Mobile communication technologies range from personal area networks (PANs; a range of about 10 meters) and local area networks (a range of about 100 meters) to wide area networks (WANs; a few kilometers). From a network-topology perspective, most networks are based on a client-server model. A few are based on the peer-to-peer model.
Wireless PANs
A wireless personal area network allows the different devices that a person uses around a cubicle, room, or house to be connected wirelessly. Such devices may include the computer, personal digital assistants (PDAs), cell phone, printer, and so forth. (Table 1)
Table 1. Summary of the wireless PANs
| Technology | Radio Frequency | Maximum Distance | Data Capacity |
| Bluetooth | 2.4 GHz | 10 meters | 721 Kbps |
| HomeRF | 2.4 GHz | 50 meters | 0.4-10 Mbps, depending on distance |
| ZigBee | 2.4 GHz | 75 meters | 220 Kbps |
Bluetooth is a global de facto standard for wireless connectivity (Bluetooth SIG, 2005). The technology is named after the 10th-century Danish King Harald, who united Denmark and Norway and traveled extensively.
HomeRF is an early technology for wireless home networking, first marketed in 2000.
The Institute of Electrical Engineers (IEEE) 802.15 wireless-PAN effort (IEEE, 2005a) focuses on the development of common standards for personal area networks or short-distance wireless networks. One technology out of this effort is ZigBee, which is based on the IEEE 802.15.4 standard.
ZigBee is a low-cost, low-power-consumption, wireless communication-standard proposal (ZigBee Alliance, 2005). Formerly known as FireFly, ZigBee is being developed as the streamlined version of HomeRF. A streamlined version would allow most of the functionality with less integration and compatibility issues.
ZigBee’s topology allows as many as 250 nodes per network, making the standard ideal for industrial applications. Radio-frequency-based ZigBee is positioned to eventually replace infrared links. To achieve low power consumption, ZigBee designates one of its devices to take on the coordinator role. The coordinator is charged with waking up other devices on the network that are in a sleep mode, moments before packets are sent to them. ZigBee also allows coordinators to talk to one another wirelessly. This will allow for opportunities for wireless sensors to continuously communicate with other sensors and to a centralized system.
For enterprise computing, the wireless PANs are within the corporate firewall. They do not create new requirements for the enterprise architecture to extend access to applications. However, they do require security measures to make sure the device that is receiving information is a recognized device. It also creates an opportunity for the computing infrastructure to potentially know where a particular device, and most likely the associated user, is located. How these are handled will be discussed later in the description of the proposed service-oriented architecture.