Advantages and challenges

Operational advantages
Wi-Fi allows local area networks (LANs) to be deployed without wires for client devices, typically reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.

Wireless network adapters are now built into most laptops. The price of chipsets for Wi-Fi continues to drop, making it an economical networking option included in even more devices. Wi-Fi has become widespread in corporate infrastructures.

Different competitive brands of access points and client network interfaces are inter-operable at a basic level of service. Products designated as "Wi-Fi Certified" by the Wi-Fi Alliance are backwards compatible. Wi-Fi is a global set of standards. Unlike mobile telephones, any standard Wi-Fi device will work anywhere in the world.

Wi-Fi is widely available in more than 220,000 public hotspots and tens of millions of homes and corporate and university campuses worldwide.[5] Wi-Fi Protected Access encryption (WPA and WPA2) is not easily cracked if strong passwords are used. New protocols for Quality of Service (WMM) make Wi-Fi more suitable for latency-sensitive applications (such as voice and video), and power saving mechanisms (WMM Power Save) improve battery operation.


Limitations
Spectrum assignments and operational limitations are not consistent worldwide. Most of Europe allows for an additional 2 channels beyond those permitted in the U.S. for the 2.4 GHz band. (1–13 vs. 1–11); Japan has one more on top of that (1–14). Europe, as of 2007, was essentially homogeneous in this respect. A very confusing aspect is the fact that a Wi-Fi signal actually occupies five channels in the 2.4 GHz band resulting in only three non-overlapped channels in the U.S.: 1, 6, 11, and three or four in Europe: 1, 5, 9, 13 can be used if all the equipment on a specific area can be guaranteed not to use 802.11b at all, even as fallback or beacon. Equivalent isotropically radiated power (EIRP) in the EU is limited to 20 dBm (100 mW).

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Reach

Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or 802.11g with a stock antenna might have a range of 32 m (120 ft) indoors and 95 m (300 ft) outdoors. Range also varies with frequency band. Wi-Fi in the 2.4 GHz frequency block has slightly better range than Wi-Fi in the 5 GHz frequency block. Outdoor range with improved (directional) antennas can be several kilometres or more with line-of-sight.

Wi-Fi performance decreases roughly quadratically as the range increases at constant radiation levels.

Due to reach requirements for wireless LAN applications, power consumption is fairly high compared to some other low-bandwidth standards. Especially Zigbee and Bluetooth supporting wireless PAN applications refer to much lesser propagation range of <10m (ref. e.g. IEEE Std. 802.15.4 section 1.2 scope). The high power consumption of Wi-Fi makes battery life a concern for mobile devices.


Mobility

Speed vs. Mobility of wireless systems: Wi-Fi, HSPA, UMTS, GSMBecause of the very limited practical range of Wi-Fi, mobile use is essentially confined to such applications as inventory taking machines in warehouses or retail spaces, barcode reading devices at check-out stands or receiving / shipping stations. Mobile use of Wi-Fi over wider ranges is limited to move, use, move, as for instance in an automobile moving from one hotspot to another (Wardriving). Other wireless technologies are more suitable as illustrated in the graphic.