Abstract:
An antenna system and a method for reporting enhanced Reference Signal Receiving Power (eRSRP) of the same are provided. According to an embodiment of the present invention, the method for reporting eRSRP includes: transmitting, by an evolved Node Base (eNB), different reference signals to different transport points being distributed; measuring, by a user equipment (UE), eRSRP of the different transport points; and reporting, by the UE, the measured eRSRP of the different transport points to the eNB. Compared with the prior art, the eNB can obtain channel information of path loss of each transport point, to fundamentally solve the problem of unbalanced power, and can perform other optimization operations based on the information to improve the system throughput and other performance.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an antenna system and a method for reporting Reference Signal Receiving Power (RSRP) of the same, and more particularly to a distributed antenna system (DAS) and a method for reporting RSRP of the same. 
         [0003]    2. Description of the Prior Art 
         [0004]    In downlink Multiple Input Multiple Output (MIMO), a typical case of a DAS is deploying distributed antennas for indoor and outdoor use. The DAS is different from a conventional centralized wire system in that, path loss from distributed antenna ports at different geographical positions to a user equipment (UE) is different, thereby often causing the problem of unbalanced power. In order to solve the problem of unbalanced power, some technical solutions of adjustment and improvement may be performed at an evolved Node Base (eNB) side, in which the technical solutions include power compensation, transport point selection, and the like. These technical solutions require channel information of path loss of different transport points; however, in the current DAS, the eNB cannot obtain the information. 
         [0005]    An application scenario of distributed antennas shown in  FIG. 1  is taken as an example. In the scenario, an eNB  500  is disposed in a cell  50 . In the figure, only a part of a macro base station (BS) node is shown. The eNB  500  allocates four distributed antennas  501 ,  502 ,  503 , and  504  for serving a UE  505 . The distributed antenna  501  is disposed on the macro BS node  500 . Ports of the distributed antennas  501 ,  502 ,  503 , and  504  are set to RRH0, RRH1, RRH2, and RRH3 respectively. Although reference signals, for example, channel state information-reference signals (CSI-RSs) CSI-RS0, CSI-RS1, CSI-RS2, and CSI-RS3, of the distributed antennas  501 ,  502 ,  503 , and  504  are transparent to the UE  505 , the UE  505  can report only one RSRP value to the eNB  500 . Generally, the RSRP value is obtained by the UE  505  averaging measured RSRP0 and RSRP1 of the ports RRH0 and RRH1 of the distributed antennas. Due to lack of channel information of path loss of the distributed antennas  501 ,  502 ,  503 , and  504 , the eNB  500  cannot solve the problem of unbalanced power. 
         [0006]    In fact, since the eNB cannot know the channel information of path loss of each distributed antenna, other problems, such as being inconvenient for transport point selection, being incapable of flexibly allocating resources, and reducing the system throughput, may be caused. 
         [0007]    Therefore, the existing DAS and the method for reporting the RSRP need to be improved, to fundamentally solve the problem of unbalanced power. 
       SUMMARY OF THE INVENTION 
       [0008]    An objective of the present invention is to provide an antenna system and a method for reporting receiving power of the same, to make the technical solution for solving the problem of unbalanced power feasible. 
         [0009]    According to an embodiment of the present invention, a method for reporting receiving power includes: transmitting, by an eNB, different reference signals to different transport points being distributed; measuring, by a UE, eRSRP of the different transport points; and reporting, by the UE, the measured eRSRP of the different transport points to the eNB. 
         [0010]    According to another embodiment of the present invention, the method for reporting receiving power further includes: notifying, by the eNB by means of signaling, the UE of reporting the eRSRP of the different transport points periodically or in an event triggering manner. An event for triggering the event triggered report includes: receiving, by the UE, an instruction of the eNB; or obtaining, through measurement by the UE, |eRSRP x -eRSRP y |&gt;T, where eRSRP x  is eRSRP of a transport point with a port number x among the different transport points, eRSRP y  is eRSRP of a transport point with a port number y among the different transport points, and T is a preset receiving power difference threshold or a threshold configured by the eNB for the UE. The UE only reports the eRSRP of a part of the transport points according to an indication of the eNB, or the UE only reports the eRSRP of the transport points that satisfy an event triggering condition. 
