Method and apparatus for cooperative transmission
A technology for cooperative transmission and equipment, applied in transmission systems, digital transmission systems, radio transmission systems, etc., and can solve problems such as damage improvement, large overhead, etc.
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no. 1 example
[0083] According to a first embodiment of the invention, CoMP transmission combined with frequency shifting (eg as defined in Release 8) is considered.
[0084] A prior art related to this is described below.
[0085] For LTE Release 8, a grid of so-called Common Reference Signals (CRS) has been defined. For example, antenna port AP1 has an RS at every 6th subcarrier in OFDM symbols 1, 5, 9 and 12. Since LTE is a cellular radio system with frequency reuse 1, all cells transmit a cell-specific CRS with a specific scrambling sequence. In order to reduce inter-cell interference between CRSs from different cells, another 3 different so-called frequency shifts are defined, which means: At the corresponding OFDM symbol, the CRS of cell 1 starts with e.g. subcarrier (SC) SC1 , the CRS of cell 2 starts with SC2, and the CRS of cell 3 starts with SC3. The frequency shift is tightly coupled to the cell ID and avoids that CRSs from neighboring cells always collide with the same RS sig...
no. 2 example
[0125] According to the second embodiment, similarly to the first embodiment, it is also considered that the reference unit including the specific unit is not used for CoMP. However, according to the present embodiment, an example of such a specific unit is a control channel symbol, such as a PDCCH symbol. This is explained in more detail below.
[0126]That is, the second embodiment relates to a CoMP solution in case of PDCCH mismatch, as will be described below.
[0127] The prior art related to this is first described below.
[0128] As already mentioned, in the background section of this application, for LTE-Advanced, the so-called Coordinated Multipoint Transmission (CoMP) is investigated within the research project, and there has been agreement on the direction of development, namely that there should be Sparse RS for CSI estimation and precoding dedicated reference signal (pDRS) for demodulation. pDRS is used for demodulation and is only transmitted on those PRBs wit...
no. 3 example
[0169] The third embodiment relates to space division multiplexing (SDM) for minimal overhead pDRS design, but is not limited thereto. In detail, according to the third embodiment, optimal allocation of pre-decoding reference signals (pDRS) for cooperative multi-point transmission (CoMP) can be realized.
[0170] This is explained in more detail below, wherein the prior art related to this is first described.
[0171] As already mentioned, for LTE-Advanced, Coordinated Multipoint Transmission (CoMP) is investigated within the Study Item (SI) and there has been agreement on the direction of development, i.e. there is RS (CSI-RS) and precoded dedicated reference signal (pDRS) for demodulation. pDRS is used for demodulation and is only transmitted on those PRBs with data transmission, saving unnecessary overhead. The pDRS is precoded with the same precoder as the corresponding data signal. Since pDRSs will have to support demodulation of the highest modulation and coding schem...
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