Feature: T&M
Figure 4: User experience scenarios for CMW RF pre-conformance testing solution
The TSM method provides accuracy equivalent to that of
TOSM, and reduces the number of calibration steps from seven to five. The automatic calibration unit ZN-Z154 with up to 24
ports is shown on the right in Figure 3. The user can connect adapters to it to match different connector types on the DUT. The unit can be re-characterised, together with the adapters, and it can store the resulting data in its internal memory. The ZN-Z51 model is a special version that can be factory- configured with a mix of connectors.
Test and measurement solutions for wireless and high-speed digital interfaces In the wireless sector, the R&S CMW500 platform of testers simplify testing of Bluetooth Low Energy (BLE) devices and wearables. A variety of BLE solutions perform RF pre- conformance tests over the air, without a control cable and in shielded chambers. They support the test mode for Bluetooth Classic and direct test mode (DTM) up to BLE 5.1 standard. Test solutions for various wireless interfaces and WLAN, including IEEE 802.11ac and 11ax, are also available. This platform provides different rack-mount testing solution for wireless and high-speed digital interfaces (Figure 4), and can serve for the following applications:
User experience testing scenario The proliferation of wireless devices has led the skyrocketing growth in global IP traffic. At the same time, users are demanding better audio quality, video streaming and data transmission. Network operators, device manufacturers and app
developers need to optimise a higher quality of service (QoS) and enhance testing facilities implementing CMW testers together with a CMWrun sequencer PC software tool, shown at left in Figure 4.
44 December/January 2021
www.electronicsworld.co.uk
Audio and performance testing To ensure a high QoS, network operators roll out voice over LTE (VoLTE) services for voice and video telephony in their networks, and voice over WLAN (VoWLAN) to pro vide seamless multimedia service coverage within build ings; see Figure 4, middle. The audio quality of VoLTE, VoWLAN and legacy
standards (GSM, WCDMA, CDMA2000) depends on several network and DUT factors. A key technology for integrating voice services in LTE or WLAN networks is the IP multimedia subsystem (IMS), which offers a framework that supports IP-based multimedia services. The CMW500 wideband radio communication tester
is designed to test voice and video-call mechanisms on mobile devices, from the access technologies to all the necessary servers, e.g. an internal IMS server. It tests the handover between LTE and WLAN, as well as legacy standards for single radio voice call continuity (SRVCC). With its integrated audio board, the CMW supports all important codes, including the new audio codec enhanced voice service (EVS) that is a key milestone on the road to high-quality audio connec tions.
Video testing Video stability and performance are key factors for end-to-end (E2E) video streaming; see Figure 4, middle. They must be optimised for various standards, including LTE, WCDMA/HSPA, GSM and WLAN. Complex measurements are needed for services such as LTE-evolved multimedia broadcast multicast service (eMBMS) based on the 3rd Generation Partnership Project (3GPP). The LTE broadcast system, also known as LTE Multicast, is a “one-to-many” technique used to distribute the same content to many users simultaneously on an LTE.
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