Accelerating Carrier Acceptance Testing for 5G Devices

5G is moving across the mobile ecosystem fast. Timelines are more aggressive than in previous generations, despite greater scope and difficulty. The third-generation partnership project (3GPP) accelerated the deployment of 5G with the approval of the 5G new radio (NR) non-standalone deployment (NSA) options in December 2017. In mid-2018, the standalone (SA) deployment option was approved. Standards continue to evolve rapidly. Release 16 is expected for March 2020, and content definition for Release 17 is planned for December 2019.

Fig. 1 Key milestones and cardinal dates for the 5G standards.

The 5G Use Case(s)

5G represents a broad range of new services and paradigms. Enhanced mobile broadband (eMBB) focuses on high data throughput. It aims to provide lightning-fast downloads, augmented reality and high-definition videos. Massive machine-type communications (mMTC) focuses on connecting billions of “things.” Use cases include smart farming and optimal traffic management. Ultra-reliable low-latency communications (URLLC) will enable autonomous vehicles, remote surgery and virtual medical visits. 5G requires testing a large matrix of use cases that vary widely.

5G requires technical advances in the physical layer to provide greater flexibility and scalability for its many new use cases. Massive MIMO and millimeter wave (mmWave) beamsteering are also changing the way devices connect across sub-6 GHz and mmWave operating bands.

These changes increase the importance of validating device quality of experience (QoE) and performance on networks. Device engineers are under significant pressure to deliver higher performance while accelerating conformance and carrier acceptance testing (CAT) to advance to commercialization.

Fig. 2 5G use cases and requirements. Source: ITU: 5D/TEMP/390-E.

CAT Programs Are Not All Created Equal

Despite the exponential increase in complexity of 5G, participants in the mobile value chain from chipsets and components to devices and base stations make constant progress. 5G products are advancing in the workflow steadily, from design and conformance to manufacturing and deployment.

Between conformance and manufacturing, CAT is an important phase in the device workflow. CAT aims to ensure that devices meet user expectations in terms of functionality and performance. 5G devices need to meet the key performance indicators of specific mobile networks to achieve that goal.

Networks are mobile network operators’ most precious possession. Customer retention is also vital due to a high level of competition in mobile communications services. To protect their networks and meet customer expectations, mobile operators have implemented entry qualifications to their network that include performance and quality metrics. 5G devices must demonstrate adequate performance and security features for operators to accept them on their network and reach the hands of consumers.

Operator device acceptance programs can span network vendor interoperability, field trials, conformance and network simulation. Network vendor interoperability testing ensures that devices can run on infrastructure equipment from different vendors. Field trials ensure that devices operate in different locations and usage scenarios. Conformance testing ensures device compliance with 3GPP requirements and regulations for emissions and safety. Network simulation focuses on device performance and interoperability using network simulators.

Fig. 3 Typical workflow for devices, including the CAT steps.

All CAT programs do not encompass all four aspects. All network operators conduct network vendor interoperability testing and field trials. Most perform conformance testing. Only the largest operators typically perform network simulation. However, this type of testing is of greater interest to operators in the context of 5G, due to increased complexity and competition. Network simulation offers the greatest assurance of robust device and network performance.

CAT programs also differ between operators, to focus on aspects that are essential to their business. The tests focus on features and functions specific to their networks, such as network reliability or coverage.

Testing Ahead to Accelerate CAT at Operators

Confidentiality is another hurdle faced by device engineers while trying to ensure successful device acceptance testing at first try. Network operators evolve in a highly competitive environment driving significant focus on their intellectual property.

Toolsets Provide Head Start for Conformance Testing in Carrier Acceptance

Testing ahead of time is challenging, but conformance and carrier acceptance test toolsets can help. Generic test suites span RF characteristics, radio resource management and protocol. They represent the most likely network configurations and are enough for some use cases.

Flexible conformance test solutions that allow customization of test cases beyond the certification requirements enable device engineers to test for configurations and use cases that are specific to a given network. Network emulation capability allows engineers to verify devices under a range of scenarios in a lab environment.

