Despite the recent reduction in enthusiasm for mobile communications, and for third generation in particular, it is likely that 3G services will play an important role in satisfying future communication needs. Ovum research has recently forecasted that by 1 January 2003, the total number of 3G connections worldwide will reach 11.4 million, increasing to 66.4 million by 2005 and more than 251 million by 1 January 2007. Meanwhile mobile operators, having invested heavily in obtaining 3G licences, are working tirelessly to develop new networks supporting exciting new services for their subscribers.

Careful planning is critical to the success of 3G. The network infrastructure represents the major part of the capital cost in rolling out 3G. As demonstrated below, the design of the network infrastructure is determined by the services to be offered. Operators will need to be cautious in their plans and will rely heavily on planning tools to develop an infrastructure that is robust, flexible and cost effective in meeting future needs. These are some of the issues they will need to consider.

1. 3G planning is different from 2G planning
Although there is now some interest in data transmission, 2G networks have principally been concerned with a single service - voice. The technical requirements are well understood and planning a new 2G network has largely been driven by on the need for coverage, with only a limited analysis of the traffic demand.

3G, however, demands a totally different approach. Quality targets will be different for every service and the services to be offered must therefore be defined at the start. Furthermore, although 3G is efficient in sharing the radio spectrum, the consequence is that every service is affected by the presence of all other services. Thus to determine service coverage and availability requires the precise mix of services to be defined from the start.

2. The role of marketing in network design!
To provide the inputs required, operators must ensure that marketing and technical teams collaborate closely from the start. Detailed traffic demand forecasts will be needed for each new service broken down by area. In a highly populated area for example, the services and content may be substantially different from those required in a more rural environment, and this will impact on the level of coverage and capacity required in each area. Since performance will also be affected by mobile speed and whether the subscriber is indoors or out, the particular mix of subscribers in each environment should also be defined.

In practice a number of different scenarios may be defined, driven by different tariff assumptions and models of market growth.

3. Use the correct tools
Once the alternative traffic scenarios have been defined, a high quality radio planning tool is needed that is able accurately to represent the services and to model the interactions between them. As we have seen:

• As more and more subscribers use the network, using the same frequency, they create the potential for more and more interference.

• Users of high bandwidth services create even more interference and can degrade the quality, or coverage, experienced by other users.

• As the network becomes congested, certain services (for example email delivery) may be halted or proceed at a lower rate.

It has been shown that for reliable results a full traffic simulation, down to the level of individual calls, must be used.

Operators will wish to consider a number of different scenarios (each representing a different service mix). Each traffic scenario consisting of many individual services must be analysed to determine the likely performance. By repeating the simulations frequently as network design evolves and new sites are added, planners may be confident in the effectiveness of their designs in meeting the required quality targets in a cost effective manner.

4. A learning curve for all
The radio planning tool is essential not only for radio planners but for marketing and others concerned with service and tariff development. The output of each simulation is a comprehensive set of performance statistics for every service. By considering a number of representative areas it is possible to understand the effect of different service combinations on the overall network design. Alternative tariff structures can be compared to identify those that maximise revenue and minimise infrastructure costs. By performing multiple ‘what if’ analysis, the robustness, or otherwise, of the network to different service usage patterns and their impact on network cost can be identified.

From these, it is possible to distil a set of general design rules that can be applied consistently across the network, allowing junior planners to design efficient 3G networks.

Conclusion
As this article has shown, detailed market forecasting, supported by high quality simulation are essential elements in developing cost effective 3G networks and services. By making a small investment in resources and tools at the start, both time and money can be saved and the chances of commercial success will be considerably enhanced.

By Richard Fuller, consultant, Xenicom