Methods, systems, and devices for wireless communications are described. A first wireless device may identify a set of data resource elements for transmitting data in one or more symbols periods. The first wireless device may generate, for the one or more symbol periods based on the set of data resource elements, a sequence of a set of pilot resource elements associated with the set of data resource elements, the sequence of the set of pilot resource elements including a demodulation reference signal. The first wireless device may transmit, to a second wireless device in the one or more symbol periods, the set of data resource elements and the set of pilot resource elements. The second wireless device may decode a first subset of the set of pilot resource elements based on a second subset of the set of pilot resource elements to determine the demodulation reference signal.

A transmitter is provided. The transmitter includes: a Low Density Parity Check (LDPC) encoder configured to encode input bits to generate parity bits; a parity permutator configured to group-wise interleave a plurality of bit groups including the parity bits; and a puncturer configured to select some of the parity bits in the group-wise interleaved bit groups and puncture the selected parity bits, wherein the parity permutator group-wise interleaves the bit groups such that some of the bit groups at predetermined positions in the bit groups before the group-wise interleaving are positioned serially after the group-wise interleaving and a remainder of the bit groups before the group-wise interleaving are positioned without an order after the group-wise interleaving so that the puncturer selects parity bits included in the some of the bit groups sequentially and selects parity bits included in the remainder of the bit groups without an order.

Methods, systems, and devices for wireless communications are described. A device (e.g., a base station or a user equipment (UE)) may identify a sequence length corresponding to a number of resource blocks, and select a modulation scheme based on the sequence length. The device may select, from a set of sequences associated with the modulation scheme, a sequence having the sequence length. In some examples, the set of sequences may include at least one of a set of time domain phase shift keying computer-generated sequences or a set of frequency domain phase shift keying computer-generated sequences. The device may generate a reference signal for a data transmission based on the sequence and transmit the reference signal within the number of resource blocks.

An example according to the present specification relates to a technique relating to a configuration of a preamble in a wireless LAN (WLAN) system. A reception STA can receive a PPDU. The reception STA can perform a modulo operation with respect to whether or not an L-SIG field is repeated and a value of a length field. The reception STA can determine the received PPDU as an EHT PPDU on the basis of the modulo operation with respect to whether or not the L-SIG field is repeated and the value of the length field.

An example according to the present specification relates to a technique for configuring a preamble in a wireless LAN (WLAN) system. A transmitting STA may generate and transmit an EHT PPDU. The EHT PPDU may comprise an L-SIG field, an RL-SIG field, a first control field, and a second control field. A result of “modulo 3 operation” for a length field value of the L-SIG field may be set to “0.” The RL-SIG field may be configured to be the same as the L-SIG field. The first control field may comprise 3-bit information on the version of a PPDU, 6-bit information on a BSS color, and 7-bit information on TXOP.

An example according to the present specification relates to a technique for configuring a preamble in a wireless LAN (WLAN) system. A transmitting STA may generate and transmit an EHT PPDU. The EHT PPDU may comprise an L-SIG field, an RL-SIG field, a first control field, and a second control field. A result of “modulo 3 operation” for a length field value of the L-SIG field may be set to “0.” The RL-SIG field may be configured to be the same as the L-SIG field. The first control field may comprise 3-bit information on the version of a PPDU, 6-bit information on a BSS color, and 7-bit information on TXOP.

An access point (AP) that supports the IEEE 802.11ba protocol may transmit a frame including a physical layer (PHY) preamble to one or more stations (STAs) over a channel. The PHY preamble may include a plurality of repeated modulated legacy signal (L-SIG) fields to spoof a recipient of the frame and protect a wake up signal (WUS) to be subsequently transmitted by the AP. The AP may transmit the WUS to at least a first STA of the one or more STAs, wherein the at least the first STA is a IEEE 802.11ba compliant STA.

An OFDM (orthogonal frequency division multiplexing) transmitter includes an inverse fast Fourier transform circuit, which, in operation, generates, based on digital input data, a complex time-varying digital signal having real and imaginary components; and a multiplexer adapted to generate a time-multiplexed digital signal by time-multiplexing one or more of the real components with one or more of the imaginary components.

A MIMO system comprises a remote radio unit (RRU) and central unit. The RRU comprises: a binary phase shift keying (BPSK) modulator, configured to modulate a BPSK waveform by a local oscillator (LO) signal to generate a stimulus signal, wherein the LO signal is derived from a downlink optical signal received via downlink radio over fiber (DL-ROF) from a central unit (CU); and an optical signal generator, in particular a laser, configured to generate an uplink optical signal based on the stimulus signal for transmission via uplink radio over fiber (UL-ROF) to the CU.

A MIMO system comprises a remote radio unit (RRU) and central unit. The RRU comprises: a binary phase shift keying (BPSK) modulator, configured to modulate a BPSK waveform by a local oscillator (LO) signal to generate a stimulus signal, wherein the LO signal is derived from a downlink optical signal received via downlink radio over fiber (DL-ROF) from a central unit (CU); and an optical signal generator, in particular a laser, configured to generate an uplink optical signal based on the stimulus signal for transmission via uplink radio over fiber (UL-ROF) to the CU.