Method for preparing random access procedures and terminal thereof

• US 8,467,343 B2
• Filed: 03/24/2011
• Issued: 06/18/2013
• Est. Priority Date: 06/18/2008
• Status: Active Grant

• Current Assignee: Optis Cellular Technology LLC (Brevet Capital)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Yi, Seung-June, Park, Sung-Jun, Lee, Young-Dae, Chun, Sung-Duck
• Primary Examiner(s): Jiang, Charles C
• Application Number:
  US13/071,280
• Publication Number:
  US 20110176513A1
• Time in Patent Office: 817 Days
• Field of Search: 370/310, 370328-334, 455/403, 455/422.1, 455450-454
• US Class Current: 370/329
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 74/002 Transmission of channel access control information
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A random access procedure between a mobile terminal and a network is performed based upon the characteristics of a RACH preamble. If the RACH preamble was explicitly signaled by the network, a downlink channel is monitored until a new transmission is indicated according to radio resource allocation information received from the network. If the RACH preamble was not explicitly signaled by the network, a contention resolution timer is started and the downlink channel is monitored until the contention resolution timer expires. Such monitoring of downlink channels in a more efficient manner, results in effective reduction in power consumption.

Claims

1. A method of performing a random access procedure between a mobile terminal and a network, the method performed by the mobile terminal and comprising:

transmitting, a first type of Random Access Preamble or a second type of Random Access Preamble, to the network;

receiving a Random Access Response sent from the network in response to the first type of Random Access Preamble or the second type of Random Access Preamble;

wherein the first type of Random Access Preamble is based on preamble selection by the mobile terminal, and the second type of Random Access Preamble is not based on preamble selection by the mobile terminal; and

performing a discontinuous reception (DRX) operation that controls how the mobile terminal monitors a downlink channel based on whether the first type of Random Access Preamble or the second type of Random Access Preamble is used,

wherein the discontinuous reception (DRX) operation employs an active time that denotes a time duration in which the mobile terminal monitors the downlink channel, and the active time includes a time while;

an On-Duration timer or a DRX Inactivity timer or a DRX Retransmission timer or a Contention Resolution timer is running,

a Scheduling Request procedure is pending,

an uplink grant for a retransmission can occur, or

a PDCCH indicating a new transmission addressed to a C-RNTI of the mobile terminal has not yet been received after successful reception of the Random Access Response.

2. The method of claim 1, wherein the step of transmitting the first type of Random Access Preamble comprises:

selection of a random access preamble among a set of random access preambles indicated via system information or a handover command;

selection of PRACH resources to be used in transmitting said selected random access preamble; and

performing transmission of said selected random access preamble using the selected PRACH resources.

3. The method of claim 1, wherein the transmitting step, the receiving step, and the performing step being carried out for the first type of Random Access Preamble denote a contention-based random access procedure and the first type of Random Access Preamble is a contention-based preamble.

4. The method of claim 3, further comprising:

starting a contention resolution timer;

monitoring the downlink channel while the contention resolution timer operates;

applying a back-off time if the identifier that indicates allocation of radio resources for a new transmission is not received upon expiration of the contention resolution timer; and

performing random access procedures again after the back-off time,

wherein the downlink channel is not monitored during the back-off time.

5. The method of claim 3, further comprising:

performing contention resolution procedures by using a contention resolution timer, and the downlink channel is no longer monitored by the mobile terminal when the contention resolution timer expires.

6. The method of claim 4, further comprising:

performing contention resolution procedures by using a back-off timer in addition to the contention resolution timer, and the downlink channel is not monitored by the mobile terminal while the back-off timer operates.

7. The method of claim 1, wherein the transmitting step, the receiving step, and the performing step being carried out for the second type of Random Access Preamble denote a non-contention-based random access procedure and the second type of Random Access Preamble is a dedicated preamble.

8. The method of claim 1, wherein the second type of Random Access Preamble is based on explicit signaling from the network instead of preamble selection by the mobile terminal.

