ENERGY EFFICIENCY IN WIRLESS COMMUNICATION SYSTEMS

• US 20110255571A1
• Filed: 04/20/2010
• Published: 10/20/2011
• Est. Priority Date: 04/20/2010
• Status: Active Grant

• Current Assignee: TRIAD National Security, LLC
• Original Assignee: Los Alamos National Security LLC (Government of the United States of America)
• Inventors: Caffrey, Michael Paul, Palmer, Joseph McRae
• Granted Patent: US 8,331,417 B2
• Time in Patent Office: Days
• US Class Current: 375/141
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2201/70703 using multiple or variable rates

Abstract

Wireless communication systems and methods utilize one or more remote terminals, one or more base terminals, and a communication channel between the remote terminal(s) and base terminal(s). The remote terminal applies a direct sequence spreading code to a data signal at a spreading factor to provide a direct sequence spread spectrum (DSSS) signal. The DSSS signal is transmitted over the communication channel to the base terminal which can be configured to despread the received DSSS signal by a spreading factor matching the spreading factor utilized to spread the data signal. The remote terminal and base terminal can dynamically vary the matching spreading factors to adjust the data rate based on an estimation of operating quality over time between the remote terminal and base terminal such that the amount of data being transmitted is substantially maximized whilst providing a specified quality of service.

Claims

1. A wireless communication system comprising:

at least one remote terminal;

at least one base terminal; and

a communication channel between said at least one remote terminal and said at least one base terminal;

wherein said remote terminal is configured to;

apply a direct sequence spreading code to a data signal at a spreading factor to provide a direct sequence spread spectrum (DSSS) signal; and

transmit said DSSS signal over said communication channel to said base terminal;

wherein said base terminal is configured to;

receive said DSSS signal from said remote terminal;

despread said received DSSS signal by a spreading factor matching said spreading factor utilized to spread the data signal; and

wherein said remote terminal and said base terminal are configured to;

dynamically vary the matching spreading factors to adjust the data rate based on an estimation of operating quality over time between the remote terminal and base terminal such that the amount of data being transmitted is substantially maximized whilst providing a specified quality of service.

2. The system of claim 1, further comprising a back channel between said remote terminal and said base terminal;

wherein said base terminal is further configured to dynamically;

monitor said received DSSS signal to estimate said operating quality over time;

determine if said estimated operating quality has exceeded a limit of a quality margin;

in response to said estimated operating quality exceeding said quality margin limit, estimate a next data transmission rate that is sufficient to provide an operating quality within said quality margin such that said specified quality of service is met for said next data rate;

send a command over said back channel to said remote terminal for adjusting the spreading factor to adjust to the next data rate; and

wherein said remote terminal and said base terminal are configured to dynamically adjust said matching spreading factors to adjust the data rate to the next data rate such that said operating quality is maintained within said quality margin thereby maintaining said specified quality of service.

3. The system of claim 2, wherein said base terminal is further configured to:

determine said operating quality has exceeded a minimum threshold of said quality margin;

determine a lower data transmission rate that is sufficient for providing an operating quality within said quality margin to meet said specified quality of service in response to said operating quality exceeding said minimum threshold;

transmit to said remote terminal over said back channel an increase spreading factor command for commanding said remote terminal to increase said spreading factor to adjust to said lower data transmission rate;

wherein said first terminal and base terminal are configured to;

increase said matching spreading factors to lower the data rate to provide said specified quality of service at said lower data transmission rate;

wherein said base terminal is configured to;

determine said operating quality has exceeded a maximum threshold of said quality margin;

determine a higher data transmission rate that is sufficient for providing an operating quality within said quality margin to meet said specified quality of service in response to said operating quality exceeding said maximum threshold;

transmit to said remote terminal over said back channel a new spreading factor command for commanding said remote terminal to decrease said spreading factor to adjust to said higher transmission rate; and

wherein said first terminal and base terminal are configured to;

decrease said matching spreading factors to provide said specified quality of service at said higher data transmission rate.

4. The system of claim 1, wherein said remote terminal is further configured to incorporate pilot polarity sequences in said DSSS signal for signaling an adjustment in said data rate and said spreading factor;

and

wherein said base terminal is configured to utilize said pilot polarity sequence to synchronize said adjustment of said matching spreading factor to despread said signal.

5. The system of claim 1, wherein said remote terminal is further configured to:

incorporate a transmit pilot sequence in said DSSS signal being transmitted; and

wherein said base terminal is configured to;

search and detect said pilot sequence of said transmitted DSSS signal; and

acquire said transmitted DSSS signal utilizing said searched pilot sequence.

