Encouraged by the success of passive infrastructure sharing, the government, in 2008, allowed sharing of active infrastructure in order to expedite the rollout of telecom networks in rural areas. It was stipulated that active infrastructure sharing would be limited to antennas, feeder cables, Node B, radio access networks (RANs) and transmission systems, which ruled out the possibility of spectrum sharing.

The active components of telecom infrastructure include base stations, RANs, microwave radio equipment, switches, antennas, feeder cables and transmission systems, the core network and even spectrum. Base station controllers (BSCs) and transcoders/packet control units, base transceiver stations (BTSs), operations and maintenance centres (OMCs) (the management platform of the Wi-Max RAN which provides operators with all the services needed to deploy, operate and maintain commercial Wi-Max), transmission media, antennas and connecting feeder cables can be shared. However, spectrum, network elements up to the mobile switching centres (MSCs) for voice services, and the combined global sensor network (CGSN) for data services cannot be shared.

There are four basic shared network solutions: a common shared network based on national roaming, a geographical split network, a shared radio network based on virtual radio network controllers, and hybrid solutions that are a combination of the first three solutions.

Common shared network
A common shared network consists of operators sharing radio and gateway cores, frequency and capacity amongst themselves. The companies also maintain individual home networks, which handle subscriber data and interconnection services and add to individual coverage. Common shared networks are generally operated by a third-party entity such as a joint venture (JV) or a consortium.

Geographical split network
The models for geographic sharing are: a full split between operators, a unilateral shared region between operators, a common shared region between operators, and full sharing between operators.

Each operator has its own network.Coverage is coordinated between companies which cover different parts of the country. This leads to better coverage.

In contrast, under a non-sharing model, each operator provides full service coverage only in those regions where it operates its own network. The operators have access only to their own networks.

Shared radio network
This consists of a shared physical radio network. Antennas, feeders and most hardware in the base station are shared.There are two or more logical radio network controllers (RNCs), which are separated into individual RNCs by software.The shared radio network model includes sharing of business support systems and RANs between two operators. This involves sharing network elements, RNCs, BTSs and related site and transmission equipment. However, site selection, network planning and rollout are up to the individual operator.

These network sharing options are supported by different business models.First, a single operator could own the resources and provide services to other parties. Second, two or more parties could independently own their resources and provide mutual services. Third, several operators may have a share in a JV owning the shared resources and providing services to the parent companies. Fourth, an independent network provider could own the shared resources and provide services to operators irrespective of whether the operators own shares in the network provider.

Opportunities and challenges
There are many advantages of active RAN sharing, the most important being a reduction in capital and operating expenditure as a result of the fall in feeder cable, antenna and transmission costs. Depending on the network sharing solution, savings of up to 40 per cent can be achieved. Additional cost savings estimated at 10-15 per cent can be achieved if the 3G overlay network is shared as well.

With active RAN sharing, there is no need for additional OMCs or network operations centres. There are also high economies of scale. A reduction in operating expenditure comes about as a result of lower space and power requirements for media gateways, BTSs and BSCs, reduction in the cost of support services and upgrades, and lower manpower requirements for proactive/reactive maintenance, spares and inventory management, etc.

The other advantages include faster rollouts, better business prospects while penetrating rural towns, improvement in the city skyline and better utilisation of national resources.There are several challenges as well.The operator must select the right model for network sharing, as well as the right partners whose business model is complementary to its own strategy. The other challenges include serving customers without mobile virtual network operator (MVNO) regulations and lack of additional spectrum for sharing.

3G
3G network sharing, set to become a prominent trend worldwide, will significantly benefit mobile operators and vendors. In the coming years, mobile operators will face major expenses and will thus not be able to invest sufficient amounts to exploit 3G’s full potential. Cost savings from 3G infrastructure sharing are critical, particularly in the initial coveragebuilding phase of the service. The investment in coverage is substantial and the early traffic and revenues are not enough to compensate for the investments. 3G infrastructure sharing can lead to each party decreasing its capex and opex by 50 per cent, which will ultimately facilitate faster rollouts.

3G RAN sharing is at a nascent stage. However, Huawei and Nokia Siemens Networks have already come out with products to enable 3G active infrastructure sharing.

Wi-Max
For Wi-Max services, passive infrastructure such as towers, shelters, foundations, outdoor and indoor electricals, power supply and diesel generator sets, optical cables and ducts may be shared. This saves on opex and capex and is also beneficial from an environmental point of view. Passive sharing for Wi-Max has already begun amongst operators in India. Sharing of Wi-Max active infrastructure, based on mutual agreements entered into by telecom operators, is possible for antennas, feeder cables, base stations and RAN.

Infrastructure sharing for Wi-Max services will receive a boost with the entry of MVNOs. These are a new class of licensees capable of providing broadband wireless access services without spectrum allocation. Their entry will also shorten time-to-market and increase the level of competition. The sustainability of MVNOs is, however, dependent on network operators.
Mayank Mittal, AVP, Technology, Tata Teleservices; Nitin Dahiya, Head, SSM RA, India, Nokia Siemens Networks; Bharat Bhatia, Chairman, RWG, WiMAX Forum, India Chapter