Wireless Waveform Selection via Delay Spread Feedback
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Solution Overview
Problem
Current wireless communication systems face challenges in selecting the optimal waveform for beamformed communications, particularly in determining whether to use OFDM or SC-FDM waveforms based on channel characteristics, as existing methods do not effectively utilize delay spread measurements for waveform selection.
Innovation Solution
User equipment (UE) measures delay spread by receiving reference signals from the base station and transmits this information to assist the base station in selecting the appropriate waveform for data transmissions, using feedback mechanisms over control channels, which can include delay spread measurements, waveform recommendations, and power amplifier capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If delay spread measurements are utilized for waveform selection, then communication quality is improved, but device complexity increases
Solution Approach 1:
The UE performs delay spread measurements on reference signals in advance before data transmission begins. These measurements are reported to the base station through feedback mechanisms (UCI, MAC CE, or CSI report), allowing the base station to pre-determine the optimal waveform type (OFDM or SC-FDM) based on the measured delay spread values and configured thresholds, thereby improving communication quality without adding complexity during the actual data transmission phase
Solution Approach 2:
The patent implements feedback mechanisms where the UE reports delay spread measurements and optionally waveform recommendations to the base station. The base station uses this feedback to select the appropriate waveform type for downlink and uplink transmissions. This feedback-driven approach enables adaptive waveform selection that improves communication quality while keeping the decision-making logic centralized at the base station, limiting the complexity increase at the UE side
2Measurement precision
If multiple feedback mechanisms are implemented for waveform selection, then waveform selection accuracy is improved, but signaling overhead increases
Solution Approach 1:
The patent provides dynamic feedback mechanisms where the UE can adaptively choose different feedback types based on conditions. The UE may report only delay spread measurements when basic waveform selection is needed, or additionally report waveform recommendations when the UE has strong preferences or when operating in conditions where its recommendation would be beneficial. This dynamic feedback approach improves waveform selection accuracy while allowing the signaling overhead to vary according to actual needs rather than being constantly maximal
Solution Approach 2:
The system allows configuration of multiple threshold values for delay spread that correspond to different waveform selection criteria. The base station can configure different threshold sets for different scenarios, and the UE can report delay spread measurements that are compared against these configurable thresholds. This parameter-based approach enables precise waveform selection through threshold comparison while keeping the feedback signaling relatively simple and configurable according to specific deployment requirements
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may transmit, to a base station, feedback information that indicates delay spread information. The UE may receive control signaling that indicates to use a first waveform of a set of different waveforms for a first data transmission via a first beam based on the feedback information. The UE may then communicate the first data transmission via the first beam using the first waveform