5G Needs Cohesive Pre- And Post-Silicon Verification

While 5G doesn’t start from a clean slate, it does make significant changes to the 4G architecture. These changes mean that the ecosystem from chips to operators is evolving, giving opportunities to more companies to engage in this growing market.

Realignment in fronthaul, midhaul and backhaul
In particular, the radio access network (RAN) has been redefined as Cloud RAN (sometimes called Centralized RAN), or C-RAN. The backhaul has been split into two, with a centralized unit (CU) handling baseband processing before sending signals to the distributed units (DUs) in the base stations. The connection between the CU and the DUs is now called fronthaul, and, technically, backhaul now occurs between the CU and the core.

5G backhaul, midhaul and fronthaul based network architecture (Credit: Xilinx)

Higher-level networking layers are also being virtualized on standard computing equipment for greater flexibility and agility. This network-function virtualization (NFV) and software-defined networking (SDN) implementation makes it possible to configure and reconfigure networks as needed to make optimal use of the available radio antennas and other resources.

While adding flexibility and lowering operating costs, these new configurations create the opportunity for many more configurations than would have been possible with 4G and prior – and all of those configurations must be verified.

Verification challenges brought on by 5G include:

• Many of the prior technologies have been pulled apart, reassembled, and reinvented.
• New applications mean many more standards and use cases.
• Much of the technology is being virtualized.
• Performance requirements will be tough: much tighter latency, higher bandwidth, and higher frequencies.

The number of possible combinations of technologies and equipment configurations makes it entirely impractical to build prototypes and then test out their capabilities and resilience. Verification must be done pre-silicon, and there’s only one practical way to accomplish that: hardware emulation.

Employing a far reaching verification strategy is paramount
The challenge is not just in running a long list of tests; it’s also in pushing boundaries and stressing systems, seeing where they break. Each system will contain one or more SoCs, and each SoC must be run through a variety of realistic verification tests to ensure that, once deployed, it will be up to the many tasks it must perform.

The litany of tests that must be performed include but are not limited to:

• Latency: minimum and maximum;
• Power: peak, average, and minimum – and compliance with a comprehensive power intent specification;
• Fault coverage metrics that identify whether all of the testing has been comprehensive enough.

Why is pre-silicon testing so important?
In a 5G SoC, the communications, computing, and memory requirements are much greater than in 4G SoCs, and there are many blocks that have to work together seamlessly for the SoC to perform effectively. An example Marvell baseband unit is shown below.

The OCTEON Fusion CNF7100 baseband processor (Credit: Marvell)

Emulation is the ideal technology to test, at the pre-silicon stage, a diverse and exacting range of performance tests to ensure 5G component functionality. Because emulation performs on the order of 1000 times faster than simulation, it is possible to test real-world scenarios involving both hardware and software.

The key traits that make an emulation system the right choice for 5G pre-silicon testing converge around delivering a virtual environment. This virtual environment includes protocol test modules, such as the VirtuaLAB units and other comprehensive pieces of verification IP that can be instantiated within or connected to an emulator. Each protocol used to connect 5G system components can be modeled and virtualized to drive and receive data from the design-under-test (DUT). And they can be instantiated remotely in a data center.

Emulation is also more accurate because all pieces of the test system are clock-aligned. If a failure occurs, we can track the cycle it occurred on and correlate that with the exact input data and system state in place when the error happened. This takes an enormous amount of guesswork out of the debugging process, streamlining efforts to correct design flaws and deliver a fully verified design.

Finally, huge portions of the test plan and results used for pre-silicon verification can be used directly for post-silicon verification. That eliminates an enormous amount of test generation work, and it makes debugging far easier in the event that any issues arise in the silicon check-out.

To download the complete story go to 5G Verification is Impossible without Emulation. Mentor, a Siemens Business, is at the forefront of understanding 5G deployment and making sure that reliable verification/validation flows are available now.