Multicarrier frequency hopping communications system
First Claim
1. A multicarrier frequency hopping spread spectrum communications system comprising at least two stations each of which includes a transmitter section and a receiver section, communication between stations being via a communications channel between the transmitter section of one station and the receiver section of another station;
- characterized in that;
the transmitter section of each station comprisesencoding means for encoding data symbols of a signal to be transmitted, the encoding being in accordance with a constellation of code values;
mixing means coupled to said encoding means for assigning samples of the encoded data symbols to particular ones of a predetermined series of fixed carrier frequencies, the frequency assignments being periodically mixed in accordance with a frequency hopping code; and
multiplexing means coupled to said mixing means for combining the samples of encoded data symbols and their assigned carrier frequencies in accordance with an inverse Fourier transform, so as to multiplex the samples of encoded data symbols by an orthogonal frequency division modulation; and
the receiver section of each station comprises;
demultiplexing means for receiving multiplexed samples of encoded data symbols transmitted by the transmitter section of another station, and applying a direct Fourier transform to demodulate by reversing the orthogonal frequency division modulation performed on the samples of encoded data symbols in the transmitter section of said other station;
demixing means coupled to said demultiplexing means for combining the demodulated samples of encoded data symbols in accordance with the inverse of the frequency hopping code employed in the transmitter section of said other station, thereby recovering said samples of encoded data symbols; and
decoding means coupled to said demixing means for decoding the samples of encoded data symbols produced thereby in accordance with the inverse of the constellation of code values employed in the transmitter section of said other station.
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Accused Products
Abstract
A multicarrier frequency hopping spread spectrum communications system wherein a transmitting station assigns encoded data symbols to particular ones of a predetermined series of fixed carrier frequencies, the frequency assignments being periodically mixed according to a frequency hopping code, and the encoded data symbols are combined with their assigned carrier frequencies in accordance with an inverse Fourier transform so as to multiplex the encoded data symbols by orthogonal frequency division modulation. A receiving station performs demultiplexing and de-mixing of such multiplexed signals in accordance with the inverse of the multiplexing and mixing performed at the transmitter. The system thereby provides frequency hopping operation without requiring a rapidly tunable and accurately phase controlled oscillator at each of the transmit/receive stations.
339 Citations
6 Claims
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1. A multicarrier frequency hopping spread spectrum communications system comprising at least two stations each of which includes a transmitter section and a receiver section, communication between stations being via a communications channel between the transmitter section of one station and the receiver section of another station;
- characterized in that;
the transmitter section of each station comprises encoding means for encoding data symbols of a signal to be transmitted, the encoding being in accordance with a constellation of code values; mixing means coupled to said encoding means for assigning samples of the encoded data symbols to particular ones of a predetermined series of fixed carrier frequencies, the frequency assignments being periodically mixed in accordance with a frequency hopping code; and multiplexing means coupled to said mixing means for combining the samples of encoded data symbols and their assigned carrier frequencies in accordance with an inverse Fourier transform, so as to multiplex the samples of encoded data symbols by an orthogonal frequency division modulation; and the receiver section of each station comprises; demultiplexing means for receiving multiplexed samples of encoded data symbols transmitted by the transmitter section of another station, and applying a direct Fourier transform to demodulate by reversing the orthogonal frequency division modulation performed on the samples of encoded data symbols in the transmitter section of said other station; demixing means coupled to said demultiplexing means for combining the demodulated samples of encoded data symbols in accordance with the inverse of the frequency hopping code employed in the transmitter section of said other station, thereby recovering said samples of encoded data symbols; and decoding means coupled to said demixing means for decoding the samples of encoded data symbols produced thereby in accordance with the inverse of the constellation of code values employed in the transmitter section of said other station. - View Dependent Claims (3, 4, 5, 6)
- characterized in that;
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2. A communication system as claimed in 1, wherein said mixing means in the transmitter section and said demixing means in the receiver section each comprise a memory for storing the samples of encoded data symbols and an address generator for producing variable address sequences for said memory;
- the memory in said mixing means being written with the samples of encoded data symbols to be mixed and the memory in said demixing means being written with the samples of encoded data symbols to be demixed;
mixing and demixing being produced by providing a different address sequence for writing the samples of encoded data symbols into said memory than for reading the samples of encoded data symbols therefrom, the address sequence employed determining the applicable frequency hopping code.
- the memory in said mixing means being written with the samples of encoded data symbols to be mixed and the memory in said demixing means being written with the samples of encoded data symbols to be demixed;
Specification