System and method for two-dimensional equalization in an orthogonal time frequency space communication system
A system and method for receiving communication signals that have been spread in two dimensions. The method includes receiving signals representative of data that has been two-dimensionally spread and transmitted over a communication channel. The method further includes processing the signals to determine equalization coefficients based upon a two-dimensional [time-frequency] impulse response of the communication channel. A two-dimensional signal equalization procedure is then performed using the equalization coefficients.
1. A communication device, comprising:
an antenna;
a receiver configured to:
receive, from the antenna, signals representative of data that has been two-dimensionally spread and transmitted over a communication channel;
process the signals to determine equalization coefficients based upon a two-dimensional impulse response of the communication channel;
perform a two-dimensional signal equalization procedure using the equalization coefficients; and
a transmitter configured to:
receive a stream of input data;
generate two-dimensionally pre-equalized data;
transmit the pre-equalized data;
wherein the transmitter is further configured to generate the two-dimensionally pre-equalized data by pre-equalizing the input data in accordance with corrective information relating to echo reflections and frequency shifts present within the communication channel.
2. The communication device of claim 1 wherein the equalization coefficients include a plurality of feedforward equalization coefficients and a plurality of feedback equalization coefficients.
3. A method of receiving communication signals, the method comprising:
receiving signals representative of data that has been two-dimensionally spread and transmitted over a communication channel;
processing the signals to determine equalization coefficients based upon a two-dimensional impulse response of the communication channel;
performing a two-dimensional signal equalization procedure using the equalization coefficients;
receiving a stream of input data;
generating two-dimensionally pre-equalized data; and
transmitting the pre-equalized data;
wherein the generating includes pre-equalizing the input data in accordance with corrective information relating to echo reflections and frequency shifts present within the communication channel.
4. The method of claim 3 wherein the equalization coefficients include a plurality of feedforward equalization coefficients and a plurality of feedback equalization coefficients.
5. A communication device, comprising:
an antenna arrangement; and
a transmitter configured to:
receive a stream of input data;
generate two-dimensionally pre-equalized data by pre-equalizing the input data in accordance with corrective information relating to echo reflections and frequency shifts present within a communication channel;
transmit the pre-equalized data.
6. The communication device of claim 5 further including a receiver configured to receive, from the antenna, signals representative of data that has been two-dimensionally spread and transmitted over the communication channel.
7. A method of providing a modulated signal useable in a signal transmission system, the method comprising:
transforming a data frame including a plurality of data elements into a two-dimensionally spread data matrix by performing a spreading operation wherein the spread data matrix includes at least N rows and at least M columns, where N and M are positive, non-zero integers greater than one and wherein the transforming includes performing a Fast Fourier Transform (FFT) operation with respect to the plurality of data elements and multiplying a result of the FFT operation in accordance with a Fourier mask;
filtering each of the at least N rows of the spread data matrix using a filter bank; and
generating the modulated signal in accordance with results of the filtering.
8. The method of claim 7 wherein the transforming includes spreading the plurality of data elements by performing a two-dimensional cyclic convolution using a spreading kernel.
9. The method of claim 7 wherein the transforming further includes performing a convolution implemented using a two-dimensional Fast Fourier Transform (FFT).