Systems and methods for improving demodulation reference signal channel estimation

1 . A computer-implemented method comprising:

receiving, as part of a demodulation reference signal (DMRS) channel estimation operation, a frequency domain channel estimation signal comprising a plurality of DMRS samples;

generating an extended channel estimation signal by determining at least one extended DMRS sample that extends at least one edge of the frequency domain channel estimation signal;

generating an augmented channel estimation signal by extrapolating, based on the extended channel estimation signal, a frequency edge for the augmented channel estimation signal;

designing, based on a measurement of a DMRS value included in the augmented channel estimation signal, a polyphase filter; and

estimating a DMRS channel by filtering the augmented channel estimation signal using the designed polyphase filter.

2 . The computer-implemented method of claim 1 , wherein:

the channel estimation signal corresponds to a plurality of slots;

designing the polyphase filter based on the measurement of the DMRS value included in the augmented channel estimation signal comprises, for a slot included in the plurality of slots:

measuring a slot DMRS value corresponding to the slot; and

designing the polyphase filter based on the measured slot DMRS value.

3 . The computer-implemented method of claim 2 , further comprising converting, via an inverse Fast-Fourier Transform (IFFT), the augmented channel estimation signal corresponding to the slot from a frequency domain signal to a time domain signal prior to measuring the slot DMRS value corresponding to the slot.

4 . The computer-implemented method of claim 3 , wherein:

the slot DMRS value comprises a first parameter, a second parameter, and a third parameter;

designing the polyphase filter comprises designing a time-domain polyphase filter having a window in the time domain comprising:

a first value in a first range, the first range corresponding to the second parameter;

the first value in a second range, the second range corresponding to the third parameter;

a first transition from the first value to a second value in a third range, the third range corresponding to the first parameter; and

a second transition from the second value to the first value in a fourth range, the fourth range corresponding to the first parameter.

5 . The computer-implemented method of claim 4 , wherein designing the polyphase filter further comprises generating a noise-reduced time-domain polyphase filter by applying a noise reduction filter to the time-domain polyphase filter.

6 . The computer-implemented method of claim 5 , wherein:

the channel estimation operation corresponds to a second DMRS configuration type; and

designing the polyphase filter further comprises applying a phase rotation to the noise-reduced time-domain polyphase filter.

7 . The computer-implemented method of claim 5 , wherein designing the polyphase filter further comprises generating a noise-reduced frequency-domain polyphase filter by applying:

a fast Fourier transform to the noise-reduced time-domain polyphase filter; and

a windowing function to an output of the fast Fourier transform.

8 . The computer-implemented method of claim 7 , wherein designing the polyphase filter further comprises:

determining an offset that corresponds to a port associated with the channel estimation signal;

adjusting the noise-reduced frequency-domain polyphase filter based on the offset; and

designating the adjusted noise-reduced frequency-domain polyphase filter as the designed polyphase filter.

9 . The computer-implemented method of claim 1 , wherein estimating the DMRS channel by filtering the augmented channel estimation signal using the designed polyphase filter comprises generating a plurality of filtered channel estimation signals by filtering the augmented channel estimation signal using the designed polyphase filter.

10 . The computer-implemented method of claim 9 , wherein estimating the DMRS channel by filtering the augmented channel estimation signal using the designed polyphase filter further comprises assembling an estimated DMRS channel from the plurality of filtered channel estimation signals.

11 . A system comprising:

a receiving module, stored in memory, that receives, as part of a demodulation reference signal (DMRS) channel estimation operation, a frequency domain channel estimation signal comprising a plurality of DMRS samples;

an extending module, stored in memory, that generates an extended channel estimation signal by determining at least one extended DMRS sample that extends at least one edge of the frequency domain channel estimation signal;

an extrapolating module, stored in memory, that generates an augmented channel estimation signal by extrapolating, based on the extended channel estimation signal, a frequency edge for the augmented channel estimation signal;

a designing module, stored in memory, that designs, based on a measurement of a DMRS value included in the augmented channel estimation signal, a polyphase filter;

an estimating module, stored in memory, that estimates a DMRS channel by filtering the augmented channel estimation signal using the designed polyphase filter; and

at least one physical processor that executes the receiving module, the extending module, the extrapolating module, the designing module, and the estimating module.

