als, the Wi-Mesh Alliance and SEEMesh (Simple, Efficient and Extensible Mesh). Wireless LAN Devices Wireless Network Interface Cards The wireless network interface card (NIC) turns a device such as a PDA, laptop or desktop computer into a wireless station and enables the device to communicate with other stations in a peer-to-peer network or with an access point. Wireless NICs are available in a variety of form factors (Figure 3-9), including PC (Type II PCMCIA) and PCI cards, as well as external USB devices and USB dongles, or compact flash for PDAs. Most wireless NICs Figure 3-9: A Variety of Wireless NIC Forms (courtesy of Belkin Corporation, D-Link (Europe) Ltd. and Linksys (a division of Cisco Systems Inc.)) Chapter Three have integrated antennas, but a few manufacturers provide NICs with an external antenna connection or detachable integrated antenna which can be useful to attach a high-gain antenna when operating close to the limit of wireless range. There are few features to distinguish one wireless NIC from another. Maximum transmitter power is limited by local regulatory requirements and, for standards based equipment, certification by the relevant body (such as Wi-Fi certification for 802.11) will ensure interoperability of equipment from different manufacturers. The exception will be proprietary extensions or equipment released prior to standard ratification, such as "pre-n" hardware announced by some manufacturers in advance of 802.11n ratification. High-end mobile products, particularly laptop computers, are increasingly being shipped with integrated wireless NICs, and with Intel's Centrino® technology the wireless LAN interface became part of the core chipset family. Access Points The access point (AP) is the central device in a wireless local area network (WLAN) that provides the hub for wireless communication with the other stations in the network. The access point is usually connected to a wired network and provides a bridge between wired and wireless devices. The first generation of access point