Methods and apparatus for cell selection/reselection in millimeter wave system

Abstract

Methods and apparatus for cell selection, cell reselection, and beam selection in MMW system are provided. The UE measures signal strength, or signal quality or both of them to get the best consolidation measurement result. During Cell Selection, the UE selects the cell with the best consolidation measurement result, or selects the cell containing the candidate control beam found firstly. In Cell Reselection, the serving cell and neighboring cells are ranked based on the consolidation measurement result. After camping on a cell, the UE selects one or more than one best control beams as the serving control beam to acquire system information and monitor paging message. Furthermore, the UE selects the best control beam or selects one control beam randomly among the serving control beams to initial access to the network.

1 . A method comprising:
 detecting multiple control beams in a millimeter wave (mmW) system by a user equipment (UE), wherein the mmW system has multiple cells each configured with multiple control beams;   obtaining a signal measurement for each detected control beam; and   calculating a consolidation measurement for each cell based on a set of qualified control beams associated with each corresponding cell using a consolidation rule, wherein at least one cell has more than one associated qualified control beams.   
     
     
         2 . The method of  claim 1 , wherein the signal measurement of a control beam is obtained based on at least one of the measurements comprising: a signal strength measurement, a signal quality measurement, a signal lifetime measurement, signal error rate, and signal AoA/DoA. 
     
     
         3 . The method of  claim 1 , wherein the set of qualified control beams of a cell consists of multiple detected control beams associated with the cell. 
     
     
         4 . The method of  claim 1 , further comprising: determining one or more candidate control beams, wherein the signal measurement of each candidate control beam is greater a candidate threshold. 
     
     
         5 . The method of  claim 4 , wherein the set of qualified control beams of a cell consists of multiple candidate control beams associated with the cell. 
     
     
         6 . The method of  claim 1 , wherein the UE is camped on a serving cell and acquires system and control information through one or more serving control beams associated with the serving cell, and wherein the set of qualified control beams for the serving cell consists of multiple serving control beams. 
     
     
         7 . The method of  claim 1 , wherein the consolidation rule determines the consolidation measurement for the set of qualified control beams is at least one selected from a group comprising: a number of qualified control beams in the set, a maximum signal measurement of the set, a minimum signal measurement of the set, a mean value of signal measurement of the set, a variance of signal measurement of the set, and a sum of the signal measurements of the set. 
     
     
         8 . The method of  claim 1 , further comprising: performing a cell selection based on consolidation measurement results. 
     
     
         9 . The method of  claim 1 , further comprising: performing a cell reselection based on consolidation measurement results. 
     
     
         10 . The method of  claim 1 , further comprising: performing handover based on consolidated measurement results. 
     
     
         11 . A method comprising:
 detecting multiple control beams in a millimeter wave (mmW) system by a user equipment (UE), wherein the mmW system has multiple cells each configured with multiple control beams;   obtaining a signal measurement for each detected control beam;   performing a cell selection to select a serving cell; and   selecting one or more serving control beams associated with the serving cell, wherein the UE receives control information and system information on the serving control beams.   
     
     
         12 . The method of  claim 11 , further comprising: determining one or more candidate control beams, wherein the signal measurement of each candidate control beam is greater a candidate threshold. 
     
     
         13 . The method of  claim 12 , wherein the serving cell is selected upon detecting the first candidate control beam, and wherein the serving cell is the cell that the first detected candidate control beams is associated with. 
     
     
         14 . The method of  claim 11 , further comprising: calculating a consolidation measurement for each cell based on a set of qualified control beams associated with each corresponding cell using a consolidation rule, wherein at least one cell has more than one associated qualified control beams, and wherein the serving cell is selected based on consolidation measurement results for each cell. 
     
     
         15 . The method of  claim 11 , wherein the consolidation rule determines the consolidation measurement for the set of qualified control beams is one selected from a group comprising: a number of qualified control beams in the set, a maximum signal measurement of the set, a minimum signal measurement of the set, a mean value of signal measurements of the set, a variance of signal measurement of the set, and a sum of the signal measurements of the set. 
     
     
         16 . The method of  claim 11 , wherein the selected serving control beams are detected control beams associated with the serving cell. 
     
     
         17 . The method of  claim 11 , wherein the selected serving control beams are candidate control beams associated with the serving cell, and wherein each candidate control beam has its signal measurement greater than a threshold. 
     
     
         18 . The method of  claim 11 , wherein the control beams of the serving cell are ranked based on the signal measurement and a predefined number of best control beams of the serving cell are selected based on the ranking as the serving control beams. 
     
     
         19 . The method of  claim 11 , further comprising: performing a serving control beam selection based on multiple control beam measurements of the serving cell. 
     
     
         20 . The method of  claim 19 , wherein the serving control beam selection involves:
 calculating a modified measurement for each serving control beam by adding an hypothesis value to the signal measurement of the corresponding serving control beam;   ranking all control beams of the serving cell based on the modified measurement; and   selecting one or more best ranked control beams as the new serving control beam candidate.   
     
     
         21 . The method of  claim 20 , wherein the hypothesis value is obtained and configured by a system information. 
     
     
         22 . The method of  claim 20 , wherein the hypothesis value is obtained and configured by a beam specific information. 
     
     
         23 . The method of  claim 11 , further comprising: selecting an access control beam from the one or more selected serving control beams. 
     
     
         24 . A method comprising:
 obtaining a consolidation serving cell measurement for cell reselection (Res_S) in a millimeter wave (mmW) system by a user equipment (UE), wherein the Res_S is calculated based on signal measurements of a set of control beams of the serving cell;   determining a measurement level by comparing the Res _S with one or more thresholds in descending order comprising: a first threshold, a second threshold and a third threshold; and   performing consolidation measurement for one or more cells based on the determined measurement level, wherein the consolidation measurement for a cell is calculated based on signal measurements of a set of control beams associated with the cell; and   performing a cell reselection based on consolidation measurement results.   
     
     
         25 . The method of  claim 24 , wherein the signal measurement of a control beam is obtained based on one or more UE measurements comprising: a signal strength measurement, a signal quality measurement, a signal lifetime measurement, signal error rate and signal AoA/DoA. 
     
     
         26 . The method of  claim 24 , wherein the measurement level is a first level when the Res_S is greater than the first threshold, and wherein the consolidation measurement is only performed for the serving cell based on serving control beams on which the UE receives system and control information. 
     
     
         27 . The method of  claim 24 , wherein the measurement level is a second level when the Res_S is smaller than the first threshold and larger than the second threshold, and wherein the consolidation measurement is performed on all detected control beams of the serving cell. 
     
     
         28 . The method of  claim 24 , wherein the measurement level is a third level when the Res_S is smaller than the second threshold and larger than the third threshold, and wherein the consolidation measurement is performed on detected control beams in the serving cell and detected or configured neighbor cell control beams with a same frequency of the serving cell. 
     
     
         29 . The method of  claim 24 , wherein the measurement level is a fourth level when the Res_S is smaller than the third threshold and wherein the consolidation measurement is performed on all detected control beams of detected control beams in the serving cell and detected or configured neighbor cell control beams with a different frequency of the serving cell.