# US 10,873,370 B2 · Method and system for enabling explicit channel state information (CSI) feedback in multiple-input-multiple-output (MIMO) > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,370 B2 - Document ID: US10873370B2 - Status: Granted - Kind: B2 - Application number: 16/346,670 - Filed: 2017-11-03 - Published: 2020-02-27 - Granted: 2020-12-22 - Earliest claimed: 2016-11-03 - Assignees: Wisig Networks Private Limited - Applicants: WiSig Networks Private Limited - Inventors: Kiran Kumar Kuchi - Web page: https://patentgrep.com/patent/US10873370B2 ## CPC - H04B 7/0417: Feedback systems - H04B 7/0626: {Channel coefficients, e.g. channel state information [CSI]} - H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting - H04L 1/0026: {Transmission of channel quality indication} - H04L 1/0035: {evaluation of received explicit signalling} - H04L 5/0023: {Time-frequency-space} - H04L 5/0053: {Allocation of signalling, i.e. of overhead other than pilot signals} - H04L 5/0057: {Physical resource allocation for CQI} - H04L 5/14: Two-way operation using the same type of signal, i.e. duplex - H04W 72/21: in the uplink direction of a wireless link, i.e. towards the network - 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) ## Abstract Embodiments of the present disclosure discloses a method for enabling CSI feedback in Multiple Input Multiple Output (MIMO) wireless communication system comprising at least one user equipment (UE) and at least one base station (BS). The UE receives a plurality of downlink (DL) channel state information CSI from the BS and generate an explicit CSI from the received DL CSI. The UE determines a range of frequency domain values and channel state values from the received DL CSI. Upon determination, the UE performs IDFT to determine time domain channel impulse response matrices for the range of frequency domain values and perform CSI quantization. In another embodiment, the processor performs CSI quantization on either full range or a partial range of the time domain channel impulse response matrices to obtain optimized time domain channel explicit CSI and transmit the generated explicit CSI as a feedback to the one or more BS. ## Claims ### Claim 1 A method for enabling channel state information (CSI) feedback in Multiple Input Multiple Output (MIMO) wireless communication system, the method comprising: receiving, by a user equipment (UE), a plurality of downlink (DL) reference signals from one or more base stations (BSs), wherein DL CSI is obtained from the DL reference signals; generating, by the UE, an explicit CSI from the DL CSI, wherein generating the explicit CSI comprises performing CSI quantization on individual DL CSI matrices using at least one or more of a codebook and a set of precoder matrices; and transmitting, by the UE, the generated explicit CSI as a feedback to the one or more BSs, wherein the CSI feedback is transmitted to the one or more BSs corresponding to one or more frequency indices. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein the step of generating explicit CSI comprising: determining a range of frequency domain values and channel state values associated with the determined range of frequency domain values from the DL CSI; applying IDFT to determine time domain channel impulse response matrices for the range of frequency domain values thus determined; and performing CSI quantization on either full range or a partial range of the time domain channel impulse response matrices to obtain optimized time domain channel explicit CSI. ### Claim 3 (depends on 2) The method as claimed in claim 2, wherein CSI quantization is performed separately on real and imaginary parts of the elements of the time domain channel impulse response matrices corresponding to one or more BSs using predetermined number of bits before transmission to BS. ### Claim 4 (depends on 2) The method as claimed in claim 2, wherein CSI quantization is performed separately on magnitude and phase values of the elements of the time domain channel impulse response matrices corresponding to one or more BSs using predetermined number of bits before transmission to BS. ### Claim 5 (depends on 4) The method as claimed in claim 4, wherein the predetermined number of bits allocated for quantization may be different for each BS. ### Claim 6 (depends on 1) The method as claimed in claim 1, wherein the explicit CSI feedback is generated using the DL CSI from associated with the one or more BSs identified based on signal power. ### Claim 7 (depends on 1) The method as claimed in claim 1, wherein CSI quantization is performed for the one or more BS with highest signal power at higher resolution. ### Claim 8 (depends on 1) The method as claimed in claim 1, further comprising transmitting interference power information of low signal BSs within the explicit CSI as feedback to the one or more BS. ### Claim 9 (depends on 1) The method as claimed in claim 1, wherein the explicit CSI feedback is transmitted with high resolution to enable TDD (Time