In a couple of years, crossing the 1Gbps threshold with a WiFi access point will be routine. That access point will likely have two radios, one for each major spectrum band, and support a host of older flavors for compatibility. Eventually, WiFi will approach the robustness and speed needed to make it a completely viable replacement for Ethernet for most users.
In today's pipeline are optional enhancements to 802.11n that have been in the works since the standard stabilized at the IEEE engineering group nearly three years ago. These enhancements will increase range and performance by up to a couple orders of magnitude, offering raw data rates of 450 Mbps and 600 Mbps.
The slated improvements will also correct for black holes, where current 802.11n gear's signals don't reach unless an excessive amount of overlapping devices are installed at relatively high expense. Even better, the boosts to 802.11n are just the start. A new IEEE committee is working on fast WiFi that will hit a raw encoding rate of 1 gigabit per second (Gbps).
All these higher speeds will be eminently affordable and reasonable choices for small-to-medium-sized businesses. It may even be possible to achieve higher performance (both for speed and network consistency) by spending less than a network upgrade would cost today: fewer, more powerful access points with better coverage may wind up saving money.
The need isn't always for speed: it may be better to have a network that works in the worst circumstances, with tons of users moving lots of data, than to move additional raw data. With the popularity of watching video (for business purposes, no less), the growth in the size of standard document files, continuous network backups, and other network loads, network capacity, quality, and support for simultaneous users and heavy-load applications will become increasingly important.
Faster WiFi paradoxically also means that more wired infrastructure is needed. With individual access points able to pump out a dual-band total of several hundreds Mbps, and future dual-band devices topping 1 Gbps, more robust and higher-performance backhaul will also be needed.
From a tiny nut, a great oak
The 802.11n standard has come a long way from its contentious origins, when MIMO (multiple in, multiple out) antenna arrays were seen as impractical, expensive, and beside the point of pushing data over the air. Now, in addition to 802.11n, all 3.5G and 4G cellular wireless standards either require or allow the use of MIMO for better coverage and performance.
At a time when 802.11g could only deliver 20 to 30 Mbps of real throughput out of a potential 54Mbps raw data or "symbol" rate, the idea of 150Mbps with 75 to 100 Mbps of actual throughput was pretty stunning.
But it got better. By the time manufacturers coalesced their efforts—after a cantankerous process—around a single approach for 802.11n, it was clear that all access points and adapters would support two radio streams, each of which would be able to handle a raw rate of 150 Mbps, for a combined 300 Mbps.
Each stream is a chain of radio components that share antennas. For sending, each stream transmits uniquely and simultaneously across space, using signal reflection in the environment in the same way that a billiards player uses bumpers to strike a ball. This is called spatial multiplexing: multiple signals encoded using space as a parameter. A receiver decodes the signals across multiple antennas, dumping each stream into a unique radio chain.
A receiver with a like number of radio chains, and often a similar number of antennas, can interpret the directionality of signals, sifting out separate streams to reconstruct the original message.
For instance, a 2x2 (two transmit, two receive) antenna array is often paired with two radio streams, or a 3x3 with three radio streams. Some devices with two radio streams might have 2x3 arrays, in which three receive antennas are used to improve signal differentiation and range.
Two chains is good. But what about three? Or four? These optional enhancements to 802.11n were eminently possible, but with the exception of wireless chipmaker Marvell and startup Quantenna, most firms sat out the dance, waiting for a shoe to drop: interoperable certification from the WiFi Alliance. (Read More)
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