In recent years, there has been a significant surge in data usage on operators’ wireless networks owing to the rising uptake of smartphones and tablets. The majority of data usage (about 70 per cent) on these devices is originating from buildings and indoor areas. However, the existing 2G and 3G networks are not capable of providing optimum indoor mobile coverage as well as bandwidth, which results in lower internet speeds and poor customer experience. In order to overcome the issue of weak signals in indoor areas, telecom service providers are increasingly deploying femtocells to support higher bandwidth requirements, as against installing new macro cell sites and using expensive spectrum for higher capacity.

For instance, Spain-based operator Telefonica is deploying femtocells to augment the indoor 3G network coverage for enterprise customers in Germany. It will install femtocells in office premises and high density areas. Similarly, Singapore-based M1 is installing these cells on the premises of enterprise customers to provide increased mobile network coverage.

Femtocells are low-cost, low-power base transceiver stations that use licensed spectrum to provide indoor wireless services to multiple user equipment simultaneously. When the customers’ device enters the frequency range assigned to the femtocell, the device is disconnected from the macro mobile network, thus vacating spectrum for other purposes. Thus, femtocells, like other in-building solutions (IBS), offer the dual advantages of enhancing indoor mobile coverage and offloading data traffic from macro cellular networks, thus reducing opex for operators.

Traditionally, IBS such as the distributed antenna system (DAS) and Wi-Fi have been the most prominent solutions for providing wireless indoor coverage and offloading data from macro cells, but their sales have been affected with the introduction of femtocells. Femtocells offer several advantages over DAS when deployed in residential areas and small enterprises. For instance, with DAS, the network management team needs to carry out technical planning and designing before installation. Integration of DAS into the operator’s radio access network also poses challenges. In contrast, femtocells essentially use the customer’s broadband network to transmit/receive data to/from the operator’s core network. Also, femtocells do not pose installation challenges including the need for technical expertise.

Deploying DAS also entails significant upfront investments, which mobile operators are not ready to bear due to unfavorable cost economics. The cost of a DAS network is significantly higher than that of a femtocell. However, the overall cost increases multiple times with a rise in the number of femtocells deployed and may be higher than that of a DAS network. Also, femtocells are useful when a single frequency band is being used for the provision of wireless services.

With the Wi-Fi solution, one of the biggest drawbacks is interference and susceptibility due to the use of unlicensed spectrum by the technology. In large enterprises and venues such as stadiums and educational institutions, multiple Wi-Fi access points can interfere with each other’s functioning if they are utilising the same spectrum. This may allow unauthorised network access and pose security risks. Also, at crowded places like airports, hospitals and malls, Wi-Fi access points serve a large number of customers using smartphones, which results in network congestion and a patchy user experience. Another issue with the Wi-Fi solution is that feature phones do not have the Wi-Fi module, which prevents users with these devices from accessing the network. In contrast, femtocells are an extended version of the macro cellular technology and do not require any special functionality for accessibility.

While femtocell technology has enabled operators to provide improved in-building wireless coverage in a cost-effective manner, its deployment comes with certain limitations. Femtocell uses the same frequency band as assigned to macro cell sites by the operators. If these sites are located near femtocell installations, radio signals will interfere and the quality of service will be affected.

Further, deployment of multiple femtocells indoor area results in issues related to backhaul network connectivity, and network operation and management. Connecting each femtocell to the customer’s broadband network is a challenging task as fibre connectivity is not available at all locations.  Moreover, due to the small coverage area of femtocells, the number of handover events per cell increases significantly, which leads to issues in network management. Moreover, femtocells use backhaul-based signalling for voice and data transmission, which leads to delays in handover.

To address the issues associated with femtocell technology, a combination of femtocells and DAS has been proposed for the provision of improved indoor wireless services. Together, femtocells and DAS can augment both capacity and coverage significantly in areas where bandwidth requirements are high. Also, since DAS allows multi-operator and multi-band functionality, infrastructure and costs can be shared among several service providers. DAS requires a dedicated fibre network from the macro base station to the aggregation point, from where each access point can be served through a coaxial cable. As a result, operators would need to install femtocells only at locations with fibre connectivity while DAS can be deployed at other locations.

In sum, femtocells offer advantages such as inexpensive deployment, restricted network usage through closed access configuration and ease of installation. However, their deployment will be limited until the shortcomings are addressed.