Wim, Welcome to the wonderful world of unlicensed spectrum!
*********** REPLY SEPARATOR ***********
On 2003-Dec-11 at 6:15 PM wbos wrote:
>Before everybody jumps to this.
>
>We have a network in the Netherlands and implemented a g backhaul + an a
>backhaul solutions. We have set up 5 5ghz links now and really got
>frustrated on this frequency. A with Tsunami and Lancom equipment. The
>technology basically does not support the hype yet.
>
>The G radio had a lower throughput than the Karlnet product with an Agere
>(orinoco) B radio. It was exactly 1/5 off the throughput. That was on a 3
>km
>link with perfect radio connection. You also have to keep in mind that with
>the ofdm, you can not use all 4 frequencies in the 2.4 ghz band.
>The major reason is the lower receiver sensitivity off the current G cards
>on the market (Advertized?? 54 Mbps: -66 dBm 802.11g 802.11b: 22 Mbps: -78
>dBm
>11 Mbps: -80 dBm.) A second problem is that the filtering off the receive
>signal is bad so a lot off disturbance form GSM sites on the network and
>the
>output signal is not stable as well causing channel seperation issues in
>the
>network.
>
>A good link that shows it for the different radio products on a b product
>is: http://www.antennspecialisten.se/en/support/t1_spektrum.html
>
>The a links are quite disappointing as well. We have disturbance from a
>radar in the area. Same problem, any frequency in the area off the 5 ghz
>overpowers the radio and disturbs the link. This is really a design problem
>in the radio's. We are trying to build a filter in the antenna to improve
>that. We know that the new radio's coming out in Q1 will have a much better
>receiver sensitivity and better filtering providing a solution for that
>problem.
>
>We also found out that the radio's is transmitting over several channels
>(similar to the bad b radio's) causing channel seperation issues.
>
>Bottom line is that we found that the technology does not support the hype
>yet.
>
>We have two 5 ghz links working now with their troubles involved. It is not
>possible to combine more from one point or tower due to the problems
>described above. Despite all the nice sales materials from Tsunami or
>others. So as long as you keep it to one link to two links from a tower
>only, you are OK. You can not use the advertized higher number. Also the
>throughput is limited, higher than the b though.
>
>Wim Bos
_______________________________________________
Karlnet mailing list
Karlnet@WISPNotes.com
http://lists.wispnotes.com/mailman/listinfo/karlnet
|