Method and apparatus for spread spectrum channel assignment

• US 5,809,059 A
• Filed: 11/21/1996
• Issued: 09/15/1998
• Est. Priority Date: 11/21/1996
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Souissi, Slim, Sawaya, Samir A.
• Primary Examiner(s): Vo, Don N.
• Assistant Examiner(s): Le, Amanda T.
• Application Number:
  US08/752,819
• Time in Patent Office: 663 Days
• Field of Search: 375/200, 375/202, 375/224, 375/227, 455/450, 455/452, 455/509, 455/512, 455/513, 455/524, 455/525, 455/67.3, 370/252, 370/329, 370/332, 370/337
• US Class Current: 375/133
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 1/715 Interference-related aspects
• CPC Class Codes: H04B 2001/7154 with means for preventing interference

Abstract

A controller (152) in a frequency hopped spread spectrum system (100) operating to assign a best available frequency hopping sequence among a plurality of sequences to at least one of a plurality of subscriber units (156) having predefined transmission intervals (12) and predefined transition intervals (14) comprises a power detector (50) that estimates a combination of a noise level and an interference level by measuring signal strength during a series of transition intervals for at least one sequence of channels among the plurality of sequences and a processor that computes an average noise and interference level for the at least one sequence of channels and ranks the at least one sequence of channels in accordance with the average noise and interference level computed.

Claims

1. A method for assigning a sequence of channels among a plurality of sequences in a spread spectrum communication system to at least one of a plurality of subscriber units having predefined transmission intervals and predefined transition intervals, comprising the steps of:

estimating a combination of a noise level and an interference level by measuring a signal strength during a series of transition intervals for at least one sequence of channels among the plurality of sequences;

computing an average noise and interference level for the at least one sequence of channels; and

selecting the at least one sequence of channels having the lowest average noise and interference level for a next transmission of information in the spread spectrum communication system.

2. The method of claim 1, wherein the method further comprises the step of estimating a combination of a signal, a noise and an interference level by measuring signal strength during a series of transmission intervals of the signal for the at least one sequence of channels among the plurality of sequences.

3. The method of claim 2, wherein the method further comprises the step of estimating a signal to noise ratio by correspondingly subtracting the signal strength measured during each of the series of transition intervals from the signal strength measured during each of the series of transmission intervals and dividing a result of such subtraction by the signal strength measurement from each of the series of transition intervals.

4. The method of claim 3, wherein the method further comprises the step of optimizing a code rate and a data rate of scheduled transmissions from the at least one of a plurality of subscriber units to the spread spectrum communication system using the signal to noise ratio estimation.

5. A method at a controller for assigning an optimum data rate and code rate for a particular frequency hopping sequence to at least one of a plurality of subscriber units in a spread spectrum communication system having predefined transmission intervals and predefined transition intervals, comprising the steps of:

estimating a combination of a noise level and an interference level by measuring signal strength during a series of transition intervals for at least one sequence of channels among a plurality of sequences;

estimating a combination of a signal, a noise and an interference level by measuring signal strength during a series of transmission intervals of the signal corresponding to the transition intervals for the at least one sequence of channels among the plurality of sequences;

estimating a signal to noise ratio by correspondingly subtracting the signal strength measured during each of the series of transition intervals from the signal strength measured during each of the series of transmission intervals and dividing a result of such subtraction by the signal strength measured during each of the series of transition intervals; and

optimizing the code rate and data rate used for scheduled transmissions from the at least one of a plurality of subscriber units to the spread spectrum communication system using the signal to noise ratio estimation.

6. The method of claim 5, wherein the method further comprises the step of computing an average noise and interference level for the at least one sequence of channels.

7. The method of claim 6, wherein the method further comprises the step of ranking the at least one sequence of channels among the plurality of sequences based on the computed average noise and interference level computed.

8. The method of claim 7, wherein the method further comprises the step of assigning a best available sequence among the plurality of sequences ranked to a particular subscriber unit.

9. A controller in a frequency hopped spread spectrum system operating to assign a best available frequency hopping sequence among a plurality of sequences to at least one of a plurality of subscriber units in a spread spectrum communication system having predefined transmission intervals and predefined transition intervals, the controller comprising:

an input that receives measurements taken at a base receiver that estimates a combination of a noise level and an interference level by measuring signal strength during a series of transition intervals for at least one sequence of channels among the plurality of sequences; and

a processor that computes an average noise and interference level for the at least one sequence of channels and ranks the at least one sequence of channels in accordance with the average noise and interference level computed.

