System and method for enhancing near vertical incidence skywave (“NVIS”) communication using space-time coding

• US 7,885,354 B2
• Filed: 04/02/2004
• Issued: 02/08/2011
• Est. Priority Date: 04/02/2004
• Status: Active Grant

• Current Assignee: Rearden, LLC
• Original Assignee: Rearden, LLC
• Inventors: Cotter, Tim S., Cheponis, Mike, Caimi, Frank M., Perlman, Stephen G.
• Primary Examiner(s): Liu; Shuwang
• Assistant Examiner(s): PATEL, DHAVAL V
• Application Number:
  US10/817,731
• Publication Number:
  US 20050220207A1
• Time in Patent Office: 2,503 Days
• Field of Search: 375/267, 375/299, 375/346, 375/347, 709/200, 455/132
• US Class Current: 375/308
• CPC Class Codes: H04L 1/0618 Space-time coding

Abstract

A system and method are described in which space-time coding techniques are used to transmit and receive multiple data streams within a near vertical incidence skywave (“NVIS”) communication system. Within the NVIS communication system, multiple independent data streams may be transmitted from a transmitting station at a high radiation angle, approaching or reaching 90 degrees. The data streams are reflected off of the ionosphere of the earth and received by one or more receiving stations. In one embodiment, the space-time coding techniques are multiple-input multiple-output (“MIMO”) signal communication techniques.

Claims

1. A method implemented within a near vertical incidence skywave (“

NVIS”

) communication system comprising;

transmitting pilot signals and data signals from a first plurality of directional antennas of a multi-antenna transceiver at near vertical incidence within a frequency range to cause the pilot signals and data signals to reflect off of the ionosphere towards a near vertical incidence skywave (“

NVIS”

) receiver system having a second plurality of directional antennas;

estimating channel state information (“

CSI”

) for the communication channels using the pilot signals, and responsively generating channel characterization data comprising at least N*M components, where N represents a number of the first plurality of directional antennas of the multi-antenna transceiver and M represents a number of the second plurality of directional antennas of the NVIS receiver system, wherein the N antennas of the multi-antenna transceiver are used to communicate with the M antennas on the NVIS receiver system, each of the N*M components defining a gain over each transmission path between each one of the N antennas of the multi-antenna transceiver and each one of the M antennas on the NVIS receiver system;

storing the channel characterization data including the N*M components;

receiving a data stream to be transmitted wirelessly over one or more communication channels in response to a client request;

coding the data stream with space-time coding techniques to create multiple statistically independent pre-coded data streams, wherein coding the data stream with space-time coding techniques comprises using each of the N*M components of the channel characterization data to pre-code each of the data streams prior to transmission from each of the antennas;

mapping each of the pre-coded data streams to a particular antenna of the N directional antennas of the multi-antenna transceiver; and

thereafter transmitting the multiple pre-coded data streams and additional pilot signals from each of the N directional antennas of the multi-antenna transceiver at near vertical incidence within a frequency range to cause the transmitted pre-coded data streams and pilot signals to reflect off of the ionosphere towards the near vertical incidence skywave (“

NVIS”

) receiver system having the M directional antennas;

continuing to measure the characteristics of the communication channels during transmission of the pre-coded data streams on a sub-one second basis to arrive at sub-one-second estimates for CSI and, in response, continually adjusting each of the N*M components of the channel characterization data; and

continually adjusting the coding of the data streams between each one of the N antennas of the multi-antenna transceiver and each one of the M antennas on the NVIS receiver system on a sub-one-second basis based on the continually adjusted N*M components.

2. The method as in claim 1 wherein the space-time coding techniques comprise multiple-input multiple-output (“

MIMO”

) signal communication techniques.

3. The method as in claim 1 further comprising:

retrieving data from a Web server responsive to a user request to retrieve the data; and

providing the data from the Web server to two or more of the multiple data streams.

4. The method as in claim 3 further comprising:

receiving the data from the Web server at a remote NVIS receiving station; and

distributing the data to one or more remote servers and/or clients.

5. The method as in claim 3 wherein the data from the Web server comprises a Web page with embedded links to other Web servers, the method further comprising:

retrieving data from the other Web servers responsive to detecting the embedded links; and

providing the data from the other Web servers to the two or more of the multiple data streams.