         [0011]    According to yet another embodiment of the present invention, the method for reporting receiving power further includes: receiving, by the eNB, the eRSRP of the different transport points from the UE, to determine a corresponding optimization scheme for solving a problem of unbalanced power at least. The problem of unbalanced power is solved by adjusting transmit power of the different transport points, a transport point selection operation, or a transport point grouping operation; and the adjustment includes increase, maintenance, or decrease. According to another embodiment of the present invention, the eRSRP is RSRP or a value of path loss, and the reference signal is a cell specific reference signal (CRS) or a CSI-RS. Moreover, in an embodiment of the present invention, when reporting the measured eRSRP of the different transport points to the eNB, the UE transmits port numbers of the corresponding different transport points. In another embodiment of the present invention, the UE reports the eRSRP of the different transport points sequentially in an order of ports allocated by the eNB to the reference signals of the different transport points. In an embodiment of the present invention, after measuring the eRSRP of the different transport points, the UE transmits the measured eRSRP to the eNB, or the UE transmits the measured eRSRP to the different transport points and then the different transport points transmit the eRSRP to the eNB. 
         [0012]    An embodiment of the present invention further provides an antenna system, including: different transport points being distributed; an eNB, configured to transmit different reference signals to the different transport points; and a UE, configured to measure eRSRP of the different transport points, and reporting the measured eRSRP of the different transport points to the eNB. 
         [0013]    Another embodiment of the present invention further provides an eNB located in a DAS and including: a reference signal transmitting component, configured to transmit different reference signals; and an eRSRP receiving component, configured to receive eRSRP of different transport points, to determine a corresponding optimization scheme for solving a problem of unbalanced power at least. In an embodiment of the present invention, the eNB further includes a signaling notification component, configured to notify, by means of signaling, the UE of reporting the eRSRP of the different transport points periodically or in an event triggering manner. 
         [0014]    Another embodiment of the present invention further provides a UE, including: a measurement component, configured to measure eRSRP of different transport points in a distributed system; and a report component, configured to report the measured eRSRP of the different transport points to an eNB in the distributed system. In an embodiment of the present invention, the UE further includes a signaling receiving component, configured to receive a signaling sent by the eNB, whereby the report component reports the eRSRP of the different transport points periodically or in an event triggering manner in response to the received signaling. 
         [0015]    Compared with the prior art, the antenna system and the method for reporting RSRP of the same provided by the present invention enable an eNB to obtain reference signal power of all transport points used for a UE, that is, know channel information of path loss of each distributed antenna, so that the problem of unbalance power can be solved by a corresponding means. Moreover, the eNB can further implement more flexible transport point selection and resource allocation, implement necessary power control, and improve the system throughput. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a schematic diagram of a scenario of an existing DAS; 
           [0017]      FIG. 2  is a schematic diagram of a scenario according to an embodiment of the present invention; 
           [0018]      FIG. 3  is a flow chart of reporting eRSRP according to an embodiment of the present invention; 
           [0019]      FIG. 4  is a schematic flow chart of a UE reporting eRSRP of transport points to an eNB in an order according to an embodiment of the present invention; and 
           [0020]      FIG. 5  is a structural block diagram of a DAS according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    In order to better understand the spirit of the present invention, the present invention is further described below using a combination of selected preferred embodiments. 
         [0022]    The Long Term Evolution (LTE) project is the largest new technology research and development project started by the 3rd Generation Partnership Project (3GPP) in recent years. This technology based on Orthogonal Frequency Division Multiplexing/Frequency Division Multiple Access (OFDM/FDMA) is regarded as a quasi-4G technology. The LTE will be the main wide area broadband mobile communication system worldwide, and in the future, all the 2G/3G/3.5G technologies will evolve to the LTE/LTE-Advanced (LTE-A) phase. At present, multiple LTE standard versions exist in the industry, but none of them solve the problem of unbalanced power in the DAS, thereby hindering further improvement and implementation of the technology. 
