TR-398 wireless test systems

Understanding TR-398

Standardised WIFI performance testing using portable test systems

TR-398 Explained

Understanding the need for and scope of standardised WIFI testing.

TR-398 is a set of test cases defined by the Broadband Forum with the goal of verifying performance between WIFI access points and a number of stations.

The need for these test cases has been driven the rapid adoption of high speed WiFi devices to support home applications such as HD / 4K TV streaming, high definition video calling, smart homes and online gaming. Consumers are becoming less accepting of poor experience within their home and are becoming more educated about the devices that deliver the services within their home and the performance they can deliver. TR-398 allows device manufacturers to perform a standardised test suite that can be used to validate the performance of their devices for release onto the market.

A number of tests are defined that cover RF capability, baseline performance, coverage, multiple station performance and stability. Each of the tests has a documented setup, a configuration for the device under test, a test procedure and a pass / fail criteria to ensure test repeatability and for meaningful comparison of test result data.

The octoScope STACK system provides the means to perform the testing as specified in TR-398 within a portable test bed the can include single or multiple shielded enclosures, rotating turntables, variable RF attenuators, RF splitters and other test modules.

Understand the tests

  • Receiver sensitivityTests the ability for the AP to receive weak RF signals and deliver error free traffic.
  • Maximum connections Verifies that the AP can support 32 stations simultaneously.
  • Maximum throughput Measures the maximum throughput over the air interface of the device under test.
  • Airtime fairness Tests that airtime is fairly allocated to devices when there are dense or high capacity connections.
  • Rate vs range Tests the effect of attenuation of WIFI signal on data throughput.
  • Spatial consistency Verifies if data throughput is affected by the position of the station in relation to the DUT.
  • Multiple stations performance Tests the effect of multiple stations connected to a WIFI device in simulated real-world environments.
  • Multiple stations association / disassociation Verifies that stations can associate & disassociate without affecting traffic performance.
  • Downlink MU-MIMO performance Measures the performance of the device under test when downlink MU-MIMO is in operation.
  • Long term stabilityMeasures the ability of the device to operate over long periods with stable performance.
  • AP co-existenceTests the effect of a secondary WIFI device on the performance of the device under test.
Receiver Sensitivity Test.
The receiver sensitivity test requires Ethernet traffic to be generated into the WIFI device under test at 65% of the theoretical maximum speed over the air interface, through a set of RF attenuators into the receiving stations and into a traffic analyser where the traffic is then measured for errors.
This test is performed over a number of iterations, where the attenuation is increased by 1dB in each iteration until there is a 10% error rate on the received signal, at which point the amount of attenuation is measured and recorded as the receiver sensitivity level.
Once the receiver sensitivity measurement has been recorded the whole sequence is repeated again, this time with the WIFI device under test (DUT) having been rotated by 45° within the test chamber. The sequence of testing is repeated until the DUT has been rotated through a full 360°.
Pass / fail criteria: Achieving specified target sensitivity measurements.

The octoScope STACK