Method for random access in wireless communication system, wireless communication system, wireless terminal, and base station unit

• US 8,737,320 B2
• Filed: 01/19/2010
• Issued: 05/27/2014
• Est. Priority Date: 08/10/2007
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ohta, Yoshiaki, Tajima, Yoshiharu, Obuchi, Kazuhisa, Kawasaki, Yoshihiro
• Primary Examiner(s): Elpenord, Candal
• Application Number:
  US12/689,639
• Publication Number:
  US 20100118788A1
• Time in Patent Office: 1,589 Days
• Field of Search: 370/328, 370/329, 370/330, 370342-343, 370/350, 370503-509, 455/450, 455/452.1
• US Class Current: 370/329
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 74/002 Transmission of channel access control information
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

In the event of detecting first information used for first random access and second information used for second random access, the second information being received from the base station unit, a wireless terminal selects one between the first information and the second information. Thereby, either one of the random accesses can be selectively performed, efficiently using resources such as signatures used for random access.

Claims

1. A method for random access in a wireless communication system including a base station unit and a wireless terminal, the method comprising:

at the wireless terminal,

detecting first information used for first random access and second information used for second random access, the second information being received from the base station unit;

selecting information among the first information and the second information, in a case of receiving a new request requesting for one random access among the first random access and the second random access while another random access among the first random access and the second random access is already ongoing;

proceeding with only one random access using the selected information from the selecting, among the first random access and the second random access; and

not proceeding with another random access which is different from the random access using the selected information from the selecting, among the first random access and the second random access.

2. The method for random access according to claim 1, further comprising:

at the wireless terminal,

creating the first information when uplink data destined for the base station unit arrive; and

receiving the second information when downlink data destined for the wireless terminal from the base station unit arrive.

3. The method for random access according to claim 1, further comprising:

at the wireless terminal,

not proceeding with the second random access; and

transmitting uplink synchronization request information as third information, which requests to establish synchronization of uplink communication for receiving downlink data, to the base station unit during the first random access.

4. The method for random access according to claim 1, further comprising:

at the wireless terminal,

not proceeding with the first random access; and

transmitting uplink data transmission request information as third information, which requests to transmit uplink data, to the base station unit during or after the completion of the second random access.

5. The method for random access according to claim 3, wherein the uplink synchronization request information is provided to an uplink message that is to be transmitted to the base station unit during the first random access.

6. The method for random access according to claim 4, wherein the uplink data transmission request information is provided to an uplink message that is to be transmitted to the base station unit during the second random access.

7. The method for random access according to claim 1, further comprising:

at the base station unit,

upon receipt of third information, which is transmitted to the base station unit during random access which is different from the random access using the selected information from the selecting, among the first random access and the second random access, after detecting the presence of the first information received from the wireless terminal and the second information that the base station unit allocates to the wireless terminal; and

releasing management of the first information or the second information.

8. The method for random access according to claim 1, further comprising:

at the wireless terminal,

receiving the second information used for the second random access in response to generation of downlink data from the base station unit before creating the first information used for the first random access in response to generation of uplink data destined for the base station unit,

transmitting third information, which is transmitted to the base station unit during the first random access, to the base station unit during or after completion of the second random access using the second information.

9. A wireless communication system including a base station unit and a wireless terminal, wherein

the wireless terminal selects information among first information used for first random access and second information used for second random access, in a case of receiving a new request requesting for one random access among the first random access and the second random access while another random access among the first random access and the second random access is already ongoing, the second information being received from the base station unit;

the wireless terminal proceeds with only one random access using the selected information, among the first random access and the second random access, and does not proceed with another random access which is different from the random access using the selected information, among the first random access and the second random access;

the base station unit receives the first information used for the first random access from the wireless terminal;

the base station unit transmits the second information used for the second random access to the wireless terminal; and

the base station unit proceeds with the random access using the selected information, among the first random access and the second random access.

10. The wireless communication system according to claim 9, wherein

the base station unit manages the first information, which is received from the wireless terminal, used for the first random access and the second information, which is transmitted to the wireless terminal, used for the second random access received from the wireless terminal;

and

the base station unit releases management of the information that is not selected among the first information and the second information.

11. A wireless terminal comprising:

a generator that generates first information used for first random access to a base station unit;

a receiver that receives, from the base station unit, second information used for second random access to the base station unit;

a selector that selects information among the first information and the second information, in a case of receiving a new request requesting for one random access among the first random access and the second random access while another random access among the first random access and the second random access is already ongoing; and

a controller that proceeds with only one random access using the selected information, among the first random access and the second random access, and that does not proceed with another random access which is different from the random access using the selected information, among the first random access and the second random access.

12. The wireless terminal according to claim 11, wherein

the selector selects the first information;

and

the transmitter transmits uplink synchronization request information, as third information, which requests to establish synchronization of uplink communication for receiving downlink data, to the base station unit during the first random access.

13. The wireless terminal according to claim 11, wherein

the selector selects the second information;

and

the transmitter transmits uplink data transmission request information, as third information, which requests to transmit uplink data, to the base station unit during the second random access.

14. The wireless terminal according to claim 12, wherein

the transmitter provides the uplink synchronization request information to an uplink message that is to be transmitted to the base station unit during the first random access.

15. The wireless terminal according to claim 13, wherein

the transmitter provides the uplink data transmission request information to an uplink message that is to be transmitted to the base station unit during the second random access.

16. A base station unit comprising:

a receiver that receives first information used for first random access received from a wireless terminal;

a transmitter that transmits second information used for second random access to the wireless terminal; and

a controller that proceeds with only one random access using information, which the wireless terminal selects among the first information and the second information in a case of receiving a new request requesting for one random access among the first random access and the second random access while another random access among the first random access and the second random access is already ongoing, among the first random access and the second random access and that does not proceed with another random access which is different from the random access using the information selected by the wireless terminal, among the first random access and the second random access.

17. The base station unit according to claim 16, wherein

a manager that manages the first information, which is received from the wireless terminal, used for the first random access and the second information, which is transmitted to the wireless terminal, used for the second random access received from the wireless terminal;

and

a determining unit that determines, based on third information, which is transmitted from the wireless terminal during random access which is different from the random access using the information selected by the wireless terminal, received from the wireless terminal, information selected by the wireless terminal among the first information and the second information, wherein

the controller proceeds with random access corresponding to the information that the determining unit determines that the wireless terminal selects and that carries out control based on the third information.

18. The base station unit according to claim 17, wherein

when the third information is uplink synchronization information, which requests to establish synchronization of uplink communication for receiving downlink data, the determining unit determines that the first information is selected by the wireless terminal.

19. The base station unit according to claim 17, wherein

when the third information is uplink data transmission request information, which requests to transmit uplink data, the determining unit determines that the second information is selected by the wireless terminal.

20. The base station unit according to claim 17, wherein

the controller releases management of information, by the manager, that the determining unit determines not to be selected.