Method for performing random access and terminal for performing same
摘要
說明書
The reason why a contention is generated in performing random access is that the number of random access preambles is basically limited. That is, since an eNodeB cannot assign UE-unique random access preambles to all pieces of UE, UE randomly selects one of common random access preambles and transmits the selected random access preamble. Accordingly, two or more pieces of UE may select the same random access preamble and transmit the selected random access preamble through the same radio resources (PRACH resources), but an eNodeB determines the received random access preamble to be one random access preamble received from one piece of UE. For this reason, the eNodeB transmits a random access response to UE and expects that the random access response will be received by one piece of UE. However, since a contention can occur as described above, the two or more pieces of UE receive the one random access response, and thus each of the pieces of UE performs an operation according to the reception of the random access response. That is, there is a problem in that the two or more pieces of UE transmit different data through the same radio resources using one UL grant included in the random access response. As a result, the transmission of the data may all fail, and the eNodeB may receive only the data of specific UE depending on the locations or transmission power of the pieces of UE. In the latter case, since all the two or more pieces of UE assume that the transmission of their own data has been successful, the eNodeB needs to inform pieces of UE that have failed in the contention of information about the failure. That is, to inform information about the failure or success of a contention is called a contention resolution.
