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100dbm
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20MHz 40MHz 60MHz . . . . 160MHz - Up-to 400Mbit/s!!

Wed Jan 17, 2007 10:21 pm

Why MikroTik not support the biger modulation channels?
The AirTegrity 3200 Series use 20MHz channels using OFDM Modulation. When operating in Turbo Mode these 20MHz channels expand to 40MHz wide to offer twice the throughput. The AV3205 supports two radios to further enhance throughput. Using two radios both operating in Turbo mode allows bitrate transfer speeds up to 216 Mbps.
Lobometrics series OSC 800 : Here
High load system central CPU and up to 400.0Mbps links
Up to 4 parallel transmitting radios with CW (Channel Width) from 20MHz to 160MHz
Transmit powers from 26.0db to 26.0db
Max. receive sensibilities from 105.0dBi to 105.0dBi
Outdoor/Indoor systems
 
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savagedavid
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Wed Jan 17, 2007 11:23 pm

Using nstreme dual and / or bonding you can achieve the same results. Turbo mode automatically uses double the bandwidth.
 
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100dbm
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Thu Jan 18, 2007 12:24 am

I know this, but this is software.. my question about OFDM modulation channel change from 20 to 40 .. or 40 to 80 .. when the signal is good ( -60 ~ -68 ) we can use biger channel on "single" wifi card, and have more bandwith without software compressions .. more that i don't want to use this link on super range :) i want to use on maximum 1 km.

what you think about this?
 
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stephenpatrick
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Thu Jan 18, 2007 1:32 am

Actually both product websites are **highly misleading**.
In both cases they appear to be using standard Atheros chipset cards running in Turbo modes, 40MHz channels giving raw bit rates of 108Mbps using OFDM QAM64 mode.
I don't understand the "QAM256" claim on airtegrity's website, that does not correspond either to the chipset (QAM64 max) or the quoted performance of 2x108Mbps from 2 cards aggregated.
Check http://en.wikipedia.org/wiki/802.11a which shows non-turbo modes
and http://www.atheros.com/pt/AR5006XS.htm for the current Atheros5414 as used in R52 etc.

Simply aggregating channels from adjacent cards is not new, MT themselves have the record with 4 turbo channels in parallel, results are on the wiki. And yes, with the right hardware you can do that with a single high speed x86 platform running RouterOS.
Such platforms are available, my co. demonstrated 200Mbps P2MP net throughput on own-brand 1GHz passively-cooled platforms running RouterOS.
However, there are practical issues in finding enough clear RF channels and potentially multiple dual-polar antennas required to implement bonded P2P links.

Compared to current-generation Atheros chipsets, stepping into the world of licensed microwave it is possible to run higher modulation schemes such as 128QAM to give 311Mbps throughput and so-called XPIC (cross-polar interference cancellation) implementing 128QAM simultaneously on H and V polarisations for 622Mbps FDX throughput etc.
However, that only works in low-noise no-interference environments, **not** in unlicensed bands (except perhaps in remote rural areas).

That being said, I gather MT is working on 802.11n chipset implementations which do have higher spectral density/throughput than current Atheros cards, and we all look forward to seeing that.

Regards

CableFree Solutions
CableFree - Wireless Excellence - Microwave, E-band Radios, Free Space Optics, High performance Radios & Routers
http://www.cablefree.net
 
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100dbm
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Fri Jan 19, 2007 7:53 pm

thank you for full-fledged answer!
Sorry for my bad english, i translate with computer translator :)
yes! you are right, with biger bandwith can work only in low-noise environments.
but I think possible to do option 128QAM or 256QAM, to example for client which use parabolic dish (on point - point connections) or distance less 500m, or if client have license on low-noise channel

I have gained DWL-G520M - MIMO, Chipset - AR5513 - 2.4 GHz
and hoped that MikroTik will work with this chip, for planning future lines on these device 2.4GHz / 5GHz models
AR5513 - this is AR5006x chipset or AR5008x chipset (802.11n)??

is this possible to see the test versions for 802.11n on February?
 
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100dbm
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Fri Jan 19, 2007 8:47 pm

I have found that AR5513 - is AR5005VA chipset... and why Mikrotik does not support this chipset?
AR5513 Multi-Radio Smart Antenna Video Processor

Integrated video/audio controller support with direct interfaces, host capability, MPEG and DMA acceleration to popular HDTV, SDTV, DVR, STB chipsets
Supports Multiple DVD-quality (6-8Mbps) or combination of HDTV-quality (19-24Mbps) and DVD-quality wireless connections
Multiple Radio Smart Antenna support with Transmit Beamforming and Receive Combining
Enhanced Quality of Service with Hardware Packet Jitter Control, MPEG Transport Stream Aggregation, and MPEG Encapsulation
Hardware accelerated AES encryption provides security and digital media content protection
Integrated MIPS R4000-class processor (180 MHz)
Super AG® support for 108Mbps data links
AR5112 Dual Band Radio-on-a-Chip

All CMOS dual band radio chip
Multiple Radio Smart Antenna Support for Two and Four
Antenna Configurations
Support for IEEE 802.11a, 802.11b, 802.11g
Operates from 2.300 - 2.500 GHz and 4.900 - 5.850 GHz
Eliminates all IF filters and most RF filters; no external voltage-controlled oscillators (VCOs) or surface acoustic wave (SAW) filters needed
Industry-leading receive sensitivity, transmit power and
multipath tolerance AR5523 Multiprotocol MAC/baseband processor

I can solder 4 sectoral antenna in one (omni) on this device ! very nice for omni :)
 
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stephenpatrick
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Fri Jan 19, 2007 11:07 pm

... actually just checking all the latest Atheros chipsets, including XSPAN (draft 802.11n) the maximum modulation rate seems to be 64QAM

http://www.atheros.com/pt/AR50083NX.htm
OFDM with BPSK, QPSK, 16 QAM, 64 QAM; DBPSK, DQPSK, CCK
and the 5005VA seems the same.

Checking 802.11n draft specs, seems 64QAM is the max modulation.

So AFAIK the "improvement" isn't higher order modulation, it's through MIMO, space-time block codes, and the 40MHz wide channel.

Regards

CableFree Solutions
 
cuccio
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Re: 20MHz 40MHz 60MHz . . . . 160MHz - Up-to 400Mbit/s!!

Wed Mar 14, 2007 5:05 pm

Lobometrics series OSC 800 : Here
High load system central CPU and up to 400.0Mbps links
Up to 4 parallel transmitting radios with CW (Channel Width) from 20MHz to 160MHz
Transmit powers from 26.0db to 26.0db
Max. receive sensibilities from 105.0dBi to 105.0dBi
Outdoor/Indoor systems
[/quote]

Lobometrics is Mikrotik based, the system is based on routing.

Best regard
Cuccio
 
nuclearcat
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Thu Mar 15, 2007 12:48 am

I heard many times, that some developers did on Atheros SoC+vxworks support for more than 40 Mhz. So in theory it must be possible. But i didnt heard about QAM256.

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