Using SR71-15 as a major backhaul link for WISP

[wispwest]

Hi,

We are currently in the process of negotiating co-location on 3 of Alltel's towers in Montana to complete a major backhaul that will stretch a total of 102 Miles and consist of the following hops lengths:

Link1 10.3Miles
Link2 24.4Miles
Link3 30 Miles
Link4 25.8 Miles
Link5 11 Miles

We have a contract allowing us (2) 3ft 5ghz Radomes on each tower. I've heard that the SR71-15 is a MIMO card and it requires 2 antennas? Can we get by with just 1 radome per radio?

My second question is what do you think the latency will be after 100 miles of backhauling?

My third question is, this is a fairly new product, does anyone know how reliable it is? The extended temp version lists a HIGHER temp, but no LOWER temp, this mountain-top towers in the rockies get to -30f in the winter, and I'LL be the one snowmobiling up to them when **** goes down....

Thanks alot for any help/advise. I'm used to using Trango and Canopy backhauls, but I'm mouth-watering over a connectorized affordable 5.4Ghz backhaul!

[wispwest]

Oh, I forgot to mention, we don't plan on using the full 300Mbps speed. I'll probably turn it down to 108Mbps or whatever. Although, if we require dual antenna's for MIMO, we'll probably just use the 802.11A 54Mbps...

[J_Hughes]

Hi.
To fully utilize the advantages of using SR71 you will WANT to use more than one antenna. However, you have not mentioned a dual-pol dish - this is what I would recomend -

As for your Backhaul links, I'm using XR5's on RB/600's for a 20mile hop and seeing around 1-10ms latency avg. I also live in northern Wisconsin and it hit -30 this winter and there were no problems.

Can't speak for the SR71 though, there are a couble reports here that it can achieve 80-100mbps (half duplex) with dual-polarity dishs - and I would have tried it allready but it is not supported by Mikrotik yet.

[wirelessrudy]

My second question is what do you think the latency will be after 100 miles of backhauling?



Radiowaves travel with the speed of light. So the lenght of a radio link doesn't have noticeable latency differences on the pure radio waves if we talk distances we can achieve within the present freq. bands and power limits.

Latency in netwoks is more a result of a mix of lots of factors.
Data processing in the router, the amount of data to process, the quality of used radio's, the quality of a radio link (data losses!), interferences/noise (data losses), QoS etc.
Basically a 100 mile link can have the same low latency as a 10 meter link.

Provided you would have the means and no power limits you could set up a 5Ghz link to the moon and have an ´almost´ real time Skype conversation with camera with your technician over there! Maybe a better quality call then I sometimes come across here on mother earth!

R.

[MRojas]

Probably about 20-30ms tops. Of course, it all really depends on your hardware. For example, with certain Canopy backhauls you can't get less than 20ms... no matter how clean or short the link is.

Your average latency will vary, though, because noise comes and goes. Plus, your routers at every hop will add a bit more.

Of course, if you could spend a gazillion dollars, there are systems that could probably cut that in half if not more.