Method for performing random access procedure in wireless communication system

#The present invention relates to wireless communication. More specifically, the invention relates to a method of performing a random access procedure in a wireless communication system.

#Third generation partnership project (3GPP) mobile communication systems based on a wideband code division multiple access (WCDMA) radio access technique are widely deployed all over the world. High speed downlink packet access (HSDPA) that can be defined as a first evolutionary stage of WCDMA provides 3GPP with highly competitive radio access technique in the mid-term future. However, since requirements and expectations of users and service providers are continuously increased and developments of competing radio access techniques are continuously in progress, new technical evolutions in 3GPP are required to secure competitiveness in the future. Decrease of cost per bit, increase in service availability, flexible use of frequency bands, simple architecture and open interface, low power consumption of a user equipment and the like are suggested as requirements of next generation communication systems.

#Generally, one or more cells are allocated to a base station. A plurality of user equipments can be placed in a cell. A user equipment generally performs random access procedure before accessing to a network. The objectives of the random access procedure may include 1) initial access, 2) handover, 3) scheduling request (request for radio resources), 4) timing synchronization, and the like.

#FIG. 1 is a block diagram showing a wireless communication system.

#FIG. 2 is a block diagram showing a functional split between evolved universal terrestrial radio access network (E-UTRAN) and evolved packet core (EPC).

#FIG. 3 is a block diagram showing the radio protocol architecture of a user plane.

#FIG. 1 is a block diagram showing a wireless communication system. This may be the network architecture of an evolved-universal mobile telecommunications system (E-UMTS). The E-UMTS may be referred to as a long term evolution (LTE) system. The wireless communication system is widely deployed to provide a variety of communication services such as audio data, packet data, or the like.

#Referring to FIG. 1, evolved-UMTS terrestrial radio access network (E-UTRAN) includes a base station (BS) 20 for providing control plane and user plane.

#A user equipment (UE) 10 can be fixed or mobile and can be referred to as other terminologies such as a mobile station (MS), user terminal (UT), subscriber station (SS), wireless device, or the like. The base station 20 generally means a fixed station that communicates with the user equipment 10 and can be referred to as other terminologies such as an evolved-NodeB (eNB), base transceiver system (BTS), access point, or the like. The base station 20 cane serves for at least one cell. An interface for transmitting user traffics or control traffics can be used between base stations 20. Hereinafter, downlink means communication from the base station 20 to the user equipment 10, and uplink means communication from the user equipment 10 to the base station 20.