Advanced multi-user detector

• US 8,982,928 B2
• Filed: 09/30/2013
• Issued: 03/17/2015
• 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: Candell, Richard, Ebert, Paul, Fossaceca, John, Handermann, Greg, Holland, Mark, Johnson, Lajuana, McKinley, Bruce L., Wang, Bo, Crenshaw, Ralph Eugene
• Primary Examiner(s): KASSA, ZEWDU A
• Application Number:
  US14/041,491
• Publication Number:
  US 20140029649A1
• Time in Patent Office: 533 Days
• Field of Search: 375/148, 375/346, 375/316, 375/130, 375/144, 375/142, 375/150, 455/136
• US Class Current: 375/148
• 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 of detecting multi-user signals, the method comprising:

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

attempting to decode a first user signal from the first energy burst;

in accordance with a determination that the first user signal is decoded from the first energy burst, cancelling out the first user signal from the first energy burst;

attempting to decode a second user signal from the first energy burst, wherein the second user signal is different from the first user signal;

in accordance with a determination that the second user signal is not decoded from the first energy burst, discarding the second user signal from the first energy burst;

detecting a second energy burst including a second plurality of user signals, wherein the second energy burst detection is conducted when all user signals within the first energy burst are either cancelled out or discarded; and

in accordance with a determination that the first user signal is decoded from the first energy burst, cancelling out the first user signal from the second energy burst.

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

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

detecting a second energy burst including a second plurality of user signals, wherein the second energy burst detection is conducted in accordance with predetermined statistical information corresponding to how often energy burst detections should be made; and

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

4. The method of claim 3, further comprising:

attempting to decode a first user signal from the first energy burst;

in accordance with a determination that the first user signal is decoded from the first energy burst, cancelling out the first user signal from the first energy burst;

attempting to decode a second user signal from the first energy burst, wherein the second user signal is different from the first user signal; and

in accordance with a determination that the second user signal is not decoded from the first energy burst, discarding the second user signal from the first energy burst.

5. The method of claim 3, 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.

6. 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;

a decoder for attempting to decode a user signal from the energy burst; and

an interference canceller for cancelling out a decoded user signal from the energy burst,

wherein, after the decoded user signal is cancelled out, the interference canceller determines whether to direct the energy burst to the decoder or the burst energy detector.

7. The apparatus of claim 6, wherein a user signal is discarded if the user signal is not decoded from the energy burst.

8. The apparatus of claim 7, wherein, after the decoded user signal is cancelled out, the energy burst is input into the burst energy detector when all user signals within the energy burst are either cancelled out or determined to be discarded.

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