trying to get better understanding of what's going on ??

[aliitp]

Hi,

I just joined the forums to get better understanding of the recent 802.11ac and other Wi-Fi technologies, I have been reading recently on SNB and gone across many reviews for recent AC5400 Routers and AC3200, I myself got 2x Netgear AC1900 (R7000) and its ok, not considering change soon, unless am convinced of real wifi throughput benefits when it comes to 802.11ac, I currently connect at link rate of 1300Mbps and won't settle to less than that, but i also got a second R7000 configured as a bridge since day one which am considering connecting to via ethernet to get maybe 400-500 Mbps throughput ??..

Anyways, my concerns regarding recent 802.11ac routers in the market are:-
1) What bands does the new AC5400 support ? (ie. 40/80/160 MHz??) and if anyone can explain to me do all 802.11ac nowadays operate on the same bands ??... and will there be 320 MHz band or not ??..

2) Tri-Band is eqv. to 1x 2.4 GHz + 1x 5 Ghz Band + 1x 5 GHz Band, is it not ??...

3) What is a Broadcom 4x4 and is it the same as MIMO or not ?

4) What is a Four Stream Performance test and is it safe to assume running 4x (+) concurrent uploads/downloads between bridged clients over Wireless can yield the same results of almost 1 Gigabit throughput as in some tests for recent AC5400 routers found here in SNB ??

5) Really confused since Wi-Fi ever came out how can theoretical speeds of 2167Mbps+ be achieved at the first place ? It has been said those speeds can be achieved in laboratory conditions, so what are those conditions exactly and whether it's all about interference (coz 5Ghz band is almost free of interference I believe) or what ??...

Thanks,

 

[thiggins]

1) What bands does the new AC5400 support ? (ie. 40/80/160 MHz??) and if anyone can explain to me do all 802.11ac nowadays operate on the same bands ??... and will there be 320 MHz band or not ??..

Wi-Fi bands are 2.4 and 5 GHz. You are referring to channel bandwidth.
AC5300/5400 supports 20/40 MHz bandwidth in 2.4 GHz and 20/40/80 in 5 GHz.

2) Tri-Band is eqv. to 1x 2.4 GHz + 1x 5 Ghz Band + 1x 5 GHz Band, is it not ??...

Yes. "Tri-band" is really just tri-radio. The two 5 GHz radios split the 5 GHz band into low (Ch 36-44) and high (149-165).
AC3200 class is tri-radio using 3x3 radios. AC5300/5400 is tri-radio using 4x4 radios.

3) What is a Broadcom 4x4 and is it the same as MIMO or not ?

I think you are referring to MU-MIMO. MIMO is a technology used since 802.11n.
4x4 means an architecture using 4 transmitters and 4 receivers (chains). The more chains, the higher the maximum link rate and the higher the possible usable throughput.
Multiple vendors make 4x4 chipsets, including Broadcom and Qualcomm Atheros (QCA). QCA was first to have working MU-MIMO in consumer routers. Broadcom is still trying to get their MU-MIMO to work.

4) What is a Four Stream Performance test and is it safe to assume running 4x (+) concurrent uploads/downloads between bridged clients over Wireless can yield the same results of almost 1 Gigabit throughput as in some tests for recent AC5400 routers found here in SNB ??

X stream performance is measured using router/AP and client supporting the same number of streams.
Under strong signal, best case conditions, a 4x4 connection is capable of supporting Gigabit rates.

5) Really confused since Wi-Fi ever came out how can theoretical speeds of 2167Mbps+ be achieved at the first place ? It has been said those speeds can be achieved in laboratory conditions, so what are those conditions exactly and whether it's all about interference (coz 5Ghz band is almost free of interference I believe) or what ??...

The big numbers you see are link rates, i.e. the raw capacity of the connection. They are equivalent to referring to 1000 Mbps for a Gigabit Ethernet connection.

Actual application-level usable throughput is always lower due to protocol overhead. You can generally take the link rate and cut it in half to get the maximum throughput you might be able to get.

These big numbers require advanced coding schemes that work only with strong signals and, for practical purposes, devices using the same chipset. In some cases the numbers also require using non-standard methods.

Broadcom has played this game twice, introducing 256 QAM in 2.4 GHz to create AC1900 class products and 1024 QAM to create AC3100 / AC5300/5400 classes.

Actually achieving 256 QAM is difficult enough; getting a 1024 QAM connection outside a lab is near impossible, at least with current designs.

