CDMA Receiver Sensitivity Test Using SNR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing receiver sensitivity test methods for CDMA wireless devices, as defined by TIA/EIA/98E, are excessively time-consuming for mass production, requiring up to 80 seconds per device, which is costly and inefficient, especially when thousands of units need to be tested.
Innovation Solution
The method involves determining the relationship between correlated energy or SNR and frame error rate (FER) using simulated traffic, allowing for a new test criteria based on these parameters to reduce test time while maintaining or exceeding the required confidence level, utilizing a baseband processor to estimate energy per chip to interference density ratio (Ec/Io) or signal to noise ratio (SNR), and establishing pass/fail thresholds for correlated energy or SNR measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing FER-based receiver sensitivity test method is used, then the test confidence level is maintained at 95%, but the test time is excessively long (up to 80 seconds per device)
Solution Approach 1:
The patent changes the test parameter from Frame Error Rate (FER) to Signal-to-Noise Ratio (SNR) or Energy per Chip to Interference Density Ratio (Ec/Io). This parameter substitution allows the test to achieve the same reliability confidence level but with significantly reduced test time (from 80 seconds to 22 seconds per device), as SNR/Ec/Io can be measured more directly without requiring extensive frame transmission and error counting
Solution Approach 2:
The patent replaces the mechanical counting and evaluation process of FER (which requires transmitting multiple frames and counting errors) with a direct signal quality measurement approach using SNR or Ec/Io. This substitution eliminates the time-consuming iterative frame transmission process while maintaining test reliability through established statistical relationships between SNR and FER
2Loss of time
If the maximum number of frames is limited to 1000 to reduce test time, then the test time is reduced, but the required 95% confidence level may not be achieved
Solution Approach 1:
By changing from FER-based testing to SNR/Ec/Io-based testing, the patent achieves a fundamental improvement where high confidence levels can be obtained with fewer frames or even single-frame measurements. The SNR parameter provides a more direct and statistically robust measure of receiver sensitivity that converges faster than FER, resolving the contradiction between test speed and confidence level
3Reliability
If the TIA/EIA/98E standard test procedure is followed, then the test meets industry standards, but the testing cost and complexity increase for mass production
Solution Approach 1:
The patent maintains standard compliance by establishing statistical equivalence between the new SNR/Ec/Io-based test and the traditional FER-based TIA/EIA/98E test. Through proper calibration and threshold setting, the simplified SNR measurement method achieves the same reliability assurance with dramatically improved productivity, making it suitable for mass production environments where thousands of devices need testing
Solution Approach 2:
The patent replaces the complex FER measurement mechanism (requiring multiple frame transmissions, error counting, and statistical analysis) with a simpler direct SNR measurement approach. This substitution reduces testing complexity and cost while maintaining compliance with industry standards through mathematically equivalent test outcomes
Data Source
AI summary
The application relates to wireless networks and more particularly to a method of reducing factory test time of receiver sensitivity in a Code Division Multiple Access (CDMA) wireless device. Under TIA/EIA/-98E, the radio frequency (RF) sensitivity of a CDMA wireless receiver is the minimum received power, measured at the mobile station antenna connector, at which the frame error rate (FER) does not exceed 0.5% with 95% confidence. In order to reduce the test time of FER test method, the relation between correlated energy (or Ec/Io) and FER is determined using simulated traffic and the correlated energy (or Ec/Io) measurement is then used as the test parameter on like models to achieve the same or superior test confidence with significantly reduced test time.