Various WLL technologies and deployment options should be evaluated in terms of the following:

• population density of the service area
• connection cost (i.e., equipment and installation)
• level of penetration
• whether the country/area served is developing or developed

A comparison of PHS, DECT, digital cellular, analog cellular, and proprietary protocols was conducted in 1997, taking into account the above variables. The results are shown in Figure 5 and Figure 6. Costs included in the model are base-station site and infrastructure costs, costs of radio equipment (varies with channels used per site), costs of antenna equipment (varies with sectorization of base station), costs of baseband processing and protocol-conversion equipment, costs of backhaul from base station, costs of subscriber-premise equipment, and installation costs.

Figure 5. Connection Cost versus Population Density (penetration 65 percent, 120 mE)

Figure 6. Connection cost versus Population Density (penetration 15 percent, 30 mE)

It should be noted that this analysis assumes that backhaul costs are similar for all systems, yet this is probably not the case for microcellular systems. The costs shown in the two figures above are for installation only and do not include operation and maintenance or system/subscriber management software. Finally, it should be kept in mind that incremental investment costs must also be considered.

Based on the data in Figure 5 and Figure 6, the appropriate technologies for various WLL market segments—both in developed and emerging countries—can be summarized as follows:

	Developed	Emerging
urban/suburban	digital cellular DECT PHS proprietary	DECT PHS digital cellular proprietary
rural	digital cellular proprietary	digital cellular analog cellular proprietary

Table 4. WLL Technologies by Market Segment

As can be seen, no one system is best for all applications. The right choice should be based on subscriber densities, traffic conditions, and data-support requirements. The conventional wisdom that microcellular (cordless) systems are better for urban areas and that macrocellular (cellular) systems are better for rural areas is not true for all conditions.

In summary, there are clear market opportunities in emerging economies for WLL, as well as an enormous potential upside in developed economies. The potential market is huge, but its various segments require the right system costs and features. Finally, more than one technology will evolve as the leader; for example microcellular applications will call for DECT and PHS, whereas macrocellular systems are better suited to TDMA, CDMA, and GSM.