APPARATUS AND METHOD FOR RANDOM ACCESS IN WIRELESS COMMUNICATION SYSTEM

• US 20100255847A1
• Filed: 04/01/2010
• Published: 10/07/2010
• Est. Priority Date: 04/01/2009
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: KIM, Seong Hun, KWON, Sung Oh, LEE, Neung Hyung
• Granted Patent: US 8,285,286 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 52/362 Aspects of the step size
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 74/004 in the uplink, i.e. towards network
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

A method and an apparatus are provided that transmit and receive a random access preamble in a wireless communication system. A plurality of random access parameters having different values in accordance with a plurality of events for triggering random access are set. When one of the plurality of events for triggering random access has occurred, random access is performed according to at least one of the plurality of random access parameters corresponding to the event. Therefore, the time delay of random access can be reduced.

Claims

1. A method for random access of user equipment, comprising the steps of:

setting a plurality of random access parameters having different values in accordance with a plurality of events for triggering random access; and

when one of the plurality of events for triggering random access has occurred, performing random access according to at least one of the plurality of random access parameters corresponding to the event.

2. The method of claim 1, wherein:

the plurality of random access parameters comprise initial transmission power parameters and ramping power parameters; and

performing random access comprises;

transmitting a preamble using a transmission power corresponding to an initial transmission power parameter corresponding to the event; and

when a response corresponding to the preamble has not been received, increasing the transmission power by a ramping power corresponding to a ramping power parameter corresponding to the event and re-transmitting the preamble using the increased transmission power.

3. The method of claim 2, wherein:

when the initial transmission power parameter corresponds to one of an idle to connected mode transition event and a Radio Resource Control (RRC) connection re-establishment event, the initial transmission power parameter corresponds to a preset minimum value; and

when the initial transmission power parameter corresponds to one of a handover event and an uplink or downlink data resume event, the initial transmission power parameter corresponds to a value greater that the preset minimum value.

4. The method of claim 2, wherein:

the plurality of random access parameters further comprise retrial number parameters; and

re-transmitting the preamble comprises;

when a response corresponding to the preamble has not been received, retransmitting the preamble using a same transmission power as a previous preamble transmission, for a number of re-transmissions corresponding to a retrial number parameter corresponding to the event before increasing the transmission power by the ramping power corresponding to the ramping power parameter corresponding to the event.

5. The method of claim 4, wherein:

when the retrial number parameter corresponds to one of an idle to connected mode transition event and an RRC connection re-establishment event, the preamble is not re-transmitted using the same transmission power as the previous preamble transmission; and

when the retrial number parameter corresponds to one of a handover event and an uplink or downlink data resume event, the preamble is retransmitted one or more times using the same transmission power as the previous preamble transmission.

6. The method of claim 1, wherein setting random access parameters comprises:

receiving the random access parameters from a base station; and

setting the random access parameters according to the received random access parameters.

7. An apparatus for random access in a user equipment, comprising:

a storage unit for storing a plurality of random access parameters that differ from each other according to a plurality of events for triggering random access;

a random access preamble configuration unit for generating a random access preamble when one of the plurality of events for triggering random access has occurred;

a user equipment communication unit for transmitting the random access preamble; and

a random access preamble power controller for controlling transmission power of the random access preamble according to at least one of the plurality of random access parameters stored in the storage unit.

8. The apparatus of claim 7, wherein:

the plurality of random access parameters comprise initial transmission power parameters;

the RA preamble power controller controls a transmission power of the random access preamble in accordance with an initial transmission power parameter corresponding to the event;

when the initial transmission power parameter corresponds to one of an idle to connected mode transition event and a Radio Resource Control (RRC) connection re-establishment event, the initial transmission power parameter comprises a preset minimum value; and

when the initial transmission power parameter corresponds to one of a handover event and an uplink or downlink data resume event, the initial transmission power parameter comprises a value greater that the preset minimum value.

9. The apparatus of claim 7, further comprising:

a random access preamble transmission period controller that waits for a time indicated by a backoff window, based on one of the plurality of random access parameters stored in the storage unit, and controls the user equipment communication unit to re-transmit the preamble.

10. The apparatus of claim 7, wherein:

the random access parameters further comprise retrial number parameters and ramping power parameters; and

when a response corresponding to the preamble has not been received, the RA preamble power controller retransmits the preamble using a same transmission power as a previous preamble transmission, for a number of re-transmissions corresponding to a retrial number parameter corresponding to the event before increasing the transmission power by a ramping power corresponding to a ramping power parameter corresponding to the event.

11. The apparatus of claim 10, wherein:

when the retrial number parameter corresponds to one of an idle to connected mode transition event and an RRC connection re-establishment event, the preamble is not retransmitted using the same transmission power as the previous preamble transmission; and

when the retrial number parameter corresponds to one of a handover event and an uplink or downlink data resume event, the preamble is retransmitted one or more times using the same transmission power as the previous preamble transmission.

12. The apparatus of claim 7, wherein:

the user equipment communication unit receives the random access parameters from a base station; and

the storage unit stores the received random access parameters.