Frequency / time selective precoding for positioning reference signals

A user equipment (UE) configured to process reference signals for positioning estimation over a multipath multiple-input multiple-output (MIMO) channel, comprising:

• a memory;
• at least one transceiver;
• and
• at least one processor coupled to the memory and the at least one transceiver, the at least one processor configured to:
• transmit, via the at least one transceiver, to a base station, a recommendation of a first reference signal resource set;
• transmit, via the at least one transceiver, to the base station, a recommendation of a second reference signal resource set;
• receive, via the at least one transceiver, from the base station, a first set of reference signals on the first reference signal resource set, wherein the first reference signal resource set is scheduled on a first set of physical resource blocks of the MIMO channel with a first periodicity, and wherein each reference signal resource in the first reference signal resource set utilizes at least a first MIMO precoder;
• receive, via the at least one transceiver, from the base station, a second set of reference signals on the second reference signal resource set, wherein the second reference signal resource set is scheduled on a second set of physical resource blocks of the MIMO channel with a second periodicity, and wherein each reference signal resource in the second reference signal resource set utilizes at least a second MIMO precoder;
• identify at least one reference signal transmitted on the first and second reference signal resource sets as following a line of sight (LOS) path between the UE and the base station;
• and
• perform a time difference of arrival (TDOA) measurement based on the at least one reference signal.

A method for transmitting reference signals for positioning estimation over a multipath multiple-input multiple-output (MIMO) channel performed by a base station, comprising:

• receiving, from a UE, a recommendation of a first reference signal resource set for transmission of a first set of reference signals, wherein the first reference signal resource set is scheduled on a first set of physical resource blocks of the MIMO channel with a first periodicity, and wherein each reference signal resource in the first reference signal resource set utilizes at least a first MIMO precoder;
• receiving, from the UE, a recommendation of a second reference signal resource set for transmission of a second set of reference signals, wherein the second reference signal resource set is scheduled on a second set of physical resource blocks of the MIMO channel with a second periodicity, and wherein each reference signal resource in the second reference signal resource set utilizes at least a second MIMO precoder;
• transmitting, to the UE over the MIMO channel, the first set of reference signals using the first reference signal resource set on the first set of physical resource blocks of the MIMO channel with the first periodicity;
• and
• transmitting, to the UE over the MIMO channel, the second set of reference signals using the second reference signal resource set on the second set of physical resource blocks of the MIMO channel with the second periodicity,
• wherein the first and second sets of reference signals are transmitted to assist the UE to perform a positioning measurement based on processing of the first and second sets of reference signals.

A method for processing reference signals for positioning estimation over a multipath multiple-input multiple-output (MIMO) channel performed by a user equipment (UE), comprising:

• transmitting, to a base station, a recommendation of a first reference signal resource set;
• transmitting, to the base station, a recommendation of a second reference signal resource set;
• receiving, from the base station, a first set of reference signals on the first reference signal resource set, wherein the first reference signal resource set is scheduled on a first set of physical resource blocks of the MIMO channel with a first periodicity, and wherein each reference signal resource in the first reference signal resource set utilizes at least a first MIMO precoder;
• receiving, from the base station, a second set of reference signals on the second reference signal resource set, wherein the second reference signal resource set is scheduled on a second set of physical resource blocks of the MIMO channel with a second periodicity, and wherein each reference signal resource in the second reference signal resource set utilizes at least a second MIMO precoder;
• identifying at least one reference signal transmitted on the first and second reference signal resource sets as following a line of sight (LOS) path between the UE and the base station;
• and
• performing a time difference of arrival (TDOA) measurement based on the at least one reference signal.