Method And Apparatus For Selecting Enhanced Dedicated Channel Transport Format Combination In Cell_Fach State And Idle Mode

• US 20130003665A1
• Filed: 12/28/2011
• Published: 01/03/2013
• Est. Priority Date: 03/20/2008
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Inventors: Pelletier, Benoit, Marinier, Paul, Roy, Vincent, Pani, Diana, Cave, Christopher R.
• Granted Patent: US 8,700,087 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

A method and apparatus for selecting an enhanced dedicated channel (E-DCH) transport format combination (E-TFC) in Cell_FACH state and idle mode are disclosed. A wireless transmit/receive unit (WTRU) transmits a random access channel (RACH) preamble and receives an index to an E-DCH resource in response to the RACH preamble. The WTRU may estimate a power headroom based on the maximum WTRU transmit power, power offset value, and the last successfully transmitted RACH preamble transmit power. The WTRU restricts an E-TFC based on the estimated power headroom, and selects an E-TFC based on a set of supported E-TFCs. The WTRU then generates, and transmits, a protocol data unit (PDU) based on the selected E-TFC.

Claims

1. A method for performing enhanced dedicated channel (E-DCH) transport format combination (E-TFC) restriction for E-DCH transmissions in Cell Forward Access Channel (Cell_FACH) state or idle mode, the method comprising:

a WTRU transmitting a random access channel (RACH) preamble;

the WTRU receiving an index to an E-DCH resource in response to the RACH preamble;

the WTRU estimating the power headroom for at least an initial E-TFC restriction based on at least a WTRU maximum transmit power, a power offset value and a last transmitted RACH preamble transmit power; and

the WTRU performing E-TFC restriction to determine a set of supported E-TFCs based on the estimated power headroom.

2. The method of claim 1 wherein the WTRU estimates the power headroom for a predetermined duration, following reception of the index.

3. The method of claim 1, wherein the WTRU bases the E-TFC restriction on the estimated power headroom for a duration of a variable number of first dedicated physical control channel (DPCCH) slots or of a variable number of first transmission time intervals (TTIs).

4. The method of claim 3, wherein after the duration, the E-TFC restriction is calculated based on a DPCCH power measurement.

5. The method of claim 1, wherein the WTRU receives a power offset value via system information.

6. The method of claim 1 further comprising:

the WTRU selecting an E-TFC from the set of supported E-TFCs;

the WTRU generating a protocol data unit (PDU) based on the selected E-TFC; and

the WTRU transmitting the PDU.

7. The method of claim 1 further comprising the WTRU sending scheduling information including the estimated power headroom to a network.

8. The method of claim 1 wherein the WTRU estimates the power headroom and performs E-TFC restriction every time a RACH preamble is transmitted during power ramp-up.

9. The method of claim 1 wherein the WTRU estimates the power headroom, performs E-TFC restriction, selects an E-TFC, and generates a PDU every time a RACH preamble is transmitted during power ramp-up.

10. The method of claim 1 wherein the WTRU performs the E-TFC restriction based on the estimated power headroom for a first E-DCH transmission following a RACH preamble transmission.

11. A wireless transmit/receive unit (WTRU) for performing (E-DCH) transport format combination (E-TFC) restriction for E-DCH transmissions in Cell Forward Access Channel (Cell_FACH) state or idle mode, the WTRU comprising:

a transmit/receive unit configured to transmit a random access channel (RACH) preamble, receive an index to an E-DCH resource in response to the RACH preamble; and

a controller configured to estimate a power headroom for at least an initial E-TFC restriction based on a WTRU maximum transmit power, a power offset value, and a last transmitted RACH preamble transmit power, and perform E-TFC restriction based on the estimated power headroom to determine a set of supported E-TFCs

12. The WTRU of claim 11 wherein the controller is configured to estimate the power headroom for a predetermined duration, following reception of the index.

13. The WTRU of claim 11 wherein the controller is configured to base the E-TFC restriction on the estimated power headroom for a duration of a variable number of first dedicated physical control channel (DPCCH)slots or of a variable number of first transmission time intervals (TTIs).

14. The WTRU of claim 13 wherein, after the duration, the controller is configured calculate the E-TFC restriction based on a DPCCH power measurement.

15. The WTRU of claim 11 wherein the transmit/receive unit is configured to receives a power offset value via system information.

16. The WTRU of claim 15 wherein the controller is configured to select an E-TFC from the set of supported E-TFCs, generate a protocol data unit (PDU) based on the selected E-TFC, and transmit the PDU.

17. The WTRU of claim 15 wherein the transmit/receive unit is configured to send scheduling information including the estimated power headroom to a network.

18. The WTRU of claim 15 wherein the controller is configured to estimate the power headroom and perform E-TFC restriction every time a RACH preamble is transmitted during power ramp-up.

19. The WTRU of claim 15 wherein the controller is configured to estimate the power headroom, performs E-TFC restriction, select an E-TFC, and generate a PDU every time a RACH preamble is transmitted during power ramp-up.

20. The WTRU of claim 15 wherein the controller is configured to perform the E-TFC restriction based on the estimated power headroom for a first E-DCH transmission following a RACH preamble transmission.