Switched telecommunication systems: design and planning
G. Smol, M. P. R. Hamer, M. T. Hills · 2023
Decisions about which techniques and technologies should be used in a particular element of a switched system and decisions about the detailed structure of the system are not generally clear-cut issues. Many of the decisions depend on a comparison of alternatives involving a number of factors which cannot easily be reduced to a common parameter such as cost. A choice or decision usually involves weighing up a mixture of qualitative and quantitative factors. Only where all the relevant factors are reducible to quantitative terms can an optimal solution be found. In a large switched telecommunication system, such as a public telephone system, the design of equipment is dominated by two factors: compatibility and modularity. The result of the need for compatibility is that new versions of elements of the system are generally more costly than their counterparts would be in a completely new system, and they may even be more costly than the old element using older technology.