SC-FDMA Uplink Baseband Compression for Fronthaul Bandwidth Reduction
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Solution Overview
Problem
The existing communication systems face challenges in efficiently compressing LTE uplink baseband signals to reduce transmission bandwidth between the Baseband Unit (BBU) and the Remote RF Unit (RRU), particularly due to high peak-to-average power ratio (PAPR) issues in OFDM systems, which require expensive power amplifiers and limit terminal power utilization.
Innovation Solution
The implementation of an uplink baseband compression device and method that performs inverse discrete Fourier transform (IDFT), amplitude/phase conversion, and quantization on the physical uplink shared channel (PUSCH) signal to compress the LTE uplink baseband signal, leveraging the low PAPR characteristic of SC-FDMA modulation, and corresponding decompression processing at the BBU side to recover user data, thereby reducing transmission bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM modulation is used in LTE uplink to achieve high data rates, then wireless spectrum efficiency is improved, but peak-to-average power ratio increases requiring expensive power amplifiers
Solution Approach 1:
The patent changes the modulation parameter from traditional OFDM to SC-FDMA (Single Carrier Frequency Division Multiple Access), which maintains frequency division multiplexing benefits while using single carrier modulation to reduce peak-to-average power ratio. This parameter change allows the system to achieve high data rates without requiring expensive high-power amplifiers, as SC-FDMA produces lower peak power variations
2Productivity
If wide bandwidth is allocated for LTE uplink to increase system capacity, then transmission bandwidth is improved, but baseband signal transmission bandwidth between BBU and RRU increases
Solution Approach 1:
The patent extracts and removes the cyclic prefix from the SC-FDMA signal before transmission to the BBU. By taking out this redundant portion of the signal that does not contain useful information, the system maintains wide bandwidth allocation for high system capacity while reducing the actual baseband signal transmission bandwidth between RRU and BBU, improving resource utilization efficiency
Solution Approach 2:
The patent inverts the traditional processing order by performing compression and cyclic prefix removal at the RRU side before transmission, rather than processing the full bandwidth signal at the BBU. This inversion allows wide bandwidth allocation for capacity while reducing the transmitted signal bandwidth, as only the essential signal portions are transmitted
Data Source
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AI summary
Embodiments of the present invention disclose an RRU, which performs IDFT on a PUSCH signal that is obtained after resource block demapping, where due to a characteristic of an extremely low peak to average power ratio of SC-FDMA modulation, a signal after IDFT has an extremely low peak to average power ratio at this time, and an amplitude range of the signal changes slightly; amplitude/phase conversion is performed on the signal after the IDFT, where the signal after the IDFT is represented by using amplitude and phase, and then amplitude quantization and phase quantization are performed respectively to obtain a quantized amplitude signal and a quantized phase signal respectively. Accordingly, embodiments of the present invention further provide a BBU, an uplink baseband signal compression method and decompression method, and a base station system. With the foregoing technical solutions, a transmission bandwidth of a baseband signal can be greatly reduced, thereby improving utilization efficiency of a resource.