Hello ppl!
I need to setup a link 7km and my client asked me to give him 3 options

1) a link that it be able to provide 30mbps of real bandwith
2) a link that it will be able to provide 50 mbps of real bandwith
3) a link that will be able to provide 100mbps of real bandwith ?

im open to your sugestions!


Thank you advance!

P.S so far i have setup 7 links all with rb411 routerboards , r52nm mini pci cards
and 23 db panels that seems to be working pretty well (not even a single call from a client)
but this configuration seems to be able to give me a max of 20mbps on send or receive and about 10mbps on both send-receive

1) 411AH, R52nM, single chain, 20MHz, nstreme (or nv2) and single polarity 32dBi solid dish antenna.
2) 411AH, R52nM, single chain, 40MHz, nstreme (or nv2) and single polarity 32dBi solid dish antenna.
3) 411AH, R52nM, dual chain, 40MHz, nstreme (or nv2) and dual polarity 32dBi solid dish antenna.

When you see wireless bandwidth you're normally getting an aggregate number that is the total of send and receive together.

So applied to wireless systems you're looking for.
1) 60Mbps
2) 100Mbps
3) 200Mbps

The advertised numbers of wireless systems may match this, but those are theoretical maximums for perfect links. You will rarely, if ever, see anything close to it.

Every link is different so there's no 100% guarantee that if you use X gear you will get X performance. It's very likely you'll have to use multiple radios and links bonded together to get those speeds. With that in mind you'll want to look at something like the RB433, R52Hn and good quality dual polarity antennas. That'll give you the option of adding more radios should you need it, and you likely will.

The only way to truly tell what kind of performance you'll get out of a link is to set it up and see.

thank you both for your replys

tsatasos quite cover me

one last question

if i want to setup a point to multipoint link for example

1 point to 3 points that will be able to give me 30 mbps of actual bandwith (at least theoriticaly) should i

1) setup 3 diferent pairs of links with rb41ha with r52nm cards
2) setup a single point with rb433 routerboard and 3 r52nm and rb411ah with r52nm on the other 3 spots?

thank you in advance

1) 411AH, R52nM, single chain, 20MHz, nstreme (or nv2) and single polarity 32dBi solid dish antenna.
2) 411AH, R52nM, single chain, 40MHz, nstreme (or nv2) and single polarity 32dBi solid dish antenna.
3) 411AH, R52nM, dual chain, 40MHz, nstreme (or nv2) and dual polarity 32dBi solid dish antenna.

tasos since the r52nm cards are able to provide 23db of tx power why should i use 32dbi antenna ?



P.S karmas edded

power of your wireless card(23dbm) and power of your antenna(32dbi) are two different things.

at 7 Km I suspect you can have a link at 40MHz under city conditions. prolly u need a 100 mtr tower for that. At our place we have to go for 10Mhz to get anything above 5km. and a mast height of around 30 mtr.

Some questions/itms to consider:
- R52nM only has 23dBm output when both chains enabled. With only one chain max. output is 21dBm.
Maybe better use R52Hn cards. They given an extra 2dBm output. (25dBm) or, if allowed, use even higher power cards if needed.
- What are the cable losses (height of tower?) and connector losses?
- Fresnel zone of 2,4Ghz 7km link is only 9 meters. So tower of 10mtrs on both end is sufficient if space in between is flat soil. Make sure you stay at least this distance above all obstacles in the LOS. For 5Ghz slightly smaller Fresnel applies.
- Single chain (802.11a/b/g) with 40Mhz channel width is in most countries (Europe!) not allowed. So make sure that what you do is not illegal!
- Use ´n´ mode dual chain antenna link. This way high throughput can be achieved and although here also 40mhz can be used it is harder to detect by simple scanner so less change of fine by regulating body....
- When using high gain antenna's, also realize in most countries you are stepping over the allowed EIRP of the antenna!
- On the other hand, using very high gain antenna's gives you the option to actually decrease the EIRP of the antenna where the other end would still pick up reasonable signals....
- Interferences of other spectrum usage. How is the situation on that? High gain antenna's together with quality antenna's and shielded radio's will help here as well in avoiding problems.

Does the client need given speeds symmetric? Or only download (cq upload)? In case of symmetric, full duplex or semi? Makes all lots of differences...

I suggest you use a good link budget calculator before any promises/purchases. Many to be found on the web.
Building reliable links is not as simple as some present it.

For more than 30Mb of traffic over the router board if there is some processing to take place on the data (firewall, mangle, routing) will push the rb to high cpu usages.
For 100Mb you really need rb800 at least or you will easy run into problems.
Rule of thumb would be never to exceed 60% of board cpu usage for prolonged times under heaviest circumstances.

For the PtMP option with 30Mb for each client (?, only download, or symmetric?) you really should start thinking of a rb800.

I hope these suggestions are helpful.

Hello again

i missed to say that the area that im setting my links is vergin from noise and inteference

I have succesfully setuped a link of 16km from one small town to another here with rb411, r52nm card and 23db panel with -60 signal on 5ghz and still no problems at all
the heights of the buildings on all my links are no more than 11m and the heigh of the antenna from the building was not more than 3m

interference is not my problem but a good bandwith result

so a final sugestion for hardware on a point to 3 points link with real bandwith of 30mbps ?

thank you in advance


p.s rudy very imformative post! karma added!

1) 411AH, R52nM, single chain, 20MHz, nstreme (or nv2) and single polarity 32dBi solid dish antenna.
2) 411AH, R52nM, single chain, 40MHz, nstreme (or nv2) and single polarity 32dBi solid dish antenna.
3) 411AH, R52nM, dual chain, 40MHz, nstreme (or nv2) and dual polarity 32dBi solid dish antenna.

tasos since the r52nm cards are able to provide 23db of tx power why should i use 32dbi antenna ?

P.S karmas edded

I'm always using the biggest possible antennas for point to point links no matter if the distance is 1, 5, 10 or more kms, because it is better having a big antenna with low tx power than using a small antenna with tx power at max.

I have 2 5-6km links with 80cm offset dishes and 5GHz feeders and i have -60dBs signal strength with 0 tx power, CCQ over 90% at idle, 100% when there is traffic. There is no noise in tha areas. -115dBs

I'm using 433AH and R52nM.

One of them is 802.11n, single chain 40Mhz, nstreme Best Fit 3200, ROS 4.16, over 100Mbps UDP one way, 55Mbps TCP one way with internal Bandwidth test. The link is very very stable. It has over 200 days uptime.

I also have a 12km link with the same equipment, -70dBs with 0 Tx Power and around -60 at 10 Tx Power, 90-100% CCQ, low noise in the area, 802.11a, 20MHz, nstreme Best Fit 3200, ROS 5.4, 45Mbps UDP, 35Mbps TCP. This link can't achive very high uptime (perhaps due to ROS 5.4).

As for your 3 links question, sure it is better using 3x 411AH instead of 1x 433AH, but for 30Mbps it is easier and less expensive using one 433AH with 3x R52nM.

Always keep in mind about noise floors in your area.

PS. Thanks for karma.