Reference signal interference management in heterogeneous network deployments

Abstract

Methods and apparatus for enabling interference coordination in a communication network. A base station includes a plurality of antenna ports. Each antenna port is configured to transmit a reference signal, and each antenna port is associated with a respective cell. The base station determines a set of cells where transmissions of reference signals is to be performed from a reduced set of the plurality of antenna ports. The base station determines a subset of antenna ports in at least one cell of the determined set of cells to enable interference coordination in the network, and transmits the reference signal from the subset of antenna ports.

What is claimed is: 
     
       1. A method in a coordinating network node for enabling interference coordination in a communication network, the method comprising:
 acquiring information about a set of interfering cells among a plurality of cells in a communication network; 
 generating assistance data based on the acquired information, wherein the assistance data includes a number of antenna ports to be used for transmissions by a network node in one of the interfering cells; and 
 transmitting the assistance data to a user equipment. 
 
     
     
       2. The method of  claim 1 , wherein the transmitting of the assistance data is triggered by detecting predetermined interference conditions for the user equipment in the communication network. 
     
     
       3. The method of  claim 1 , wherein the coordinating network node is associated with an interfering macro cell. 
     
     
       4. A network node for enabling interference coordination in a communication network, the network node comprising:
 a processor configured to
 acquire information about a set of interfering cells among a plurality of cells in a communication network; and 
 generate assistance data based on the acquired information, wherein the assistance data includes a number of antenna ports to be used for transmissions by a network node in one or more of the interfering cells; and 
 
 one or more antennas configured to transmit the assistance data to a user equipment. 
 
     
     
       5. The network node of  claim 4 , wherein the transmitting of the assistance data is triggered by detecting predetermined interference conditions for the user equipment in the communication network. 
     
     
       6. The network node of  claim 4 , wherein the network node is associated with an interfering macro cell. 
     
     
       7. A method for operating a user equipment in a communication network, the method comprising:
 acquiring information about a set of interfering cells among a plurality of cells;   identifying a set of time-frequency resources affected by the set of interfering cells; and   measuring a reference signal and while measuring the reference signal excluding the identified time-frequency resources or setting weights on the identified time-frequency resources to zero.    
     
     
       8. The method according to claim 7, wherein the set of interfering cells is based on at least one of: user equipment capability, cell grouping, a desired number of most critical interfering cells to account for the exclusion of—or setting of weights to zero on—the identified time-frequency resources, and impact on an interference level.  
     
     
       9. The method according to claim 7, wherein the information about interfering cells comprises assistance data, which assistance data is configured to assist the user equipment in the exclusion of—or setting of weights to zero on—the identified time-frequency resources.  
     
     
       10. The method according to claim 9, wherein the assistance data comprises at least one of: a set of physical layer cell identities, a transmit bandwidth of an interfering cell, channel-related information and a number of antenna ports.  
     
     
       11. The method according to claim 9, further comprising:
 autonomously extracting the assistance data from the acquired information.    
     
     
       12. The method according to claim 7, wherein the information about interfering cells is acquired from a serving cell or a network node within the communication network.  
     
     
       13. The method according to claim 7, wherein the identifying a set of time-frequency resources is based on a reference signal transmit pattern.  
     
     
       14. The method according to claim 7, wherein each cell in the set of interfering cells is associated with a strong interfering signal, which strong interfering signal has a signal strength above a threshold.  
     
     
       15. A user equipment comprising:
 a processor configured to:
 acquire information about a set of interfering cells among the plurality of cells; 
 identify a set of time-frequency resources affected by a set of interfering cells; and 
 measure a reference signal and while measuring the reference signal excluding the identified time-frequency resources or setting weights on the identified time-frequency resources to zero.  
   
     
     
       16. The user equipment according to claim 15, wherein the set of interfering cells is based on at least one of: user equipment capability, cell grouping, a desired number of most critical interfering cells to account for the exclusion of—or setting of weights to zero on—the identified time-frequency resources, and an impact on an interference level.