RF Transceiver PER Testing With Alternating Power Levels
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Solution Overview
Problem
Current wireless device test systems inaccurately measure packet error rate (PER) during link-based testing due to the device searching for a different access point, leading to misinterpretation of packet errors when signal power is low, which is not reflective of actual packet errors occurring during normal operation.
Innovation Solution
The method involves transmitting test data packets with alternating higher and lower power levels to differentiate between actual packet errors and access point searches, ensuring the device remains in receive mode by maintaining a cumulative count based on reception ratios and adjusting transmission power accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If link-based PER testing is performed with low signal power to test worst case performance, then the device receiver sensitivity is tested, but the device may begin searching for a different access point, causing inaccurate PER measurement
Solution Approach 1:
The tester transmits data packets in alternating intervals of higher and lower nominal transmitted signal powers. This periodic variation allows the system to distinguish between packet errors and access point searches by comparing reception ratios during high power intervals (when DUT should remain connected) versus low power intervals (when DUT may search for other access points).
Solution Approach 2:
The system changes the transmitted signal power parameter between higher and lower nominal levels in alternating intervals. By monitoring the DUT's reception ratio at these different power levels, the system can identify when the DUT transitions to searching for alternative access points, thereby isolating true packet errors from connection loss events.
2Measurement precision
If the DUT is prevented from initiating an access point search during testing, then accurate PER results can be obtained, but the testing technique does not reflect normal driver operation and requires modification of the DUT
Solution Approach 1:
The DUT operates in its normal mode without requiring special test drivers or modifications. The tester autonomously analyzes the DUT's transmission behavior during alternating power intervals to detect when access point searches occur, allowing the DUT to naturally exhibit its normal operational characteristics including access point searching at low signal levels.
3Ease of operation
If multiple data packets with sufficient signal power are transmitted to force the DUT to return to RX mode, then the DUT can be brought back from search mode, but this may interrupt the testing process and increase test time
Solution Approach 1:
The tester transmits data packets at higher nominal transmitted signal power during alternating intervals before the DUT fully transitions to search mode. This preliminary high-power transmission serves as a reminder signal that prevents the DUT from completely losing connection, allowing the test to continue without interruption while still testing worst-case performance at lower power levels.
Data Source
AI summary
Method for testing a radio frequency (RF) data packet signal transceiver device under test (DUT) in which test data packets with varying power levels are transmitted to the DUT for testing the DUT while still ensuring that the DUT remains in receive (RX) mode and is prevented from searching for another data packet signal. Alternatively, in the event that the DUT becomes unresponsive due to searching for another data packet signal, multiple test data packets with sufficient signal power levels to ensure reception by the DUT are transmitted to the DUT to cause the DUT to cease searching for another data packet signal and return to RX mode.