5th International ICST Conference on Communications and Networking in China

Research Article

Power offset compensation schemes between CRS and DRS for downlink dual layer beamforming in LTE system

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  • @INPROCEEDINGS{10.4108/chinacom.2010.158,
        author={Lilei Wang and Peter Skov and Chunye Wang and Li Zhang},
        title={Power offset compensation schemes between CRS and DRS for downlink dual layer beamforming in LTE system},
        proceedings={5th International ICST Conference on Communications and Networking in China},
        publisher={IEEE},
        proceedings_a={CHINACOM},
        year={2011},
        month={1},
        keywords={L TE beam/orming power offset between CRS and DRS RI CQI},
        doi={10.4108/chinacom.2010.158}
    }
    
  • Lilei Wang
    Peter Skov
    Chunye Wang
    Li Zhang
    Year: 2011
    Power offset compensation schemes between CRS and DRS for downlink dual layer beamforming in LTE system
    CHINACOM
    ICST
    DOI: 10.4108/chinacom.2010.158
Lilei Wang1,*, Peter Skov1, Chunye Wang1, Li Zhang1
  • 1: Nokia Siemens Networks Beijing
*Contact email: lilei.l.wang@nsn.com

Abstract

LTE Release 9 supports a new DL transmission mode which combines UE specific beamforming and spatial multiplexing. As one option this transmission mode can be operated based on UE (user equipment) feedback of channel rank. However in this case, the rank is in many cases not very accurate due the difference in precoding between the signal used for data demodulation (DRS - dedicated reference signal) and the signal used for estimating rank (CRS - common reference signal). To maintain good performance it is necessary to introduce a compensation factor to inform the UE about the difference between the channel experienced on DRS and CRS to obtain reasonable rank indication (RI). In this paper we study two compensation schemes, named UE-specific scheme and cell-specific scheme. System level simulations are used to validate the performance of the proposed schemes and support the view that cell-specific compensation is sufficient.