Multi-line RF technology

[David2006]

S dnešním oznámením nových AC outdoorových APček přišla i multi-lane RF technology. Nejspíš to pak dají do Nanobeamu a dalších. Snad o pár zastávek zase ujel Mikrotiku vlak... .Co to asi dělá psal dnes Pera:


Guys -- we will reveal more about multi-lane RF technology with time. It is a game changer. Here is the basic idea behind it:

For those of you who go as far back as the PRISM 2.5 chipset and 802.11b days, you might recall that those radios worked much better outdoors in noisy environments...one of the main reason is because the receiver had much better adjacent channel rejection characteristics. If you were operating on Channel 1 for example, the radio would largely tolerate strong co-located signals on Channels 6 and Channels 11.

Fast forward to todays' world of tighty integrated low-cost single chip CMOS zero-IF radios, one of the big weaknesses in these solutions is the poor selectivity and adjacent channel rejection performanc. If signals are relatively high, there is longer such a thing as non-overlapping channels. Even if an AP is on a clean Channel 1 for example, if there are reasonably strong interferers at Channel 6 or Channel 11, the receiver performance will start tanking.

You can't solve this by simply putting channel filters up front on the RF side. Why? Because the fractional Bandwidth of a 20MHz channel at 2.4gHz is too small and very hard to filter tightly unless you use a monster external cavity filter. And even then, the radio becomes locked to single channel operation. So what do you do?



Welcome to Multi-Lane RF Technology...

We put our own synthesizer in front that is tied to the Wifi radio and downconvert the carrier to a 374MHz intermediate frequency (the same IF the old PRISM 2.5 chipset used). By doing this, we have significantly increased the fractional bandwidth of the carrier to allow near brickwall filtering. After filtering, we upconvert the signal back in to the radio.



The results in the lab have been pretty exciting. With an added 30dB+ of adjacent channel rejection through this active filtering design, we are able to get 2-3x the performance in crowded environments. There is a lot more we are going to do with this technology in the coming year.

[raven-il]

S dnešním oznámením nových AC outdoorových APček přišla i multi-lane RF technology. Nejspíš to pak dají do Nanobeamu a dalších. Snad o pár zastávek zase ujel Mikrotiku vlak... .Co to asi dělá psal dnes Pera:


Guys -- we will reveal more about multi-lane RF technology with time. It is a game changer. Here is the basic idea behind it:

For those of you who go as far back as the PRISM 2.5 chipset and 802.11b days, you might recall that those radios worked much better outdoors in noisy environments...one of the main reason is because the receiver had much better adjacent channel rejection characteristics. If you were operating on Channel 1 for example, the radio would largely tolerate strong co-located signals on Channels 6 and Channels 11.

Fast forward to todays' world of tighty integrated low-cost single chip CMOS zero-IF radios, one of the big weaknesses in these solutions is the poor selectivity and adjacent channel rejection performanc. If signals are relatively high, there is longer such a thing as non-overlapping channels. Even if an AP is on a clean Channel 1 for example, if there are reasonably strong interferers at Channel 6 or Channel 11, the receiver performance will start tanking.

You can't solve this by simply putting channel filters up front on the RF side. Why? Because the fractional Bandwidth of a 20MHz channel at 2.4gHz is too small and very hard to filter tightly unless you use a monster external cavity filter. And even then, the radio becomes locked to single channel operation. So what do you do?



Welcome to Multi-Lane RF Technology...

We put our own synthesizer in front that is tied to the Wifi radio and downconvert the carrier to a 374MHz intermediate frequency (the same IF the old PRISM 2.5 chipset used). By doing this, we have significantly increased the fractional bandwidth of the carrier to allow near brickwall filtering. After filtering, we upconvert the signal back in to the radio.



The results in the lab have been pretty exciting. With an added 30dB+ of adjacent channel rejection through this active filtering design, we are able to get 2-3x the performance in crowded environments. There is a lot more we are going to do with this technology in the coming year.

Zajimave, kdo za tim stoji ?

[goblajz]

Zajimave, kdo za tim stoji ?

UBNT http://www.ubnt.com/unifi

[jopo]

predsa PRISM = PRISM od NSA = amici a ich tajna sluzba. pekne zaobaleny nejaky backdoor a mozu sa tesit

[Insider]

Aha, takze vsichni vyrobci na svete se snazi bezet k zero IF, jenom Rob se vraci ke korenum .)

[hapi]

hmm aha takže starý prism chipsety to měli integrovaný do jednoho chipu a oni se tady ohání tím že to dneska nejde? nemělo by se spíš došlápnout na atherosa?

[David2006]

http://dl.ubnt.com/marketing/Tolly21312 ... rmance.pdf

[hapi]

přijde mi divný, že tam maji připojený obyč klienty a ti nemusí mít tuhle technologii.

[Insider]

přijde mi divný, že tam maji připojený obyč klienty a ti nemusí mít tuhle technologii.

Nemusí, protože se klienti mezi sebou nikdy rušit nebudou. Maji jasne definovane time sloty a v těch můžou být "špinaví" jak chtějí. Upřimně je to šlápnutí vedle, ale to si musí každý zjistit sám.. Krok k vlastnímu silikonu je chvály hodný, ale dohánět, 10let Atherosu byl těžký oříšek i pro Ralinky a Intely.
Existují daleko lepší techniky než používat "tvrde" filtry na 1 MF. Pokud nebyli schopni dotahnout ani TDMA s GPS synchonizací, jak si poradí s timhle? Bude to cesta do kapsy zákazníka, FPGA na LLO+filtr+synteza+HF filtr+Switch.. Vítej v klubu Robe..

[hapi]

klienti mají timesloty? možná v rámci jednoho AP ale ne v rámci více AP.

[Insider]

klienti mají timesloty? možná v rámci jednoho AP ale ne v rámci více AP.

Ale klienti od sebe nesedí 30 cm Na metru máš útlum -80dB, na deseti metrech je -90db.. Pokles na spektru vedlejsiho kanalu je dalsích 25db. Takže ti to v podstatě nevadí.. Důležitý je chránit aktivní spektrum hlavního kanálu a i Perovi technici si uvedomují že sračky u OFDM na vedlejších kanálech jsou zlo a řeší to vloženým víceobvodovým filtrem na 1MF. Já jenom říkám kluci do toho a půl je hotovo.. Kde myslíte, že skončili u GPS? na 95 procentech ?

[hapi]

jo, tuhle reakci sem čekal tak pak se ptám proč neumístit APčka dál od sebe

[Insider]

jo, tuhle reakci sem čekal tak pak se ptám proč neumístit APčka dál od sebe

A proc se ptas me? My jsme tenhle problem davno vyresili

[David2006]

https://store.ubnt.com/unifi/uap-outdoor-ac.html

[ppp76]

Funguje vubec nekde nekomu ta gps synchronizace??? patral sem a zatim to nikdo nepredvedl funkcni , po velkem nadseni velke ticho