Dispersion compensation in mm-wave communication over plastic waveguide using OFDM
A millimeter-wave communication system includes a transmitter and a receiver. The transmitter is configured to be connected to a waveguide that is transmissive at millimeter-wave frequencies, the waveguide having a propagation parameter that varies with frequency at the millimeter-wave frequencies. The transmitter is configured to generate a millimeter-wave signal comprising multiple sub-carriers that are modulated with data, wherein each sub-carrier is modulated with a respective portion of the data and is subjected to only a respective fraction of a variation in the propagation parameter, and to transmit the millimeter-wave signal into a first end of the waveguide. The receiver is configured to receive the millimeter-wave signal from a second end of the waveguide, and to extract the data from the multiple sub-carriers.
1. A millimeter-wave communication system in an automobile, comprising:
a transmitter in the automobile, configured to be connected to a first end of a plastic waveguide in the automobile that is transmissive at millimeter-wave frequencies, the plastic waveguide having a propagation parameter dominated by waveguide dispersion and that varies with frequency at the millimeter-wave frequencies, the transmitter configured to generate a millimeter-wave signal comprising multiple sub-carriers that are modulated with data, wherein each sub-carrier is modulated with a respective portion of the data and is subjected to only a respective fraction of a variation in the propagation parameter, wherein a number of the subcarriers is defined by the waveguide dispersion of the plastic waveguide and a carrier frequency offset of the transmitter, and to transmit the millimeter-wave signal into the first end of the plastic waveguide; and
a receiver in the automobile, configured to be connected to a second end of the plastic waveguide in the automobile, to receive the millimeter-wave signal from the second end of the plastic waveguide, and to extract the data from the multiple sub-carriers;
wherein a channel estimation dynamically estimates a channel response of the plastic waveguide and of in-line connectors in response to mechanical vibrations in the automobile, wherein the plastic waveguide is connected between the transmitter and the receiver and the in-line connectors connect multiple plastic waveguide sections of the plastic waveguide, wherein an adaptive equalizer compensates the estimated channel response of the plastic waveguide and the in-line connectors based on the channel estimation, and wherein a duration of a payload packet of the millimeter-wave signal is selected to be less than a coherence time of the plastic waveguide.
2. The millimeter-wave communication system according to claim 1 , wherein the variation in the propagation parameter causes a delay spread, and wherein the transmitter is configured to generate the millimeter-wave signal with guard intervals that are larger than the delay spread.
3. The millimeter-wave communication system according to claim 1 , wherein the transmitter is configured to modulate the data onto the sub-carriers using Orthogonal Frequency Division Multiplexing (OFDM).
4. The millimeter-wave communication system of claim 3 , wherein the data comprises OFDM symbols and no prefix is added between the OFDM symbols.
5. The millimeter-wave communication system of claim 3 , wherein a spacing between adjacent subcarriers is greater than the carrier frequency offset.
6. The millimeter-wave communication system according to claim 1 , wherein the propagation parameter comprises a propagation velocity at the millimeter-wave frequencies, and wherein the transmitter is configured to generate the millimeter-wave signal with each sub-carrier subjected to only a respective fraction of the variation in the propagation velocity.
7. The millimeter-wave communication system according to claim 1 , wherein the propagation parameter comprises a complex gain at the millimeter-wave frequencies, and wherein the transmitter is configured to generate the millimeter-wave signal with each sub-carrier subjected to only a respective fraction of the variation in the complex gain.
8. The millimeter-wave communication system according to claim 7 , wherein the receiver is configured to extract the data from the multiple sub-carriers while compensating for variations in the complex gain caused by the one or more in-line connectors.
9. The millimeter-wave communication system according to claim 7 , changed to wherein the receiver comprises the adaptive equalizer that is configured to compensate for variations in the complex gain.
10. The millimeter-wave communication system of claim 1 , wherein the waveguide dispersion defines a subcarrier bandwidth.
11. A method for millimeter-wave communication in an automobile, comprising:
in a transmitter in the automobile, which is connected to a first end of a plastic waveguide in the automobile that is transmissive at millimeter-wave frequencies, the plastic waveguide having a propagation parameter dominated by waveguide dispersion that varies with frequency at the millimeter-wave frequencies, generating a millimeter-wave signal comprising multiple sub-carriers that are modulated with data and, wherein each sub-carrier is modulated with a respective portion of the data and is subjected to only a respective fraction of a variation in the propagation parameter, wherein a number of the subcarriers is defined by the waveguide dispersion of the plastic waveguide and a carrier frequency offset of the transmitter, and transmitting the millimeter-wave signal into the first end of the waveguide; and
in a receiver in the automobile, which is connected to a second end of the plastic waveguide in the automobile, receiving the millimeter-wave signal and extracting the data from the multiple sub-carriers;
wherein a channel estimation dynamically estimates a channel response of the plastic waveguide and of in-line connectors in response to mechanical vibrations in the automobile, wherein the plastic waveguide is connected between the transmitter and the receiver and the in-line connectors connect multiple plastic waveguide sections of the plastic waveguide, wherein an adaptive equalizer compensates the estimated channel response of the plastic waveguide and the in-line connectors based on the channel estimation, and wherein a duration of a payload packet of the millimeter-wave signal is selected to be less than a coherence time of the plastic waveguide.
12. The method according to claim 11 , wherein the variation in the propagation parameter causes a delay spread, and wherein generating the millimeter-wave signal comprises inserting in the millimeter-wave signal guard intervals that are larger than the delay spread.
13. The method according to claim 11 , wherein generating the millimeter-wave signal comprises modulating respective portions of the data onto the sub-carriers using Orthogonal Frequency Division Multiplexing (OFDM).
14. The method of claim 13 , wherein the data comprises OFDM symbols and no prefix is added between the OFDM symbols.
15. The method of claim 13 , wherein a spacing between adjacent subcarriers is greater than the carrier frequency offset.
16. The method according to claim 11 , wherein the propagation parameter comprises a propagation velocity at the millimeter-wave frequencies, and wherein generating the millimeter-wave signal comprises subjecting each sub-carrier to only a respective fraction of the variation in the propagation velocity.
17. The method according to claim 11 , wherein the propagation parameter comprises a complex gain at the millimeter-wave frequencies, and wherein generating the millimeter-wave signal comprises subjecting each sub-carrier to only a respective fraction of the variation in the complex gain.
18. The method according to claim 17 , wherein extracting the data comprises compensating for variations in the complex gain caused by the one or more in-line connectors.
19. The method according to claim 17 , wherein extracting the data comprises compensating for variations in the complex gain using the adaptive equalizer.
20. The method of claim 11 , wherein the waveguide dispersion defines a subcarrier bandwidth.