Wireless Signal Compression and Noise Shaping for EVM and ACLR
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Solution Overview
Problem
Existing wireless communications systems face challenges in achieving a good trade-off between signal compression ratio and latency without compromising quality metrics such as error vector magnitude (EVM) and adjacent channel leakage ratio (ACLR) due to compression noise distribution across the entire sampling bandwidth.
Innovation Solution
Integrating a block compression circuit with a noise shaping circuit to redistribute compression noise from the entire sampling bandwidth to a selected portion, either in-band or out-band, effectively suppressing and filtering it out during signal decompression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If block compression is applied to downlink/uplink signals, then compression ratio is improved, but compression noise is distributed across the entire sampling bandwidth degrading signal quality
Solution Approach 1:
The patent extracts compression noise from the in-band signal by redistributing it to out-of-band frequencies through noise shaping filtering. This separates the harmful noise component from the useful signal, allowing compression to be applied while maintaining signal quality metrics such as EVM and ACLR.
Solution Approach 2:
The patent applies different quality characteristics to different frequency regions. The in-band signal maintains high quality with preserved signal characteristics, while the out-of-band region contains the redistributed compression noise. This localized quality management allows compression noise to be pushed to frequencies where it does not interfere with the useful signal.
2Productivity
If higher compression ratio is achieved, then throughput is improved, but latency increases and signal quality degrades
Solution Approach 1:
The patent employs feedback mechanisms where compression noise is continuously shaped and redistributed based on signal characteristics. The noise shaping filter adapts to maintain optimal balance between compression ratio and latency by feedback control of the noise redistribution process, preventing excessive latency accumulation while maintaining high throughput.
3Productivity
If compression noise is distributed across entire sampling bandwidth, then compression is effective, but noise suppression becomes difficult
Solution Approach 1:
The patent introduces noise shaping filters as intermediary components between the compression process and the transmitted signal. These filters act as mediators that redirect compression noise to out-of-band frequencies, making the noise controllable and suppressible without affecting the in-band signal quality. The intermediary filtering stage enables effective noise management while preserving compression benefits.
Data Source
AI summary
Signal compression and noise shaping in a wireless communications system (WCS) is provided. Herein, a block compression circuit is integrated with a noise shaping circuit to concurrently perform downlink/uplink signal compression and noise shaping in the WCS. The block compression circuit performs block scaling compression on the downlink/uplink signal, which can cause a compression noise being distributed across an entire sampling bandwidth of the downlink/uplink signal. As such, the noise shaping circuit is configured to redistribute the compression noise from the entire sampling bandwidth to a selected portion of the sampling bandwidth. Accordingly, the redistributed compression noise can be effectively suppressed and/or filtered out when the downlink/uplink signal is received and decompressed. By concurrently performing block compression and noise shaping on the downlink/uplink signal, it is possible to achieve a good trade-off between compression ratio and latency, without compromising quality metrics of the downlink/uplink signal.