Mobile terminal and base station involved in downlink channel operations including radio channel estimation based on demodulation reference signal

1 . A mobile terminal comprising:

a processing circuitry, which, in operation, assumes that a base station is configured to use for downlink control channel and corresponding demodulation reference signal transmissions to the mobile terminal one of a plurality of transmission beams; and

a transceiver, which, in operation, receives a downlink control channel candidate and a corresponding demodulation reference signal from the base station using one of a plurality of reception beams corresponding to the assumed one of the plurality of transmission beams;

wherein, the processing circuitry, in operation, performs radio channel estimation based on the received demodulation reference signal and, depending on a radio channel estimation quality, demodulates the downlink control channel candidate using the radio channel estimation,

wherein, the channel estimation is performed using a demodulation reference signal sequence which is generated observing an association which associates the generated sequence with the assumed one of the plurality of transmission beams such that at least two of the plurality of transmission beams are associated with different demodulation reference signal sequences, and

wherein, the processing circuitry, in operation, generates the demodulation reference signal sequence from a base sequence corresponding to a scrambling identification including applying a cyclic shift to the demodulation reference signal sequence corresponding to a cyclic shift value which is associated with the assumed one of the plurality of transmission beams.

2 . The mobile terminal according to claim 1 , wherein, performing the radio channel estimation includes:

the processing circuitry correlating the received demodulation reference signal with the generated demodulation reference signal sequence; and

the processing circuitry determining a radio channel estimation quality based on the correlation result, and/or

wherein, in case the radio channel estimation quality is below a threshold, the processing circuitry does not demodulate the received downlink control channel candidate.

3 . The mobile terminal according to claim 1 , wherein the processing circuitry, in operation, generates the demodulation reference signal sequence from the base sequence which includes:

an identification of the assumed one of the plurality of transmission beams,

such that the generated demodulation reference signal sequence is associated with the assumed one of the plurality of transmission beams.

4 . The mobile terminal according to claim 3 , wherein the processing circuitry, in operation, generates the demodulation reference signal sequence from the base sequence which additionally includes at least one of:

at least a part of an identification of the cell comprising the assumed transmission beam; and

at least a part of an identification of the network comprising the cell;

wherein, the at least parts of the identification of the cell or of the network correspond to a predetermined number of least significant bits of the respective identification.

5 . The mobile terminal according to claim 3 , wherein the processing circuitry, in operation, de-scrambles the demodulated downlink control channel candidate using the base sequence.

6 . The mobile terminal according to claim 1 , wherein the processing circuitry, in operation, generates the demodulation reference signal sequence from the base sequence corresponding to the scrambling identification including using an orthogonal cover code which is associated with the assumed one of the plurality of transmission beams.

7 . The mobile terminal according to claim 1 , wherein

the demodulated downlink control channel candidate is included in a common search space carrying downlink control information which is intended for a group of plural mobile terminals, and

the downlink control information corresponds to at least DCI-Format 1-0 with a CRC scrambled with a random access radio network temporary identifier.

8 . The mobile terminal according to claim 1 , wherein

the demodulated downlink control channel candidate is included in a common search space carrying downlink control information which is intended for a group of plural mobile terminals, and

the downlink control information corresponds to at least one of a DCI-Format 2_0 or any other DCI-format conveying indications of a channel occupation time structure with a CRC scrambled with a slot format radio network temporary identifier.

9 . The mobile terminal according to claim 1 , wherein, the transceiver, in operation, receives a configuration of monitoring locations for channel occupation time indications including a beam common preamble sequence at configured monitoring locations.

