h's preferred device mode would meet this requirement. Mobility Is the network required to be moveable between locations (portability) or to operate while the user is physically moving? For example, IrDA is not suitable if any device is mobile in view of the need for port alignment. Implementing Wireless PANs Table 11-1: PAN User Requirement Types - cont'd Requirement type Considerations Device The required functionality must be implemented in both interoperability devices to enable interoperability. For example, a mobile phone may have a headset profile implemented to inter-operate with a Bluetooth headset, but will not provide Internet connectivity if the dial-up networking profile is not implemented. Operating Are there specific requirements in the environment where environment the PAN will operate, for example will it need to operate in the presence of narrow band or other RF interference, perhaps from a co-located WLAN? Battery life How often will the user need to recharge battery operated devices? Are features to conserve battery power easy to access and configure? It goes without saying that the user will want value for money in the chosen solution, but other soft issues may play a part here too. Particularly for PAN equipment, the aesthetic aspects of personal accessories may also be an implicit or explicit requirement. Establishing Technical Requirements Technical requirements follow from user requirements, translating these into the related technical attributes (Table 11-2). For example, if a user requirement is Internet access from a mobile device, then the required technical attribute is an IP networking capability. Alternatively, a user Table 11-2: PAN Technical Attributes Requirement type Considerations Application support Does the technology support the specific usage models required by the user? Effective data rate The required data rate will be dictated by the usage model, specifically the typical size of data objects that will be transmitted across the PAN, and the user's performance expectation