Division Duplex) channel calibration at the one or more BSs. ### Claim 10 (depends on 1) The method as claimed in claim 1, wherein the explicit CSI feedback is transmitted with moderate resolution to enable the one or more BSs to use the explicit CSI information for precoding the data in a FDD (Frequency Division Duplex) system. ### Claim 11 (depends on 1) The method as claimed in claim 1, wherein performing CSI quantization comprising quantizing the CSI in frequency domain using one of equal and unequal number of bits allocated to each BS. ### Claim 12 (depends on 1) The method as claimed in claim 1, further comprising determining one or more bits for the DL CSI corresponding to the transmission power of the BS. ### Claim 13 (depends on 1) The method as claimed in claim 1, wherein the set of precoder matrices is used to perform CSI quantization using predetermined number of bits. ### Claim 14 A user equipment (UE) for enabling channel state information (CSI) feedback in Multiple Input Multiple Output (MIMO) wireless communication system, the UE comprising: a processor; a memory communicatively coupled to the processor; and at least one transceiver coupled to the processor and the memory, comprising at least one receiver and at least one transmitter; wherein the processor is configured to: receive, via the at least one receiver, one or more downlink (DL) reference signals from one or more base stations (BS) coupled with the UE, wherein DL CSI is obtained from the DL reference signals; generate an explicit CSI from the received DL CSI by performing CSI quantization on individual DL CSI matrices using at least one or more of a codebook and a set of precoder matrices; and transmit, via the at least one transmitter, the generated explicit CSI as a feedback to the one or more BSs corresponding to one or more frequency indices. ### Claim 15 (depends on 14) The system as claimed in claim 14, wherein the processor is configured to generate explicit CSI by steps comprising: determining a range of frequency domain values and channel state values associated with the determined range of frequency domain values from the DL CSI; applying IDFT to determine time domain channel impulse response matrices for the range of frequency domain values thus determined; and performing CSI quantization on either full range or a partial range of the time domain channel impulse response matrices to obtain optimized time domain channel explicit CSI. ### Claim 16 (depends on 15) The system as claimed in claim 15, wherein the processor performs CSI quantization separately on real and imaginary parts of the elements of the time domain channel impulse response matrices corresponding to the one or more BSs using predetermined number of bits before transmission to the one or more BS. ### Claim 17 (depends on 15) The system as claimed in claim 15, wherein the processor is configured to perform CSI quantization separately on magnitude and phase values of the elements of the time domain channel impulse response matrices corresponding to one or more BSs using predetermined number of bits before transmission to BS. ### Claim 18 (depends on 17) The system as claimed in claim 17, wherein the processor allocates a different predetermined number of bits for quantization for each BS. ### Claim 19 (depends on 15) The system as claimed in claim 15, wherein the processor is configured to perform CSI quantization for the one or more BS with highest signal power at higher resolution. ### Claim 20 (depends on 15) The system as claimed in claim 15, wherein the processor is further configured to transmit interference power information of low signal BSs within the explicit CSI as feedback to the one or more BS. ### Claim 21 (depends on 14) The system as claimed in claim 14, wherein the processor is configured to generate the explicit CSI feedback using the DL CSI associated with the one or more BSs identified based on signal power. ### Claim 22 (depends on 14) The system as claimed in claim 14, wherein the transmitter transmits the explicit CSI feedback with high resolution to enable TDD (Time Division Duplex) channel calibration at the one or more BSs. ### Claim 23 (depends on 14) The system as claimed in claim 14, wherein the transmitter transmits the explicit CSI feedback with moderate resolution to enable the one or more BSs to use the explicit CSI for precoding the data in a FDD (Frequency Division Duplex) system. ### Claim 24 (depends on 14) The system as claimed in claim 14, wherein the processor is configured to perform CSI quantization by quantizing the CSI in frequency domain using one of equal and unequal number of bits allocated to each BS. ### Claim 25 (depends on 14) The system as claimed in claim 14, wherein the processor is further configured to determine one or more bits for the DL CSI corresponding to the transmission power of the BS. ### Claim 26 (depends on 14) The system as claimed in claim 14, wherein the set of precoder matrices is used to perform CSI quantization using predetermined number of bits.