6. The system of claim 5, wherein said spreading factor is dynamically variable between spreading factors of 1 to N in integer steps, and wherein N is 2048 or more.

7. The system of claim 1, wherein said remote terminal is configured to transmit said DSSS signal to said base terminal at substantially constant power, substantially constant chip rate, and substantially constant bandwidth.

8. The system of claim 1, further comprising stored preset spreading factor commands for commanding said remote terminal and base terminal to dynamically adjust said spreading factors based on a forecast of channel quality such that the amount of data being transmitted is substantially maximized whilst providing said specified quality of service;

and wherein said remote terminal and said base terminal are configured to access said stored presets spreading factor commands and dynamically adjust said spreading factors according to said preset spreading factor commands to adjust the data rate.

14. The system of claim 1, wherein each one of said remote terminal comprises a CDMA transmitter and wherein said base terminal comprises a CDMA receiver;

and wherein said shared communication channel comprises a CDMA communication channel.

9. A multiple access wireless communication system comprising:

a plurality of remote terminals;

at least one base terminal;

a shared communication channel between said plurality of remote terminals said at least one base terminal; and

a plurality of back channels between said plurality of remote terminals and said base terminal;

wherein each one of said remote terminals is configured to;

apply a direct sequence spreading code to a data signal utilizing an associated spreading code and spreading factor to provide a direct sequence spreading spectrum (DSSS) signal; and

transmit said DSSS signal over said shared communication channel to said at least one base terminal;

wherein said base terminal is configured to;

receive respective DSSS signals from respective remote terminals;

despread received DSSS signals utilizing respective spreading codes and spreading factors matching the spreading codes and spreading factors utilized in respective remote terminals;

wherein, for each one of said received DSSS signals, said base terminal is further configured to dynamically;

monitor said DSSS signal to estimate said operating quality over time between the remote terminal transmitting said DSSS signal and said base terminal;

determine that said estimated operating quality has exceeded a limit of a quality margin;

in response to said estimated operating quality exceeding said quality margin limit, estimate a next data transmission rate that is sufficient to provide an operating quality within said quality margin such that said specified quality of service is met for said next data rate;

send a command over a back channel to said remote terminal transmitting said DSSS signal for adjusting the spreading factor to adjust the data rate to said estimated next data rate; and

wherein, for each one of said received DSSS signals, said remote terminal transmitting said DSSS signal and said base terminal are configured to dynamically adjust said matching spreading factors to dynamically adjust said data rate to said next data rate such that the amount of data transmitted is substantially maximized whilst providing the specified quality of service for the remote terminal transmitting said DSSS signal.

10. The system of claim 9, wherein said plurality of remote terminals comprise a first remote terminal and a second remote terminal;

wherein said first remote terminal is configured to transmit a DSSS signal over said shared communication channel at an initial specified quality of service and initial data rate;

wherein said base terminal is further configured to;

determine for said first remote terminal a lower data transmission rate that is sufficient to provide an operating quality within a quality margin in response to said operating quality exceeding a minimum threshold of said quality margin as a result of said second remote terminal joining said shared communication channel; and

transmit to said first remote terminal over said back channel an increase spreading factor command for commanding said first remote terminal to increase said spreading factor to adjust to said lower data transmission rate;

wherein said first terminal and base terminal are configured to;

increase said matching spreading factors to provide said operating quality within said quality margin and thereby meet said specified quality of service at said lower data transmission rate.

11. The system of claim 10,

wherein said base terminal is further configured to:

determine for said first remote terminal a higher data transmission rate that is sufficient to provide an operating quality within said quality margin in response to said operating quality exceeding a maximum threshold of said quality margin as a result of said second remote terminal leaving said shared communication channel;

transmit to said first remote terminal over said back channel a decrease spreading factor command for commanding said first remote terminal to decrease said spreading factor to adjust to said higher data transmission rate;

wherein said first terminal and base terminal are configured to;

increase said matching spreading factors to provide said operating quality within said quality margin and thereby provide said specified quality of service at said higher data transmission rate.

12. The system of claim 9, wherein each one of said plurality of remote terminals is further configured to incorporate a header sequence in the DSSS signal to indicate said next data rate and said spreading factor;

and

wherein, for each DSSS signal being transmitted, said base terminal is configured to utilize the spreading factor in the header sequence to despread the DSSS signal associated with the header sequence.

13. The system of claim 9, wherein each one of said plurality of remote terminals is further configured to:

incorporate a transmit pilot sequence in the DSSS signal being transmitted; and

wherein, for each DSSS signal being transmitted, said base terminal is configured to;

search and detect said pilot sequence of said DSSS signal; and

acquire said DSSS signal utilizing said detected pilot sequence.

