eNB Channel Training Signal Subspace Selection
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Solution Overview
Problem
In FD-MIMO systems, the overhead associated with transmitting channel training signals increases linearly with the number of antenna elements, leading to prohibitive resource usage and potential throughput reduction due to latency introduced by time sharing these signals, which may not accurately reflect changing radio resources caused by interference or UE movement.
Innovation Solution
The solution involves selectively transmitting channel training signals to specific signal subspaces identified by beamforming vectors that produce high signal energy, while skipping the null subspace to reduce overhead, with the eNB dynamically updating these subspaces based on feedback to maintain efficient resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If channel training signals are transmitted for all antenna elements in FD-MIMO systems, then channel training accuracy is improved, but resource overhead increases linearly with the number of antenna elements
Solution Approach 1:
The patent segments the antenna elements into two groups: a first set of antenna elements that transmit channel training signals, and a second set of antenna elements that do not transmit channel training signals. This segmentation allows the system to maintain channel training functionality with fewer transmitting antenna elements, thereby reducing the linear overhead growth associated with transmitting training signals from all antenna elements while preserving measurement accuracy through the representative first set.
Solution Approach 2:
The patent extracts and removes the requirement for channel training signal transmission from the second set of antenna elements. By taking out the channel training transmission function from certain antenna elements (specifically the second set), the system reduces resource overhead while maintaining essential channel training capabilities through the first set of antenna elements.
2Quantity of substance
If channel training signals are time shared among antenna elements, then resource overhead is reduced, but latency increases and feedback may not accurately reflect changing radio resources
Solution Approach 1:
The patent segments antenna elements into permanent transmission groups rather than time-sharing them. The first set of antenna elements is designated to transmit channel training signals while the second set does not, creating a spatial segmentation that eliminates the need for time sharing. This approach reduces latency by providing continuous, dedicated channel training transmission capacity without the temporal delays inherent in time-sharing schemes.
3Loss of information
If channel training signals are transmitted for all antenna elements, then complete channel information is obtained, but throughput gains from FD-MIMO are offset by overhead
Solution Approach 1:
The patent segments antenna elements into functional groups where only the first set transmits channel training signals. This segmentation reduces the overhead associated with channel training transmission, thereby preserving throughput gains from FD-MIMO while obtaining sufficient channel information through the representative first set of antenna elements.
Solution Approach 2:
The patent extracts the channel training transmission requirement from the second set of antenna elements, removing unnecessary overhead while maintaining essential channel information acquisition through the first set. This extraction prevents overhead from offsetting throughput gains while preserving adequate channel information for system operation.
Data Source
AI summary
In embodiments, apparatuses, methods, and storage media may be described for reducing the overhead associated with the transmission of channel training signals from an eNodeB (eNB) of a wireless network. Specifically, the eNB may receive feedback from a user equipment (UE) regarding the received signal energy of a first and second beamformed signal produced with a first and second beamforming vector, respectively. The eNB may identify, based on the feedback of the received signal energy, a signal subspace and a null subspace. The eNB may then transmit a channel training signal to the signal subspace.