A Femto Cell is traditionally considered to be a customer-owned base station. Typically situated in a house or small business, a Femto Cell, also referred to as a Small Cell, is able to provide targeted network coverage, which significantly increases the bandwidth available to mobiles within its local area. Figure 1 illustrates a typical Femto Cell deployment, where it can be seen that connectivity to the mobile service provider’s network is based on a broadband Internet connection. This is typically DSL (Digital Subscriber Line) or Cable technology, which is not only cost effective for the service provider but also provides suitable data rates for transporting traffic from the customer site to the network.
Figure 1 Typical Femto Cell Architecture
The Femto Cell concept is applicable to 2G, 3G, 4G and 5G architectures. As can be seen in Figure 1, a gateway device is typically located in the mobile service provider’s network which acts as a concentration point for connectivity from the many customer sites which need to be supported.
The introduction of Femto Cells by a service provider may be able to solve some of the challenges they currently face, in addition to enhancing their offering to subscribers. The benefits of Femto Cells include:
Figure 2 Femto Cell Benefits
Although the technology behind Femto Cells has advanced quickly, a number of challenges remain. These include, but are not limited to:
Figure 3 Femto Cell Challenges
For 5G, the use of Small Cells is a key feature of 5G radio coverage. This can be largely attributed to the high operating frequencies used in 5G. That is, due to the requirement for large radio channels in order to fulfil capacity and data rate requirements, 5G networks typically operate at much higher frequency (between 6 and 100GHz, although lower frequencies will also be used). Radio propagation characteristics at these high frequencies mean that the range of any given cell is reduced, potentially down to hundreds of metres or less. As such, cell densification occurs, with multiple small cells in a small geographic region providing the overall 5G RAN coverage.
Note that this approach is different to the aforementioned Femto Cells, which are considered to be deployed in the customer premises. Although 5G Small Cells can also be deployed within the customer premises, they also form an integral part of the service provider’s overall 5G NG-RAN deployment.
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