# US 10,771,998 B2 · Method for CSI feedback > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,771,998 B2 - Document ID: US10771998B2 - Status: Granted - Kind: B2 - Application number: 15/517,785 - Filed: 2015-10-06 - Published: 2017-10-26 - Granted: 2020-09-08 - Earliest claimed: 2014-10-10 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (publ) - Inventors: Mattias Frenne; Johan Furuskog; Robert Mark Harrison; George Jöngren - Web page: https://patentgrep.com/patent/US10771998B2 ## CPC - H04W 24/10: Scheduling measurement reports {; Arrangements for measurement reports} - H04B 7/0626: {Channel coefficients, e.g. channel state information [CSI]} - H04B 7/0647: {Variable feedback rate} - H04L 1/0026: {Transmission of channel quality indication} - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L 5/0053: {Allocation of signalling, i.e. of overhead other than pilot signals} - H04L 5/0057: {Physical resource allocation for CQI} - H04W 72/21: in the uplink direction of a wireless link, i.e. towards the network - H04W 72/541: using the level of interference - H04W 76/27: Transitions between radio resource control [RRC] states - H04L 5/0023: {Time-frequency-space} - H04L 5/0035: {Resource allocation in a cooperative multipoint environment} - H04L 5/0094: {Indication of how sub-channels of the path are allocated} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Embodiments of systems and methods for flexible Channel State Information (CSI) feedback in a cellular communications network are disclosed. In some embodiments, a base station configures a wireless device with a set of CSI-RS resources, dynamically configures a CSI-RS resource from the set of CSI-RS resources for measurement, and receives a CSI report from the wireless device determined from the CSI-RS resource dynamically configured for measurement. In this manner, the base station is enabled to dynamically configure and re-configure the CSI-RS resource(s) for measurement by the wireless device, which in turn provides flexible CSI feedback that is particularly well-suited for embodiments in which the base station transmits beamformed CSI-RS. ## Claims ### Claim 1 A method of operation of a base station of a cellular communications network to enable flexible Channel State Information (CSI) feedback, comprising: configuring a wireless device, via a Radio Resource Control (RRC) message, with a set of non-zero power Channel State Information Reference Signal (CSI-RS) resources and a set of Channel State Information Interference Measurement (CSI-IM) resources; dynamically configuring a non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources for measurement and dynamically configuring a CSI-IM resource from the set of CSI-IM resources for interference measurement via a Downlink Control Information (DCI) message; receiving an acknowledgement from the wireless device that indicates that the dynamic configuration of the non-zero power CSI-RS resource was received by the wireless device; receiving a CSI report from the wireless device determined from the non-zero power CSI-RS resource dynamically configured for measurement and the CSI-IM resource dynamically configured for interference measurement; and discarding any CSI reports received from the wireless device for a predefined amount of time after receiving the acknowledgement from the wireless device. ### Claim 2 (depends on 1) The method of claim 1, wherein the base station transmits beamformed CSI-RS, each beamformed CSI-RS corresponding to a different beam direction. ### Claim 3 (depends on 1) The method of claim 1, wherein: the wireless device uses two or more CSI processes for CSI reporting, and configuring the wireless device with the set of non-zero power CSI-RS resources comprises configuring the wireless device with the set of non-zero power CSI-RS resources for a particular CSI process of the two or more CSI processes of the wireless device; and dynamically configuring the non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources for measurement comprises dynamically configuring the non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources such that the non-zero power CSI-RS resource is configured for measurement for the particular CSI process. ### Claim 4 (depends on 3) The method of claim 3 further comprising: configuring the wireless device with a respective set of non-zero power CSI-RS resources for each additional CSI process of the two or more CSI processes of the wireless device; and for each additional CSI process of the wireless device, dynamically configuring a non-zero power CSI-RS resource from the respective set of non-zero power CSI-RS resources for measurement. ### Claim 5 (depends on 1) The method of claim 1, wherein the wireless device uses two or more CSI processes for CSI reporting, the set of non-zero power CSI-RS resources is a common set of non-zero power CSI-RS resources for the two or more CSI processes, and dynamically configuring the non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources for measurement comprises dynamically configuring the non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources such that the non-zero power CSI-RS resource is configured for measurement for the two or more CSI processes. ### Claim 6 (depends on 1) The method of claim 1, wherein configuring the wireless device with