Femtocell Technology

Personal base stations, also known as "femto cells", have the potential to transform communications by making the mobile device the tool of choice even in home settings.  However, vendors and operators face substantial technical challenges to realize the potential of femtocells.  For example, femtocells will increase the number of base stations by several orders of magnitude over the existing “macro” base station infrastructures.  This increase will demand new approaches to areas such as mobility and interference mitigation.  At such volumes, femtocell vendors will also need to follow an aggressive cost curve.  Femtocells will require new approaches to installation and configuration, because they will be installed by non-technical users.

Airvana’s experience in IP-based radio access networks, combined with close working relationships with operators and other vendors, is being directed to address the challenges inherent in femtocells.  Airvana’s femtocell technology consists of the following elements:

• A flat network architecture
• A flexible hardware architecture based on programmable processing elements 
• An extensive software/firmware technology that will implement the radio, networking, and security functions of a femtocell 
• A suite of proprietary algorithms designed to optimize the performance and robustness of the femtocell system
• A scalable service manager to facilitate the management of femtocells by the network operator 

Flat femtocell network architecture collapses the base station, radio network controller, and packet data nodes of a macro-cellular radio network into a small femtocell access point.  This combination simplified deployments by eliminating complex hierarchical PDSN-RNC-Base Station relationships that characterize traditional macro access networks.

            Femtocell Access to Operator Networks

An essential element of the flat femto cell network architecture is the Universal Access Gateway (UAG), which provides the critical security protections necessary for connecting femtocells to an operator’s core network using the public Internet. The UAG allows femtocells to deliver differentiated features that enhance femtocell operation, while maintaining open standard interfaces to ensure vendor interoperability.

Airvana’s approach is designed to provide flexible options to connect to a wireless carrier’s core network. Connection options include existing circuit-switched core networks, which include mobile switching centers, or state-of-the-art packet-switched core networks based on the session initiation protocol (SIP) or IP multimedia system (IMS).

	Key Technology Approaches
Key Challenges	Flat Architecture	Programmable Processors	Algorithm Development	Core Network Component (UAG)	Service Manager
Micro Mobility			X	X
Interference Mitigation			X
Spectrum Management			X
Deployment Complexity	X			X	X
Network Security				X
Access Security			X		X
Evolving Core Networks (circuit to packet)		X	X	X
Feature and Service Differentiation		X		X
Cost Sensitivity		X
Non-technical user	X				X