Resource Element Skipping for Beam Switching Cyclic Prefix Extension
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Solution Overview
Problem
In wireless communication systems, particularly with 5G NR, beam switching at higher frequencies results in a reduction of data throughput due to the need to skip symbols, leading to missing information during beam changes, especially when the cyclic prefix (CP) is shorter than the beam switching time.
Innovation Solution
Implementing resource element (RE) skipping in the frequency domain to generate repetitions of a time domain signal within a symbol, allowing for a longer effective cyclic prefix during beam changes, by allocating bits to every Nth resource element and using inverse and fast Fourier transforms to maintain signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beam switching is performed at higher frequencies in 5G NR, then communication capability is improved, but data throughput is reduced due to symbol skipping
Solution Approach 1:
The patent segments the frequency domain resource elements by selecting every Nth resource element for transmission. This segmentation creates a sparse frequency domain pattern that, after IFFT, generates time domain repetitions of the same signal segment. The segmentation allows the system to maintain beam switching capability while ensuring complete signal reception through repetitions, thereby preventing data throughput reduction.
Solution Approach 2:
The patent creates copies of the time domain signal by transmitting the same waveform multiple times within a single symbol period. These repetitions are generated through the IFFT of sparsely spaced frequency domain resource elements. The copying ensures that even if beam switching causes some signal portions to be missed, the receiver can reconstruct the complete signal from the repeated segments, thus maintaining data throughput.
2Productivity
If cyclic prefix duration is shortened to increase data throughput, then productivity is improved, but reliability of beam switching deteriorates when CP is shorter than beam switching time
Solution Approach 1:
The patent prepares for potential beam switching failures by pre-creating signal repetitions before transmission. The time domain signal is structured to contain multiple identical segments that can serve as fallback options. This preliminary action ensures that if beam switching causes signal loss, the receiver already has redundant signal copies available for reconstruction, maintaining reliability without requiring a longer cyclic prefix.
Solution Approach 2:
The patent changes the frequency domain spacing parameter (transmitting every Nth resource element) to achieve time domain signal repetitions. This parameter change transforms the signal structure from a continuous waveform to a segmented repeated waveform, enabling the system to tolerate beam switching interruptions while maintaining short cyclic prefix duration for high data throughput.
3Duration of action of moving object
If resource elements are spaced apart in frequency domain, then time domain signal repetitions are generated for extended cyclic prefix, but device complexity increases due to FFT processing requirements
Solution Approach 1:
The patent makes the FFT processing serve multiple functions: it transforms the sparsely spaced frequency domain resource elements into time domain signal, and simultaneously generates the desired signal repetitions pattern. The same FFT operation that performs frequency-to-time domain conversion also creates the repeated waveform structure needed for extended cyclic prefix effect. This multi-functionality avoids additional processing complexity while achieving the desired signal structure.
Data Source
AI summary
Example implementations include a method, apparatus and computer-readable medium of wireless communication for applying resource element (RE) skipping to a symbol where a beam change is to occur. A transmitter and a receiver determine that a beam change is to occur during the symbol. The transmitter allocates bits to a subset of REs for the symbol in a frequency domain allocation. Each RE of the subset is spaced apart by a number of empty REs. The transmitter performs an inverse fast Fourier transform (IFFT) on the REs to generate a time domain signal including a number of repetitions of a transmitted waveform. The receiver receives the time domain signal during at least a portion of the symbol. The receiver performs a fast Fourier transform (FFT) on the time domain signal and determines transmitted bits or a channel from the subset of REs output from the FFT.