802.11a through z: the latest wireless networking technology

MIMO

As mentioned, the future 802.11n standard -though implementation remains vague- is based on the so-called MIMO technology. MIMO stands for Multiple Input Multiple Output and works with several antennas on the transmission as well as the reception side of things. The technology uses the until now shunned side-effect of wireless communication: when data is sent from a wireless access point to a PC, the generated radio waves will reach the PC several times. If it's possible, the signal will travel just once directly, but seeing as radio waves bounce from walls or furniture all transmitted signals will reach the receiver with some delay and loss of strength. Manufacturers have tried to minimise this side-effect and thus conventional WLAN products are designed to work with just the largest and therefore most direct radio wave. It must not be underestimated how much potential broadcasting power is wasted in this system.

MIMO works with several antennas that all send different packages of data at the same time. The receiver also has multiple antennas that collect the different signals and their respective reflections. Instead of trying to marginalise reflections, a MIMO receiver makes use of them to determine which data was sent at the same time. By optimising use of reflections and transmitting several packages at the same time, MIMO can first of all create higher transfer rates and secondly improves the coverage, especially with many obstacles between the transmitter and the receiver.

MIMO manages to improve bandwidth and range of wireless networks by also using the reflections of radio waves.