Random Access Process in Carrier Aggregation

• US 20170006640A1
• Filed: 07/05/2016
• Published: 01/05/2017
• Est. Priority Date: 07/05/2015
• Status: Active Grant

• Current Assignee: Ofinno, LLC
• Original Assignee: Ofinno Technologies, LLC
• Inventors: Dinan, Esmael Hejazi
• Granted Patent: US 10,420,147 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 76/27 Transitions between radio resource control [RRC] states

Abstract

A MAC layer instructs a physical layer to transmit a preamble as a part of a random access (RA) procedure on a licensed assisted access (LAA) cell. The wireless device performs an LBT for transmission of the preamble. The wireless device considers the RA procedure unsuccessfully completed if a first condition based on a first counter is met. The wireless device considers the RA procedure unsuccessfully completed if a condition based on a second counter is met.

Claims

1. A method comprising:

receiving a control order to transmit a preamble as a part of a random access (RA) procedure on a cell;

instructing, a physical layer by a MAC layer, to transmit the preamble on the cell; and

when a corresponding RA response is not received;

considering the RA procedure unsuccessfully completed if a first condition based on a first counter is met regardless of whether the cell is licensed or licensed-assisted-access (LAA), the first counter configured to count a number of physical layer transmissions of the preamble,

otherwise considering the RA procedure unsuccessfully completed if a second condition based on a second counter is met and the cell is LAA, the second counter is employed only if the cell is LAA, and the second counter configured to limit a time duration that the preamble is used for the RA procedure on the cell.

2. The method of claim 1, further comprising setting a preamble power parameter employing the first counter.

3. The method of claim 1, further comprising, in response to receiving the control order:

starting the first counter; and

starting the second counter.

4. The method of claim 1, further comprising, when the cell is LAA:

performing, by the physical layer, listen-before-talk (LBT) for transmission of the preamble at a transmission opportunity;

transmitting, by the physical layer, the preamble if the LBT succeeds, otherwise dropping transmission of the preamble; and

receiving, by the MAC layer, a power ramping suspension indication from the physical layer when the transmission of the preamble is dropped due to a failure of the LBT.

5. A method of claim 1, further comprising considering the random access procedure successfully completed when the wireless device receives the corresponding random access response.

6. The method of claim 1, wherein the second counter configured to count a number of transmission opportunities of the preamble

7. The method of claim 5, further comprising selecting random access resources for preamble transmission if:

the corresponding random access response is not received;

the first condition is not met; and

the second condition is not met.

8. The method of claim 1, further comprising considering the first condition met when the first counter reaches a maximum counter value.

9. The method of claim 8, further comprising receiving a radio resource control (RRC) message indicating the maximum counter value.

10. The method of claim 1, further comprising considering the second condition met when the second counter reaches the maximum counter value.

11. The method of claim 10, further comprising receiving an RRC message indicating the maximum counter value.

12. The method of claim 1, further comprising monitoring a downlink channel for the corresponding random access response within a random access response window, the corresponding random access response comprising a preamble identifier that matches the preamble.

13. The method of claim 1, further comprising:

increasing the first counter when the preamble is transmitted by the physical layer; and

increasing the second counter when the physical layer performs LBT for transmission of the preamble at a transmission opportunity of the preamble.

14. The method of claim 1, wherein the control order is a physical downlink control channel (PDCCH) comprising a preamble index and a random access mask index.

15. The method of claim 1, further comprising receiving at least one RRC message comprising:

configuration parameters of a plurality of cells comprising the cell;

random access resource information elements of a random access channel (RACH) on the cell;

a random access response window information element; and

a maximum RA transmission counter information element.

16. A method comprising:

instructing, a physical layer by a MAC layer, to transmit a preamble as a part of a random access (RA) procedure on a licensed assisted access (LAA) cell;

performing an LBT for transmission of the preamble at a transmission opportunity of the preamble;

when a corresponding random access response is not received;

increasing a first counter when the LBT is successful;

increasing a second counter regardless of success or failure of the LBT; and

considering the RA procedure unsuccessfully completed if a first condition based on the first counter is met,

otherwise considering the RA procedure unsuccessfully completed if a second condition based on the second counter is met.

17. The method of claim 16, further comprising

performing, by the physical layer, listen-before-talk (LBT) for transmission of the preamble at a transmission opportunity;

and

transmitting, by the physical layer, the preamble if the LBT succeeds, otherwise dropping transmission of the preamble.

18. The method of claim 16, further comprising considering the random access procedure successfully completed when the wireless device receives the corresponding random access response.

19. The method of claim 16, further comprising:

receiving a control order configured to initiate the random access procedure on the LAA cell;

starting the first counter in response to receiving the control order; and

starting the second counter in response to receiving the control order.

20. A wireless device comprising:

one or more processors; and

memory storing instructions that, when executed, cause the wireless device to;

instruct, a physical layer by a MAC layer, to transmit a preamble as a part of a random access (RA) procedure on a licensed assisted access (LAA) cell;

perform an LBT for transmission of the preamble at a transmission opportunity of the preamble;

when a corresponding random access response is not received;

increase a first counter when the LBT is successful;

increase a second counter regardless of success or failure of the LBT; and

consider the RA procedure unsuccessfully completed if a first condition based on the first counter is met,

otherwise consider the RA procedure unsuccessfully completed if second a condition based on the second counter is met.