Channel State Information Feedback Using Basis Matrix and Coefficients

The patent segments the channel state information feedback into two distinct parts: a basis matrix indicator (indicating selected beam vectors from a codebook) and combination coefficients (providing continuous precision adjustments). This segmentation allows the system to use a simplified codebook structure for the basis matrix while adding precision through the combination coefficients, thereby improving channel state information precision without completely redesigning the feedback scheme architecture.

The patent adds a new dimension to the traditional codebook-based feedback by introducing combination coefficients that operate alongside the basis matrix indicator. Instead of relying solely on selecting from discrete codebook entries, the combination coefficients provide an additional degree of freedom for precise channel representation, effectively moving from a one-dimensional codebook selection to a two-dimensional feedback structure (discrete basis + continuous coefficients).

The patent performs preliminary action by pre-defining a codebook of basis vectors at both the base station and UE before actual channel feedback occurs. This pre-established codebook structure maintains implementation ease and compatibility, while the subsequent combination coefficients provide the necessary precision for MU-MIMO operations without requiring complex real-time computations.

The combination coefficients act as an intermediary between the discrete codebook structure and the continuous channel state information. Instead of directly quantizing the entire channel matrix (which would be complex), the system uses the codebook as an intermediary basis and represents the channel as a linear combination of these basis vectors with continuous coefficients, thereby maintaining implementation simplicity while achieving high precision.

The patent transitions from a one-dimensional linear antenna array (with only horizontal beam adjustment) to a two-dimensional planar antenna array that enables beam adjustment in both horizontal and vertical directions. This dimensional expansion adds vertical adaptability to the system, allowing optimization of downlink performance for users at different spatial locations without significantly increasing overall system complexity.

The planar antenna array structure provides multi-functionality by enabling both horizontal and vertical beamforming capabilities within a single array configuration. This universal structure can serve multiple purposes: maintaining compatibility with existing horizontal beam adjustment while adding vertical dimension optimization, thereby improving adaptability without requiring separate antenna systems for different directions.