Backscatter link channel estimation with PSD limitation

An apparatus of wireless communication at a network entity, comprising:

• memory;
• and
• at least one processor coupled to the memory and, based at least in part on information stored in the memory, the at least one processor is configured to:
• transmit, to a user equipment (UE), multiple continuous wave (CW) signal sets, wherein each CW signal set of the multiple CW signal sets comprises at least one CW signal;
• receive, from the UE, a set of reference signals corresponding to CW signals in the multiple CW signal sets, wherein the set of reference signals is obtained based on a frequency spread and a frequency shift on the CW signals in the multiple CW signal sets;
• and
• measure, based on the set of reference signals, a channel between the UE and the network entity, wherein to transmit the multiple CW signal sets, the at least one processor is configured to:
• successively transmit the multiple CW signal sets based on an orthogonal frequency division multiplexing (OFDM) modulation scheme, and wherein each CW signal in the multiple CW signal sets corresponds to one subcarrier in the OFDM modulation scheme and has a power less than a power spectrum density (PSD) limitation,
• wherein each CW signal set of the multiple CW signal sets comprises one first CW signal of multiple first CW signals corresponding to a first frequency band in a frequency domain, and the set of reference signals is based on the frequency spread and the frequency shift on each first CW signal in the multiple CW signal sets,
• and wherein the set of reference signals is obtained based on the frequency shift on each first spread signal corresponding to each first CW signals of the multiple first CW signals, wherein an amount of the frequency shift is different for each first CW signal, and wherein the first spread signal corresponding to each first CW signal is based on the frequency spread on each first CW signal, wherein the first spread signal corresponds to a second frequency band wider than the first frequency band in the frequency domain.

A method of wireless communication at a user equipment (UE), comprising:

• receiving, from a first reader device, multiple continuous wave (CW) signal sets, wherein each CW signal set of the multiple CW signal sets comprises at least one CW signal;
• generating a set of reference signals corresponding to CW signals in the multiple CW signal sets, wherein the set of reference signals is generated based on a frequency spread and a frequency shift on the CW signals in the multiple CW signal sets;
• and
• transmitting, to the first reader device or a second reader device different from the first reader device, the set of reference signals corresponding to the multiple CW signal sets for a measurement of a channel between the UE and the first reader device or between the UE and the second reader device, wherein receiving the multiple CW signal sets comprises:
• successively receiving the multiple CW signal sets based on an orthogonal frequency division multiplexing (OFDM) modulation scheme, and wherein each CW signal in the multiple CW signal sets corresponds to one subcarrier in the OFDM modulation scheme and has a power less than a power spectrum density (PSD) limitation,
• wherein each CW signal set of the multiple CW signal sets comprises one first CW signal of multiple first CW signals corresponding to a first frequency band in a frequency domain, and wherein generating the set of reference signals corresponding to the CW signals in the multiple CW signal sets comprises:
• performing the frequency spread on each received first CW signal to obtain a first spread signal, wherein the first spread signal corresponds to a second frequency band wider than the first frequency band in the frequency domain, and
• performing the frequency shift on each first spread signal corresponding to the multiple first CW signals to obtain the set of reference signals, wherein an amount of the frequency shift is different for each first CW signal.

A method of wireless communication at a network entity, comprising:

• transmitting, to a user equipment (UE), multiple continuous wave (CW) signal sets, wherein each CW signal set of the multiple CW signal sets comprises at least one CW signal;
• receiving, from the UE, a set of reference signals corresponding to CW signals in the multiple CW signal sets, wherein the set of reference signals is obtained based on a frequency spread and a frequency shift on the CW signals in the multiple CW signal sets;
• and
• measuring, based on the set of reference signals, a channel between the UE and the network entity, wherein transmitting the multiple CW signal sets comprises:
• successively transmitting the multiple CW signal sets based on an orthogonal frequency division multiplexing (OFDM) modulation scheme, and wherein each CW signal in the multiple CW signal sets corresponds to one subcarrier in the OFDM modulation scheme and has a power less than a power spectrum density (PSD) limitation,
• wherein each CW signal set of the multiple CW signal sets comprises one first CW signal of multiple first CW signals corresponding to a first frequency band in a frequency domain, and the set of reference signals is based on the frequency spread and the frequency shift on each first CW signal in the multiple CW signal sets,
• and wherein the set of reference signals is obtained based on the frequency shift on each first spread signal corresponding to each first CW signals of the multiple first CW signals, wherein an amount of the frequency shift is different for each first CW signal, and wherein the first spread signal corresponding to each first CW signal is based on the frequency spread on each first CW signal, wherein the first spread signal corresponds to a second frequency band wider than the first frequency band in the frequency domain.