Communications system using adaptive baseband injected pilot carrier symbols and related method

• US 7,664,143 B2
• Filed: 05/01/2007
• Issued: 02/16/2010
• Est. Priority Date: 05/01/2007
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Chester, David B.
• Primary Examiner(s): Nguyen, Brian D
• Application Number:
  US11/742,738
• Publication Number:
  US 20080273555A1
• Time in Patent Office: 1,022 Days
• Field of Search: 370/500, 370/491, 370/206, 370/207, 370/252, 370/332, 370/333, 370/336, 370/338, 370/478
• US Class Current: 370/500
• CPC Class Codes: H04L 1/0004 applied to control information
• CPC Class Codes: H04L 1/0005 applied to payload information
• CPC Class Codes: H04L 1/003 Adaptive formatting arrangements particular to signalling, e.g. variable amount of bits
• CPC Class Codes: H04L 25/0226 sounding signals per se

Abstract

A system, method and apparatus includes a transmitter that has an encoder and baseband modulator that encodes and modulates a sequence of payload data symbols as a signal constellation to be communicated. An amble generator and baseband modulator generates amble symbols as a known sequence of M symbol times in length every N symbol times. A multiplexer multiplexes the data and amble symbols together to form a communications signal that is transmitted over a communications channel.

Claims

1. A system for communicating, comprising:

a transmitter comprising,

an encoder and baseband modulator that encodes and modulates a sequence of payload data symbols as a signal constellation to be communicated;

an amble generator and baseband modulator that generates amble symbols as a known sequence of M symbol times in length, every N symbol times, wherein N defines the periodicity in symbols of the amble and M defines the number of symbols;

a multiplexer that multiplexes the data and amble symbols together to form a communications signal that is transmitted over a communications channel; and

a receiver that receives the communications signal and separates the data symbols from the amble symbols and determines performance metrics such that said transmitter either increases or decreases at least one of the length of the amble or frequency of ambles to bring a performance metric above or below a threshold without changing a symbol rate.

2. The system according to claim 1, wherein said multiplexer comprises a time division multiplexer for time multiplexing the data and amble symbols together.

3. The system according to claim 1, wherein said amble symbols comprise either a different modulation format than the data symbols or a subset of the data symbols.

4. The system according to claim 1, wherein the duration of an amble symbol is the same as a data symbol.

5. The system according to claim 1, wherein the transmitter is operative for transmitting the communications signal such that at the beginning of a transmission of an N symbol sequence the first M symbols are amble symbols and the remaining N-M symbols are data symbols.

6. The system according to claim 1, and further comprising a control channel between the transmitter and receiver that is orthogonal to the communications channel.

7. The system according to claim 1, wherein said receiver further comprises an amble generator for generating a local version of the amble symbols and comparing with received amble symbols to determine dynamics of the communications channel to determine performance metrics of the communications channel.

8. The system according to claim 1, and further comprising a control channel for transmitting control data.

9. An apparatus for transmitting a communications signal, comprising:

an encoder and baseband modulator that encodes and modulates a sequence of payload data symbols as a signal constellation to be communicated;

an amble generator and baseband modulator that generates amble symbols as a known sequence of M symbol times in length, every N symbol times, wherein N defines the periodicity in symbols of the amble and M defines the number of symbols; and

a multiplexer that multiplexes the data and amble symbols together to form a communications signal that is transmitted over a communications channel such that at least one of the length of the amble or frequency of ambles are decreased or increased to bring a performance metric above or below a given threshold without changing a symbol rate.

10. The apparatus according to claim 9, wherein said multiplexer comprises a time division multiplexer for time multiplexing the data symbols and amble symbols together.

11. The apparatus according to claim 9, wherein said amble symbols comprise either a different modulation format than the data symbols or a subset of the data symbols.

12. The apparatus according to claim 9, wherein the duration of an amble symbol is the same as a data symbol.

13. The apparatus according to claim 9, wherein communications signal are transmitted such that at the beginning of a transmission of an N symbol sequence the first M symbols are amble symbols and the remaining N-M symbols are data symbols.

14. The apparatus according to claim 9, and further comprising a control channel for transmitting control data.

15. A method for communicating, which comprises:

generating within an encoder an encoded sequence of payload data symbols as a signal constellation to be communicated;

multiplexing the sequence of data symbols with amble symbols as a known training sequence of M symbol times in length, every N symbol times to form a communications signal that is transmitted along a communications channel, wherein N defines the periodicity in symbols of the amble and M defines the number of symbols; and

either increasing or decreasing at least one of the length of the amble or frequency of ambles based on monitored performance metrics of the communications channel to bring a performance metric above or below a given threshold without changing a symbol rate.

16. The method according to claim 15, which further comprises time multiplexing the sequence of data symbols and amble symbols.

17. The method according to claim 15, which further comprises generating amble symbols with a different modulation format than the data symbols or as a subset of the data symbols.

18. The method according to claim 15, wherein the duration of an amble symbol is the same as a data symbol.

19. The method according to claim 15, which further comprises transmitting the communications signal such that at the beginning of a transmission of an N symbol sequence the first M symbols are amble symbols and the remaining N-M symbols are data symbols.

20. The method according to claim 15, which further comprises transmitting performance metrics along a control channel that is orthogonal to the communications channel.

21. The method according to claim 15, which further comprises receiving the communications signal within a receiver and separating the data symbols from the amble symbols.

22. The method according to claim 21, which further comprises generating a local version of the amble symbols at the receiver and comparing with received amble symbols to determine dynamics of the communications channel to determine performance metrics of the communications channel.

23. The method according to claim 15, which further comprises counting recovered symbols at both a transmitter and receiver for synchronizing changes in amble characteristics.

24. The method according to claim 15, which further comprises embedding control data within payload data to be transmitted.

25. The method according to claim 15, which further comprises monitoring at least one of a signal-to-noise ratio, bit error rate (BER) and packet error rate (PER) as performance metrics.

26. The method according to claim 15, which further comprises encoding the sequence of data signals with a Forward Error Correction (FEC) code.

27. The method according to claim 15, which further comprises baseband modulating the sequence of data symbols.

28. The method according to claim 15, which further comprises transmitting control data along a control channel.