macworld news antenna

IEEE approves the following draft 802.11n

The draft has been voted favorably by about 83 percent of the members of the working group, although 75 percent would have already been sufficient for approval. The vote indicates that after more than a year of debate, the group has already agreed beyond the issues relating to the core of the technology.

One practical effect is that manufacturers of WLAN adapters and access points may introduce products that should not require significant changes once the standard is licensed.

The Wi-Fi Alliance announced last year that it was preparing an interoperability test program for the second draft equipment. Alliance representatives have indicated that if the second draft was approved later this month, as planned, then testing would begin in June 2007 or even earlier.

The heart of the new standard consists of a technique called MIMO (multiple inputs, multiple outputs). MIMO takes a data stream by dividing it into several independent streams to transmit over two or more antennas. The streams are received by two or more antennas and rejoin into the original stream. Due to how the process is carried out, and the way in which MIMO antennas exploit radio reflections (called “multipath”), it is possible to pack more information into these transmissions.

The IEEE standard originally pursued a minimum data flow greater than 100 Mbps; Although the products called “draft 1” or “pre-11n” available in the market were already capable of providing between 140 and 160 Mbps. With more antennas, more power and some adjustments, several manufacturers hope to reach around 200 Mbps or even higher figures.

Currently there are two main products incorporating 802.11n: the AirPort Extreme base station as well as the upcoming Apple TV, in addition to the current range of Apple equipment with AirPort cards as standard.