination of the individual one of the data modulations and the individual one of the spreading codes. A single spreading code may be used instead of the N spreading codes.

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Young M Kim