costs, as well as cause a low level of disruption to
the existing operations of an operator's core and
macro networks.
cost-effectively scale to support the deployment
of hundreds of thousands (if not millions) of
femtocells.
for the interface between femtocells and the core
network in order to support a robust femtocell
market.
defined Iu-b interface that exists between 3G Radio
Network Controller (RNCs) and 3G radio antennas (Node
Bs). Primarily proposed by RNC vendors, these solutions
allowed operators to leverage the same RNC to support
femtocells in addition to macro network NodeBs.
(Iu-CS and Iu-PS), they meet the operator requirement for
full-service transparency, as well as the requirement for
low initial deployment cost and network disruption. As a
result, these solutions were initially viewed positively.
scaling this approach is in the basic design of RNCs, which
are typically optimized to support a relatively low number
of very high-capacity macro base stations.
a very large number of low-capacity base stations.
vendor. As a result, there has been hesitancy to fully
standardize the Iu-b interface in order to open up the
femtocell market.
is to use a new SIP-based protocol between the mobile core
network and the femtocells. Operators would deploy a new
SIP-based MSC (mobile switching center) that operates
in parallel with their existing circuit and packet-based
core network. When a handset is connected to a femtocell,
it receives all of its services from the new SIP-MSC core
network.
based infrastructure, these solutions were also initially
viewed positively. SIP-based MSC approaches also held
the promise of cost-effective support for large-scale
deployments.
are on the macro radio network, service transparency
becomes a significant challenge for SIP-based MSC
solutions. For every service an operator makes available on
its macro network, it now needs to replicate that service
on its new SIP-based MSC network.
network, the initial deployment costs and overall