[mythtv-users] Does your wireless work better than mine?

Jim Cuzella TrinitronX at gmail.com
Mon Jan 19 04:19:39 UTC 2009


Travis Tabbal wrote:
> I've tried wireless G without a hop in the middle and it couldn't
> handle it. And I don't have neighboors running wireless to interfere.
> Wireless G, IMO, isn't up to the challenge. A hop will make it worse,
> not better. The router in the middle has to receive a packet, store
> it, and re-transmit it to the next machine. That's where the 1/2 speed
> penalty comes in when people are doing that. Only one device can
> transmit at a time on wireless, so everything has to wait while one
> station transmits. Wired networks (switched) don't have this problem.
> An HD stream is about 20 mbit/sec, that's about what most wireless G
> networks can handle with some interference or walls, etc.. If you get
> any other traffic at all on the network, even DHCP and ARP requests,
> you won't be able to get the streams through without loss. Since
> you're streaming, you can't afford to wait and re-transmit. Don't
> worry too much about the connection speed reported by the wireless
> stuff. It really doesn't mean anything. There is a ton of overhead
> involved that they don't tell you about. Just because they SAY it's
> connected at 54 Mbit/sec, that doesn't mean you can get that much data
> to the other end.
>
There are ways to squeeze every last drop out of your wireless
connection.  For instance, with my old setup I had a 14 dbi high gain
directional antenna connected to my desktop's wireless card.  This
allowed me to get an excellent signal to the router from that machine,
even with other clients connected.  In essence, the high gain signal
would allow this one machine to "talk over" other clients on the
network... essentially a hardware form of "psuedo-QoS" with no CPU
overhead for that client.  I had also set it to be on a channel
currently not in use by neighbors.  I rarely saw anything below 54
Mbit/sec on the speed stats.  The main router is a WHR-54-HP running
dd-wrt.  The 4dbi omnidirectional antenna on this AP with the internal
amplifier circuits are awesome :-D.  Plus, it doesn't hurt that dd-wrt
supports adjustment of Tx power.
> Short version, wireless sucks for this sort of thing, run the
> cat5/cat6. Even powerline devices would probably be better.
I'd have to disagree if you have the right equipment.  However, the
performance you'll see most definitely has *everything* to do with your
equipment!  I do admit my hardware is an "edge case", and most people's
routers are not hacked up like mine to allow for this excellent
performance.  Still, the max rated speeds for things like HomePlug also
vary due to hardware standards in the range of 14-189 Mbps.  So if you
have the right hardware setup & antennae, 802.11g can give better
performance than these network over power line solutions currently on
the market.

Of course, so far cat6 with gigabit ethernet wins over all these
technologies.  Wireless N currently fits in between 802.11g and cat6
with ratings of 600 Mbps.  Note that most 802.11n products currently on
the market are "draft n", and are not guaranteed to be fully standards
compliant.

Here's a quick breakdown of *Rated* speeds (YMMV):
HomePlug 1.0 - Theoretical speed 14 Mbit/s
HomePlug 1.0 "Turbo" - 85 Mbit/s
HomePlug "AV" - 189 Mbit/s  (Dumb overhead due to mandatory encryption
of HD signals... Defective By Design!)
802.11b - 11 Mbit/s
802.11a - 54 Mbit/s
802.11g - 54 Mbit/s
10BASE-T - 10 Mbit/s
100BASE-TX - 100 Mbit/s
802.11n - 600Mbit/s
1000BASE-T - 1000 Mbit/s (1 Gbit/s speeds require cat5e or cat6 w/ <
100m cable length)

Cheers,
- Jim C.

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