         [0023]    It should be noted that, due to the development of the technology and the update of the standard, components having the same function usually have different names. For example, in the DAS, a transport point, a distributed antenna, and a remote radio head (RRH) are often alternately used by persons skilled in the art. Technical terms used in the patent application of the present invention are provided to explain and demonstrate the technical solution of the present invention. For example, generally, the transport point, the distributed antenna, and the RRH are generically called the transport point. When interpreting the terms, the functions commonly known in the art that associate with the terms prevail, and the terms cannot be interpreted arbitrarily in view of the differences in names. 
         [0024]      FIG. 2  is a schematic diagram of a scenario according to an embodiment of the present invention. In the scenario, provided are a cell  10 , an eNB  100  located in the cell  10 , four transport points  101 ,  102 ,  103 , and  104  geographically separated, and a UE  105 . In the LTE and LTE-A standards, an eNB represents a BS and corresponds to a UE. For the sake of convenience,  FIG. 2  only shows a part of a macro BS node of the eNB  100 . The four distributed transport points  101 ,  102 ,  103 , and  104  all provide signal transmission services for the UE  105  and may be RRHs. Generally, the eNB  100  allocates corresponding port numbers. For example, the transport point  101  has a port number 0, the transport point  102  has a port number 1, the transport point  103  has a port number 2, and the transport point  104  has a port number 3, that is, RRH0, RRH1, RRH2, and RRH3 respectively. 
         [0025]    In  FIG. 2 , the UE  105  reports eRSRP of the transport points  101 ,  102 ,  103 , and  104  to the eNB  100  through a process according to an embodiment of a report method of the present invention shown in  FIG. 3 . The eRSRP refers to receiving power of a reference signal transmitted by a certain transport point, in which the receiving power is measured by the UE. In the present invention, the eRSRP includes parameters capable of reflecting channel information of path loss, for example, RSRP and a value of path loss. 
         [0026]    In Step  200 , the eNB  100  transmits different reference signals to the different transport points  101 ,  102 ,  103 , and  104  being distributed. The reference signal may be a CRS or a CSI-RS. In  FIG. 2 , the eNB  100  transmits different CSI-RSs to the transport points  101 ,  102 ,  103 , and  104 . 
         [0027]    In Step  201 , the eNB  100  notifies, by means of signaling, the UE  105  of reporting the eRSRP of the different transport points  101 ,  102 ,  103 , and  104  periodically or in an event triggering manner. The trigger event includes that, the UE  105  receives an instruction of the eNB  100 ; or the UE  105  obtains |eRSRP x -eRSRP y |&gt;T through measurement, where eRSRP x  is eRSRP of a transport point with a port number x among the different transport points  101 ,  102 ,  103 , and  104 , eRSRP y  is eRSRP of a transport point with a port number y among the different transport points  101 ,  102 ,  103 , and  104 , and T is a preset receiving power difference threshold or a threshold configured by the eNB for the UE. For example, when the UE  105  performs measurement to obtain that an eRSRP difference between the transport point  101  with the port number 0 and the transport point  102  with the port number 1 is greater than the preset threshold, the eRSRP is automatically reported to the eNB  100 . 
         [0028]    In Step  202 , the UE  105  measures the eRSRP for the reference signals of the transport points  101 ,  102 ,  103 , and  104 . 
         [0029]    In Step  203 , the UE  105  reports the measured eRSRP of the transport points  101 ,  102 ,  103 , and  104  to the eNB  100 . Multiple kinds of specific report manners exist. For example, when reporting the eRSRP of the transport points  101 ,  102 ,  103 , and  104  to the eNB  100 , the UE  105  transmits the port numbers of the corresponding transport points; or the UE  105  reports the eRSRP of the different transport points  101 ,  102 ,  103 , and  104  in an order predetermined by the eNB  100 , for example, in an order of the ports allocated to the reference signals of the transport points  101 ,  102 ,  103 , and  104 . For details, reference may be made to  FIG. 4  and relevant description. Moreover, when reporting, the UE  105  may select to transmit the measured eRSRP to the eNB  100 , or transmit the measured eRSRP to the different transport points  101 ,  102 ,  103 , and  104  and then the different transport points transmit the eRSRP to the eNB. In some embodiments, the UE  105  may only report the eRSRP of a part of the transport points according to an indication of the eNB  100 , or the UE  105  only reports the eRSRP of the transport points that satisfy an event triggering condition. 
