# US 2017/0288759 A1 · Channel estimation for per-tone continuous precoding in downlink mimo transmission > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0288759 A1 - Document ID: US20170288759A1 - Status: Published application - Kind: A1 - Application number: 15/469,806 - Filed: 2017-03-27 - Published: 2017-10-05 - Earliest claimed: 2016-03-31 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: June NAMGOONG; Alexandros MANOLAKOS; Joseph Binamira SORIAGA; Jing JIANG; Tingfang Ji - Web page: https://patentgrep.com/patent/US20170288759A1 ## CPC - H04B 7/0639: {Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection} - H04B 7/0408: using two or more beams, i.e. beam diversity - H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting - H04B 7/0842: {Weighted combining} - H04L 1/0015: {characterised by the adaptation strategy} - H04L 1/0031: {Multiple signaling transmission (H04L1/1664, F15 take precedence)} - H04L 5/0017: {in which a distinct code is applied, as a temporal sequence, to each frequency} - H04L 5/0023: {Time-frequency-space} - H04L 5/005: {of common pilots, i.e. pilots destined for multiple users or terminals} - H04L 25/0204: {of multiple channels} - H04L 25/0212: {of impulse response} - H04L 25/0224: {using sounding signals} - H04L 25/03891: {Spatial equalizers (MIMO diversity systems H04B7/0413)} - H04W 52/0258: {controlling an operation mode according to history or models of usage information, e.g. activity schedule or time of day} - H04W 52/04: Transmission power control [TPC] - H04W 52/262: {taking into account adaptive modulation and coding [AMC] scheme} - Y02D 30/70: in wireless communication networks - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The apparatus may receive a transmission over a precoded channel. The transmission may include a layer having a plurality of symbols, each symbol having a plurality of modulated tones precoded on a per-tone basis. The receive layer may be associated with a power delay profile. The apparatus may estimate the precoded channel based on a time support of the power delay profile. ## Claims ### Claim 1 An apparatus for wireless communications, comprising: a processing system configured to: receive a transmission over a precoded channel, the transmission comprising a layer having a plurality of symbols, each symbol having a plurality of modulated tones precoded on a per-tone basis, the received layer being associated with a power delay profile; and estimate the precoded channel based on a time support of the power delay profile. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the processing system is further configured to estimate the time support of the power delay profile from a dominant path of the receive layer. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the transmission further comprises an additional layer, the additional layer having a second plurality of symbols, each symbol having a second plurality of modulated tones precoded on a per-tone basis. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the processing system is further configured to receive the transmission through a plurality of antennas. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein the received layer further comprises a reference signal comprising one or more of the plurality of symbols, and wherein the processing system is further configured to estimate the time support of the power delay profile from the reference signal received through one of the plurality of antennas. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the reference signal comprises an apparatus specific reference signal. ### Claim 7 (depends on 5) The apparatus of claim 5, wherein the processing system is further configured to receive an indicator identifying said one of the plurality of antennas through which the reference signal is received, wherein the reference signal is used to estimate the time support of the power delay profile. ### Claim 8 (depends on 5) The apparatus of claim 5, wherein the processing system is further configured to locate a dominant path of the received layer by applying an IFFT to the reference signal received through said one of the plurality of antennas and use the dominant path to estimate the time support of the power delay profile. ### Claim 9 (depends on 2) The apparatus of claim 2, wherein the processing system is further configured to estimate the time support by aligning a center of the time support of the power delay profile with the dominant path. ### Claim 10 (depends on 9) The apparatus of claim 9, wherein the processing system is further configured to estimate the time support by using a value proportional to a delay spread for a propagation channel as a length of the time support of the precoded channel. ### Claim 11 (depends on 10) The apparatus of claim 10, wherein the processing system is further configured to receive a cell specific reference signal and estimate the delay spread for the propagation channel from the cell specific reference signal. ### Claim 12 (depends on 9) The apparatus