« September 2007 | Main | November 2007 »

October 04, 2007

What's up with MIMO? - Part Deux

In my first episode on MIMO (What's up with MIMO), I introduced the concept of multiple antennas and the home audio analogy. In this example, I discussed one particular mode of MIMO that transmits the same stream across all antennas, and makes use of multipath to increase the chance of correctly decoding the received signal - thus lowering the bit error rate. This method exploits what is known as spatial diversity, which is one of the simplest method to achieve MIMO gains. But MIMO is much more than that.

There is also another mode of MIMO that is ideal in environments that experience few errors, which is called spatial multiplexing. In this mode, the transmitter would treat each antenna as a "separate channel" - much like you would experience in a 5 channel home audio system. These systems send the audio stream that provides directionality to the whole experience. Of course, in MIMO systems, we don't care much about directionality, but we certainly care about sending multiple streams to increase the overall effective bandwidth.

So for instance, if an AP wanted to send a packet, it could split the packet up into three "chunks", and transmit each "chunk" across each of its three antennas simultaneously. This would effectively reduce the transmit time - and therefore increase the overall capacity of the network.

Posted by Pat Calhoun at 11:26 AM Permalink | Comments (4) | TrackBacks (0)

October 02, 2007

What's mobility to an SMB?

When it comes to WLAN applications, small and medium businesses clearly have a different set of priorities than enterprise customers. In a much more direct way, their IT strategy (if there is one) is driven by immediate business needs. For example, I recently spoke with the administrator of a small medical group. He needs to move the clinic from a paper based operation to an electronic medical records system. His key business problem is moving paper charts around – across multiple sites. To use his words, it’s a nightmare. This medical group has no wireless network today. Security continues to be his greatest concern. However, when they do implement an EMR system in the next 6 months, it will drive the need for a pervasive, reliable, and of course secure wireless network.

So how’s this different then enterprise? He’s not even thinking about niceties such as guest access, VoWLAN, location or asset tracking. His mobility application is EMR, plain and simple. He readily ticks off the benefits from improved staff productivity, more accurate records, and therefore better patient care.

BTW – his most trusted technical advisor is his son. He has one outsourced, part time IT guy. And he still needs to figure out what it means to be HIPAA compliant in a wireless world.

Posted by Georganne Benesch at 10:04 PM Permalink | Comments (1) | TrackBacks (0)