15. A method for improving channel utilization in a wireless communication system comprising:

direct sequence spectrum spreading a data signal by a spreading factor to provide a direct sequence spreading spectrum (DSSS) signal;

transmitting said DSSS signal from a remote terminal over a communication channel to a base terminal;

receiving said DSSS signal from said remote terminal;

despreading said received DSSS signal by a spreading factor matching said spreading factor utilized to spread the data signal; and

dynamically vary the matching spreading factors to adjust the date rate based on an estimation of operating quality over time between the remote terminal and base terminal such that the amount of data transmitted is substantially maximized whilst providing the specified quality of service.

16. The method of claim 15, further comprising

monitoring said received DSSS signal to estimate said operating quality over time;

determining said operating quality has exceeded a limit of a quality margin;

estimating a next data transmission rate that is sufficient to provide an operating quality within said quality margin to meet said specified quality of service in response to determining said operating quality has exceeded said quality margin limit;

sending a command over a back channel to said remote terminal for adjusting the spreading factor to adjust to said next data rate;

adjusting said matching spreading factors to provide said operating quality within said quality margin such that said specified quality of service is met at said next data rate; and

dynamically performing said monitoring, said estimating next date rate, said sending said command and said adjusting said matching spreading factors to provide said specified quality of service at a substantially maximum data rate.

17. The method of claim 16, further comprising

estimating a lower data transmission rate that is sufficient to provide said operating quality within said quality margin in response to said operating quality exceeding a minimum threshold of said quality margin;

transmitting to said remote terminal over said back channel an increase spreading factor command for commanding said remote terminal to increase said spreading factor to adjust to said lower data transmission rate;

increasing said matching spreading factors to provide said operating quality within said quality margin at said lower data transmission rate;

estimating a higher data transmission rate that is sufficient to provide said operating quality within said quality margin in response to said operating quality exceeding a maximum threshold of said quality margin;

transmitting to said remote terminal over said back channel a decrease spreading factor command for commanding said remote terminal to decrease said spreading factor to adjust to said higher data transmission rate; and

decreasing said matching spreading factors to provide said operating quality within said quality margin at said higher data transmission rate.

18. The method of claim 16, further comprising

incorporating a transmit pilot sequence in said DSSS signal being transmitted;

and

searching and detecting said pilot sequence of said DSSS signal; and

acquiring said transmitted DSSS signal utilizing said detected pilot sequence.

19. The method of claim 16, further comprising

direct sequence spectrum spreading data signals utilizing respective spreading codes and spreading factors to provide a plurality of direct sequence spreading spectrum (DSSS) signal;

and

transmitting said DSSS signals from respective remote terminals over a shared communication channel to at least one base terminal;

receiving respective DSSS signals from respective remote terminals;

despreading received DSSS signals utilizing respective spreading codes and spreading factors matching the spreading codes and spreading factors utilized in respective remote terminals; and

for each one of said DSSS signals;

monitoring said DSSS signal to estimate operating quality over time;

determining said operating quality has exceeded a limit of a quality margin;

estimating a next data transmission rate that is sufficient to provide said operating quality within said quality margin such that said specified quality of service is met in response to determining said operating quality has exceeded said quality margin limit;

sending a command over said back channel to the remote terminal transmitting said DSSS signal for adjusting the spreading factor to adjust to next data rate; and

adjusting said spreading factors to provide said operating quality within said quality margin at said next data rate; and

dynamically performing said monitoring, said estimating said next transmission rate, said sending a command and said adjusting said matching spreading factors such that the amount of data transmitted is substantially maximized whilst providing the specified quality of service.

20. A remote terminal for communicating with a base terminal over a communication channel;

wherein said remote terminal comprises;

direct sequence spread spectrum circuitry for applying a direct sequence spreading code to a data signal at a spreading factor to provide a direct sequence spread spectrum (DSSS) signal;

transmitter circuitry for transmitting said DSSS signal over said communication channel to said base terminal; and

a controller for dynamically vary the spreading factor to adjust the data rate based on an estimation of operating quality over time between the remote terminal and base terminal such that the amount of data being transmitted is substantially maximized whilst providing a specified quality of service.

21. A base terminal for receiving a DSSS signal transmitted from at least one remote terminal over a communication channel;

wherein said base terminal comprises;

receiver circuitry for receiving said DSSS signal;

direct sequence spread spectrum despreading circuitry for despreading said received DSSS signal by a spreading factor matching said spreading factor utilized to spread the data signal;

a controller for dynamically varying the spreading factor to adjust the data rate based on an estimation of operating quality over time between the remote terminal and base terminal such that the spreading factor amount of data being received is substantially maximized whilst providing a specified quality of service.