Random access method and device

Abstract

The invention discloses a random access method which is used for realizing random access procedure, in particularly for realizing random access procedure in a secondary cell, so as to secure uplink synchronization of a user side and a network side. The method comprises the following steps: a random access preamble sequence to be sent to a cell in which random access is conducted by a current sub-frame and physical random access channel (PRACH) resource used for sending the preamble are identified by user equipment (UE); the preamble sequence is sent to an eNB on the PRACH resource; based on the PRACH resource, among K PDSCH resources used for transmitting random access response (RAR) allocated to the cell in semi-static manner, the PDSCH resource bearing RAR is identified by the UE in the cell to which the preamble sequence is sent, and then the RAR is received by the UE on the PDSCH resource; and timing advance (TA) value of the cell is obtained by the UE from the received RAR. The invention also discloses a random access device used for realizing the random access method.

Description

technical field [0001] The present invention relates to the communication field, in particular to a random access method and device. Background technique [0002] Random access procedure (Random access procedure) is used to establish uplink synchronization between user equipment (UE, User Equipment) and base station (eNB), by using PRACH (Physical Random Access) in the uplink subframe configured in the system for random access Access Channel, physical random access channel) sends a random access preamble (preamble) sequence, and receives a random access response (RAR, Random Access Response) fed back by the base station, to achieve uplink synchronization. The random access process is divided into contention random access and non-contention random access. [0003] The contention random access is generally triggered by the medium access control (MAC, Medium Access Control1) layer of the UE itself. The preamble sent by the UE can be randomly selected from a specific preamble s...

AI Technical Summary

Problems solved by technology

However, there is currently no uplink synchronization solution for the above scenarios

If the random access process in the prior art is directly applied to the Scell, in order not to increase the blind detection of the PDCCH by the UE, the PDCCH scrambled by the RA-RNTI of the RAR that schedules the Scell ​​needs to be transmitted in the common search space of the Pcell, When the UE transmits the same Preamble sequence on multiple Scells or on the same PRACH resource on Scell ​​and Pcell, the RA-RNTI corresponding to the RAR of the preamble sequence on multiple Scells or Scell ​​and Pcell is the same, so the UE cannot transmit the same Preamble sequence from the Pcell The cell corresponding to the RAR scheduled by the PDCCH is identified in the RA-RNTI scrambled PDCCH transmitted in the common search space of the PDCCH. In addition, if multiple different UEs corresponding to the same Pcell use the same PRACH resource on different cells to send the same In the preamble sequence, the RARs of the preamble sequences sent by different UEs on different cells correspond to the same RA-RNTI, and multiple UEs cannot identify the PDCCH from the RA-RNTI scrambled PDCCH transmitted in the common search space on the Pcell The UE corresponding to the scheduled RAR

If the above problems are solved through a special scheduling mechanism, the scheduling method will be very complicated, especially when there are multiple Scells, the complexity of scheduling will be greatly increased, and the signaling overhead will be significantly increased

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