6.5.6. Active mobile network sharing

In addition to sharing passive infrastructure, operators may also share active elements of their wireless networks. Box 1 outlines the active elements of a wireless network that can be shared. Operators may share those elements and keep using different parts of the spectrum assigned to them. Although active infrastructure sharing is more complex, it is technically possible. Equipment manufacturers can supply packages that have expressly been designed for active mobile sharing.

This section will describe several options available for active mobile sharing. Most of the examples used in this section focus on 3G network sharing, but the techniques could be applied to 2G mobile or broadband wireless networks, as well. [1]

Active mobile sharing may not be permitted under the licensing regimes of some countries. This is the case in India, for example, where the licensing regime for mobile telecommunications does not permit active sharing. Other regulatory agencies may allow active sharing only with strict conditions, in the belief that competing operators should utilize their own infrastructure independently. However, there are indications that many authorities are reconsidering this as operators increasingly compete based on the price and quality of their services and not on the features of their networks. The Telecommunications Regulatory Authority of India (TRAI) has recommended a review of the existing licensing regime in India with respect to active infrastructure sharing.

This section will explore the different options available for operators that wish to share their 3G mobile networks. This information is also relevant for sharing of networks based on other technologies, since their basic configuration is similar. Figure 1 provides a graphical overview of the elements of a 3G mobile network that could be shared. These elements include:

• The Node-B: This term refers to a base station placed next to an antenna. The Node-B contains equipment necessary to control the transmission and reception of signals: power amplifiers, power supplies, air conditioning, support cabinets, alarm systems, the transmission switch (in case of UMTS this is based on asynchronous transfer mode or “ATM” technology) and the TRX. Also described as a transceiver, the TRX contains both a transmitter and a receiver and is responsible for sending and receiving signals at the frequency assigned to the operator. The TRX is a very important device, because it enables communication with mobile handsets.
• The Radio Network Controller (RNC): This piece of equipment controls the Node-B. One RNC is usually connected to several Node-Bs (100 to 200). The RNC performs several important functions in a mobile access network, such as traffic and mobility management. The RNC tracks where the subscribers of a mobile network are located and assigns them to the base station closest to them. The RNC also controls the handoff of calls between cells.

Figure 1: Design of a Typical 3G Mobile Network



Source: Camila Borba Lefèvre, Mobile Network Sharing, at: www.itu.int/ITU-D/treg/Events/Seminars/GSR/GSR08/papers.html

• The Core Network: This is the intelligent part of the network and includes the mobile switching centres (MSCs). In modern mobile network architecture, the MSC is physically split into a mobile gateway (MG) and a mobile switching server (MSS). The MG switches the traffic to and from the radio network and from external networks (the public switched telephone network and other mobile operators). The MSS controls the traffic and customer services. In addition to the switching and control components, the core network contains several databases, such as the subscriber data base or home location register (HLR), which identifies the subscribers that are authorized to use the mobile network

Another element of the core network is the operations and maintenance centre (OMC). Part of the OMC controls the radio network components, such as the RNCs and Node-Bs, and is responsible for traffic management on the network. In more intensive network-sharing agreements, parties may have to share the OMC. This may raise competitive concerns, because operators would be able to access information relating to competitors’ traffic and volume. Regulators may require operators to create an independent OMC to ensure that information from the sharing parties remains separate. This would also allow independent network optimization, ensuring competitive differentiation. Because of these regulatory issues, the OMC may be one of the elements not shared among operators.

[1] Many European mobile operators have contemplated active sharing of their 3G mobile networks. This was triggered, among other reasons, by the high licence costs paid for 3G licences in Europe, the economic downturn that followed the 2000 3G-auctions and the increasing doubt about the development of the UMTS-technology and the availability of adequate handsets. The need for a much larger number of base stations for 3G, as compared with 2G, also made operators contemplate infrastructure sharing in order to reduce costs.