Method and apparatus for adaptive processing gain for multiple source devices in a communications system

• US 7,218,641 B2
• Filed: 03/11/2003
• Issued: 05/15/2007
• Est. Priority Date: 03/11/2003
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Gurney, David P., Kuffner, Stephen
• Primary Examiner(s): Harper; Kevin C.
• Application Number:
  US10/385,886
• Publication Number:
  US 20040179547A1
• Time in Patent Office: 1,526 Days
• Field of Search: 370/431, 370461-462, 370/203, 370208-209, 370/465, 370/252, 370/445
• US Class Current: 370/445
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0018 based on latency requirement
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 72/00 Local resource management

Abstract

A method of dynamically adapting the number of available channels in a first set of available channels for use by at least one signal source in a communications system. The method includes the steps of computing at least one received signal statistic; determining an adjustment to the number of available channels in the first set based on the at least one computed received signal statistic; and signaling to each active signal source in the system to cause the signal sources to use the adjusted number of available channels for transmitting signals.

Claims

1. A method of dynamically adapting the number of available channels in a set of available data transmission channels for use by at least one source device to transmit stored information to a destination device, said method comprising the steps of:

computing, at the destination device, at least one received signal statistic;

determining, at the destination device, an adjustment to the number of available channels in said set based on said at least one computed received signal statistic;

sending a signal from the destination device to the at least one source device indicating the adjusted number of available data transmission channels for transmitting the stored information; and

independently selecting, at the source device, a data transmission channel from the adjusted number of available data transmission channels for transmitting the stored information according to a multiple pass transmission algorithm having at least one transmission pass, wherein the data transmission channel is selected based at least in part on the stored information, and wherein the step of sending the signal from the destination device to the at least one source device is at least one of performed at the beginning of and performed during a transmission pass in the multiple pass transmission algorithm.

2. The method of claim 1, wherein said at least one received signal statistic further comprises a measure of system loading.

3. The method of claim 2, wherein the measure of system loading is computed from a collision severity indicator.

4. The method of claim 3, wherein the collision severity indicator is determined by a ratio of a number of channels determined to be in collision to the total number of available channels.

5. The method of claim 3, wherein the collision severity indicator is determined by a measure of a signal variance on a channel containing collisions.

6. The method of claim 2, wherein the measure of system loading is computed from an unoccupied channel indicator.

7. The method of claim 1, wherein the at least one computed received signal statistic comprises at least one of a received signal carrier to interference ratio (CIR), a received signal to noise ratio (SNR), and a measure of transmission errors.

8. The method of claim 7, wherein the measure of transmission errors is computed from a bit error indicator.

9. The method of claim 7, wherein the measure of transmission errors is computed as determined by a cyclic redundancy check (CRC).

10. The method of claim 7, wherein the measure of transmission errors is computed from soft error decoding information.

11. The method of claim 7, wherein the measure of transmission errors is computed as determined during forward error correction (FEC).

12. The method of claim 1, wherein the data transmission channel is selected based directly on a predetermined subset of the stored information.

13. The method of claim 1, wherein the adjustment to the number of available channels is determined when a received signal statistic crosses a threshold.

14. The method of claim 1, wherein the adjustment to the number of available channels is determined to minimize an overall data transmission time.

15. The method of claim 1, wherein the step of determining the adjustment to the number of available channels and the step of signaling data to each active signal source in the system is performed prior to said signal sources transmitting signals.

16. The method of claim 1, wherein said at least one received signal statistic is computed using information gathered during a prior signal source transmission.

17. The method of claim 1, wherein said at least one received signal statistic is computed based on an expected number of signal sources present in the system.

18. The method of claim 1, wherein the number of available channels in said set is adjusted by increasing said available channels by a fixed amount.

19. The method of claim 1, wherein the number of available channels in said set is adjusted by decreasing said available channels by a fixed amount.

20. The method of claim 1, wherein said signaling represents a total number of available data transmission channels for transmitting signals based on the adjustment to said set.

21. The method of claim 1, wherein said signaling represents only the adjustment to said set of available data transmission channels.

22. The method of claim 1, wherein the step of signaling to each active signal source in the system is performed via pulse width modulation.

23. The method of claim 1, wherein said signal sources transmit according to a spread spectrum technique.

24. A communications system comprising:

at least one source device having stored identification data, a signal source, and a channel selector, the signal source adapted for transmitting at least part of the identification data in an active state over a data transmission channel, the channel selector adapted for independently choosing at the source device the data transmission channel from an adjusted number of available data transmission channels based directly on a predetermined subset of the stored identification data; and

at least one destination device adapted for computing at least one received signal statistic based on a measure of a number of unoccupied channels, determining the adjusted number of available data transmission channels from a first set of available data transmission channels based on said at least one computed received signal statistic, and signaling to each active signal source in the system to cause the signal sources to use the adjusted number of available data transmission channels for transmitting the identification data.

25. The system of claim 24, wherein said signal sources transmit stored identification data according to a multiple pass transmission algorithm having at least one transmission pass.

26. The system of claim 24, wherein the number of available channels is the same for all active signal sources.

27. The system of claim 24, wherein said at least one destination device signals to each said active signal source via pulse width modulation.

28. The system of claim 24, wherein said at least one destination device is further adapted such that said signaling further causes the signal sources to be synchronized for transmitting signals using the adjusted number of available channels.

29. The system of claim 24, wherein the at least one computed received signal statistic comprises at least one of a received signal carrier to interference ratio (CIR), a received signal to noise ratio (SNR), a computation based on a measure of severity of collisions and a computation based on error decoding information.