# US 9,439,096 B2 · Method and apparatus to support channel refinement and multi-stream transmission in millimeter wave systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,439,096 B2 - Document ID: US9439096B2 - Status: Granted - Kind: B2 - Application number: 13/963,746 - Filed: 2013-08-09 - Published: 2014-02-13 - Granted: 2016-09-06 - Earliest claimed: 2012-08-13 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Samsung Electronics Co., LTD - Inventors: Kaushik Morapakkam Josiam; Richard Stirling-Gallacher; Zhouyue Pi - Web page: https://patentgrep.com/patent/US9439096B2 ## CPC - H04W 24/10: Scheduling measurement reports {; Arrangements for measurement reports} - H04B 7/0408: using two or more beams, i.e. beam diversity - H04B 7/0617: {for beam forming} - H04B 7/0626: {Channel coefficients, e.g. channel state information [CSI]} - H04B 7/063: {Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection} - H04B 7/0632: {Channel quality parameters, e.g. channel quality indicator [CQI]} - H04B 7/0639: {Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection} - H04W 72/54: based on quality criteria - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04B: TRANSMISSION ## Abstract Methods and apparatus for sending and receiving mobile station (MS) specific channel state indication reference symbols (CSI-RS) is provided. A common CSI-RS is sent from a base station (BS) and is received by an MS. First feedback is sent to the BS from the MS based on the common CSI-RS. A configuration of an MS-specific CSI-RS is sent from the BS and received by the MS. An MS specific CSI-RS is sent from the BS and is received by the MS. Second feedback is sent to the BS from the MS based on the MS specific CSI-RS. ## Claims ### Claim 1 A method for a mobile station (MS), the method comprising: receiving, from a base station (BS), a common channel state indicator-reference symbol (CSI-RS) over a millimeter wave radio frequency comprising a radio frequency of 30 giga hertz (GHz) to 300 GHz; sending, to the BS, a request message over the millimeter wave radio frequency to request additional reference symbols; sending, to the BS, a first feedback associated with the common CSI-RS over the millimeter wave radio frequency; receiving, from the BS, a configuration message for an MS-specific CSI-RS over the millimeter wave radio frequency; receiving, from the BS, the MS specific CSI-RS over the millimeter wave radio frequency; and sending, to the BS, a second feedback associated with the MS specific CSI-RS over the millimeter wave radio frequency. ### Claim 2 (depends on 1) The method of claim 1, wherein the receiving of the MS specific CSI-RS is in response to a request from the MS. ### Claim 3 (depends on 1) The method of claim 1, wherein the first feedback comprises at least one preferred beam index chosen from one or more indices of beams that have been used in the common CSI-RS transmission and a rank indication. ### Claim 4 (depends on 1) The method of claim 1, wherein the MS comprises an advanced receiver and the second feedback comprises estimated angle of arrival, angle of departure, and channel gain for each channel between the MS and the BS that is estimated via the advanced receiver. ### Claim 5 (depends on 1) The method of claim 1, wherein the receiving of the MS specific CSI-RS is in response to the BS needing additional channel state infonnation. ### Claim 6 (depends on 1) The method of claim 1, wherein the first feedback comprises a preferred beam index and rank parameters while the second feedback comprises channel parameters that capture instantaneous channel information and include a baseband precoder and channel state information. ### Claim 7 (depends on 1) The method of claim 1, wherein the MS specific CSI-RS is transmitted over the channel in accordance with a spatial direction indicated by the MS. ### Claim 8 (depends on 1) The method of claim 1, wherein the MS specific CSI-RS is transmitted to estimate baseband precoding to be used in multi-stream transmission. ### Claim 9 (depends on 1) The method of claim 1, wherein the MS-specific CSI-RS is specified by a different power beam-width, a different beamforming gain, and a different overhead than the common CSI-RS. ### Claim 10 (depends on 1) The method of claim 1 , wherein the second feedback comprises at least one preferred data beam index, a spatial beam direction, and a channel quality indicator for each channel between the MS and the BS. ### Claim 11 A mobile station (MS) comprising: a transceiver; and processing circuitry configured to: receive, via the transceiver, a common channel state indicator-reference symbol (CSI-RS) from a base station (BS) over a millimeter wave radio frequency comprising a radio frequency of 30 giga hertz (GHz) to 300 GHz; send, via the transceiver, a request message to the BS over the millimeter wave radio frequency to request additional reference symbols; send, via the transceiver, a first feedback associated with the common CSI-RS to the BS over the millimeter wave radio frequency; receive, via the transceiver, a configuration message for an MS-specific CSI-RS from the BS over the millimeter wave radio frequency; receive, via the transceiver, the MS specific CSI-RS from the BS over the millimeter wave radio frequency; and send, via the transceiver, a second feedback associated with the MS specific CSI-RS to the BS over the millimeter wave radio frequency. ### Claim 12 (depends on 11) The MS of claim 11, wherein the receipt of the MS specific CSI-RS is in response to a request from the MS. ### Claim 13 (depends on 11) The MS of claim 11, wherein the first feedback comprises at least one preferred beam index chosen from one or more indices of beams that have been used in the common CSI-RS transmission and a rank indication. ### Claim 14 (depends on 11) The MS of claim 11, wherein the transceiver comprises an advanced receiver and the second feedback comprises estimated angle of arrival, angle of departure, and channel gain for each channel between