Wireless Receiver Gain Control Using Frequency-Domain Reference Signals
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Solution Overview
Problem
In OFDMA systems like LTE, measuring signal power in the time domain for automatic gain control (AGC) is prone to errors due to dynamic resource allocation and varying symbol powers, leading to incorrect gain settings and potential data loss, especially when narrow band allocations occur.
Innovation Solution
The solution involves measuring signal power in the frequency domain using reference signals (pilots) included in each sub-frame, which are transmitted with predetermined power independent of resource allocation, allowing for accurate power estimation and gain adjustment based on these measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If signal power is measured in the time domain for automatic gain control, then the measurement process is simple, but the measurement precision deteriorates due to dynamic resource allocation and varying symbol powers
Solution Approach 1:
The patent extracts reference signals from the received signal and measures power only on these extracted reference signals in the frequency domain, rather than measuring the entire received signal in the time domain. This isolation of reference signals eliminates the impact of dynamic resource allocation and varying symbol powers on measurement accuracy.
Solution Approach 2:
The patent transitions from time domain power measurement to frequency domain power measurement. By converting the received signal through FFT and measuring power on reference signals in the frequency domain, the system achieves more accurate power estimation that is independent of time-varying resource allocation patterns.
2Ease of operation
If gain is adjusted based on time domain power measurements, then the control process is straightforward, but the reliability deteriorates leading to incorrect gain settings and potential data loss
Solution Approach 1:
The patent introduces frequency domain transformation (FFT) as an intermediary step between signal reception and power measurement. This intermediary transformation enables accurate reference signal power measurement by separating reference signals from data signals in the frequency domain, thereby improving gain control reliability without significantly complicating the overall control process.
3Adaptability or versatility
If narrow band allocations occur in dynamic resource allocation, then system adaptability is improved, but measurement precision deteriorates due to varying symbol powers
Solution Approach 1:
The patent extracts and isolates reference signals from the composite received signal containing both reference and data signals. By measuring power only on the extracted reference signals in the frequency domain, the system achieves measurement accuracy that is independent of the data signal characteristics and resource allocation patterns, including narrow band allocations.
Data Source
AI summary
A system including a first power measuring module, a gain control module, and a signal processing module. The first power measuring module is configured to generate a first power measurement of a signal received by a receiver of a wireless device based on a plurality of reference signals received in the signal by the receiver of the wireless device. Each of the plurality of reference signals is transmitted at a predetermined power. The first power measurement is generated in frequency domain. The first power measurement is generated during a first frame of the signal received by the receiver of the wireless device. The gain control module is configured to adjust a gain of the receiver of the wireless device based on the first power measurement. The signal processing module is configured to process a second frame in the signal subsequent to the first frame at the adjusted gain.