Radio Access Network:
Radio access for consists of a flat
architecture in which the base stations, or eNodeBs, are connected directly to
the core network without the need for an intermediate radio network controller.
The eNodeB contains Radio Frequency (RF) modules and a baseband processing
module that has control and modem units. These can all be integrated into a
single cabinet. Otherwise, the baseband unit and RF units, or remote radio
heads (RRHs), can be deployed separately and linked by a cable. The RRH
contains the RF power amplifier and RF filter.
To enable more flexible deployment options, baseband
units are located in station telecom rooms and RRHs are located in the outdoor
track area, for the current railway environment. Upcoming Next generation radio
access, offers further architecture flexibility by being able to take advantage
of cloud technologies that offer enhanced reliability, flexibility, and easy
scalability of capacity to meet actual demand. Radio functions can either be run
in large centralized data centers or smaller distributed sites, or a
combination of both with all components treated as a single cloud for easy and efficient
Due to its easier site acquisition, low
deployment costs, and reduced site rentals, the mobile industry has adopted the
distributed base station architecture in the recent years. A distributed
architecture also has the advantage of a better uplink (UL) budget because of
lower RF cable losses. Therefore, fewer sites would be needed compared to the
integrated cabinet option. While all railway operators can enjoy these
advantages, the compact size of distributed deployments is particularly
beneficial for metro operators facing the challenge of deploying equipment in
restricted tunnel spaces that may not easily accommodate conventional
integrated deployments. For metro railways, deployment of small cells can also
be considered as they are generally easier to install in underground and other
Core network solutions currently available are
suitable for a variety of network requirements – compact units to serve deployable
and small networks, mid-sized core for full network deployments, and data
center solutions for pan India networks. Further flexibility comes from virtualization
and cloud technology.
Depending on the railway operator’s strategy,
the core solution is constructed from various components: Compact Core, IMS,
VoLTE/open TAS core, and HSS. Further enhancements are achieved by application servers
that provide railway-specific functionalities together with the mission
critical application server used in the public safety domain. Solutions include
Group Communication Server that is fully aligned with 3GPP.
Backhaul network solutions with integrated
packet microwave and optical transport have shared services network
infrastructure which can be deployed flexibly with no performance degradation.
This helps meet diverse connectivity requirements and allows for future growth.
Ready for software defined networks (SDN), they allow for future network
evolution. In hybrid and commercial network deployments, these solutions support
QoS with prioritization of emergency calls and mission critical voice/ data over
non-mission critical and commercial voice/ data.
The solutions also support policy management, traffic
engineering, QoS-capable backhaul and radio networks, user differentiation
based on 3GPP standard QCIs, load balancing and admission control. Currently
available backhaul solutions are complemented by comprehensive services to
simplify the evolution to high speed mission critical networks while assuring
mission critical reliability and performance. Services include systems
integration, network design and build, transformation consulting, managed
services and care.