Method for operating a radio station in a mobile network

Abstract

The present invention relates to a secondary station comprising means for communicating with at least one primary station, the secondary station comprising means for receiving from the primary station a subset of reference symbols selected out a set of possible reference symbols, the reference symbols of the subset being associated with a spatial channel, wherein a transmission characteristic of the subset of reference symbols depends on the spatial channel.

1 . A method for operating a primary station comprising means for communicating with a plurality of secondary stations, the method comprising the primary station transmitting to a secondary station a first subset of reference symbols selected out a set of possible reference symbols, the reference symbols of the first subset being associated with a spatial channel, wherein a transmission characteristic of the first subset of reference symbols depends on the spatial channel. 
     
     
         2 . The method of  claim 1 , wherein the transmission characteristic of the set of reference symbols comprises at least one of a modulation sequence, a spreading sequence, a cyclic shift to a spreading sequence, a scrambling sequence and a plurality of time/frequency resource elements. 
     
     
         3 . The method of  claim 1 , wherein the first subset of reference symbols of the secondary station is mutually orthogonal with at least one other subset of reference symbols transmitted to the secondary station. 
     
     
         4 . The method of  claim 1 , wherein the first subset of reference symbols transmitted to a secondary station is mutually orthogonal with at least one other subset of reference symbols transmitted to a further secondary station. 
     
     
         5 . The method of  claim 3 , wherein the at the at least one other subset of reference symbols is obtained by multiplying the complex conjugate of each symbol of the first subset of reference symbols by a sequnce comprising substantially equal numbers of symbols of values x and symbols of value-x. 
     
     
         6 . The method of  claim 5  wherein the sequnce comprising substantialy equal numbers of symbols of values x and symbols of value-x is a sequence of symbols successively alternating between a value of 1 and a value of −1. 
     
     
         7 . The method of  claim 1 , wherein a portion of the first subset of reference symbols is arranged in both time and frequency domains and is mutually orthogonal to a corrsponding portion of at least one other subset of reference symbols identically arranged in both time and frequency domains. 
     
     
         8 . The method of  claim 1 , wherein the primary station operates for a cell, and wherein the set of possible reference symbols depends on an identifier of the primary station cell. 
     
     
         9 . The method of  claim 1 , wherein the set of possible reference symbols is an ordered list and wherein each subset of reference symbols is associated sequentially, and where a starting value of the subset for a spatial channel depends on a respective spatial channel index. 
     
     
         10 . The method of  claim 9 , wherein the primary station operates for a cell, and wherein the starting value is determined from an identifier of the primary station cell. 
     
     
         11 . The method of  claim 1 , wherein the subset of reference symbols further depends on at least one of the following:
 An identifier of the secondary station   An identifier of the primary station   A subframe number   An OFDM symbol number   A resource block index   A sub-block within a resource block   An index to a group of resource blocks   A carrier frequency   A carrier index.   
     
     
         12 . The method of  claim 1 , wherein the subset of reference symbols further varies with the time. 
     
     
         13 . The method of  claim 1 , where a spatial channel is associated with an antenna or an antenna port. 
     
     
         14 . A method for operating a secondary station comprising means for communicating with at least one primary station, the method comprising the secondary station receiving from the primary station a subset of reference symbols selected out a set of possible reference symbols, the reference symbols of the subset being associated with a spatial channel, wherein a transmission characteristic of the subset of reference symbols depends on the spatial channel. 
     
     
         15 . A primary station comprising means for communicating with a plurality of secondary stations, the primary station comprising means for transmitting to a secondary station a subset of reference symbols selected out a set of possible reference symbols, the reference symbols of the subset being associated with a spatial channel, wherein a transmission characteristic of the subset of reference symbols depends on the spatial channel. 
     
     
         16 . A secondary station comprising means for communicating with at least one primary station, the secondary station comprising means for receiving from the primary station a subset of reference symbols selected out a set of possible reference symbols, the reference symbols of the subset being associated with a spatial channel, wherein a transmission characteristic of the subset of reference symbols depends on the spatial channel.