Progressive channel state information

Abstract

Embodiments of system, device, and method configurations for implementing a progressive channel state indicator (CSI) evaluation are disclosed herein. In one example, techniques for increasing the precision of channel feedback information by detecting a best beam index in a progressively scanning grid of beams is deployed in a Long Term Evolution (LTE) network. The use of a progressive CSI technique may be used to improve the robustness of beamforming in network configurations deploying multi-user multiple input multiple output (MU-MIMO) transmission modes.

What is claimed is: 
     
         1 . A method performed by an evolved Node B (eNodeB) for conducting a progressive channel state indicator (CSI) operation, the method comprising:
 scanning with a grid of beams, the grid of beams distributed by beamforming in a plurality of beam groups, wherein the grid of beams transmit respective reference signals among a distributed area; and   determining, for a particular User Equipment (UE), a highest CSI in the grid of beams from progressively evaluating the respective CSI values produced from scanning with the grid of beams, the determining including:
 receiving, from the UE, an indication of a best beam index in response to a strongest beam received at the UE from the grid of beams; and 
 selecting the highest CSI in the grid of beams for the particular UE based on the best beam index. 
   
     
     
         2 . The method of  claim 1 , further comprising:
 performing subsequent beamforming operations from the eNodeB to the particular UE, using a result indicated by the highest CSI, wherein the subsequent beamforming operations are used in a multi-user multiple input multiple output (MU-MIMO) transmission mode.   
     
     
         3 . The method of  claim 1 , wherein scanning with a grid of beams includes performing horizontal scanning within a progressive scanning period, wherein the grid of beams is configured to transmit the respective reference signals among a horizontal domain for a coverage area of the eNodeB. 
     
     
         4 . The method of  claim 3 , wherein scanning with a grid of beams further includes performing vertical scanning within the progressive scanning period, wherein the grid of beams is configured to transmit the respective reference signals among an elevation domain for the coverage area of the eNodeB. 
     
     
         5 . The method of  claim 3 , wherein performing horizontal scanning within a progressive scanning period includes conducting a horizontal scan for each beam group CSI sub-period in the plurality of beam groups;
 wherein sets of CSI reference signals provided in each beam group CSI sub-period are spaced among the plurality of beam groups with a periodicity of a plurality of subframes.   
     
     
         6 . The method of  claim 5 , wherein the periodicity of the plurality of subframes is based on a period of: 5, 10, 20, 40, or 80 subframes. 
     
     
         7 . The method of  claim 3 , wherein performing horizontal scanning within a progressive scanning period includes conducting a high-density horizontal scan, wherein multiple CSI reference signals are included within one frame. 
     
     
         8 . The method of  claim 7 , wherein a pattern of the high-density horizontal scan repeats in direct or reverse order every m·n subframes, where m=a number of the plurality of beam groups and n=2, 4, 8, or 16. 
     
     
         9 . The method of  claim 1 , wherein feedback parameters used with conducting the scanning are calculated by a k-th UE connected to the eNodeB, the k-th UE providing the feedback parameters on channel H k  for transmission to the eNodeB in a feedback procedure. 
     
     
         10 . The method of  claim 9 , wherein the best beam index is identified in the feedback procedure and is progressively forwarded to the eNodeB; and
 wherein, at an end of a period for scanning with the grid of beams, the eNodeB is adapted to identify a Pre-coding Matrix Indicator PMI* k  for the k-th UE, wherein   
       
         
           
             
               
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         11 . The method of  claim 1 , wherein a respective UE calculates the strength of a particular beam by measuring signal-to-interference-plus-noise ratio (SINR) with a corresponding CSI reference signal; and
 wherein, at the beginning of a feedback procedure, a Modulation and Coding Scheme (MCS) index corresponding to a Channel Quality Indication CQI 0 =max i=0, . . . , 7 |H k φ 0,i | 2  is provided to the eNodeB.   
     
     
         12 . An evolved NodeB (eNodeB), comprising circuitry arranged to perform progressive channel state information (CSI) acquisition with operations to:
 perform a vertical CSI acquisition for an elevation domain;   perform a horizontal CSI acquisition by scanning a horizontal domain with a grid of beams, wherein the scanning is customized to the elevation domain;   collect progressive CSI feedback from the horizontal CSI acquisition, wherein the eNodeB determines a set of Pre-coding Matrix Indicators PMI*={PMI* 1 , PMI* 2 , . . . , PMI* K }, wherein the set of PMI* is a set indicating best beam indices for active UEs connected to the eNodeB;   wherein the PMI* is used to adapt different beamforming schemes for subsequent transmissions from the eNodeB to the active UEs.   
     
