Method of allocating radio resouces in a wireless communication system
A method of allocating radio resources in a wireless communication system is disclosed. In one aspect of the present invention, in a wireless communication system, a user equipment requests a base station to allocate radio resources for uplink data transmission of at least one time in accordance with a first radio resource allocation request mode. The user equipment requests the base station to allocate the radio resources for uplink data transmission in accordance with a second radio resource allocation request mode if a predetermined condition is satisfied.
1. A method of requesting allocation of radio resources at a user equipment (UE) in a wireless communication system, the method comprising:
receiving, from a base station, a radio resource control (RRC) message which includes a pre-defined number of times for the UE to transmit a scheduling request (SR) to the base station;
determining whether or not the UE has first allocated uplink radio resources for data transmission;
if the UE has the first allocated uplink radio resources, transmitting the first buffer status report to the base station using the first allocated uplink resources;
determining whether or not the UE has a SR channel configured for transmission of a scheduling request (SR) if the UE does not have the first allocated uplink radio resources;
if the UE has the SR channel, transmitting the scheduling request (SR) to the base station to request allocation of second uplink radio resources for transmission of the first buffer status report, the scheduling request (SR) transmitted the pre-defined number of times until the second uplink radio resources are allocated by the base station;
performing a first random access procedure to request the allocation of the second uplink radio resources, if the UE does not have the SR channel or if the requested second uplink radio resources have not been allocated even after the scheduling request (SR) is transmitted the pre-defined number of times, wherein performing the first random access procedure comprises:
transmitting a random access preamble to the base station;
receiving a random access response message from the base station, the random access response message including information about the second uplink radio resources;
transmitting the first buffer status report to the base station through the second uplink radio resources; and
receiving a contention resolution message from the base station, the contention resolution message including an identifier of the user equipment;
starting a timer after receiving the contention resolution message to check whether third uplink radio resources are allocated or not;
initiating transmission of a second buffer status report by performing a second random access procedure or sending another SR channel, if the third uplink radio resources are not allocated until the timer expires; and
receiving indication information from the base station, the indication information instructing the user equipment to stop transmitting any buffer status report, SR channel or random access preamble,
wherein the user equipment stops transmitting any buffer status report, SR channel or random access preamble after receiving the indication information.
2. The method of claim 1 , wherein the UE terminates the transmission of the scheduling request (SR), if the UE is allocated the uplink radio resources while transmitting the scheduling request (SR) the pre-defined number of times.
3. The method of claim 1 , wherein the scheduling request (SR) is 1-bit information.
4. The method of claim 1 , wherein the first buffer status report is included in a medium access control protocol data unit (MAC PDU) to be transmitted to the base station,
wherein the first buffer status report is either a short buffer status report or a long buffer status report, wherein the short buffer status report comprises one buffer size field for indicating an amount of data of one logical channel group, and the long buffer status report comprises four buffer size fields for indicating an amount of data of four logical channel groups, and wherein a logical channel group includes maximum four logical channels,
wherein a header of the MAC PDU comprises an identifier which indicates whether the first buffer status report is either the short buffer status report or the long buffer status report.