12 . The system of claim 11 , wherein:

the channel estimation signal corresponds to a plurality of slots;

the designing module designs the polyphase filter based on the measurement of the DMRS value included in the augmented channel estimation signal by, for a slot included in the plurality of slots:

measuring a slot DMRS value corresponding to the slot; and

designing the polyphase filter based on the measured slot DMRS value.

13 . The system of claim 12 , wherein the designing module further converts, via an inverse Fast-Fourier Transform (IFFT), the augmented channel estimation signal corresponding to the slot from a frequency domain signal to a time domain signal prior to measuring the slot DMRS value corresponding to the slot.

14 . The system of claim 13 , wherein:

the slot DMRS value comprises a first parameter, a second parameter, and a third parameter;

the designing module designs the polyphase filter by designing a time-domain polyphase filter having a window in the time domain comprising:

a first value in a first range, the first range corresponding to the second parameter;

the first value in a second range, the second range corresponding to the third parameter;

a first transition from the first value to a second value in a third range, the third range corresponding to the first parameter; and

a second transition from the second value to the first value in a fourth range, the fourth range corresponding to the first parameter.

15 . The system of claim 14 , wherein the designing module designs the polyphase filter by further generating a noise-reduced time-domain polyphase filter by applying a noise reduction filter to the time-domain polyphase filter.

16 . The system of claim 15 , wherein:

the channel estimation operation corresponds to a second DMRS configuration type; and

the designing module further designs the polyphase filter by further applying a phase rotation to the noise-reduced time-domain polyphase filter.

17 . The system of claim 15 , wherein designing the polyphase filter further comprises:

generating a noise-reduced frequency-domain polyphase filter by applying:

a fast Fourier transform to the noise-reduced time-domain polyphase filter; and

a windowing function to an output of the fast Fourier transform;

determining an offset that corresponds to a port associated with the channel estimation signal;

adjusting the noise-reduced frequency-domain polyphase filter based on the offset; and

designating the adjusted noise-reduced frequency-domain polyphase filter as the designed polyphase filter.

18 . The system of claim 11 , wherein the estimating module estimates the DMRS channel by filtering the augmented channel estimation signal using the designed polyphase filter by:

generating a plurality of filtered channel estimation signals by filtering the augmented channel estimation signal using the designed polyphase filter; and

assembling an estimated DMRS channel from the plurality of filtered channel estimation signals.

19 . A system comprising:

a fifth-generation new radio base station that receives an uplink signal from a user equipment device, the uplink signal comprising a frequency domain channel estimation signal comprising a plurality of demodulation reference signal (DMRS) samples;

a DMRS channel estimation device comprising:

a receiving module that receives, as part of a demodulation reference signal (DMRS) channel estimation operation, a frequency domain channel estimation signal comprising a plurality of DMRS samples;

an extending module that generates an extended channel estimation signal by determining at least one extended DMRS sample that extends at least one edge of the frequency domain channel estimation signal;

an extrapolating module that generates an augmented channel estimation signal by extrapolating, based on the extended channel estimation signal, a frequency edge for the augmented channel estimation signal;

a designing module that designs, based on a measurement of a DMRS value included in the augmented channel estimation signal, a polyphase filter; and

an estimating module that estimates a DMRS channel by filtering the augmented channel estimation signal using the designed polyphase filter.

20 . The system of claim 19 , wherein:

the channel estimation signal corresponds to a plurality of slots;

the designing module designs the polyphase filter based on the measurement of the DMRS value included in the augmented channel estimation signal by, for a slot included in the plurality of slots:

measuring a slot DMRS value corresponding to the slot; and

designing the polyphase filter based on the measured slot DMRS value.