     
         13 . The eNodeB of  claim 12 , the circuitry arranged to perform a determination of a PMI value for a particular User Equipment (UE), in the set of PMI* by:
 determining a highest CSI in the grid of beams in response to scanning with the grid of beams;   receiving, from the particular UE, an indication of a best beam index in response to a strongest beam received at the UE from the grid of beams; and   selecting the highest CSI in the grid of beams for the particular UE based on the best beam index.   
     
     
         14 . The eNodeB of  claim 12 , wherein the beamforming schemes for subsequent transmissions are used in a multi-user multiple input multiple output (MU-MIMO) transmission mode. 
     
     
         15 . The eNodeB of  claim 12 , wherein the operations to perform the horizontal CSI acquisition by scanning include conducting a horizontal scan for each beam group CSI sub-period in a plurality of beam groups; and
 wherein sets of CSI reference signals provided in each beam group CSI sub-period are spaced among the plurality of beam groups with a periodicity of a plurality of subframes.   
     
     
         16 . The eNodeB of  claim 15 , wherein the periodicity of the plurality of subframes is directed to a period of: 5, 10, 20, 40, or 80 subframes. 
     
     
         17 . The eNodeB of  claim 12 , wherein the operations to perform the horizontal CSI acquisition by scanning include conducting a high-density horizontal scan, wherein multiple CSI reference signals are included within one frame, wherein a pattern of the high-density horizontal scan repeats in direct or reverse order every m·n subframes, where m=a number of beam groups and n=2, 4, 8, or 16. 
     
     
         18 . The eNodeB of  claim 12 , wherein feedback parameters for scanning are calculated by a k-th UE connected to the eNodeB with channel H k  for transmission to the eNodeB in a feedback procedure;
 wherein the best beam index is identified in the feedback procedure and is progressively forwarded to the eNodeB; and   wherein, at an end of a period for scanning with the grid of beams, the eNodeB is adapted to identify PMI* k  for the k-th UE, wherein   
       
         
           
             
               
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         19 . A user equipment (UE), comprising:
 multiple antennas arranged to receive transmissions from an evolved NodeB (eNodeB), the eNodeB operating in accordance with a standard from a 3GPP Long Term Evolution (LTE) standards family;   multiple transceivers operably coupled to the multiple antennas and arranged to receive and transmit wireless communications from the eNodeB, the wireless communications including transmissions received from the eNodeB from a channel state information (CSI) scan performed on a vertical domain and on a horizontal domain; and   processing circuitry arranged to process the transmissions received from the eNodeB from the CSI scan and provide progressive CSI feedback in response to the transmissions received from the eNodeB from the CSI scan, wherein an indication of a best beam index is progressively provided in the CSI feedback in response to a determination of a strongest beam received at the UE from the CSI scan.   
     
     
         20 . The UE of  claim 19 , wherein the processing circuitry is further arranged to transmit, to the eNodeB, the indication of the best beam index in response to the strongest beam received at the UE from a grid of beams of the CSI scan;
 wherein the eNodeB operates to determine a highest CSI in the grid of beams for the UE based on the best beam index.   
     
     
         21 . The UE of  claim 19 , wherein the CSI scan performed on the horizontal domain includes a horizontal scan for each beam group CSI sub-period in a plurality of beam groups; and
 wherein sets of CSI reference signals provided in each beam group CSI sub-period are spaced among the plurality of beam groups with a periodicity of a plurality of subframes, wherein the periodicity of a plurality of subframes is directed to a period of: 5, 10, 20, 40, or 80 subframes.   
     
     
         22 . The UE of  claim 19 , wherein the CSI scan performed on the horizontal domain includes a high-density horizontal scan, wherein multiple CSI reference signals are inserted within one frame. 
     
     
         23 . The UE of  claim 21 , wherein a pattern of the high-density horizontal scan repeats in direct or reverse order every m·n subframes, where m=a number of beam groups and n=2, 4, 8, or 16. 
     
     
         24 . The UE of  claim 19 , wherein feedback parameters for the scanning are calculated by the UE for transmission to the eNodeB in a feedback procedure, wherein the best beam index is identified in the feedback procedure and is progressively forwarded to the eNodeB.