Tuesday, November 9, 2010

7Gbps wireless a step backwards?

A lot of noise is being made over the new 7Gbps WiGig standard, which, at first glance, is about a thousand times faster than my laptop gets at home.  This has gotta be good, right?

Well, as is typical of anything having to do with wireless, the real story is a lot more complicated than just peak bandwidth.  The range is just terrible compared to even 802.11B, with full performance only achieved within a 15-foot radius with line-of-sight - and don't think about transmitting through walls because the bandwidth  will be awful if the connection doesn't completely drop.  This is played up as a good thing, because it prevents neighbors from stepping on each other's bandwidth, but that also makes it unsuitable for most in-home purposes as well.

The practical uses of such bandwidth are also hard to come by.  Most hard drives won't read much faster than 60GB/sec in sequential mode, which is 480mbps, or about 1/15th the bandwidth for which WiGig has been designed.   Sequential read speeds for blazing fast SSD hard drives are only 2gbps, still not pushing the limit.  A favorite scenario that is often cited is the ability to transfer a Blu-ray in under a minute - but, ignoring the fact that movies would have to be decrypted, the fastest Blu-ray drives are 12x, where 1x is equal to 4.5MB/sec, 12x is 54MB/sec, or 432mbps; i.e. also less than 1/15th the optimial WiGig speed.  And let's not get started on the abysmal "broadband" speeds in the U.S. for which existing WiFi is already overpowered - where I pay $60/month for 20mbps and in reality get 5mbps (a data rate that transfers just fine on 7-year-old 802.11B cards) - or about 1,000x slower than WiGig.

I'm not saying WiGig won't be great for connecting external screens (in the same room) wirelessly, because it will be, but that is a fairly niche purpose.  In fact, people don't plug in devices to screens all that often (a friend bringing over the new PlayStation would be an exception, but that only happens once every ten years, right?), so WiGig isn't really replacing wires, it's just making things wireless that most of us rarely do to begin with.

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