[mythtv-users] Wireless Pre-N for Linux?

gchris gchris at bellsouth.net
Mon Mar 26 16:49:40 UTC 2007

On 3/26/07, Jarod Wilson wrote:
>> On 3/25/07, William Munson <william_munson at bellsouth.net> wrote:
>>> > > Ken Mandelberg wrote:
>>>> > > > My 802.11G wireless setup is just two slow for HD between the front and
>>>> > > > backends. Are their Pre-N solutions with Linux drivers (USB, PC card
>>> > >
>>> > > nics)?
>>> > > There are a number of wireless solutions for linux however its still not
>>> > > going to allow you to view HD over a wireless network. 802.11G is just
>>> > > not fast enough.  From what I can see, the only option is cat5/6 cable.
>> >
>> > Will 108Mbit do it?  With a matching (D-LINK) wireless router, the D-Link
>> > DWL-820 will do 108Mbit.  It's a wireless gaming adapter that plugs into
>> > the ethernet port, so it doesn't need drivers.
>> >
>> > http://www.mythpvr.com/mythtv/hardware/wireless_gaming_adapter-802.11g.html
>> >
>> > I use it with a standard 54g network, so I can't really speak to the 108
>> > aspects, but it says it does it.  I use mine for a SD MiniMyth frontend.
> You might have better results with the supposed 108Mbps stuff. I'd suggest 
> trying a file transfer benchmark. Simply scp a large file over your 
> connection and see what sort of throughput you get, taking note along the way 
> of any stalls, drops in speed, etc.
>> > Come to think of it 108Mbit is higher than 100Mbit, so looking at the raw
>> > numbers, your 100Mbit ethernet would be the bottleneck.  In practice, I bet
>> > the wireless has overhead that eats up a chunk of the bandwidth before
>> > getting to ethernet.  Hmm...not like it really matters.
> Wireless bandwidth claims are a joke -- more marketing bullshit than fact. 
> Unless you have a clean line of sight and zero interference, good luck 
> getting even *half* of the supposed throughput. I've got an 802.11g bridge at 
> home, Linksys WAP54G as the base station on the main floor, Linksys WRT54GS 
> as the bridge device upstairs, not much in between them but the 
> ceiling/floor. Very typical setup someone would have in a home, and I can't 
> get anything better than about 20Mbps sustained throughput.
There are some additional considerations.  The D-Link 108Mb adapters 
require two clear channels and an unimpeded path to come close to 
achieving their rated speed.  Even if the adapters have a clear line of 
sight between them, interference from a neighbors wifi network can make 
108Mb iffy, and my experience with these cards suggests that only a 
small improvement over 54Mb cards is the norm.

Using an external game adapter or a spare router configured as a network 
bridge works better for two reasons.  Placing a wifi adapter inside your 
backend can desensitize some TV capture cards.  My HD3000s see reported 
signal strength drop 8-12% when a D-Link DWL G520 is installed next to 
them in the backend.  Also, an external wifi adapter allows you to 
optimize antenna placement in ways that are impossible when you've got a 
card plugged inside the box and it also saves a slot and reduces power 
and cooling requirements.  Beware of game adapters that use a USB 
connection because Linux drivers are not easy to come by for that kind 
of setup.

I used a D-Link DWL-G132 USB dongle very successfully for SD with a Suse 
box and Linuxant drivers.  Unfortunately, Fedora kernels use a small 4k 
stack size which is not amenable to the Linuxant drivers.

Bottom line, a wired connection is still the cheapest and most reliable 
connection for distributing HD.


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