Six key factors for module design in 5G devices

This article originally appeared on ElectronicProducts.com

At the end of 2021, 5G was on track to exceed 540 million connections and 220 commercial networks worldwide, according to Omdia and TeleGeography. What do these numbers mean for engineers, system designers and others responsible for adding cellular connectivity to their devices and workflows?

One conclusion is the benefits of volume. The more devices and networks there are, the faster 5G goes down the cost curve. This makes 5G increasingly viable for highly price-sensitive applications such as the Internet of Things and consumer electronics.

This trend may seem like a perfectly clear signal to start using 5G instead of 4G. To a large extent this is true. But the situation is not so clear-cut. Here’s why – along with six key things to consider when deciding if, when and how to start using 5G.

Navigate the spectrum options

Spectrum selection directly affects your product’s performance, reliability, battery life, carrier selection, addressable market, and cost. 5G is designed to operate in 63 bands, far more than any previous generation. These bands also range from 600 MHz to 48 GHz, placing many of them well outside the traditional cellular bands. This means that even if you have experience integrating cellular modems into devices, 5G still comes with a steep learning curve.

For example, each band has its own signal propagation characteristics and bandwidth capabilities. The millimeter wave (mmWave) spectrum — 24 GHz and higher — supports multi-gigabit speeds, which is ideal for bandwidth-intensive applications such as transmitting 4K CCTV cameras or streaming 8K video to street digital signage.

One caveat is that mobile operators typically deploy mmWave base stations only in certain areas, such as malls, malls, business parks, and stadiums. This is because the higher the frequency, the shorter the signal range, meaning the operator needs to deploy more sites to cover an area. An mmWave base station on top of a street light pole may have a coverage area of ​​only a few hundred meters. Only densely populated areas have a large enough pool of potential customers for the operator to recoup the capital and operating costs of all these additional sites.

What if the application needs gigabit speeds in additional locations, such as small towns and interstates? Then its 5G module must support bands on other, lower frequencies to ensure that the connection is always available. This may also require carrier aggregation (CA)where multiple signals at multiple frequencies are combined to achieve the target bandwidth.

Another factor is physical obstacles. At higher frequencies, walls, windows, and even greenery can attenuate signals to the point that bandwidth drops sharply—or the connection is lost altogether. That’s why it’s important to consider where the devices will be used: Indoors? Outdoor? Both? The same question applies to 5G base stations. For example, if the devices are used indoors, such as for factory automation, throughput will be more consistent and connections more reliable if the base stations are also inside, rather than trying to push signals through exterior walls.

Who owns the 5G network?

The factory automation scenario highlights another key consideration: Who owns the 5G network your devices will use? If the product is aimed at the business market, it can be a private network, which can take one of three forms:

• The enterprise owns the core and radio access network (RAN), just like a mobile operator.
• The enterprise uses a virtual, private part of the mobile operator’s public 5G network.
• A hybrid combination where the enterprise owns the local network but also uses a private part of a public 5G network for wide area coverage.

Mobile operators have access to many more bands than private operators. For example, in the US a private network can use CBRS spectrum (3.55 to 3.7 GHz)also known as Band 48. So if the device’s target market is US enterprises that own a 5G network, then its module and antenna will need to support CBRS.

If some of the target customers use a virtual part of a public network or a hybrid combination, then another consideration is the availability of 5G. Although there were approximately 220 5G networks in commercial service at the end of 2021, it will take several more years of construction to reach the nearly 700 networks that 4G currently has. In fact, TeleGeography ratings that by the end of 2023, 5G will still be less than halfway there, with about 329 networks worldwide.

As a result, the module will need to support 4G for use in areas where a 5G stand-alone network – public or private – is not yet available. Known as “dual connectivity” or EN-DC, this capability increases the complexity of the module, which also creates additional challenges and costs associated with regulatory approval and mobile operator certification.

Pre-certifications reduce development time and costs

Even if a module does not need 4G support, certifications are a key consideration because they affect the cost and time to market of a 5G product. To minimize both, look for 5G modules that have been pre-certified by major mobile operators and regulators such as the Federal Communications Commission (FCC), the PCS Type Certification Review Board (PTCRB), the Radio Equipment Directive (RED), the Global Forum on certification (GCF), Japan Radio Law (JRL), Japan Telecommunications Business Law (JTBL) and Korea Communications Commission (KCC).

Operator and regulatory certifications also affect the addressable market and revenue potential of 5G devices. The more there are, the more countries and regions where it can be sold. This flexibility can also be particularly attractive to multinational enterprise customers.

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