6. The method as in claim 1 wherein the space-time coding techniques code the data streams to be statistically independent data streams.

7. The method as in claim 1 wherein the channel state information is stored as a matrix H comprised of separate components measured for each transmit antenna.

8. The method as in claim 1 wherein using each of the N*M components of the channel characterization data to pre-code each of the data streams comprises providing spatial weighting of each of the antennas and/or linear antenna space time precoding.

9. A near vertical incidence skywave (“

NVIS”

) communication system comprising;

a network link to receive a data stream over a network, the data stream to be transmitted wirelessly over one or more communication channels in response to a client request;

a space-time coding module to transmit pilot signals and data signals from a first plurality of directional antennas of a multi-antenna transceiver at near vertical incidence within a frequency range to cause the pilot signals and data signals to reflect off of the ionosphere towards a near vertical incidence skywave (“

NVIS”

) receiver system having a second plurality of directional antennas;

the space time coding module estimating channel state information (“

CSI”

) for the communication channels using the pilot signals, and responsively generating channel characterization data comprising at least N*M components, where N represents a number of the first plurality of directional antennas of the multi-antenna transceiver and M represents a number of the second plurality of directional antennas of the NVIS receiver system, wherein the N antennas of the multi-antenna transceiver are used to communicate with the M antennas on the NVIS receiver system, each of the N*M components defining a gain over each transmission path between each one of the N antennas of the multi-antenna transceiver and each one of the M antennas on the NVIS receiver system;

the space time coding module storing the channel characterization data including the N*M components in a memory;

the space-time coding module to receive a data stream to be transmitted wirelessly over one or more communication channels in response to a client request and to code the data stream using space-time coding techniques to create multiple statistically independent pre-coded data streams, and to use each of the N*M components of the channel characterization data to pre-code each of the data streams prior to transmission from each of the antennas;

the space-time coding module further to map each of the pre-coded data streams to a particular antenna of the N directional antennas of the multi-antenna transceiver; and

thereafter transmit the multiple pre-coded data streams and additional pilot signals from each of the N directional antennas of the multi-antenna transceiver at near vertical incidence within a frequency range to cause the transmitted data streams and pilot signals to reflect off of the ionosphere towards the near vertical incidence skywave (“

NVIS”

) receiver system having the M directional antenna; and

to continue to measure the characteristics of the communication channels during transmission of the pre-coded data streams on a sub-one second basis to arrive at sub-one-second estimates for CSI and to continually adjust each of the N*M components of the channel characterization data; and

to continually adjust the coding of the data streams between each one of the N antennas of the multi-antenna transceiver and each one of the M antennas on the NVIS receiver system on a sub-one-second basis based on the continually adjusted N*M components.

10. The system as in claim 9 wherein the space-time coding techniques comprise multiple-input multiple-output (“

MIMO”

) signal communication techniques and the space-time coding module is a MIMO space-time coding module.

11. The system as in claim 9 wherein one or more of the directional antennae further receive one or more of the multiple data streams reflected from the ionosphere, the one or more of the multiple data streams having previously been transmitted from another NVIS station.

12. The system as in claim 9 further comprising:

a network link communicatively coupling the NVIS communication system to the Internet, the NVIS communication system retrieving data from a Web server over the network link responsive to a user request to retrieve the data; and

providing the data from the Web server to two or more of the multiple data streams.

13. The system as in claim 12 further comprising:

the NVIS receiver system to receive the data from the Web server; and

a second communication link over which the NVIS receiver system distributes the data to one or more remote servers and/or clients.

14. The system as in claim 9 wherein the space-time coding techniques code the data streams to be statistically independent data streams.

15. The system as in claim 9 wherein the channel state information is stored as a matrix H of the N*M components including separate components measured for each transmit antenna.

16. The system as in claim 9 wherein using each of the N*M components of the channel characterization data to pre-code each of the data streams comprises providing spatial weighting of each of the antennas and/or linear antenna space time precoding.