10 . The mobile terminal according to claim 1 , wherein:

the processing circuitry, in operation, is provided with information specifying that the base station is configured to use specific time instances for a specific format of downlink control channel and corresponding demodulation reference signal transmissions to the mobile terminal with a specific wide transmission beam which is different from the plurality of transmission beams;

the transceiver, in operation, receives at a specific time instant a downlink control channel candidate of the specific format and a corresponding demodulation reference signal from the base station using one of the plurality of reception beams suitable for receiving the specific wide transmission beam; and

the processing circuitry, in operation, performs radio channel estimation based on the received demodulation reference signal and, depending on a radio channel estimation quality, demodulates the downlink control channel candidate using the radio channel estimation, and decodes the demodulated downlink control channel candidate according to the specific format,

wherein the specific format prescribes the decoded downlink control channel candidate to carry downlink control information including:

a time duration for which the downlink control information is held to be valid; and

an identification of at least one of the plurality of transmission beams which is being used by the base station for downlink control channel candidate and a corresponding demodulation reference signal transmissions during at least a part of the time duration,

wherein the processing circuitry uses the identification of at least one of the plurality of transmission beams to generate demodulation reference signal sequences in relation to the association which are to be used for performing channel estimation during the at least a part of the time duration.

11 . A base station, comprising:

a processing circuitry which, in operation, assumes that a mobile terminal is configured to use for downlink control channel and corresponding demodulation reference signal receptions at the mobile terminal one of a plurality of reception beams; and

a transceiver which, in operation, transmits a downlink control channel and a corresponding demodulation reference signal to the mobile terminal using one of a plurality of transmission beams corresponding to the assumed one of the plurality of reception beams;

wherein, the processing circuitry, in operation, modulates the downlink control channel to be transmitted and generates a demodulation reference signal sequence to be transmitted as the corresponding demodulation reference signal,

wherein, the demodulation reference signal sequence is generated observing an association which associates the generated sequence with the one of the plurality of transmission beams such that at least two of the plurality of transmission beams are associated with different demodulation reference signal sequences, and

wherein, the demodulation reference signal sequence is generated from a base sequence corresponding to a scrambling identification including applying a cyclic shift to the demodulation reference signal sequence corresponding to a cyclic shift value which is associated with the one of the plurality of transmission beams.

12 . A reception method for a mobile terminal, comprising:

assuming that a base station is configured to use for downlink control channel and corresponding demodulation reference signal transmissions to the mobile terminal one of a plurality of transmission beams;

receiving a downlink control channel candidate and a corresponding demodulation reference signal from the base station using one of a plurality of reception beams corresponding to the assumed one of the plurality of transmission beams;

performing radio channel estimation based on the received demodulation reference signal and, depending on a radio channel estimation quality, demodulating the downlink control channel candidate using the radio channel estimation,

wherein, the channel estimation is performed using a demodulation reference signal sequence which is generated observing an association which associates the generated sequence with the assumed one of the plurality of transmission beams such that at least two of the plurality of transmission beams are associated with different demodulation reference signal sequences, and

generating the demodulation reference signal sequence from a base sequence corresponding to a scrambling identification including applying a cyclic shift to the demodulation reference signal sequence corresponding to a cyclic shift value which is associated with the assumed one of the plurality of transmission beams.

13 . A transmission method for a base station, comprising

assuming that a mobile terminal is configured to use for downlink control channel and corresponding demodulation reference signal receptions at the mobile terminal one of a plurality of reception beams;

transmitting a downlink control channel and a corresponding demodulation reference signal to the mobile terminal using one of a plurality of transmission beams corresponding to the assumed one of the plurality of reception beams;

modulating the downlink control channel to be transmitted and generating a demodulation reference signal sequence to be transmitted as the corresponding demodulation reference signal,

wherein, the demodulation reference signal sequence is generated observing an association which associates the generated sequence with the one of the plurality of transmission beams such that at least two of the plurality of transmission beams are associated with different demodulation reference signal sequences,

wherein, the demodulation reference signal sequence is generated from a base sequence corresponding to a scrambling identification including applying a cyclic shift to the demodulation reference signal sequence corresponding to a cyclic shift value which is associated with the one of the plurality of transmission beams.