So you want to design a small cell system

For those unfamiliar with the technology, small cell systems are fast becoming the preferred choice when it comes to localized mobile network coverage. Low-powered indoor and outdoor radio base stations, this technology offers a limited range serving a limited number of users, and it’s typically managed by a single operator for the purpose of providing the user with a seamless mobile network experience. 

Now, while the technology was first used for consumer services, there’s been an increase in demand from the business sector, resulting in a blending of the two service types. Nowadays, this technology is seen in all sorts of areas where the demand for mobile networking is high, including shopping mall stores, airport wait areas, college campuses, and office buildings. 

There are plenty of reasons why we’re seeing such a fast adoption rate of the technology — for one, there’s lower delay, meaning users will experience lower latency for data services; this, in turn, means they’ll enjoy faster download and upload times. 

Better outdoor-to-indoor coverage is another plus, especially when you consider most mobile traffic starts in the user’s home and work. 

Also, macros base stations are notorious for providing poor coverage at the cell edge — small cells, on the other hand, are specifically designed to address this matter, and provide users with a much better cell-edge performance. 

As with any technology, though, there are many challenges when it comes to designing a small cell system, especially when it’s a Digital Radio Front End system (the more common approach). One thing a small cell designer must consider is how best to reduce the system’s peak-to-average ratio — the reason being that by addressing this matter, they will be able to reduce the system’s overall power consumption, thereby leading to smaller component size which, in turn, reduces the overall component cost and bill of materials. 

Another issue small cell designers typically face is in being able to provide a more linear performance from the system’s power amplifier. You see, as the device nears its peak driver point, the power amplifier’s efficiency moves away from a linear performance line. And if a power amplifier is not operating efficiently, the system ends up wasting power and generating excessive heat.

An additional item to consider is that when one is designing a system, the goal is to achieve a high throughput low pin-count interface. This not only increases performance, but also allows for fewer lanes on the board. Naturally, this is easier said than done, especially when you consider the time and effort it takes to establish communication links between ADCs, DACs, FPGAs, and DSPs in the entire system. 

While these challenges — plus others not even touched upon, including interference management, network security, and access control — still exist, fortunately for today’s small cell designer, manufacturers like Avago are addressing these matters via the company’s comprehensive portfolio of RF product solutions, including power amplifiers, low noise amplifiers, FBAR filters and duplexers, and integrated GPS / GNSS LNA filter modules. All of these components are specially designed to overcome the many challenges associated with small cell mobile coverage. 

To gain a better understanding of how these technologies (and others) can assist you with the design of a more efficient and effective small cell system, download Avago’s “Selection Guide – Small Cell Product Solutions” via the image / link below.