Network Emulators and Power Analyzers Deliver Early Insights into Battery Life

Battery consumption remains a key competitive advantage for mobile devices. More features and functions are continuously added, impacting battery life. In 5G, mmWave operating bands and 4G Long Term Evolution (LTE)/5G NR dual connectivity make it critical for devices to maintain quality communications with base stations — eNodeBs (eNBs) and gNodeBs (gNBs).

The various 5G use cases also have widely different battery requirements and performance. eMBB requires higher processing power that quickly drains the device battery. mMTC requires the support of small data packets transmitting over very long timeframes.

Device manufacturers should proactively select representative use cases and stress their devices to ensure battery life with many different permutations and combinations of activities. Battery performance under different usage scenarios of data consumption, talk time or with the use of location-based services is a common test. Engineers can conduct various battery tests using a network emulator and power analyzer to evaluate power consumption under real-world conditions.

Virtual Drive Testing Increases Device Performance and QoE Cost-Effectively

New initial access procedures in 5G NR have increased the importance of testing for handovers compared to 4G. In the NSA deployment options, 5G devices operate alongside and with the 4G infrastructure. Conformance tests are valuable but not sufficient to determine the user experience during different field conditions and to cover all operator-specific handover scenarios.

Field testing is needed to evaluate real-world handovers between radio networks. However, traditional drive testing is expensive. Testing the many different scenarios in all geographic locations would require countless hours and significant resources.

Virtual drive testing (VDT) can help device makers test the real-world handover performance of their devices prior to deployment in a live network. VDT uses data captured in the field to build tests that replay drive or indoor test routes by emulating real-world RF network conditions in a controlled laboratory environment.

Engineers conduct fault analysis and performance optimization by applying different test cases and channel scenarios to identify potential issues with their devices. VDT delivers better QoE and performance prior to completing traditional drive testing and helps reduce the time needed for field testing, in turn accelerating acceptance testing.

CAT Starts in Device Manufacturers’ Labs

5G is disrupting the entire wireless communications industry. Increased complexity and various technical aspects are transforming the mobile ecosystem. As a result, performing CAT has become more important for device manufacturers than with 4G. Operators want to ensure that the new equipment they receive for their networks will not disrupt their infrastructure and create issues with customers. If a device causes dropped calls or crashes the network, consumers typically blame the operator. Network operators must stress test devices to ensure that they live up to customer expectations.

In the past, device manufacturers had a greater focus on passing conformance tests. However, the technical and business drivers behind 5G have changed the device workflow, increasing the importance of connections across stages and between participants in the ecosystem. Device engineers need to find ways to accelerate CAT for their devices. They find themselves performing tasks that would have previously only been done by the carriers.

Fig. 4 5G ecosystem.

5G has given rise to the connected mobile ecosystem. To win the 5G race, device manufacturers need to proactively test their devices in their labs beyond 3GPP conformance tests and regulations to accelerate CAT at operators enabling mass commercialization for their devices.

The 5G market represents a significant opportunity for device manufacturers, particularly for smartphones. Research firm IDC expects 5G smartphone shipments to increase from 6.7 million in 2019 to 401.3 million in 2023. 5G smartphones will represent about 25 percent of all shipped smartphones in 2023.

Jumpstarting device acceptance testing in the labs of device manufacturers is easier said than done, though. However, solutions exist that address the challenges engineers face. They include leveraging developed and flexible conformance test solutions, network emulation and power analyzers and VDT.

5G standards continue to evolve. It is important to select test tools that incorporate regular software updates to ensure testing against the latest standards. Your test partner should be actively involved in industry and standard bodies including the 3GPP, the global certification forum (GCF), and the PCS Type Certification Review Board (PTCRB), to support you effectively.

It is also beneficial to choose a platform that can cover 4G and 5G, as well as the range from sub-6 GHz to mmWave frequencies to cover the necessary test scenarios. Adopting the same platform in early R&D through design validation and into conformance and device acceptance testing also provides continuity. Expertise becomes embedded into the platform benefiting the entire device workflow and enabling accelerated time to market.

For more information on the challenges faced by participants in the mobile ecosystem across the workflow and their possible solutions, click here.

Jessy Cavazos is responsible for 5G industry solutions marketing at Keysight Technologies.