Shorten Dynamic Frequency Selection Test Time from Days to Hours

Organization

• A leading wireless networking company in the United States

Challenges

• dated pre-compliance test system

• semi-automated software with limited test cases

Solutions

• IOT0047A regulatory test solution

• IoT regulatory compliance software

Results

• reduced test time by 75% through enablement of DUT control; automation of 200+ test cases

• shortened DFS test time from days to hours

As the Internet of Things (IoT) and wireless standards continue to evolve, so do regulatory compliance tests. Wireless regulatory compliance testing used to cover simple tests for power, bandwidth, and frequency. Over time, it became more complex, impacting the test process and timeline. Standards bodies and regulatory agencies updated the regulations to include new tests such as dynamic frequency selection (DFS), adaptivity, and contention-based protocol. Although these tests are complicated and time-consuming — requiring the collection of large volumes of data at high speed with precise timing of the behavior of the device-under-test (DUT) — they help ensure effective and efficient use of the radio spectrum.

A leading wireless networking company in the United States specializing in servers, storage, and networking services was having trouble running these tests. With its dated pre-compliance test systems, regulatory compliance testing took up more resources than it should have. The company’s engineers spent more time configuring their systems to perform DFS testing, with semi-automated software covering limited test cases. The company needed to replace its test systems.

Challenge: Trends in Wireless Regulatory Compliance Test

As the radio LAN (RLAN) band expands to include nearby frequencies, existing services in the band require protection from new unlicensed users. For example, radar services that operate in the 5 GHz range might experience interference when the industrial, scientific, and medical (ISM) band expands to allow operation in the 5 GHz frequency

The International Telecommunication Union imposed the DFS test for devices operating in the 5 GHz Unlicensed National Information Infrastructure (U-NII) band, where the radar systems have spectrum protection. DFS is a spectrum-sharing mechanism that allows wireless devices operating in 5 GHz bands to coexist with radar systems. Regulatory bodies such as the US Federal Communications Commission (FCC) and the European Telecommunications Standards Institute (ETSI) established the DFS requirements. If the transmitter detects a signal, it vacates or flags the channel associated with the radar signal as unavailable for use

The use of radar varies by geography. Based on its operating frequency, the device must show a certain probability to detect a radar signal. It needs to cease operation or rapidly move its network to another channel to keep off the radar frequency for 30 minutes. Figure 1 explains the DFS test sequences in detail

The regulatory tests for DFS are challenging because they require significant behavior sequences and timing in the RLAN device. Many types of radar signals are in use, and the DFS test needs to cover every radar signal. Furthermore, radar signals may be present on different channels. Automated systems can significantly reduce the overall test time for these tedious and repetitive DFS tasks

DFS testing is one of the main challenges the wireless networking company faced. It took the company two weeks to complete the DFS test. Its test engineers needed to manually run and rerun the tests. The company’s pre-compliance process was inefficient and prolonged its solution release timeline because the DFS test tends to fail in the test lab