the MS and the BS that is estimated via the advanced receiver. ### Claim 15 (depends on 11) The MS of claim 11, wherein receipt of the MS specific CSI-RS is in response to a need of the BS for additional channel state information. ### Claim 16 (depends on 11) The MS of claim 11, wherein the first feedback comprises a preferred beam index and rank parameters while the second feedback comprises channel parameters that capture instantaneous channel information and include a baseband precoder and channel state information. ### Claim 17 (depends on 11) The MS of claim 11, wherein the MS specific CSI-RS is transmitted over the channel in accordance with a spatial direction indicated by the MS. ### Claim 18 (depends on 11) The MS of claim 11, wherein the MS specific CSI-RS is transmitted to estimate baseband precoding to be used in multi-stream transmission. ### Claim 19 A base station (BS) comprising: a transceiver; and processing circuitry configured to: send, via the transceiver, a common channel state indicator-reference symbol (CSI-RS) to a mobile station (MS) over a millimeter wave radio frequency comprising a radio frequency of 30 giga hertz (GHz) to 300 GHz; receiving, via the transceiver, a request message from the MS over the millimeter wave radio frequency to request additional reference symbols; receive, via the transceiver, a first feedback associated with the common CSI-RS from the MS over the millimeter wave radio frequency; send, via the transceiver, a configuration message for an MS specific CSI-RS to the MS over the millimeter wave radio frequency; send, via the transceiver, the MS specific CSI-RS over the millimeter wave radio frequency; and receive, via the transceiver, a second feedback associated with the MS specific CSI-RS from the MS over the millimeter wave radio frequency. ### Claim 20 (depends on 19) The BS of claim 19, wherein the sending of the MS specific CSI-RS is in response to a request from the MS. ### Claim 21 (depends on 19) The BS of claim 19, wherein the first feedback comprises at least one preferred beam index chosen from one or more indices of beams that have been used in the common CSI-RS transmission and a rank indication. ### Claim 22 (depends on 19) The BS of claim 19, wherein the second feedback comprises estimated angle of arrival, angle of departure, and channel gain for each channel between the MS and the BS that is estimated via an advanced receiver of the MS. ### Claim 23 (depends on 19) The BS of claim 19, wherein sending of the MS specific CSI-RS is in response to a need of the BS for additional channel state information. ### Claim 24 (depends on 19) The BS of claim 19, wherein the first feedback comprises a preferred beam index and rank parameters while the second feedback comprises channel parameters that capture instantaneous channel information and include a baseband precoder and channel state information. ### Claim 25 (depends on 19) The BS of claim 19, wherein the MS specific CSI-RS is transmitted over the channel in accordance with a spatial direction indicated by the MS. ### Claim 26 (depends on 19) The BS of claim 19, wherein the MS specific CSI-RS is transmitted to estimate baseband precoding to be used in multi-stream transmission. ### Claim 27 A wireless communication system that includes a number of base station (BSs) configured to communicate with a number of mobile stations (MS), the wireless communications system comprising: at least one base station (BS) comprising: a plurality of antenna coupled to a transceiver; and processing circuitry configured to: send, via the transceiver, a common channel state indicator-reference symbol (CSI-RS) to a mobile station (MS) over a millimeter wave radio frequency comprising a radio frequency of 30 giga hertz (GHz) to 300 GHz; receive, via the transceiver, a request message over the millimeter wave radio frequency to request additional reference symbols; receive, via the transceiver, a first feedback associated with the common CSI-RS from the MS over the millimeter wave radio frequency; send, via the transceiver, a configuration message for an MS specific CSI-RS to the MS over the millimeter wave radio frequency; send, via the transceiver, the MS specific CSI-RS over the millimeter wave radio frequency; and receive, via the transceiver, a second feedback associated with the MS specific CSI-RS from the MS over the millimeter wave radio frequency. ### Claim 28 (depends on 27) The wireless communications system of claim 27, wherein the sending of the MS specific CS1-RS is in response to a request from the MS. ### Claim 29 (depends on 27) The wireless communications system of claim 27, wherein the first feedback comprises at least one preferred beam index chosen from one or more indices of beams that have been used in the common CS1-RS transmission and a rank indication. ### Claim 30 (depends on 27) The wireless communications system of claim 27, wherein the second feedback comprises estimated angle of arrival, angle of departure, and channel gain for each channel between the MS and the BS that is estimated via an advanced receiver of the MS. ### Claim 31 (depends on 27) The wireless communications system of claim 27, wherein sending of the MS specific CSI-RS is in response to a need of the BS for additional channel state information. ### Claim 32 (depends on 27) The wireless communications system of claim 27, wherein the first feedback comprises a preferred beam index and rank parameters while the second feedback comprises channel parameters that capture instantaneous channel information and include a baseband precoder and channel state information. ### Claim 33 (depends on 27) The wireless communications system of claim 27, wherein the MS specific CSI-RS is transmitted over the channel in accordance with a spatial direction indicated by the MS. ### Claim 34 (depends on 27) The wireless communications system of claim 27, wherein the MS specific CSI-RS is transmitted to estimate baseband precoding to be used in multi-stream transmission.