Storage requirements for reliable 5G gateways in industrial systems

Manufacturing and production are being revolutionized by the increasing use of digital technologies to automate and communicate between systems. Access to real-time data enables more efficient use of resources and preemptive maintenance to minimize downtime and maximize the life of equipment.

After the introduction of the steam engine, electrification and computers, the application of connectivity, big data analytics and the Industrial Internet of Things is often referred to as the Fourth Industrial Revolution or Industry 4.0.

The growth in the number of connected devices in industrial applications requires highly reliable communication products to integrate public and private networks. This in turn leads to an increasing demand for industrial storage, especially when it is applied to industrial IoT gateways.

Growth of the 5G market

By 2023, there could be more than 4 billion machine-to-machine (M2M) connections in a growing number of applications. This includes navigation systems in vehicles, asset tracking in logistics, wearable medical components that monitor patients’ vital signs in real time, and industrial manufacturing.

It is expected that more and more communications infrastructure will move to "standalone" 5G networks; that is, they will not rely on existing 4G/LTE infrastructure. Therefore, future investments are likely to focus on 5G New Radio (NR) infrastructure rather than legacy systems.

This will enable wider adoption of 5G’s enhanced capabilities and new features: higher data rates, very low latency, improved synchronization, and greater reliability. Developers of industrial systems hope to take advantage of these features to enable innovative new applications.

Gateway to 5G

In order to reap the benefits of 5G in an industrial environment, it is necessary to establish an interface between the many different internal devices that make up the Industrial IoT and the 5G network. This gateway must transmit 5G performance to the Industrial IoT network.

In an industrial setting, a 5G gateway aggregates the various protocols used by many different connected devices in a factory, such as sensors, actuators, and automated machinery. It encapsulates data into a format suitable for transmission over a 5G wireless interface and performs reverse processing on data received from the 5G network.

Gateway Software Requirements

5G gateways need to run large, complex software. The code base will consist of an operating system, a network layer, and the protocols needed to interface with legacy devices. This means millions of lines of code and tens of GB of persistent storage. This storage requirement can only be met using NAND flash, which has system-level requirements of its own.

To deliver the performance levels required by these industrial applications, gateways need to meet the same service level specifications (SLS) as the 5G networks themselves. This means that gateways must match or exceed the capabilities of cellular networks while also meeting the requirements of connected industrial systems. They must also operate in harsh environmental conditions, potentially outdoors, and often in extreme temperatures.

Therefore, every component in the system must be selected or designed to meet reliability and lifetime requirements. This includes electromechanical components, power supplies, semiconductor components, and especially non-volatile storage for mission-critical code and data.

Specifying secure, reliable storage using a flash controller optimized for the system mission profile is extremely important to achieving the specified performance and operational life. The storage system must enable the gateway to meet the same performance standards as the 5G network itself.

Service life requirements

System replacement rates in many industries are measured in decades. The cost of unplanned downtime can be high, so gateways installed today must continue to operate and provide the same quality of service and reliability for many years.

Semiconductor manufacturers use design rules, power analysis, simulation, and accelerated life testing to quantify the behavior of a device and how environmental factors will affect it. This enables manufacturers to accurately specify the operating life under given conditions.

Some devices are designed and characterized for consumer use. They are expected to be active only a few hours a day and have a lifetime of 5 years operating at normal room temperature. This is very different from industrial components that are specified to operate 24 hours a day, 7 days a week, for at least ten years under a wider range of environmental conditions: industrial semiconductors are typically qualified over an operating temperature range of -40 to 85°C.

The Importance of Thermal Management

Temperature is one of the key design issues that must be considered. It affects many operating parameters of the transistors in the chip, including leakage current. As the ambient temperature increases from 50°C to 100°C, the leakage current of an NMOS transistor typically increases by a factor of 10. This is important because as leakage current increases, power consumption also increases. Therefore, effective thermal management is critical.

High temperatures also have a significant negative impact on the lifespan of a device. In the case of NAND flash memory, both high temperatures and temperature variations can stress the cells, leading to higher error rates, which can shorten the overall lifespan of the storage system.

The ability of a flash memory cell to retain data decreases rapidly as temperature increases. A 20°C increase can reduce data retention time by a factor of 10. On the other hand, low temperatures make it more difficult to accurately program a specific charge level on the cell. Raw error rates and the time required for program and erase cycles vary with temperature in complex ways.

All of this is worse for multi-level cell (MLC) flash devices that store more than one bit in each memory cell, because the charge levels that need to be accurately programmed and read are much closer. As a result, industrial systems tend to rely on single-level cell (SLC) or pseudo-SLC (pSLC) memory because of their higher reliability and longer lifespan.

Flash controllers can use a variety of mechanisms to manage the effects of environmental stress and maximize lifespan. For example, wear leveling ensures that data is written evenly to each block in the flash memory so that no block becomes unusable prematurely. Complex error correction codes can be used to detect and correct errors in the memory cells. By tracking the number of errors that need to be corrected, the controller can determine when a block of memory needs to be rewritten to avoid any potential data loss. Ultimately, this can also provide an early warning that the device has reached the end of its lifespan.

Using a flash controller that is optimized for the performance and environmental requirements of the application is critical to creating a high-quality storage system that achieves a specified operating life.

in conclusion

When designing an Industrial IoT 5G gateway, the performance, storage, and security profiles need to be as close as possible to the 5G network. This ensures that the system as a whole can meet its end-to-end service level specifications and meet the requirements of emerging applications.

In order to meet all the requirements of industrial applications, it is critical to select the right storage technology, supplier, and supply chain. In particular, you need to confirm that the selected storage system (including the NAND flash devices used) meets these requirements.

Selecting the right NAND flash controller and firmware will ensure that the inherent physical characteristics of the memory technology and its inherent weaknesses are properly managed. This enables the storage to reliably meet its mission profile.