of claim 9, wherein the processing system is further configured to receive a delay spread for the received layer from a remote apparatus and estimate the time support using the delay spread as a length of the time support of the precoded channel. ### Claim 13 (depends on 2) The apparatus of claim 2, wherein at least one of the plurality of modulated tones precoded on a per-tone basis are phase ramp compensated, and wherein the processing system is further configured to use the dominant path to adjust a position of an FFT window of a receiver. ### Claim 14 A method of wireless communications, comprising: receiving a transmission over a precoded channel, the transmission comprising a layer having a plurality of symbols, each symbol having a plurality of modulated tones precoded on a per-tone basis, the received layer being associated with a power delay profile; and estimating the precoded channel based on a time support of the power delay profile. ### Claim 15 (depends on 14) The method of claim 14, further comprising estimating the time support of the power delay profile from a dominant path of the receive layer. ### Claim 16 (depends on 14) The method of claim 14, wherein the transmission further comprises one or more additional layers, each of the one or more additional layers having a plurality of symbols, each symbol having a plurality of modulated tones precoded on a per-tone basis. ### Claim 17 (depends on 14) The method of claim 14, wherein the transmission is received through a plurality of antennas. ### Claim 18 (depends on 17) The method of claim 17, wherein the layer further comprises a reference signal comprising one or more of the plurality of symbols, and wherein the time support of the power delay profile is estimated from the reference signal received through one of the plurality of antennas. ### Claim 19 (depends on 18) The method of claim 18, wherein the reference signal comprises an apparatus specific reference signal. ### Claim 20 (depends on 18) The method of claim 18, further comprising receiving an indicator identifying said one of the plurality of antennas through which the reference signal is received, wherein the reference signal is used to estimate the time support of the power delay profile. ### Claim 21 (depends on 18) The method of claim 18, wherein the estimating the time support comprises locating a dominant path of the receive layer by applying an IFFT to the reference signal received through said one of the plurality of antennas, wherein the dominant path is used to estimate the time support of the power delay profile. ### Claim 22 (depends on 15) The method of claim 15, wherein the time support is estimated by aligning a center of the time support of the power delay profile with the dominant path. ### Claim 23 (depends on 22) The method of claim 22, wherein the time support is estimated by using a value proportional to a delay spread for a propagation channel as a length of the time support of the precoded channel. ### Claim 24 (depends on 23) The method of claim 23, further comprising: receiving a cell specific reference signal; and estimating the delay spread for the propagation channel from the cell specific reference signal. ### Claim 25 (depends on 22) The method of claim 22, further comprising receiving a delay spread for the layer from a remote apparatus, wherein the time support is estimated using the delay spread as a length of the time support of the precoded channel. ### Claim 26 (depends on 15) The method of claim 15, wherein the plurality of modulated tones precoded on a per-tone basis are phase ramp compensated, the method further comprising using the dominant path to adjust a position of an FFT window of a receiver. ### Claim 27 An apparatus for wireless communications, comprising: means for receiving a transmission over a precoded channel, the transmission comprising a layer having a plurality of symbols, each symbol having a plurality of modulated tones precoded on a per-tone basis, the receive layer being associated with a power delay profile; and means for estimating the precoded channel based on a time support of the power delay profile. ### Claim 28 (depends on 27) The apparatus of claim 27, further comprising means for estimating the time support of the power delay profile from a dominant path of the receive layer. ### Claim 29 (depends on 27) The apparatus of claim 27, wherein the transmission further comprises one or more additional layers, each of the one or more additional layers having a plurality of symbols, each symbol having a plurality of modulated tones precoded on a per-tone basis. ### Claim 30 A computer-readable medium storing computer executable code, comprising code to: receive a transmission over a precoded channel, the transmission comprising a layer having a plurality of symbols, each symbol having a plurality of modulated tones precoded on a per-tone basis, the receive layer being associated with a power delay profile; and estimate the precoded channel based on a time support of the power delay profile.