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In this paper, codebook design for massive MIMO systems with 32/64Tx transmit branches is investigated. Using the same parameterized codebook framework of LTE Rel-13 for 16Tx, 32/64Tx codebooks are discussed and evaluated through system level simulations. In addition, to deal with the larger feedback overhead, three codebook sub-sampling methods are discussed. These methods aim to achieve a tradeoff...
In this paper, CSI feedback for massive MIMO system with planar antenna array is studied. A hybrid channel state information feedback mechanism is proposed. The proposed mechanism is based on combination of beamformed CSI-RS and non-beamformed CSI-RS transmission. Each codeword in the codebook for feedback regarding the non-beamformed CSI-RS is associated with a beamformed CSI-RS. By utilizing this...
In this paper codebook for massive MIMO system with planar array is studied. To separate spatially correlated and spatially uncorrelated parts of the channel, antennas are divided into a number of blocks according to their position in the array. Antennas in a block are spatially correlated and antennas across blocks tend to be spatially uncorrelated. A codebook design approach is proposed based on...
Active antenna system (AAS) is a system with features the ability of advanced beam-forming techniques to take full advantage of spatial freedom in cellular network deployment, which enables improvement in network capacity and coverage. One of recent applications for AAS is vertical sectorization where the conventional sector is split into two vertical sector, i.e. inner sector and outer sector. The...
The increased number of antennas for massive MIMO system implies that the quantization codebook size needs to be significantly larger, which increases precoder search complexity accordingly. This paper compares the vertical/horizontal channel characteristics and finds that the vertical channel has a much longer coherence time than the horizontal channel. Based on these results, a two-dimension CSI...
In this paper, practical CSI acquisition methods for massive MIMO systems are investigated. The implementation issues of channel reciprocity based feedback in TDD are discussed, and a two-dimension feedback mechanism for FDD is proposed where the horizontal and vertical domain channels are reported separately. System level evaluation results demonstrate that massive MIMO with the two-dimensional feedback...
TDD (Time Division Duplex) is one of the two duplex modes. TD-SCDMA (Time Division Synchronous CDMA) is the first TDD-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also the first cellular mobile system which adopted smart antenna technology (also called as beamforming). As the long term evolution of TD-SCDMA, TD-LTE(A) (Time Division-Long Term Evolution,...
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