the set of non-zero power CSI-RS resources comprises configuring the wireless device with the set of non-zero power CSI-RS resources via higher layer signaling. ### Claim 7 (depends on 1) The method of claim 1, further comprising: receiving one or more additional CSI reports from the wireless device determined from the non-zero power CSI-RS resource dynamically configured for measurement, wherein the one or more additional CSI reports are transmitted at predetermined time instants. ### Claim 8 (depends on 7) The method of claim 7, further comprising receiving an indication from the wireless device confirming that the non-zero power CSI-RS resource was used for the CSI report. ### Claim 9 (depends on 1) The method of claim 1, further comprising: receiving a subsequent CSI report from the wireless device determined from a default non-zero power CSI-RS resource. ### Claim 10 (depends on 1) The method of claim 1, wherein dynamically configuring the non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources for measurement comprises dynamically configuring the non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources for measurement such that the dynamic configuration of the non-zero power CSI-RS resource holds until a subsequent dynamic configuration of a new non-zero power CSI-RS resource is provided to the wireless device. ### Claim 11 (depends on 1) The method of claim 1, wherein Physical Downlink Shared Channel (PDSCH) rate matching is provided over the set of non-zero power CSI-RS resources. ### Claim 12 A base station of a cellular communications network, the base station comprising: at least one transmitter; at least one receiver; at least one processor; and memory storing software instructions executable by the at least one processor whereby the base station is operative to: configure, via the at least one transmitter via a Radio Resource Control (RRC) message, a wireless device with a set of non-zero power Channel State Information Reference Signal (CSI-RS) resources, and a set of Channel State Information Interference Measurement (CSI-IM) resources; dynamically configure, via the at least one transmitter, a non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources for measurement and dynamically configure a CSI-IM resource from the set of CSI-IM resources for interference measurement via a Downlink Control Information (DCI) message; receive, via the at least one receiver, an acknowledgement from the wireless device that indicates that the dynamic configuration of the non-zero power CSI-RS resource was received by the wireless device; receive, via the at least one receiver, a CSI report from the wireless device determined from the non-zero power CSI-RS resource dynamically configured for measurement and the CSI-IM resource dynamically configured for interference measurement; and discard any CSI reports received from the wireless device for a predefined amount of time after receiving the acknowledgement from the wireless device. ### Claim 13 (depends on 12) The base station of claim 12, wherein the base station is operative to transmit beamformed CSI-RS, each beamformed CSI-RS corresponding to a different beam direction. ### Claim 14 (depends on 13) The base station of claim 13, wherein each non-zero power CSI-RS resource in the set of non-zero power CSI-RS resources is beamformed and each non-zero power CSI-RS resource corresponds to a different beam direction. ### Claim 15 (depends on 13) The base station of claim 13, wherein the wireless device uses two or more CSI processes for CSI reporting, and the base station is further operative to: configure the wireless device with the set of non-zero power CSI-RS resources for a particular CSI process of the two or more CSI processes of the wireless device; and dynamically configure the non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources such that the non-zero power CSI-RS resource is configured for measurement for the particular CSI process. ### Claim 16 (depends on 12) The base station of claim 12, wherein the wireless device uses two or more CSI processes for CSI reporting, the set of non-zero power CSI-RS resources is a common set of non-zero power CSI-RS resources for the two or more CSI processes, and the base station is further operative to dynamically configure the non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources such that the non-zero power CSI-RS resource is configured for measurement for the two or more CSI processes. ### Claim 17 (depends on 12) The base station of claim 12, wherein the base station is further operative to receive a subsequent CSI report from the wireless device determined from a default non-zero power CSI-RS resource. ### Claim 18 (depends on 12) The base station of claim 12, wherein the base station is further operative to dynamically configure the non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources for measurement such that the dynamic configuration of the non-zero power CSI-RS resource holds until a subsequent dynamic configuration of a new non-zero power CSI-RS resource is provided to the wireless device. ### Claim 19 (depends on 12) The base station of claim 12, wherein the base station is further operative to configure a different non-zero power CSI-RS resource from the set of non-zero power CSI-RS resources for interference measurement.