 

[aliitp]

Wi-Fi bands are 2.4 and 5 GHz. You are referring to channel bandwidth.
AC5300/5400 supports 20/40 MHz bandwidth in 2.4 GHz and 20/40/80 in 5 GHz.
Yes. "Tri-band" is really just tri-radio. The two 5 GHz radios split the 5 GHz band into low (Ch 36-44) and high (149-165).
AC3200 class is tri-radio using 3x3 radios. AC5300/5400 is tri-radio using 4x4 radios.
I think you are referring to MU-MIMO. MIMO is a technology used since 802.11n.
4x4 means an architecture using 4 transmitters and 4 receivers (chains). The more chains, the higher the maximum link rate and the higher the possible usable throughput.
Multiple vendors make 4x4 chipsets, including Broadcom and Qualcomm Atheros (QCA). QCA was first to have working MU-MIMO in consumer routers. Broadcom is still trying to get their MU-MIMO to work.
X stream performance is measured using router/AP and client supporting the same number of streams.
Under strong signal, best case conditions, a 4x4 connection is capable of supporting Gigabit rates.
The big numbers you see are link rates, i.e. the raw capacity of the connection. They are equivalent to referring to 1000 Mbps for a Gigabit Ethernet connection.

Actual application-level usable throughput is always lower due to protocol overhead. You can generally take the link rate and cut it in half to get the maximum throughput you might be able to get.

These big numbers require advanced coding schemes that work only with strong signals and, for practical purposes, devices using the same chipset. In some cases the numbers also require using non-standard methods.

Broadcom has played this game twice, introducing 256 QAM in 2.4 GHz to create AC1900 class products and 1024 QAM to create AC3100 / AC5300/5400 classes.

Actually achieving 256 QAM is difficult enough; getting a 1024 QAM connection outside a lab is near impossible, at least with current designs.

Great info, thanks a lot really !..

But isn't there 160 MHz channel bandwidth ? am sure the higher the channel bandwidth the more bandwidth/throughput to expect from a router ?!...

And can we replicate Four stream performance test say by doing for instance 4+ concurrent FTP/File Transfer Uploads/Downloads to get near 1 Gbps throughput ?...

Sorry to ask such lame questions but this is really what I can think of getting higher throughput by doing more (to a limit) concurrent data transfers...

thanks again,,,

 

[thiggins]

But isn't there 160 MHz channel bandwidth ? am sure the higher the channel bandwidth the more bandwidth/throughput to expect from a router ?!...

160 MHz is starting to appear on some products. But it's implemented as two chunks of 80 MHz bandwidth because there isn't 160 MHz of contiguous bandwidth available (80 MHz bandwidth requires four 5 GHz channels; 160 MHz requires eight).

Just like MU-MIMO, however, it requires device chipsets to also support it. It also requires strong signal levels. Check the NETGEAR R7800 review for more info and test results.

And can we replicate Four stream performance test say by doing for instance 4+ concurrent FTP/File Transfer Uploads/Downloads to get near 1 Gbps throughput ?...

The number of connections you use for testing has nothing to do with # of streams a wireless connection supports. Four streams require devices capable of four streams at both ends of the connections. Today, that means another copy of the router set to wireless bridge mode.

 

[aliitp]

160 MHz is starting to appear on some products. But it's implemented as two chunks of 80 MHz bandwidth because there isn't 160 MHz of contiguous bandwidth available (80 MHz bandwidth requires four 5 GHz channels; 160 MHz requires eight).

Just like MU-MIMO, however, it requires device chipsets to also support it. It also requires strong signal levels. Check the NETGEAR R7800 review for more info and test results.

The number of connections you use for testing has nothing to do with # of streams a wireless connection supports. Four streams require devices capable of four streams at both ends of the connections. Today, that means another copy of the router set to wireless bridge mode.

Thanks a lot for that info it sure was valuable, at least for me so am adding this page to my favorites forever...

Just one last thing, it's strange to me on the link provided for the R7800 review that although 160 MHz mode appears more appealing and powerful it fall behind the 4x streams performance test !!...

Also my router is R7000 and a second configured as a bridge, almost in a line of sight and I get solid 1300 Mbps signal rate, the R7000 is I believe 3x3 capable, is it safe to assume you can get at least 500 Mbps throughput when BRIDGED in 5 GHz AC mode or not ?? And since it is only 3x3 i don't think i can do 4x4 performance test can I ??...

does 4x4 routers or 3x3 have to do with the number of antennas or that's not necessary the case ?...

many thanks again for all that !...

 

[thiggins]

does 4x4 routers or 3x3 have to do with the number of antennas or that's not necessary the case ?...

The numbers refer to the number of transmit and receive radio chains. Each chain must have an antenna. But the number of antennas you see on a router can be misleading.

Many routers use dual-band antennas. So you may see only four antennas on a 4x4 router instead of eight. Some routers use a combination of internal and external antennas.

You can't assume anything about throughput you will get. It depends on many factors, not least of which is the distance between the router and bridge. You should get maximum throughput when they are in the same room, at least 6 feet apart. Throughput falls off pretty quickly as soon as you put walls and distance between router and bridge.

 

[sfx2000]

The number of connections you use for testing has nothing to do with # of streams a wireless connection supports. Four streams require devices capable of four streams at both ends of the connections. Today, that means another copy of the router set to wireless bridge mode.

there is a tangible benefit to 4-stream Router/AP's, even when the clients are not - it's additional gain, both at the RF and coding levels...