Editor’s note: Since this article was originally published, CommScope has posted an update to our definition of indoor small cells. Please visit the latest Definitions blog, and our new small cell products and solutions pages, for more information.
This blog post is part of a series called “CommScope Definitions,” in which we will explain common terms in communications network infrastructure.
One of the more recent developments in the wireless industry is deploying “small cells” to provide coverage and capacity both indoors and out. Small cell solutions are touted for their ability to achieve higher radio density and increase capacity. But what exactly is a small cell?
The Small Cell Forum offers a definition that is often cited in the industry. It can also be a little confusing. It defines small cells as an “umbrella term for operator-controlled, low-powered radio access nodes, including those that operate in licensed spectrum and unlicensed carrier-grade Wi-Fi.”
Does the term “operator controlled” suggest that small cells are exclusively single-operator solutions? Must it be owned by the mobile operator or can it be owned and operated by a neutral host provider?
The answers are unclear. In fact the wireless industry overall has struggled to define the term “small cell” precisely. A small cell is usually thought to be a femtocell, picocell, metrocell or microcell, all of which are concepts for small-scale cellular sites. These types of small cells differ in terms of the technology they operate on and the number of users they support, among other variables. But there are also a number of similarities, which is why they get lumped together as small cells. Each of them operates at lower power and supports a smaller number of users than a typical, large-scale cell site.
At CommScope, we think that what should define small cells is not the type of box they come in, but the function they play in the wireless network. Small cells are fundamentally about adding capacity by moving traffic off the macro network. They are all about network densification. In this sense, a distributed antenna system (DAS) can also be considered a small cell. A DAS adds capacity by offloading traffic and also operates at lower power while supporting a concentrated population of users. In fact, a DAS can be referred to as the original small cell.
The chart below summarizes key characteristics about the various types of small cells.
The bottom line is that all of them likely have a role to play depending on the application. If the wireless industry has learned anything over the past two decades, it’s that—when it comes to coverage and capacity solutions—there is no magic bullet. There is no one-size-fits-all solution.
Key Takeaway: Despite the wireless industry struggling to define the term “small cells” precisely, these low-power solutions have evolved to become an increasingly important part of wireless networks. There are many small cell technologies including femtocells, picocells, microcells, metrocells and distributed antenna systems. The best definition is based on their function, which is a network densification solution that offloads traffic from the macro network to add capacity.