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octoScope solutions for TR-398 testing

In February of 2019, the Broadband Forum published “Wi-Fi In-Premises Performance Testing”,

otherwise known as TR-398. This is the first work product from the Broadband Forum aimed at

addressing the challenges operators face when they deploy Wi-Fi networks. More activity in

this area from the Broadband Forum is anticipated.

In its own words, the “primary goal of TR-398 is to provide a set of test cases and framework to

verify the performance between Access Point (AP) (e.g., a CPE with Wi-Fi) and one or more

Station (STA) (e.g., Personal Computer [PC], integrated testing equipment, etc.). The test cases

are defined for a Device Under Test (DUT – AP only), tested against a or a set of STA.”1

The general set of test cases covered by TR-398 is illustrated by the diagram in Figure 1.

Figure 1: Test cases defined in TR-398

1 Executive Summary of TR-398, available at https://www.broadband-forum.org/download/TR-398.pdf.

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The tests fall into six main categories:

• RF performance

• Bandwidth

• Coverage

• Capacity

• Interference

• Stability

The TR-398 test plan indicates how the test environment should be configured, how the tests should be

run, and what the pass/fail criteria are for each test.

Since the publication of the TR-398 standard, octoScope has received many inquiries about how an

octoBox testbed should be configured to support TR-398 testing. In this Application Note we answer

that question.

octoBox testbed configurations and TR-398 support One of the first descriptions of TR-398 testing using an octoBox testbed was presented by

SmallNetBuilder, in an article entitled “Introduction To The TR-398 Wi-Fi Performance Test.”2 In that

article, the octoBox system used for the testing is presented, and it is shown again here in Figure 2.

Figure 2: octoBox system used by SmallNetBuilder for initial TR-398 testing

2 https://www.smallnetbuilder.com/wireless/wireless-features/33219-introduction-to-the-tr-398-wi-fi-

performance-test

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That system is capable of performing all of the tests defined by TR-398. The high-level requirements

which this solution addresses are outlined in the following table:

TR-398 Requirement Solution

All TR-398 tests are defined for both the 2.4 GHz and

5 GHz bands.

Pals are deployed in pairs, one for 2.4 GHz and one for

5 GHz.

Certain tests require rotation of the DUT. Turntable is deployed in the DUT chamber.

Some tests require a large number of client devices. Pals are able to emulate multiple virtual stations

(vSTAs), and that capability satisfies all TR-398 tests.

Some tests require that the devices be at different

“distances” from the DUT. For example, a test may

require that some devices are close, some at an

intermediate distance, and some far away.

Three sets of Pals are used so that for any given test,

one Pal (and its vSTAs) can be close, another Pal can

be at an intermediate distance, and the third Pal can be

far away.

MU-MIMO tests require that the test devices be

spatially separable.

The use of separate antenna systems to connect the

different Pal groups allows for beamforming.

TR-398 with next generation octoBox testbeds As the Wi-Fi industry has set its sights on Wi-Fi 6 technology, octoScope has developed new

technologies and architectures designed to specifically support Wi-Fi 6 testing. The details of those

technologies are described in “The Pal-6 Wi-Fi 6 (11ax) smartBox subsystem” datasheet, available from

octoScope.3 We will not repeat them here.

In the Pal-6 datasheet octoScope describes a number of standard testbed configurations. Here we will

describe how those configurations are able to support TR-398 testing.

Although the testbed shown in Figure 2 is able to implement all of the TR-398 tests, it does not support

the latest Wi-Fi technology (Wi-Fi 6) along with the interesting testing that goes along with testing that

technology (e.g. OFDMA testing.) Although TR-398 does not currently define tests for Wi-Fi 6 (802.11ax)

it is expected that upcoming revisions to TR-398 will address that technology, so it makes sense to

consider testbeds that are more highly functional, and future-proof, than the one shown above.

As described in the Pal-6 datasheet, the new Pal-6/smartBox architecture from octoScope makes possible

a number of highly functional standard testbed configurations. These are described in the Pal-6

datasheet, and they are presented again here.

The simplest Pal-6 based octoBox testbed, STACK-MIN, with one smartBox and one regular octoBox is

shown in Figure 3.

3 http://www.octoscope.com/English/Collaterals/Documents/Pal-6_datasheet.pdf

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Figure 3: STACK-MIN with embedded Pal-6

Figure 4, below, shows octoScope’s STACK-MAX testbed.

Figure 4: STACK-MAX testbed supporting 8x8 MIMO and OFDMA with packet analysis, mesh, roaming,

band steering and BT testing

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The STACK-MID testbed (Figure 5) is a powerful OFDMA testbed that falls between STACK-MIN and

STACK-MAX in complexity.

Figure 5: STACK-MID testbed supporting 10 RUs based on Pal-6 radios in the 5 GHz band plus 5 RUs in the 2.4 GHz band plus more RUs base on real STAs; packet analysis, mesh, roaming, band steering, BT testing

While the complete capabilities of STACK MIN/MID/MAX are detailed in the Pal-6 datasheet, here we

discuss specifically which of the TR-398 tests they are capable of performing, along with relevant notes.

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TESTBED CAPABILITIES AS RELATED SPECIFICALLY TO TR-398 TESTS

STACK-

Notes MIN MID MAX

Test area Test

number

Test name

RF Capability

6.1.1 Receiver Sensitivity Test √ √ √ Baseline

Performance

6.2.1 Maximum Connection Test √ √ √ 6.2.2 Maximum Throughput

Test √ √ √

6.2.3 Airtime Fairness Test √ √ Requires two devices at different distances. MIN has only a single Pal-6.

Coverage 6.3.1 Range Versus Rate Test √ √ √ 6.3.2 Spatial consistency test √ √ √

Multiple STAs

Performance

6.4.1 Multiple STAs

Performance Test √ √ Requires STAs at three

different distances. 6.4.2 Multiple

Association/Disassociation

Stability Test

√ √ Requires STAs operating independently, so at least 2x Pals.

6.4.3 Downlink MU-MIMO

Performance Test √ √ Requires 3 STAs

spatially separated Stability/

Robustness

6.5.1 Long Term Stability Test √ √ Requires separate devices for traffic, and non-traffic

6.5.2 AP Coexistence Test √ √ Requires additional devices for “alien” network

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Glossary

AP = access point BBF = Broadband Forum BLE = Bluetooth low energy BT = Bluetooth CPE = Consumer Premises Equipment DUT = Device Under Test MIMO = multiple input multiple output MU = multi-user OFDMA = orthogonal frequency domain multiple access OPP = object push profile OTA = over the air RU = resource unit RvR = rate vs. range RvRvO = rate vs. range vs. orientation RvOvR = rate vs. orientation vs. range STA = station (aka client) vSTA = virtual STA

CONTACT

octoScope 305 Foster Street Littleton, MA 01460 Tel: +1.978.222.3114 sales@octoscope.com

octoScope 780 Montague Expressway Building 1 San Jose, CA Tel: +1.408.888.0478