BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

The present disclosure relates to mobile communication.

Related Art

With the success of long term evolution (LTE)/LTE-A (LTE-Advanced) for the 4th generation mobile communication, more interest is rising to the next generation, i.e., 5th generation (also known as 5G) mobile communication and extensive research and development are being carried out accordingly.

In a next 5G system, introducing a method of significantly reducing a transmission latency according to an application field is considered. In particular, when it comes to uplink (UL) transmission, instead of an existing method of scheduling by use of a physical downlink control channel (PDCCH) (or an enhanced physical downlink control channel (EPDCCH) or an machine-type communication (MTC) physical downlink control channel (MPDCCH)) including a UL grant, introducing grant-free UL transmission, in which UL transmission starts by a determination made by a UE. is considered.

Meanwhile, when grant-free UL transmission is possible, a downlink control channel may be transmitted to the UE. However, there is a problem as to how to design the DL control channel.

SUMMARY OF THE DISCLOSURE

Accordingly, a disclosure of the present specification has been made in an effort to solve the aforementioned problem.

In an aspect, a method for receiving a downlink control channel by a user equipment (UE) is provided. The method may include receiving the downlink control channel. Here, the downlink control channel may be scrambled by a scrambling sequence. The scrambling sequence may be initialized using a preset identifier (ID) different from an ID of the UE.

The preset ID may be different from a cell ID.

The preset ID may be different from a cell-radio network temporary identifier (C-RNTI) that corresponds to the ID of the UE.

The method may further include, when the downlink control channel includes a first uplink (UL) grant, performing first UL transmission based on the first UL grant, and, even when a subsequent second UL grant is not received, performing second UL transmission.

When the first uplink grant includes a transmit power control (TPC), the TPC may be used to determine power for the first UL transmission and the second UL transmission.

When the second UL transmission is performed repeatedly, power ramping may be performed for the repetition.

When the downlink control channel indicates switching from a UL grant-free transmission scheme to a UL grant-based transmission scheme, the preset ID may be used.

When the downlink control channel indicates UL grant-based UL transmission and the UL transmission may correspond to re-transmission, the preset ID is used.

The preset ID may be set differently according to a time and frequency resource to which a demodulation reference signal (DMRS) is mapped.

In another aspect, a user equipment (UE) for receiving a downlink control channel is provided. The UE may include a transceiver and a configured to receive the downlink control channel by controlling the transceiver. Here, the downlink control channel may be scrambled by a scrambling sequence. The scrambling sequence may be initialized using a preset identifier (ID) different from an ID of the UE.

According to the disclosure of the present disclosure, the problem of the conventional technology described above may be solved.

Specifically, according to the disclosure of the present disclosure, it is possible to efficiently manage a resource in Grant-free UL transmission and Grant-based UL transmission.

