Wednesday, April 11, 2012

802.11ac WiFi technology can provide gigabit speed for businesses?

Comments on the 802.11ac are in full swing, but you should not believe everything you read. The latest innovation in WiFi, the 802.11ac still a draft, should be integrated into enterprise WiFi products before 2013 and residential products even sooner.

The standard has been dubbed WiFi Gigabit and, indeed, is what it will be the largest market for WiFi, residential. But is that technology can offer gigabit speeds for business? No way.

Defined only by the frequency of high-capacity 5 GHz (495MHz), the 802.11ac offers a series of new techniques such as advanced modulation and coding, multiuser MIMO channels, and linking. Theoretically, the manufacturers claim can dramatically improve the ability of WiFi will be?

Undoubtedly, the 802.11ac is a great innovation, but like any great innovation, the danger usually is in the details. We present some details that can help demystify the 802.11ac.

 Eight channels space

A major innovation came with the WiFi space 802.11n and the spatial multiplexer, using a technique called MIMO (multiple input, multiple output). With this technology, an access point can send multiple spatial channels for a client to increase its capacity. The specification 802.11n provides up to four spatial channels.

Multiuser MIMO

802.11n presented MIMO (Multiple Input Multiple Output), which is the use of multiple antennas at the transmitter and receiver in order to increase data traffic without additional bandwidth or higher transmission power. Basically, the system spreads throughout the transmission power for all the antennas more bits per second per hertz bandwidth, with the additional benefit of improved reliability due to the great diversity of the antenna. With 802.11n, MIMO could only be used by a single client at any time. The 802.11ac is an attempt to improve this with the so-called "multi-user MIMO (MU)."

Thus, the access point may transmit 802.11ac two (or more depending on the number of radio stations) spatial channels to two or more client devices. This can represent a great advance, but is optional. And the first 802.11ac chips should not support this function. Furthermore, it is very likely that the MIME-MU not be implemented due to the complexity and configuration of the radio MAC addresses.

 Only 5GHz
Due to the approach adopted by 11AC, to achieve all of this speed (channel binding), it makes sense to support the frequency of 2.4 GHz, which has only three of 11 non-overlapping channels. This is a great news. This means that devices that want 11AC (and everyone should want to) have the ability to 5GHz. Today, a very low percentage of these devices have the ability to transmit at 5GHz, which is a shame. Now, all devices will be required to include this feature.
Linking of channels
A simple and efficient method to increase the speed of any radio communication is to use more often. For people who are not professionals, this is known as bandwidth. To get more bandwidth, 802.11n introduced binding channels: the ability to combine two 20MHz channels to work with only a single channel - basically a longer way to transmit WiFi signals This doubled the rate of transmission available.
When you create and implement a WiFi network to high densities, the preferred option is to use more channels rather than a smaller number of larger channels. Increase the number of devices occupying a single channel within a specific area reduces the efficiency of WiFi, and that's why people like wires, because each device has its own channel and no other device is occupying that channel (copper or fiber). Therefore, we obtain an immense transmission rate.
The adoption of 802.11ac in homes is a different case. It is preferable to link the channel to the 160MHz, because few devices are trying to access a single AP.
The situation is different in business. There, many APs are needed to support hundreds or thousands of users, and these APs must be allocated to different channels, as far as possible.
Ironically, the 802.11ac should prolong the viability of current 802.11n networks. With more and more customers operating in 5GHz, capacity and performance should increase with no impact on the infrastructure. This is the best news of all.

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