17. An apparatus comprising:

a signal transmitting pipeline having a space-time coding module to transmit pilot signals and data signals from a first plurality of directional antennas of a multi-antenna transceiver at near vertical incidence within a frequency range to cause the pilot signals and data signals to reflect off of the ionosphere towards a near vertical incidence skywave (“

NVIS”

) receiver system having a second plurality of directional antennas, the NVIS receiver system estimating channel state information (“

CSI”

) for the communication channels using the pilot signals, and responsively generating channel characterization data comprising at least N*M components, where N represents a number of the first plurality of directional antennas of the multi-antenna transceiver and M represents a number of the second plurality of directional antennas of the NVIS receiver system, wherein the N antennas of the multi-antenna transceiver are used to communicate with the M antennas on the NVIS receiver system, each of the N*M components defining a gain over each transmission path between each one of the N antennas of the multi-antenna transceiver and each one of the M antennas on the NVIS receiver system;

the space time coding module storing the channel characterization data including the N*M components in a memory;

the space-time coding module to receive a first plurality of data streams to be transmitted wirelessly over one or more communication channels in response to a client request and to encode the first plurality of data streams using space-time coding techniques to create multiple statistically independent pre-coded data streams and to concurrently transmit the multiple statistically independent pre-coded data streams within a common frequency band via a respective plurality of directional antennae over one or more communication channels;

wherein the space-time coding techniques further include using each of the N*M components of the channel characterization data to pre-code each of the data streams prior to transmission from each of the N directional antennas, the N directional antennae to concurrently transmit the first plurality of data streams towards the ionosphere of the earth, the frequency band selected to cause the transmitted data streams to reflect off of the ionosphere, the space-time encoding module including mapping logic to map each of the statistically independent pre-coded data streams to a particular antennae of the N directional antennae prior to transmitting;

wherein the signal transmitting pipeline continues to measure the characteristics of the communication channels during transmission of the pre-coded data streams on a sub-one second basis to arrive at sub-one-second estimates for CSI and continues to adjust each of the N*M components of the channel characterization data and continues to adjust the pre-coding of the data streams between each one of the N antennas of the multi-antenna transceiver and each one of the M antennas on the NVIS receiver system on a sub-one-second basis based on the continually adjusted N*M components; and

a signal receiving pipeline having a space-time decoding module to each of the statistically independent pre-coded data streams within the common frequency band via a respective plurality of directional antennae and to decode each of the statistically independent pre-coded data streams using space-time decoding techniques, the plurality of directional antennae to concurrently receive each of the statistically independent pre-coded data streams from the ionosphere of the earth, the space time decoding module including demapping logic to receive each of the statistically independent pre-coded data streams from a different antennae and to reconstruct a series of consecutive data blocks from each of the statistically independent pre-coded data streams.

18. The apparatus as in claim 17 wherein the space-time encoding module comprises a multiple-input multiple-output (“

MIMO”

) encoding module and wherein the space-time decoding module comprises a MIMO decoding module.

19. The apparatus as in claim 17 further comprising:

a modulator to modulate first data from a first data source to generate the first series of consecutive data blocks using a specified modulation technique; and

a demodulator to demodulate the second series of consecutive data blocks to generate second data using a specified demodulation technique.

20. The apparatus as in claim 19 wherein each of the data blocks in the first series and the second series comprise complex modulation symbols generated by the specified modulation technique.

21. The apparatus as in claim 19 further comprising:

an encoder module to encode the first data from the first data source using specified data encoding techniques prior to the modulator modulating the first data; and

a decoder module to decode the second data demodulated by the demodulator using specified data decoding techniques.

22. The apparatus as in claim 21 wherein one of the specified encoding and decoding techniques comprise Viterbi encoding and decoding, respectively.

23. The apparatus as in claim 22 wherein another of the specified encoding and decoding techniques comprise Reed-Solomon encoding and decoding, respectively.

24. The system as in claim 17 wherein the space-time coding techniques code the data streams to be statistically independent data streams.

25. The system as in claim 17 wherein the channel state information is stored as a matrix H of the N*M components including separate components measured for each transmit antenna.

26. The system as in claim 17 wherein using each of the N*M components of the channel characterization data to pre-code each of the data streams comprises providing spatial weighting of each of the directional antennas and/or linear antenna space time precoding.