         [0030]    In Step  204 , the eNB  100  receives the eRSRP of the transport points  101 ,  102 ,  103 , and  104  from the UE  105 , to know channel information of path loss of the transport points  101 ,  102 ,  103 , and  104 , and based on the channel information, determine a corresponding optimization scheme for solving the problem of unbalanced power or perform other operations including resource allocation, power control, transport point selection, and the like. 
         [0031]      FIG. 4  shows another embodiment of the present invention. In this embodiment, an exemplary process for the UE  105  to report the RSRP of the transport points  101 ,  102 ,  103 , and  104  to the eNB  100  in an order is further demonstrated. 
         [0032]    In Step  300 , the eNB  100  allocates different port numbers to different reference signals, to generate reference signals at different ports, for example, CSI-RS0, CSI-RS1, CSI-RS2, and CSI-RS3. 
         [0033]    In Step  301 , the reference signals with different reference signal ports CSI-RS0, CSI-RS1, CSI-RS2, and CSI-RS3 are transmitted to the corresponding transport points  101 ,  102 ,  103 , and  104 , that is, RRH0, RRH1, RRH2, and RRH3 respectively. The reference signals are further transmitted to the UE  105 . 
         [0034]    In Step  302 , the UE  105  measures RSRP for the reference signals CSI-RS0, CSI-RS1, CSI-RS2, and CSI-RS3 of the transport points  101 ,  102 ,  103 , and  104 , to obtain corresponding RSRP0, RSRP1, RSRP2, and RSRP3. 
         [0035]    In Step  303 , RSRP0, RSRP1, RSRP2, and RSRP3 are sequentially reported to the eNB  100 . 
         [0036]      FIG. 5  is a structural block diagram of a DAS according to an embodiment of the present invention. In the DAS, an eNB  40  includes: a reference signal transmitting component  400 , configured to transmit corresponding reference signals CSI-RS0 to CSI-RSn to different transport points RRH0 to RRHn; a signaling notification component  401 , configured to notify, by means of signaling, a UE  41  of reporting the eRSRP of the different transport points RRH0 to RRHn periodically or in an event triggering manner; and an eRSRP receiving component  402 , configured to receive eRSRP0 to eRSRPn of the different transport points RRH0 to RRHn, to determine a corresponding optimization scheme for solving a problem of unbalanced power at least. The problem of unbalanced power is solved by adjusting transmit power of the different transport points RRH0 to RRHn, a transport point selection operation, or a transport point grouping operation; and the adjustment includes increase, maintenance, or decrease. The corresponding UE  41  includes: a measurement component  410 , configured to measure the eRSRP0 to eRSRPn of the different transport points RRH0 to RRHn; a signaling receiving component  411 , configured to enable the UE  41  to report, according to received signaling sent by the eNB  40 , the eRSRP0 to eRSRPn of the different transport points RRH0 to RRHn periodically or in an event triggering manner; and a report component  412 , configured to report the measured eRSRP0 to eRSRPn of the different transport points RRH0 to RRHn to the eNB  40 . 
         [0037]    Through the antenna system and the method for reporting RSRP of the same provided by the present invention, an eNB obtains eRSRP of distributed transport points serving a UE, to know channel information of path loss of the transport points. Based on the information, the eNB may perform multiple kinds of corresponding operations, for example, solving the existing problem of unbalanced power, performing flexible transport point selection, implementing effective power control, or flexibly allocating resources, thereby greatly improving the system throughput. 
         [0038]    The technical content and technical features of the present invention are disclosed above. However, persons skilled in the art can still make replacements and modifications without departing from the spirit of the present invention based on the teaching and disclosure of the present invention. Therefore, the protection scope of the present invention shall not be limited to the content disclosed in the embodiments, but shall include various replacements and modifications without departing from the spirit of the present invention and be covered by the claims of this patent.