Method and Systems using Quasi-Synchronous Distributed CDD Systems

• US 20180115359A1
• Filed: 10/24/2016
• Published: 04/26/2018
• Est. Priority Date: 10/24/2016
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Kim, Kyeong Jin, Orlik, Philip
• Granted Patent: US 10,063,306 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 19/13 Receivers
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]

Abstract

Systems and methods for a communication system including a set of transmitters, wherein operations of the set of transmitters are synchronized with an accuracy bound by a synchronization error. A controller communicatively connected to each transmitter in the set of transmitters, wherein the controller is configured to: determine a tap delay for a communication channel between a receiver and each transmitter in the set of transmitters to produce a set of tap delays. Determine a minimal length of a cyclic prefix as a function of a sum of the synchronization error and a maximal tap delay in the set of tap delays. Finally, controls at least some transmitters in the set of transmitters to transmit a message to the receiver using a cyclic delay diversity (CDD) with the cyclic prefix having at least the minimal length.

Claims

1. A communication system, comprising:

a cyclic delay diversity (CDD) having a set of spatially distributed cooperating transmitters to transmit a message, wherein operations of the set of transmitters are synchronized with an accuracy bound by a synchronization error; and

a controller communicatively connected to each transmitter in the set of transmitters, wherein the controller is configured to;

determine a tap delay for a communication channel between a receiver and each transmitter in the set of transmitters to produce a set of tap delays;

determine a minimal length of a cyclic prefix as a function of a sum of the synchronization error and a maximal tap delay in the set of tap delays; and

control at least some transmitters in the set of transmitters to transmit the message to the receiver using the CDD with the cyclic prefix having at least the minimal length.

2. The communication system of claim 1, wherein the set of transmitters synchronize the operations by operating on a universal clock at the controller using signals from a global navigation satellite system (GNSS).

3. The communication system of claim 1, wherein the transmitters synchronize the operations using signals from a global navigation satellite system (GNSS), such that the synchronization error is at least in part due to differences in propagation of the signals from the GNSS to different transmitters in the set of transmitters.

4. The communication system of claim 1, wherein the controller is configured to:

determine a delay of transmission for each transmitter in the set of transmitters, based on the minimal length of the cyclic prefix.

6. The communication system of claim 1, wherein the message includes a packet-based Orthogonal Frequency Division Multiplexed (OFDM) transmission from at least two transmitters in the set of transmitters.

7. The communication system of claim 1, wherein at least two transmitters in the set of transmitters include a multimedia transmitting device and the transmitted message includes a packet-based orthogonal frequency division multiplexed (OFDM) transmission including multimedia content.

8. The communication system of claim 1, wherein the set of transmitters are in communication from one of a vehicle-to-X (V2X) communication network, a wireless communication network or a vehicle-infrastructure cooperative automated driving system.

5. (canceled)

9. A method using a cyclic delay diversity (CDD) that includes a set of spatially distributed cooperating transmitters for transmitting a message that is a non-data-aided signal from transmitters in the set of transmitters to a receiver, wherein operations of the transmitters are synchronized with a synchronization error, comprising:

determining a tap delay for each communication channel between the receiver and each transmitter in the set of transmitters to produce a set of tap delays;

determining a minimal length of a cyclic prefix as a function of a sum of the synchronization error and a maximal tap delay in the set of tap delays; and

transmitting the message from at least some transmitters using the CDD with the cyclic prefix having at least the minimal length, wherein steps of the method are performed by a processor.

10. The method of claim 9, wherein the set of transmitters synchronize the operations by operating on a universal clock using signals from a global navigation satellite system (GNSS) at the controller.

11. The method of claim 9, wherein operations of the set of transmitters include synchronizing each transmitter in the set of transmitters by operating on a universal clock using signals from a global navigation satellite system (GNSS).

12. The method of claim 9, further comprising:

determining a delay of transmission for each transmitter in the set of transmitters, based on the minimal length of the cyclic prefix.

13. The method of claim 9, wherein the message includes a packet-based Orthogonal Frequency Division Multiplexed (OFDM) transmission from at least two transmitters in the set of transmitters.

14. The method of claim 9, wherein the processor is configured to:

determine a length of the message;

determine a number of transmitters for transmission of the message, based on the determined length of the message and the minimal length of the cyclic prefix, so as to obtain a maximum number of transmitters for transmission;

select the maximum number of the transmitters from the set of transmitters to form a subset of transmitters, to ensure the maximum reliability at the receiver for transmitting the message; and

determine a delay of transmission for each transmitter in the subset of transmitters, based on the minimal length of the cyclic prefix.

15. A non-transitory computer readable storage medium embodied thereon a program executable by a processor for performing a method, the method is for transmitting a message comprising:

acquiring a synchronization error bounding an accuracy of a synchronization of operations of a set of transmitters,

determining a tap delay for a communication channel between a receiver and each transmitter in the set of transmitters to produce a set of tap delays;

determining a minimal length of a cyclic prefix as a function of a sum of the synchronization error and a maximal tap delay in the set of tap delays;

determine a length of the message, along with a number of transmitters for transmission of the message, and based on the determined length of the message and the minimal length of the cyclic prefix, obtain a maximum number of transmitters for transmission; and

transmitting the message using a cyclic delay diversity (CDD) with the cyclic prefix having at least the minimal length.

16. The method of claim 15, further comprising:

synchronizing the operations by operating on a universal clock using signals from a global navigation satellite system (GNSS).

17. The method of claim 15, further comprising:

determining a delay of transmission for each transmitter in the set of transmitters, based on the minimal length of the cyclic prefix.

18. The method of claim 15, further comprising:

selecting the maximum number of the transmitters from the set of transmitters to form a subset of transmitters, to ensure the maximum reliability at the receiver for transmitting the message; and

determining a delay of transmission for each transmitter in the subset of transmitters, based on the minimal length of the cyclic prefix.

19. The method of claim 15, wherein the message includes a packet-based Orthogonal Frequency Division Multiplexed (OFDM) transmission from at least two transmitters in the set of transmitters.

20. The method of claim 15, wherein the synchronization error is at least in part due to differences in propagation of the signals from the GNSS to different transmitters in the set of transmitters.

21. A communication system, comprising:

a set of transmitters, wherein operations of the set of transmitters are synchronized with an accuracy bound by a synchronization error; and

a controller communicatively connected to each transmitter in the set of transmitters, wherein the controller is configured to;

determine a tap delay for a communication channel between a receiver and each transmitter in the set of transmitters to produce a set of tap delays;

determine a minimal length of a cyclic prefix as a function of a sum of the synchronization error and a maximal tap delay in the set of tap delays;

determine a length of the message;

determine a number of transmitters for transmission of the message, based on the determined length of the message and the minimal length of the cyclic prefix, so as to obtain a maximum number of transmitters for transmission;

select the maximum number of the transmitters from the set of transmitters to form a subset of transmitters based upon a magnitude of channel gains;

determine a delay of transmission for each transmitter in the subset of transmitters, based on the minimal length of the cyclic prefix; and

control at least some transmitters in the set of transmitters to transmit a message to the receiver using a cyclic delay diversity (CDD) with the cyclic prefix having at least the minimal length.