Random access in a mobile telecommunications system

US 20040008658A1
Filed: 06/09/2003
Published: 01/15/2004
Est. Priority Date: 10/05/1998
Status: Active Grant

First Claim

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1. A method for improving the performance of a random access mobile communications system, comprising the steps of:

a mobile station transmitting a random access request; and

a base station detecting a presence of said random access request, generating an indicator signal indicating said presence of said random access request, and transmitting said indicator signal.

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Abstract

A method for processing multiple random access requests is disclosed in which a base station transmits an acquisition indicator signal, which indicates that the base station has detected the presence of a random access transmission. The acquisition indicator can be generated based on the amount of energy received on the random access channel (e.g., as opposed to the correct/incorrect decoding of a random access message). Consequently, the delay between the beginning of the random access transmission and the beginning of the acquisition indicator transmission is significantly shorter than the delay to the beginning of an acknowledgment transmission based on the reception of a correctly decoded random access message. If a mobile station does not receive a positive acquisition indicator, it should interrupt the present transmission and start to re-transmit the random access burst in the next time slot, while modifying the transmission power level accordingly between the successive re-transmissions.

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38 Claims

1. A method for improving the performance of a random access mobile communications system, comprising the steps of:
- a mobile station transmitting a random access request; and
  
  a base station detecting a presence of said random access request, generating an indicator signal indicating said presence of said random access request, and transmitting said indicator signal.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
- - 2. The method of claim 1, wherein said transmitting step comprises transmitting said indicator signal at a predetermined instant of time.
  - 3. The method of claim 1, wherein said indicator signal comprises an ON portion of an ON-OFF signal.
  - 4. The method of claim 1, further comprising the steps of:
    - if said mobile station receives said indicator signal, said mobile station continuing said transmitting of said random access request; and
      
      if said mobile station does not receive said indicator signal by a predetermined instant of time, said mobile station discontinuing said transmitting of said random access request.
  - 5. The method of claim 1, wherein said step of detecting a presence of said random access request comprises detecting a power level equal to or exceeding a predetermined threshold level.
  - 6. The method of claim 1, wherein said random access mobile communications system comprises a spread spectrum mobile communications system.
  - 7. The method of claim 1, wherein said random access mobile communications system comprises a wideband CDMA system.
  - 8. The method of claim 1, wherein said indicator signal comprises an acquisition indicator signal.
  - 9. The method of claim 1, wherein said indicator signal is transmitted on a physical channel.
  - 10. The method of claim 4, wherein said step of discontinuing said transmitting of said random access request further comprises the step of re-transmitting said random access request in a subsequent time slot.
  - 11. The method of claim 10, wherein the step of retransmitting said random access request includes retransmitting a preamble.
  - 12. The method of claim 11, wherein the step of retransmitting comprises re-transmitting said preamble with a different spreading code.
  - 13. The method of claim 11, wherein the step of re-transmitting comprises re-transmitting said preamble with a different signature.
  - 14. The method of claim 12, further comprising the step of said mobile station reducing a negative power offset for said random access request prior to said re-transmitting step.
  - 15. The method of claim 9, wherein said physical channel is a downlink channel that is orthogonal to other downlink physical channels.
  - 16. The method of claim 9, wherein said physical channel is a downlink physical channel that is non-orthogonal to other downlink physical channels.
  - 17. The method of claim 1, wherein said indicator signal is associated with a unique signature.
  - 18. The method of claim 1, wherein said indicator signal is associated with a set of unique signatures.
  - 19. The method of claim 17, wherein said indicator signal comprises an orthogonal code word associated with said unique signature.
  - 20. The method of claim 17 or 18, wherein said indicator signal comprises an ON part of an ON-OFF signal.

21. A random access communications system, comprising:
- a mobile station, said mobile station including means for transmitting a random access request; and
  
  a base station coupled to said mobile station via an air interface, said base station including means for detecting a presence of said random access request, generating an indicator signal indicating said presence of said random access request, and transmitting said indicator signal.
- View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
- - 22. The system of claim 21, wherein said means for transmitting comprises means for transmitting said indicator signal at a predetermined instant of time.
  - 23. The system of claim 21, further comprising:
    - said mobile station including means for receiving said indicator signal, and determining if said mobile station has received said indicator signal, and if so, said mobile station continuing said transmitting of said random access request; and
      
      if said mobile station does not receive said indicator signal by a predetermined instant of time, said mobile station discontinuing said transmitting of said random access request.
  - 24. The system of claim 21, wherein said means for detecting a presence of said random access request comprises means for detecting a power level equal to or exceeding a predetermined threshold level.
  - 25. The system of claim 21, wherein said random access communications system comprises a spread spectrum mobile communications system.
  - 26. The system of claim 21, wherein said random access communication system comprises a wideband CDMA system.
  - 27. The system of claim 21, wherein said indicator signal comprises an acquisition indicator signal.
  - 28. The system of claim 21, wherein said indicator signal is transmitted on a physical channel.
  - 29. The system of claim 23, further comprising means for re-transmitting said random access request in a subsequent time slot.
  - 30. The system of claim 29, wherein said means for retransmitting said random access request includes means for re-transmitting a preamble.
  - 31. The system of claim 30, wherein said means for retransmitting comprises means for re-transmitting said preamble with a different spreading code.
  - 32. The system of claim 30, wherein said means for retransmitting comprises means for re-transmitting said preamble with a different signature.
  - 33. The system of claim 29, further comprising means for reducing a negative power offset for said random access request prior to said re-transmitting.
  - 34. The system of claim 28, wherein said physical channel is a downlink channel that is orthogonal to other downlink physical channels.
  - 35. The system of claim 28, wherein said physical channel is a downlink physical channel that is non-orthogonal to other downlink physical channels.
  - 36. The system of claim 21, wherein said indicator signal is associated with a unique signature.
  - 37. The system of claim 21, wherein said indicator signal is associated with a set of unique signatures.
  - 38. The system of claim 36 or 37, wherein said indicator signal comprises an ON part of an ON-OFF signal.

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Current Assignee
Telefonaktiebolaget LM Ericsson
Original Assignee
Telefonaktiebolaget LM Ericsson
Inventors
Dahlman, Erik, Beming, Per, Gustafsson, Maria

Granted Patent

US 6,985,474 B2
Time in Patent Office

Days
Field of Search
US Class Current

370/342
CPC Class Codes

H04L 1/1867   Arrangements specially adap...

H04W 36/16   Performing reselection for ...

H04W 74/006   in the downlink, i.e. towar...

H04W 74/0833   Random access procedures, e...

Random access in a mobile telecommunications system

First Claim

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Abstract

109 Citations

38 Claims

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Random access in a mobile telecommunications system

First Claim

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Accused Products

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Abstract

109 Citations

38 Claims

Specification

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