METHOD AND APPARATUS FOR LTE RACH CHANNEL RESOURCE SELECTION AND PARTITIONING

• US 20090042582A1
• Filed: 08/08/2008
• Published: 02/12/2009
• Est. Priority Date: 08/10/2007
• Status: Abandoned Application

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Inventors: Terry, Stephen E., Wang, Peter S., Wang, Jin, Somasundaram, Shankar
• Application Number:
  US12/188,738
• Publication Number:
  US 20090042582A1
• Time in Patent Office: Days
• US Class Current: 455/450
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 74/0866 using a dedicated channel for access

Abstract

A method and apparatus for random access channel (RACH) channel selection in a long term evolution (LTE) network includes determining a distance from a wireless transmit/receive unit (WTRU) to an evolved Node-B (eNB) in a cell of the LTE network. A RACH channel is then selected based upon the distance determination.

Claims

1. A method for random access channel (RACH) channel selection in a long term evolution (LTE) network, implemented in a wireless transmit/receive unit (WTRU), comprising:

determining a distance from the WTRU to an evolved Node-B (eNB) in a cell of the LTE network; and

selecting a RACH channel based upon the distance determination.

6. The method of claim 1 wherein determining the distance from the WTRU to the eNB includes measuring a pathloss of power on a downlink (DL) channel over reference symbols.

7. The method of claim 1, further comprising receiving a transmit power indication of a downlink (DL) channel.

8. The method of claim 1 wherein determining the distance from the WTRU to the eNB includes receiving information from a global positioning system (GPS) device.

9. The method of claim 1, further comprising selecting a non-dedicated preamble of a RACH.

10. The method of claim 9 wherein the non-dedicated preamble is selected based upon a radio condition of a cell and a message size for transmission.

11. The method of claim 9 wherein the non-dedicated preamble is selected based upon a service or call priority.

12. The method of claim 9 wherein the non-dedicated preamble is selected based upon a mobility speed.

13. The method of claim 12 wherein a first group of preambles is designated for a first mobility speed and a second group of preambles is designated for a second mobility speed.

2. The method of claim 2 wherein the RACH channel includes any one of the following cyclic prefix types:

a normal type, an extended type, and a repeated type.

3. The method of claim 3, further comprising selecting a RACH channel having normal cyclic prefix type if the distance from the transmitter is a first distance, a RACH channel having an extended type if the distance from the transmitter is a second distance, and a RACH channel having a repeated type if the distance from the transmitter is a third distance.

4. The method of claim 3 wherein the first distance is less than the second and third distances.

5. The method of claim 4 wherein the second distance is less than the third distance.

14. A method implemented in a wireless transmit/receive unit (WTRU) for determining a failure cause for an unsuccessful random access channel (RACH) access, comprising:

inspecting a RACH response received by the WTRU;

determining a failure cause; and

selecting a RACH based upon the failure cause.

15. The method of claim 14 wherein detecting the failure cause includes comparing a chosen signature index and random ID to a signature index and random ID in the RACH response.

16. The method of claim 15 wherein, if the chosen signature index matches the signature index in the RACH response and the chosen random ID does not match the random ID in the RACH response, further comprising selecting a RACH channel having a longer preamble type.

17. The method of claim 14, further comprising failing to detect a signature index in the RACH response.

18. The method of claim 17, further comprising performing a RACH access backoff.

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

a receiver;

a transmitter; and

a processor in communication with the receiver and the transmitter, the processor configured to determine a distance from an evolved Node-B (eNB) in a cell of a long term evolution (LTE) network, and select a random access channel (RACH) channel based upon the distance determination.

20. The WTRU of claim 19 wherein the processor is further configured to select a RACH channel having a normal cyclic prefix type if the distance from the transmitter is a first distance.

21. The WTRU of claim 20 wherein the processor is further configured to select a RACH channel having an extended cyclic prefix type if the distance from the transmitter is a second distance.

22. The WTRU of claim 20 wherein the processor is further configured to select a RACH channel having a repeated cyclic prefix type if the distance from the transmitter is a third distance.

23. The WTRU of claim 19 wherein the processor is further configured to measure the pathloss of power on a downlink (DL) channel over reference symbols.

24. The WTRU of claim 19 wherein the processor is further configured to select a non-dedicated preamble of a RACH based upon a radio condition of a cell and a message size for transmission.

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

a receiver;

a transmitter; and

a processor in communication with the receiver and the transmitter, the processor configured to inspect a random access channel (RACH) response, determine a failure cause, and select a RACH based upon the failure cause.

26. The WTRU of claim 25 wherein the processor is further configured to compare a chosen signature index and random ID to a signature index and random ID in the RACH response.

27. The WTRU of claim 26 wherein the processor is further configured to select a RACH channel having longer preamble type if the chosen signature index matches the signature index in the RACH response and the chosen random ID does not match the random ID in the RACH response.

28. The WTRU of claim 25 wherein the processor is further configured to perform a RACH access backoff after failing to detect a signature index in the RACH response.