Cooperative Beamforming Codebook Phase Offset Signaling
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Solution Overview
Problem
Existing communication systems, such as UMTS and LTE, face challenges in defining codebooks for cooperative beamforming across multiple cells, leading to complex and inefficient signaling, especially when multiple cells need to cooperate to create spatial streams for user terminals.
Innovation Solution
The method involves using codebooks designed for single cells to report channel information across multiple cells, with a phase offset indicated between pairs of codebook indices, allowing for simple and reliable signaling and precoding in cooperative multicell MIMO communications, and enabling the use of existing codebooks by specifying phase relationships between codebooks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If codebooks are defined for cooperative beamforming across multiple cells, then transmission rate is improved, but signaling complexity increases
Solution Approach 1:
The patent applies universality by making single-cell codebooks serve dual purposes: they are used both for single-cell precoding and for multi-cell cooperative beamforming. The codebook structure is designed to be universally applicable across different cell configurations, eliminating the need for separate codebook definitions for cooperative scenarios. This reduces signaling complexity while maintaining the ability to achieve high transmission rates through cooperative beamforming.
Solution Approach 2:
The patent segments the precoding operation into cell-specific components. Each cell has its own codebook and precoding vectors, but these segmented components are combined through cooperative beamforming. The channel matrix is divided into cell-specific sub-matrices, and the precoding is applied independently to each cell's antennas before combination. This segmentation allows simple codebook usage while enabling complex cooperative transmission, resolving the contradiction between transmission rate and signaling complexity.
2Productivity
If multiple cells cooperate to create spatial streams, then transmission rate is improved, but overhead increases
Solution Approach 1:
The codebook is designed to be universally used across single-cell and multi-cell scenarios. The same codebook structure and precoding vectors are employed in both cases, eliminating the need for separate codebook signaling for cooperative beamforming. This universal approach reduces overhead while maintaining the capability to create multiple spatial streams through cooperative transmission from multiple cells.
Solution Approach 2:
The patent merges the codebook usage into a unified approach where single-cell codebooks are combined to serve multi-cell cooperative beamforming. The channel information from multiple cells is combined into a joint channel matrix, and a single precoding operation is applied across all cells. This merging eliminates redundant signaling and reduces overhead while achieving high transmission rates through cooperative spatial stream creation.
3Adaptability or versatility
If phase offset is indicated between codebook indices, then codebook reusability is improved, but signaling requirements increase
Solution Approach 1:
The codebook is designed with universal reusability across different cell configurations. By indicating phase offsets between codebook indices, the same codebook can be adapted for both single-cell and multi-cell cooperative beamforming. The phase offset information allows the codebook to maintain its universality while accommodating different transmission scenarios, improving adaptability without requiring multiple separate codebooks.
Solution Approach 2:
The patent uses parameter changes by introducing phase offset indicators between codebook indices. Instead of creating entirely new codebooks for cooperative beamforming, the system modifies existing codebook parameters through phase offset signaling. This allows the codebook to adapt to different cell configurations and transmission modes by changing phase parameters rather than requiring fundamental codebook redefinition, thus improving reusability with minimal signaling overhead.
Data Source
AI summary
The present invention relates to a method for communicating in a network, the network comprising at least a first cell and a second cell including respectively a first primary station having a first antenna array dedicated to the first cell and a second primary station having a second antenna array dedicated to the second cell, for communicating with a plurality of secondary stations, the method comprising the step of (a) providing with a co-operative beamforming transmission from the first and second primary stations to at least one first secondary station, wherein step (a) includes (a1) the first secondary station signaling at least one channel matrix to at least one of the first and second primary stations, and (a2) the first and second primary stations applying a precoding matrix across both the first antenna array and the second antenna array, and wherein the precoding matrix comprises a first vector for the first cell and a second vector for the second cell, the precoding matrix being based on the at least one channel matrix.