It is generally recommended that one
IEEE 802.11 AP should have, at a maximum, 10–25 clients. However, the actual maximum number of clients that can be supported can vary significantly depending on several factors, such as type of APs in use, density of client environment, desired client throughput, etc. The range of
communication can also vary significantly, depending on such variables as indoor or outdoor placement, height above ground, nearby obstructions, other electronic devices that might actively interfere with the signal by broadcasting on the same frequency, type of
antenna, the current weather, operating
radio frequency, and the power output of devices. Network designers can extend the range of APs through the use of
repeaters, which
amplify a radio signal, and
reflectors, which only bounce it. In experimental conditions, wireless networking has operated over distances of several hundred kilometers. Most jurisdictions have only a limited number of frequencies legally available for use by wireless networks. Usually, adjacent APs will use different frequencies (channels) to communicate with their clients in order to avoid
interference between the two nearby systems. Wireless devices can "listen" for data traffic on other frequencies, and can rapidly switch from one frequency to another to achieve better reception. However, the limited number of frequencies becomes problematic in crowded downtown areas with tall buildings using multiple APs. In such an
environment, signal overlap becomes an issue causing interference, which results in signal degradation and data errors. Wireless networking lags wired networking in terms of increasing
bandwidth and
throughput. While (as of 2013) high-density
256-QAM modulation, 3-antenna wireless devices for the consumer market can reach sustained real-world speeds of some 240 Mbit/s at 13 m behind two standing walls (
NLOS) depending on their nature or 360 Mbit/s at 10 m line of sight or 380 Mbit/s at 2 m line of sight (
IEEE 802.11ac) or 20 to 25 Mbit/s at 2 m line of sight (
IEEE 802.11g), wired hardware of similar cost reaches closer to 1000 Mbit/s up to specified distance of 100 m with twisted-pair cabling in optimal conditions (
Category 5 (known as Cat-5) or better cabling with
Gigabit Ethernet). One impediment to increasing the speed of wireless communications comes from
Wi-Fi's use of a shared communications medium: Thus, two stations in infrastructure mode that are communicating with each other even over the same AP must have each and every frame transmitted twice: from the sender to the AP, then from the AP to the receiver. This approximately halves the effective bandwidth, so an AP is only able to use somewhat less than half the actual over-the-air rate for data throughput. Thus a typical 54 Mbit/s wireless connection actually carries
TCP/IP data at 20 to 25 Mbit/s. Users of legacy wired networks expect faster speeds, and people using wireless connections keenly want to see the wireless networks catch up. By 2012, 802.11n based access points and client devices have already taken a fair share of the marketplace and with the
finalization of the 802.11n standard in 2009 inherent problems integrating products from different vendors are less prevalent. == Security ==