A method and apparatus are provided for determining a transmission mode. A method embodiment includes obtaining, by a terminal device, configuration indication information, the configuration indication information comprising one or more of: DMRS indication information, repeated-transmission indication information, or transmission configuration indication information; and determining a transmission mode based on the configuration indication information, the transmission mode is one or more of: a space division multiplexing mode, a frequency division multiplexing mode, or a time division multiplexing mode.

A terminal according to one aspect of the present disclosure includes a receiving section that receives an antenna port indication when at least one of a demodulation reference signal (DMRS) type and a maximum length of the DMRS to be configured is not 1, and a control section that controls uplink (UL) transmission corresponding to two codewords, the UL transmission using a number of layers greater than four, based on the antenna port indication. According to one aspect of the present disclosure, UL transmission with the number of layers greater than four can be appropriately controlled.

An optical communication method using deep learning in a code-division multiple access (CDMA) scheme may include obtaining an image of an optical signal from a light source and applying a first model trained to identify a location of the light source to detect the light source in the image. The method may also include detecting a preamble of an on-off keying (OOK) modulated signal from a pulse signal generated based on the identified light source using a second model trained to detect preambles in received signals, to decode the OOK modulated signal for a first user device by applying a first pseudo-random noise (PN) code. The method may further include determining a start position of an orthogonal frequency division multiplexing (OFDM) frame in an OFDM modulated signal from the pulse signal, to decode the OFDM modulated signal by applying a first Walsh code.

Methods, systems, and devices for satellite operations are described. A satellite communications system may include a transmitter that applies multiple spreading codes to a data signal to obtain multiple spread data signals. The transmitter may transmit the multiple spread data signals from multiple antenna elements in a composite signal. The satellite communications system may also include a receiver that receives the composite signal and applies multiple despreading codes to the composite signal to obtain multiple despread data signals. The receiver may combine the multiple despread data signals to obtain a combined data signal that corresponds to the data signal processed by the transmitter. To combine the multiple despread data signals, the receiver may estimate coefficients for each of the despread data signals.

A wireless device is configured to produce a signal in a time slot, the signal having a first portion and a second portion. Wherein, the first portion being a first in time in the time slot and the second portion being last in time in the time slot. Further, the first portion having data and a multiplexed first pilot and the second portion having a pilot sequence and a cyclic prefix. The wireless device transmits the produced signal in the time slot.

Methods, systems, and devices for satellite operations are described. A satellite communications system may include a transmitter that applies multiple spreading codes to a data signal to obtain multiple spread data signals. The transmitter may transmit the multiple spread data signals from multiple antenna elements in a composite signal. The satellite communications system may also include a receiver that receives the composite signal and applies multiple despreading codes to the composite signal to obtain multiple despread data signals. The receiver may combine the multiple despread data signals to obtain a combined data signal that corresponds to the data signal processed by the transmitter. To combine the multiple despread data signals, the receiver may estimate coefficients for each of the despread data signals.

A wireless device is configured to produce a signal in a time slot of a frame, wherein the time slots have variable lengths. The signal having a first portion and a second portion, wherein the first portion and the second portion are located in defined time regions in the slot. Further, the first portion having data and a multiplexed first pilot, wherein the multiplexed first pilot is derived from a pseudo random sequence, the second portion having a pilot sequence and a cyclic prefix. The wireless device transmits the produced signal in the time slot.

A wireless device is configured to produce a signal in a time slot of a frame, wherein the time slots have variable lengths. The signal having a first portion and a second portion, wherein the first portion and the second portion are located in defined time regions in the slot. Further, the first portion having data and a multiplexed first pilot, wherein the multiplexed first pilot is derived from a pseudo random sequence, the second portion having a pilot sequence and a cyclic prefix. The wireless device transmits the produced signal in the time slot.