Cooperative Precoding for Multi-CFO Mitigation in Virtual Cells
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Solution Overview
Problem
Cooperative precoding schemes in autonomous vehicle communication systems face challenges due to multiple carrier frequency offsets (CFOs) among serving access points, which degrade link quality and bit error rate performance.
Innovation Solution
A method involving a coordinating device that obtains CFO parameters of serving stations, generates and assigns cooperative encoded sequences based on these parameters, using shift-and-multiply operations to transmit sequences over multiple subcarriers, ensuring optimal alignment to mitigate CFO imperfections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cooperative precoding scheme is implemented in virtual cell with multiple serving APs, then transmit diversity gain and link quality are enhanced, but multi-CFO issues arise causing bit error rate degradation
Solution Approach 1:
The patent changes the parameter of encoded sequences by generating multiple different encoded sequences (first, second, and third encoded sequences) corresponding to different CFO conditions. The coordinating device selects and assigns appropriate encoded sequences to serving APs based on their CFO parameters, thereby adapting the transmission parameters to compensate for CFO variations and maintain link quality.
2Area of stationary object
If multiple serving APs with different CFOs transmit simultaneously, then coverage area is expanded, but CFO misalignment degrades signal quality
Solution Approach 1:
The patent applies local quality by generating different encoded sequences tailored to specific CFO conditions of individual serving APs. Each AP receives a customized encoded sequence based on its local CFO parameter, allowing each transmitter to adapt its signal characteristics to its specific frequency offset condition while maintaining overall system coherence.
Solution Approach 2:
The patent changes the encoding parameters differently for each serving AP based on its CFO characteristics. The coordinating device generates multiple encoded sequences with different parameters and assigns them selectively to APs according to their CFO values, thereby compensating for frequency offsets and maintaining signal alignment precision across the extended coverage area.
Data Source
AI summary
A cooperative precoding method, applied in a communication system comprising a coordinating device and multiple serving stations, is provided. The cooperative precoding method includes the following steps: the coordinating device obtaining multiple carrier frequency offset (CFO) parameters of the serving stations with respect to a user device; generating multiple cooperative encoded sequences; assigning the cooperative encoded sequences to the serving stations, respectively, according to an order of the plurality of CFO parameters; and the plurality of serving stations transmitting the cooperative encoded sequences, respectively, to the user device. Each cooperative encoded sequence is transmitted over multiple subcarriers.