The present disclosure provides a time-and-frequency synchronization method, a network device, and a terminal. The time-and-frequency synchronization method for the terminal includes: subsequent to determining that the terminal in an idle state or a DRX state needs to be woken up to receive a downlink signal, receiving a physical signal for time-and-frequency synchronization from the network device; and performing time-and-frequency synchronization in accordance with the physical signal.

Provided is a radio communication device which can make Acknowledgement (ACK) reception quality and Negative Acknowledgement (NACK) reception quality to be equal to each other. The device includes: a scrambling unit (214) which multiplies a response signal after modulated, by a scrambling code “1” or “e.sup.−j(π/2)”, so as to rotate a constellation for each of response signals on a cyclic shift axis; a spread unit (215) which performs a primary spread of the response signal by using a Zero Auto Correlation (ZAC) sequence set by a control unit (209); and a spread unit (218) which performs a secondary spread of the response signal after subjected to the primary spread, by using a block-wise spread code sequence set by the control unit (209).

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a base station may determine a polarization of a bandwidth part. The base station may transmit, to a user equipment, a polarization indication that indicates the polarization for the bandwidth part. Numerous other aspects are provided.

An apparatus (e.g., a user equipment (UE)) maps a plurality of mutually orthogonal sequences to each of a plurality of physical resource blocks (PRBs) within an interlace. The apparatus then performs a physical uplink control channel (PUCCH) transmission in a New Radio unlicensed spectrum (NR-U). The apparatus also receives an assignment of a set of sequences for each PRB of the plurality of PRBs from a wireless network. In response, the apparatus performs an uplink control information (UCI) transmission via the PUCCH in the NR-U.

A user equipment includes circuitry which selects a random access preamble sequence, and a transmitter which transmits the random access preamble sequence to a base station in a frequency bandwidth of an unlicensed band, and performs at least one of a first operation and a second operation. In the first operation, the circuitry selects a first sequence as the random access preamble sequence, the first sequence having a length longer than a length of a random preamble sequence used for a licensed band, and the transmitter transmits the first sequence in the frequency bandwidth of the unlicensed band. In the second operation, the circuitry selects a second sequence as the random access preamble sequence, the second sequence having a length equal to the length of a random preamble sequence used for the licensed band, and the transmitter transmits the second sequence with repetitions in the frequency bandwidth of the unlicensed band.

A user equipment includes circuitry which selects a random access preamble sequence, and a transmitter which transmits the random access preamble sequence to a base station in a frequency bandwidth of an unlicensed band, and performs at least one of a first operation and a second operation. In the first operation, the circuitry selects a first sequence as the random access preamble sequence, the first sequence having a length longer than a length of a random preamble sequence used for a licensed band, and the transmitter transmits the first sequence in the frequency bandwidth of the unlicensed band. In the second operation, the circuitry selects a second sequence as the random access preamble sequence, the second sequence having a length equal to the length of a random preamble sequence used for the licensed band, and the transmitter transmits the second sequence with repetitions in the frequency bandwidth of the unlicensed band.

When a plurality of the subcarrier spacing values are applied, a reference signal is generated by using a sequence having a sequence length corresponding to a first ratio of a first subcarrier spacing set for transmission data to the maximum settable subcarrier spacing. The sequence of the reference signal is mapped to a frequency resource at mapping intervals in accordance with a second ratio which is the reciprocal of the first ratio, and the transmission data and the reference signal are transmitted.

Methods, systems, and devices are disclosed for digital wireless communication, and more specifically, for the use of pilot sequences that improves performance of channel estimation. In one exemplary aspect, a method of wireless communication performed by a communication node is disclosed. The method includes determining, using a first index, a mask sequence from a plurality of pre-determined mask sequences, wherein the plurality of pre-determined mask sequences is determined based on permutations of values 1, −1, i, and −i or permutations of values 1+i, or 1−i, or −1+i, or −1−i; determining a Walsh sequence using a second index, wherein the Wash sequence has a same length as the mask sequence; generating a pilot sequence by combining the mask sequence and the Walsh sequence; and performing a wireless transmission using the pilot sequence.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a receiving user equipment (UE) may receive, from a transmitting UE, a sidelink reference signal in a first symbol of a slot. The receiving UE may perform a joint channel estimation and an automatic gain control (AGC) based at least in part on the sidelink reference signal received in the first symbol of the slot. Numerous other aspects are described.

A radio performs random access by receiving control information and grouping a predetermined number of sequences that are generated from a plurality of base sequences into a plurality of groups by partitioning the predetermined number of sequences. At least one of the groups is associated with a first respective range of data amounts and a first respective range of reception qualities. Sequences generated from a common base sequence are arranged in an increasing order of respective cyclic shifts associated with the sequences. A sequence is randomly selected from a plurality of sequences contained in one group of the plurality of groups. A position at which the predetermined number of sequences are partitioned is determined based on the control information. A number of sequences contained in each of the plurality of groups varies in accordance with the control information.