PRACH Detection via Time Domain Accumulation
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Solution Overview
Problem
Conventional PRACH detectors in cellular communications networks face challenges in efficiently detecting PRACH preambles at high carrier frequencies, particularly due to the large number of antenna elements and the need for coherent combining of signals, which results in high data transfer requirements and increased costs and power consumption.
Innovation Solution
The solution involves performing coherent accumulation of PRACH OFDM symbols in the time domain within the radio unit of the base station, reducing the amount of data that needs to be transferred to the digital unit and enabling a separation of antenna near radio ASIC or FPGA functionality from baseband processing, thereby reducing interface capacity requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PRACH detection is performed by transforming each PRACH OFDM symbol from time domain to frequency domain using FFT and performing matched filtering per subcarrier, then detection accuracy is maintained, but data transfer requirements and processing load increase significantly
Solution Approach 1:
The patent performs coherent accumulation of PRACH OFDM symbols in the time domain before transforming to frequency domain. By pre-processing and accumulating symbols in time domain at the radio unit, the system reduces the volume of data that needs to be transferred to the digital unit, while still maintaining accurate PRACH detection capability through subsequent frequency domain processing.
Solution Approach 2:
The patent separates the PRACH detection function into two distinct units: the radio unit that performs time domain processing and accumulation, and the digital unit that performs frequency domain processing and detection. This segmentation allows each unit to handle only the necessary computations, reducing overall data transfer requirements while maintaining detection accuracy.
2Reliability
If coherent combining of signals from multiple antenna elements is performed, then signal detection reliability improves, but interface capacity requirements and power consumption increase
Solution Approach 1:
The patent performs coherent accumulation of PRACH OFDM symbols in the time domain at the radio unit before transferring data to the digital unit. This preliminary processing reduces the amount of data that needs to be processed and transferred, thereby reducing power consumption while maintaining the reliability benefits of coherent combining through the accumulated time domain signals.
3Measurement precision
If full baseband processing is performed at the digital unit, then detection performance is optimized, but interface bandwidth requirements increase
Solution Approach 1:
The patent divides the baseband processing function into two segments: time domain processing (FFT, matched filtering) at the radio unit and frequency domain processing (IFFT, detection decision) at the digital unit. This segmentation enables the system to maintain optimized detection performance while significantly reducing the interface bandwidth required between units, as only accumulated time domain symbols need to be transferred rather than complete frequency domain data.
Data Source
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AI summary
A base station for detecting a Physical Random Access Channel (PRACH) transmission from a User Equipment device (UE) comprises a radio device and at least one additional device. The radio device comprises narrowband receivers respectively coupled to antenna elements of an antenna array. Each narrowband receiver is configured to receive a signal from a respective antenna element and process the signal to provide received symbols for a PRACH received via the respective antenna element. The radio device also comprises accumulation circuitry configured to, for each antenna element, accumulate a subset of the received symbols for the PRACH received via the antenna element to output a first averaged symbol for the PRACH received via the antenna element. The at least one additional device is configured to receive, from the radio device, the first averaged symbols and process the first averaged symbols to perform PRACH detection for one or more receive beams.