Radio Apparatus Cyclic Timing Shift for MIMO Channel Estimation
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Solution Overview
Problem
In MIMO systems using OFDM modulation, the accuracy of channel estimation is compromised when the number of streams for AGC known signals differs from those for channel estimation known signals, leading to potential distortion and errors in data demodulation due to mismatched gain settings.
Innovation Solution
A radio apparatus that generates packet signals with data signals assigned to specific streams, where known signals are staggered in timing to align received powers, using cyclic timing shifts and prioritizing timing shifts to ensure accurate channel estimation and prevent distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of streams for AGC known signals differs from those for channel estimation known signals, then the system can flexibly allocate signals to streams, but the accuracy of channel estimation deteriorates due to mismatched gain settings
Solution Approach 1:
The patent divides the packet signal into multiple streams, with some streams containing AGC known signals and others containing channel estimation known signals. This segmentation allows independent optimization of signal types while maintaining overall system functionality, resolving the contradiction between flexible allocation and estimation accuracy.
Solution Approach 2:
Different streams are assigned different signal characteristics: some streams have AGC known signals with specific gain settings, while others have channel estimation known signals. This local differentiation ensures that each stream's signal properties are optimized for its specific purpose, preventing gain mismatch errors.
2Measurement precision
If known signals are assigned to all streams for channel estimation, then channel characteristics can be accurately acquired, but the complexity of signal configuration increases
Solution Approach 1:
The patent segments known signals into different types (AGC known signals and channel estimation known signals) and assigns them to different streams. This segmentation reduces configuration complexity by allowing selective assignment rather than uniform assignment across all streams.
Solution Approach 2:
The patent designs a universal packet signal structure that can accommodate different known signal types in different streams. This multi-functional design allows the same system framework to handle various signal allocation scenarios without increasing fundamental complexity.
3Measurement precision
If timing shifts are applied to align received powers, then data demodulation accuracy improves, but the processing time increases
Solution Approach 1:
The patent applies timing shifts to known signals before data demodulation to pre-align the received powers across streams. This preliminary alignment ensures that subsequent data processing can proceed efficiently without requiring complex real-time adjustments, thus minimizing overall processing time.
Data Source
AI summary
A control unit, in cooperation with an interface (IF) unit, a modulation unit and a baseband processing unit, produces a packet signal composed of a plurality of streams. While using as a reference a first known signal assigned to one of the plurality of streams and performing a cyclic timing shift within the first known signal on a first known signal assigned to another stream, the control unit performs a timing shift also on an extensional known signal assigned to a stream where no data is assigned. The amounts of timing shift are given degrees of priority beforehand and for the stream where data signals are assigned the control unit uses the amounts of timing shift in descending degree of priority. For the stream where no data signal is assigned, the control unit uses the amounts of timing shift also in descending degree of priority.