10. The controller of claim 9, wherein the processor chooses a best available sequence of channels with a lowest average noise and interference level among the plurality of sequences ranked for use in a next transmission of information in the spread spectrum communication system.

11. The controller of claim 9, wherein a power detector further estimates a combination of a signal, a noise and an interference level by measuring signal strength during a series of transmission intervals of the signal for the at least one sequence of channels among the plurality of sequences.

12. The controller of claim 11, wherein the processor further estimates a signal to noise ratio by correspondingly subtracting the signal strength measured during each of the series of transition intervals from the signal strength measured during each of a series of transmission intervals and dividing a result of such subtraction by the signal strength measured during each of the series of transition intervals.

13. The controller of claim 12, wherein the processor further chooses an optimized code rate and data rate for scheduled transmissions from the at least one of a plurality of subscriber units to the frequency hopped spread spectrum system based on the signal to noise ratio estimation.

14. A controller system in a frequency hopped spread spectrum system operating to assign a best available frequency hopping sequence among a plurality of sequences to at least one of a plurality of subscriber units in a spread spectrum communication system having predefined transmission intervals and predefined transition intervals, the controller system comprising:

a base receiver having a power detector that estimates a combination of a noise level and an interference level by measuring signal strength during a series of transition intervals for at least one sequence of channels among the plurality of sequences; and

a processor that computes an average noise and interference level for the at least one sequence of channels and ranks the at least one sequence of channels in accordance with the average noise and interference level computed.

15. The controller system of claim 14, wherein the processor chooses a best available sequence of channels with a lowest average noise and interference level among the plurality of sequences ranked for use in a next transmission of information in the spread spectrum communication system.

16. The controller system of claim 14, wherein the power detector further estimates a combination of a signal, a noise and an interference level by measuring signal strength during a series of transmission intervals of the signal for the at least one sequence of channels among the plurality of sequences.

17. The controller system of claim 16, wherein the processor further estimates a signal to noise ratio by correspondingly subtracting the signal strength measured during each of the series of transition intervals from the signal strength measured during each of a series of transmission intervals and dividing a result of such subtraction by the signal strength measured during each of the series of transition intervals.

18. The controller system of claim 17, wherein the processor further chooses an optimized code rate and data rate for scheduled transmissions from the at least one of a plurality of subscriber units to the frequency hopped spread spectrum system based on the signal to noise ratio estimation.

19. A base receiver in a frequency hopped spread spectrum system operating to assign a best available frequency hopping sequence among a plurality of sequences to at least one of a plurality of subscriber units in a spread spectrum communication system having predefined transmission intervals and predefined transition intervals, the base receiver comprising:

a power detector that estimates a combination of a noise level and an interference level by measuring signal strength during a series of transition intervals for at least one sequence of channels among the plurality of sequences; and

a processor that computes an average noise and interference level for the at least one sequence of channels and chooses the at least one sequence of channels having a lowest average noise and interference level for a next transmission of information in the spread spectrum communication system.

20. The base receiver of claim 19, wherein the power detector further estimates a combination of a signal, a noise and an interference level by measuring signal strength during a series of transmission intervals of the signal for the at least one sequence of channels among the plurality of sequences.

21. The base receiver of claim 20, wherein the processor further estimates a signal to noise ratio by correspondingly subtracting the signal strength measured during each of the series of transition intervals from the signal strength measured during each of a series of transmission intervals and dividing a result of such subtraction by the signal strength measured during each of the series of transition intervals.

22. The base receiver of claim 21, wherein the processor further chooses an optimized code rate and data rate for scheduled transmissions from the frequency hopped spread spectrum system to a subscriber unit based on the signal to noise ratio estimation.

23. The base receiver of claim 22, wherein the base receiver forwards information concerning a choice of the optimized code rate and data rate for scheduled transmissions from the frequency hopped spread spectrum system to a subscriber unit to a controller.

24. The base receiver of claim 19, wherein the base receiver forwards information concerning a choice of the at least one sequence of channels having the lowest average noise and interference level for the next transmission of information to a controller within the spread spectrum communication system.