9. The method of claim 1, wherein, if the second type of Random Access Preamble is used, the active time includes the PDCCH indicating a new transmission addressed to a C-RNTI of the mobile terminal has not yet been received after successful reception of the Random Access Response.

10. The method of claim 1, wherein the random access procedure is performed for at least the following situations:

upon performing an initial access when there is no radio resource control (RRC) connection with the network;

upon initial access to a target cell while the mobile terminal is in handover;

upon request by a command from the network;

upon generation of data for uplink, when uplink time synchronization is not correct or when designated radio resources to be used in appropriate requesting radio resources have not yet been allocated; and

during a correction, decoding, reconstruction, or recovery procedure when there is a radio link failure or handover failure.

11. The method of claim 1, wherein the downlink channel is a PDCCH (Physical Downlink Control CHannel).

12. The method of claim 1, wherein the DRX operation includes configuring of a Long DRX Cycle, a DRX Inactivity Timer, a DRX Retransmission Timer, and optionally a Short DRX Cycle and a DRX Short Cycle Timer.

13. The method of claim 12, wherein if the Short DRX Cycle is configured, the DRX Short Cycle Timer is started or restarted.

14. The method of claim 12, wherein if the Long DRX Cycle or the Short DRX Cycle is configured, then a DRX start offset is also configured.

15. The method of claim 12, wherein the DRX operation also employs a HARQ RTT Timer.

16. A mobile terminal comprising:

an input/output means configured to provide inputs and outputs;

a microprocessor; and

a communication module, cooperating with the input/output means and the microprocessor, wherein the microprocessor causes the communication module to;

transmit a first type of Random Access Preamble or a second type of Random Access Preamble, to the network;

receive a Random Access Response sent from the network in response to the first type of Random Access Preamble or the second type of Random Access Preamble;

wherein the first type of Random Access Preamble is based on preamble selection by the mobile terminal, and the second type of Random Access Preamble is not based on preamble selection by the mobile terminal; and

perform a discontinuous reception (DRX) operation that controls how the mobile terminal monitors a downlink channel based on whether the first type of Random Access Preamble or the second type of Random Access Preamble is used,

wherein the discontinuous reception (DRX) operation employs an active time that denotes a time duration in which the mobile terminal monitors the downlink channel, and the active time includes a time while;

an On-Duration timer or a DRX Inactivity timer or a DRX Retransmission timer or a Contention Resolution timer is running, a Scheduling Request procedure is pending, an uplink grant for a retransmission can occur, or a PDCCH indicating a new transmission addressed to a C-RNTI of the mobile terminal has not yet been received after successful reception of the Random Access Response.

17. The mobile terminal of claim 16, wherein the communication module performing the transmitting step, the receiving step, and the performing step for the first type of Random Access Preamble denotes that a contention-based random access procedure is being performed and that the first type of Random Access Preamble is a contention-based preamble and, wherein the communication module performing the transmitting step, the receiving step, and the performing step for the second type of Random Access Preamble denotes that a non-contention-based random access procedure is being performed and that the second type of Random Access Preamble is a dedicated preamble.

18. The mobile terminal of claim 16, wherein the second type of Random Access Preamble is based on explicit signaling from the network instead of preamble selection by the mobile terminal.

19. The mobile terminal of claim 16, wherein, if the second type of Random Access Preamble is used, the active time includes the PDCCH indicating a new transmission addressed to a C-RNTI of the mobile terminal has not yet been received after successful reception of the Random Access Response.

20. The mobile terminal of claim 16, wherein the DRX operation includes configuring of a Long DRX Cycle, a DRX Inactivity Timer, a DRX Retransmission Timer, and optionally a Short DRX Cycle and a DRX Short Cycle Timer, wherein if the Short DRX Cycle is configured, the DRX Short Cycle Timer is started or restarted, wherein if the Long DRX Cycle or the Short DRX Cycle is configured, then a DRX start offset is also configured, and wherein the DRX operation also employs a HARQ RTT Timer.