Reference signal design for downlink high-order mimo

Abstract

In a cellular network supporting both legacy standard-compliant mobile terminals and next generation standard-compliant mobile terminals, both legacy reference signals and next generation reference signals are supported. A method of operation of a MIMO transmitter compliant with both standards includes: defining a matrix of resource blocks within an information channel of the cellular network, wherein each resource block corresponds to a region of subcarriers of a transmission timeslot at a given frequency subband; assigning a first set of reference signals (RSs) for the legacy standard-compliant mobile terminals to resource blocks at specific locations within the matrix to be transmitted by the MIMO transmitter, the specific locations being defined by the legacy standard; and assigning a second set of RSs for the next-generation standard-compliant mobile terminals to other resource blocks within the matrix to be transmitted by the MIMO transmitter.

1 . A method of operation of a MIMO transmitter, in a cellular network supporting both legacy standard-compliant mobile terminals and next generation standard-compliant mobile terminals, said method comprising:
 defining a matrix of resource blocks within an information channel of said cellular network, wherein each resource block corresponds to a region of subcarriers of a transmission timeslot at a given frequency subband;   assigning a first set of reference signals (RSs) for said legacy standard-compliant mobile terminals to resource blocks at specific locations within said matrix to be transmitted by said MIMO transmitter, said specific locations being defined by said legacy standard; and   assigning a second set of RSs for said next-generation standard-compliant mobile terminals to other resource blocks within said matrix to be transmitted by said MIMO transmitter.   
     
     
         2 . The method of  claim 1  wherein said assigning said second set of RSs comprises assigning said RSs of said second set to resource blocks adjacent in time to resource blocks assigned to RSs of said first set of RSs. 
     
     
         3 . The method of  claim 1  wherein said assigning said second set of RSs comprises assigning said RSs of said second set to resource blocks adjacent in frequency subband to resource blocks assigned to RSs of said first set of RSs. 
     
     
         4 . The method of  claim 2  further comprising transmitting some of said RSs of said second set of RSs in a different timeslot than RSs of said first set. 
     
     
         5 . The method of  claim 3  further comprising transmitting some of said RSs of said second set at a different frequency subband of a given timeslot than said RSs of said first set. 
     
     
         6 . The method of  claim 1  wherein said RSs of said first set are recognized by said next-generation standard-compliant mobile terminals. 
     
     
         7 . The method of  claim 1  wherein said second set of RSs comprise additional common RSs defined in said next-generation standard. 
     
     
         8 . The method of  claim 1  wherein said second set of RSs comprise additional dedicated RSs defined in said next-generation standard. 
     
     
         9 . The method of  claim 1  wherein said first set of reference signals are transmitted by a subset of antennas of said MEMO transmitter and said second set of reference signals are transmitted by another subset of antennas of said MEMO transmitter. 
     
     
         10 . The method of  claim 9  wherein said subset of antennas comprise 4 antennas and said another subset of antennas comprise at least 4 other distinct antennas. 
     
     
         11 . The method of  claim 1  wherein said legacy standard is LTE Rel-8. 
     
     
         12 . The method of  claim 1  wherein said next-generation standard is LTE-A. 
     
     
         13 . The method of  claim 1  wherein said information channel is the PDCCH channel defined in the LTE-Rel-8 and LTE-A standards. 
     
     
         14 . The method of  claim 4  wherein said transmitting comprises transmitting in accordance with a transmit diversity technique. 
     
     
         15 . A transmitter in a cellular network capable of operating both in accordance with a legacy-standard and a next-generation standard, said transmitter comprising:
 a plurality of antennas; and   a processor operable to cause said transmitter to:
 transmit reference signals for mobile terminals compliant with said legacy standard in a first timeslot; and 
 transmit reference signals for mobile terminals compliant with said next-generation standard in a second timeslot. 
   
     
     
         16 . The transmitter of  claim 15  wherein said transmitter is a selected one of a base station or a relay. 
     
     
         17 . The transmitter of  claim 15  comprising at least 5 physical antennas and wherein said reference signals for mobile terminals compliant with said legacy standard are transmitted with a first, second, third and fourth antenna and said reference signals for mobile terminals complaint with said next-generation standard are transmitted with remaining antenna(s) of said antenna. 
     
     
         18 . A transmitter in a cellular network capable of operating both in accordance with a legacy-standard and a next-generation standard, said transmitter comprising:
 a plurality of antennas; and   a processor operable to cause said transmitter to:
 transmit reference signals for mobile terminals compliant with said legacy standard at a first frequency subband of a given timeslot; and 
 transmit reference signals for mobile terminals compliant with said next-generation standard at a second frequency subband of said given timeslot. 
   
     
     
         19 . The transmitter of  claim 18  wherein said transmitter is a selected one of a base station or a relay. 
     
     
         20 . The transmitter of  claim 18  comprising at least 5 physical antennas and wherein said reference signals for mobile terminals compliant with said legacy standard are transmitted with a first, second, third and fourth antenna and said reference signals for mobile terminals compliant with said next-generation standard are transmitted with remaining antenna(s) of said antenna.