Method and apparatus for precoding channel state information reference signal
A channel state information and reference signal technology, applied in pilot signal allocation, transmission path sub-channel allocation, wireless communication and other directions, can solve problems such as insufficient adaptation, and achieve the effect of efficient transmission and reception
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Embodiment 1
[0181] For a 2D dual-polarization array with sufficiently small inter-element spacing, each polarization (+45 or -45)A(φ,θ) can be written as follows (see Figure 7 with Figure 8 ):
[0182]
[0183] In this case, the quantized channel coefficients The number is 2KL×N RX N F instead of 2N r N c ×N RX N F . When (0 max -θ min ) and (φ max -φ min ) is relatively small, it is estimated that KLr N c (This results in some savings in feedback requirements). This is because for a reasonable time span, low mobility UEs are located by {(φ, θ): φ∈[φ min , φ max ]∧θ∈[θ min , θ max ]} within the small cone of the AoD defined.
[0184] The proposed scheme operates based on a predetermined main set of basis functions / vectors. This master set is fixed and structured to cover the entire range of AoD values, ie {(φ,θ):φ∈[0,2π)∧θ∈[0,π)}. For a given number of rows and columns (N r , N c ), requiring at least N r values of θ (preferably well spaced span [0, π)) and ...
Embodiment 2
[0189]Note that Equation 2A and Equation 3 facilitate (or at least encourage) linear discretization in the AoD domain. Alternatively, the MIMO channel can also be represented as a linear combination of basis functions / vectors in the DFT phase domain, which is:
[0190]
[0191]
[0192] Similar to the first embodiment, in the case of a multi-cone configuration, Equation 6 and Equation 7 apply to each of the plurality of cones.
[0193] Similar to Equation 5, Δ in Equation 7 r and Δ c is the oversampling factor (an integer > 1, 1 in the special case of non-overlapping DFT beams), which produces overlapping DFT beams. In this case, the primary set associated with Equation 6 and Equation 7 is given by Equation 8A below:
[0194]
[0195] l=0,1,...,Δ r N r -1,k=0,1,...,Δ c N c -1 (8A)
[0196] As mentioned above, an oversampling factor of 1 corresponds to non-overlapping beams, i.e. critically sampled DFT vectors. Similarly, the quantized channel coefficients T...
Embodiment 3
[0199] Starting from Embodiment 1 or 2, another level of dimensionality reduction can be achieved if the channel representation in Equation 2 / 2B or Equation 6 is applied to the channel eigenvector instead of the channel itself. Using Equation 2b to illustrate this method (one skilled in the art should easily extend to the case of Equation 2 or Equation 6), the procedure is as follows:
[0200] • Perform eigendecomposition or singular value decomposition on the DL MIMO channel for each polarization and frequency subband. Here, channels associated with different receive antennas are concatenated into a channel matrix.
[0201] Based on the selected RI (eg, N=1 or 2), the UE 116 selects N dominant (strongest) eigenvectors (or right singular vectors), and the corresponding eigenvalues are reflected / captured in the N of CQI values.
[0202] • Since the UE is located within one or a few small pyramids, each of the N eigenvectors (for each polarization and frequency subband) allo...
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