Advanced multi-user detector

• US 8,548,107 B1
• Filed: 01/25/2010
• Issued: 10/01/2013
• Est. Priority Date: 01/26/2009
• Status: Active Grant

• Current Assignee: Comtech Mobile Datacom Corporation (Comtech Telecommunications Corporation)
• Original Assignee: Comtech Mobile Datacom Corporation (Comtech Telecommunications Corporation)
• Inventors: Fossaceca, John, Handermann, Greg, Crenshaw, Ralph Eugene, Candell, Richard, Ebert, Paul, Holland, Mark, Johnson, Lajuana, McKinley, Bruce L., Wang, Bo
• Primary Examiner(s): KASSA, ZEWDU A
• Application Number:
  US12/692,789
• Time in Patent Office: 1,345 Days
• Field of Search: 375/346, 375/316, 375/148, 375/130, 375/144, 375/142, 375/150, 455/136
• US Class Current: 375/346
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]

Abstract

A method for detecting multi-user signals including conducting a first energy burst detection detecting a first plurality of user signals as a first energy burst, attempting to decode a user signal from the first plurality of signals within the first energy burst, cancelling out a first user signal from the first energy burst if the first user signal is successfully decoded from the first energy burst, determining a second user signal to be discarded if the second user signal is not successfully decoded from the first energy burst, conducting a second energy burst detection detecting a second plurality of signals as a second burst, and iteratively cancelling out the first user signal successfully decoded from the first energy burst from the second energy burst, wherein the second energy burst detection is conducted when all user signals within the first energy burst are either cancelled out or determined to be discarded.

Claims

1. A method for detecting multi-user signals, the method comprising:

detecting a first energy burst including a first plurality of user signals;

attempting to decode a user signal from the first plurality of signals within the first energy burst;

cancelling out a first user signal from the first energy burst if the first user signal is successfully decoded from the first energy burst;

determining a second user signal to be discarded if the second user signal is not successfully decoded from the first energy burst;

detecting a second energy burst including a second plurality of user signals; and

iteratively cancelling out the first user signal successfully decoded from the first energy burst from the second energy burst,

wherein when to conduct the second energy burst is predetermined using statistical information on how often energy burst detections should be made.

2. The method of claim 1, further comprising conducting adaptive channel estimation detecting a direction of a Doppler shift and Doppler rate to compensate for the Doppler shift and Doppler rate.

3. An apparatus for detecting multi-user signals, the apparatus comprising:

a burst energy detector for detecting a plurality of user signals as an energy burst;

a channel estimator for estimating an amount of Doppler shift and Doppler rate; and

a decoder for attempting to decode a user signal from the plurality of signals within the energy burst;

an iterative interference canceller for iteratively cancelling out successfully decoded user signal from the energy burst,

wherein the iterative interference canceller statically determines whether the energy burst after the successfully decoded user signal is cancelled out should be input into the decoder or the burst energy detector.

4. The apparatus of claim 3, wherein a user signal is determined to be discarded if the user signal is not successfully decoded from the energy burst.

5. The apparatus of claim 3, wherein when the energy burst after the successfully decoded user signal is cancelled out should be input into the burst energy detector is predetermined using statistical information on how often energy burst detections should be made.

6. The apparatus of claim 3, wherein the channel estimator adaptively detects a direction of the Doppler shift and Doppler rate.

7. A method for detecting multi-user signals, the method comprising:

detecting a first plurality of user signals as a first energy burst;

cancelling out a first user signal of the first plurality of user signals from the first energy burst;

detecting a second plurality of signals as a second burst;

determining when to conduct the second energy burst detection using statistical information associated with the frequency of energy burst detections, and wherein the second energy burst detection is conducted based at least in response to the determination; and

cancelling out the first user signal from the second energy burst.

8. The method of claim 7 further comprising decoding the first user signal by performing at least one of an auto-correlation operation and a cross-correlation using a known basis from the first user.

9. The method of claim 7 further comprising:

determining whether the first user signal has been decoded successfully,

wherein the first user signal is cancelled from the first energy burst in response to successfully decoding the first user signal, and

wherein the first user signal is cancelled from the first energy in response to successfully decoding the first user signal.

10. The method of claim 7 further comprising identifying a second user signal of the first plurality of user signals to be discarded.

11. The method of claim 10, wherein the second user signal is identified in response to failing to successfully decode the second user signal from the first energy burst.

12. The method of claim 7, wherein the second energy burst detection is conducted when all user signals within the first energy burst are either cancelled or discarded from the first energy burst.

13. The method of claim 7, further comprising conducting adaptive channel estimation to detect at least one of Doppler shift and Doppler rate.