Method And Apparatus For Performing An Enhanced Random Access Channel Procedure In A Cell_Fach State

• US 20140016572A1
• Filed: 03/13/2013
• Published: 01/16/2014
• Est. Priority Date: 01/04/2008
• Status: Abandoned Application

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Inventors: Cave, Christopher R., DiGirolamo, Rocco, Pani, Diana, Pelletier, Benoit, Marinier, Paul
• Application Number:
  US13/800,022
• Publication Number:
  US 20140016572A1
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04W 28/26 Resource reservation
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 74/0841 with collision treatment
• CPC Class Codes: H04W 74/0866 using a dedicated channel for access

Abstract

A method and apparatus for performing an enhanced random access procedure in a Cell_FACH state are disclosed. A wireless transmit/receive unit (WTRU) transmits a random access channel (RACH) preamble for random access. If a positive acknowledgement (ACK) is received in response to the RACH preamble, the WTRU enters a contention resolution phase and transmits a message via an enhanced dedicated channel (E-DCH). If contention resolution fails, the RACH preamble is retransmitted. A contention back-off timer may be used for retransmission. A physical random access channel (PRACH) code may be reselected. The RACH preamble may be retransmitted using a reserved PRACH resource so that E-DCH resource is allocated to the collided WTRUs. Data transmitted during the contention resolution phase may remain in a hybrid automatic repeat request (HARQ) buffer. The MAC-i/is entity may be reset. All data sent during the contention resolution phase may be stored in a temporary buffer.

Claims

1. A method comprising:

entering a contention resolution phase; and

on a condition that contention resolution fails because no E-DCH absolute grant channel (E-AGCH) with a WTRU'"'"'s E-DCH radio network temporary identity (E-RNTI) is received within a period of time resetting a medium access control (MAC)-i/is entity.

2. The method of claim 1, further comprising:

initiating an enhanced dedicated channel (E-DCH) transmission on an assigned E-DCH resource;

transmitting data using the assigned E-DCH resource; and

releasing the assigned E-DCH resource on the condition that contention resolution fails because no E-AGCH with a WTRU'"'"'s E-RNTI is received within the period of time.

3. The method of claim 2, further comprising requesting access to the assigned E-DCH resource.

4. The method of claim 2, wherein when the contention resolution fails the E-DCH transmission is stopped.

5. The method of claim 1, wherein when the contention resolution fails E-DCH reception is stopped.

6. The method of claim 1, further comprising:

setting a back-off timer if the contention resolution fails; and

starting a random access procedure after expiration of the back-off timer.

7. The method of claim 1, wherein a MAC-STATUS-Ind primitive indicates the contention resolution failure, indicating a transmission was unsuccessful due to collision.

8. The method of claim 1, wherein a RACH preamble is transmitted using a reserved physical random access channel (PRACH) resource if the contention resolution fails.

9. The method of claim 1, wherein when the contention resolution fails a hybrid automatic repeat request (HARQ) buffer is flushed.

10. The method of claim 1, wherein a physical layer controls transmission of radio resource control (RRC) messages after the contention resolution fails.

11. The method of claim 1, wherein when the contention resolution fails, indicating contention resolution failure to a higher layer.

12. A wireless transmit/receive unit (WTRU) comprising:

a processor configured to;

enter a contention resolution phase; and

if contention resolution fails because no E-DCH absolute grant channel (E-AGCH) with a WTRU'"'"'s E-DCH radio network temporary identifier (E-RNTI) is received within a period of time, reset an MAC-i/is entity.

13. The WTRU of claim 12, wherein the processor is further configured to:

initiate an enhanced dedicated channel (E-DCH) transmission on an assigned E-DCH resource;

enter the contention resolution phase upon transmission of data using the assigned E-DCH resource; and

release the assigned E-DCH resource if contention resolution fails because no E-AGCH with a WTRU'"'"'s E-RNTI is received within the period of time.

14. The WTRU of claim 13, further comprising a physical layer entity configured to request access to the assigned E-DCH resource.

15. The WTRU of claim 13, wherein en the contention resolution fails, the WTRU is configured to stop the E-DCH transmission.

16. The WTRU of claim 12, wherein when the contention resolution fails, the WTRU is configured to stop E-DCH reception.

17. The WTRU of claim 12, wherein the processor is further configured to set a back-off timer if the contention resolution fails, and start a random access procedure after expiration of the back-off timer.

18. The WTRU of claim 12, wherein the processor is further configured to initiate a physical random access channel (PRACH) code selection if a maximum number of consecutive contention resolution failures occur.

19. The WTRU of claim 12, wherein the processor is further configured to transmit a RACH preamble using a reserved physical random access channel (PRACH) resource if the contention resolution fails.

20. The WTRU of claim 12, wherein a MAC-STATUS-Ind primitive indicates the contention resolution failure, indicating a transmission was unsuccessful due to collision,

21. The WTRU of claim 12, wherein when the contention resolution fails, the WTRU is configured to flush a hybrid automatic repeat request (HARQ) buffer.

22. The WTRU of claim 12, wherein when the contention resolution fails, the WTRU is configured to indicate contention resolution failure to a higher layer.