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ByJings
Aspiring Contributor
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Message 1 of 12

HH6 and 2.4 GHz Wireless N speed issue

I have had BT Infinity 1 and my first Smart Hub (HH6) for just over 4 weeks and after some initial worries over VDSL connection the broadband service is now stable apart from the annoying random hub reboots, usually when there has been some problem with losing the wifi connection on the local natwork. That is not the subject of this post however.

While checking connections on my local wired and wireless devices, I've discovered that I can't get a wireless connection on the 2.4 GHz band that is any faster than 144 Mbps. Specific details as follows;

Smart Hub : 6A
Firmware: SG4B10002244
BT Wi-fi: Not active
2.4 GHz wireless network name: xxxxxx
2.4 GHz wireless channel: Channel 6
5 GHz wireless network name: xxxxxxx-5
5 GHz wireless channel: Channel 36
Wireless security: WPA2 (Recommended)
Band steering: Off
Wireless mode: Mode 1
 
Smart setup: Off
 
Client laptop: Dell Latitude E5550
Wireless adapter: Integrated Intel dual band AC 7265 (2x2 supports a/b/g/n/ac)
 
My understanding is that the Intel AC 7265 and any other 2x2 ac adapter supports 802.11n up to 300 Mbps on 2.4 GHz band and 866.7 Mbps on 5 GHz band. By using different SSIDs on the hub, I'm able to select which band my laptop will use for connections. The wifi is working and stable, but when I check the link speed I've found that 2.4 GHz connections are never more than 144 Mbps when sitting beside the hub or in my lounge (20 feet and 2 brick walls apart). THe 5 GHz connections are 867 Mbps when beside the hub and drop off as expected to 300-600 Mbps in the lounge.
 
I have tried switching off the 5 GHz band and setting the 2.4 GHz band to auto channel select but these had no effect. I have also checked for neighbour wifi signals and there are only 2 or 3 weak signals which all use either channel 1 or 11 (hence why I set mine to channel 6). There are none using 5 GHz that I can detect but that could be down to range as I live in a low density area with detached houses and gardens so well spaced out.
 
When I was using my previous ADSL2+ hub (Netgear DGN2200 Wireless N300), the 2.4 GHz connection from the same laptop was 300 Mbps beside the hub and in my lounge. I reconnected the Netgear hub this morning and confirmed this is still the case.
 
I haven't been able to find any detailed specs for the BT HH6 (I think BT want to keep them secret), but I would expect the max 2.4 GHz rate for 802.11n to be 600 Mbps. I know my Intel AC 7265 will only go up to a max of 300 Mbps but the HH6 seems somehow to be limiting my link speed to 144 Mbps. Does anyonw know if this is a built in limit, can it be adjusted, or is it more likely that I have a faulty HH6.

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11 REPLIES 11
MorgaineD
Expert
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Message 2 of 12

Re: HH6 and 2.4 GHz Wireless N speed issue

That's a pretty good technical question regarding achievable Wifi speeds.  It would be very interesting to hear reports of the fastest speed witnessed personally by users of all current BT Hub models, to match them up against the speeds quoted by marketing.

 

It was also a good question about published technical specs for BT Hubs.  I don't have a direct BT source of specs, so tend to refer to various 3rd party sites.  Alas they're very far from complete:

 

https://en.wikipedia.org/wiki/BT_Home_Hub

https://wikidevi.com/wiki/BT_Smart_Hub

https://wiki.openwrt.org/toh/bt/start

https://wiki.openwrt.org/toh/bt/homehub_v3a

https://wiki.openwrt.org/toh/bt/homehub_v3b

https://wiki.openwrt.org/toh/bt/homehub_v4a

https://wiki.openwrt.org/toh/bt/homehub_v5a

 

In addition to specs though, there is also a test report available, albeit from BT themselves:

 

https://www.productsandservices.bt.com/products/lib/pdf/bt_smart_hub_test_report.pdf

 

That document reports that the fastest dowload speeds measured on 2.4MHz in ideal test conditions were:

 

• BT Test House, page 9 --> 119.75 Mbps

• Sagem Test House, page 18 --> 135.82 Mbps

• Best of 10 Real Homes, page 22 --> 164.7 Mbps

 

That's roughly inline with your observed 144 Mbps, and certainly nowhere near N300 or N600 speeds.  That said, download speeds and the Wifi connection speed are two different things.  The Wifi connection speed provides an asymptote or upper limit to the throughput achieveable during an actual download, minus RF protocol overheads.

 

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ByJings
Aspiring Contributor
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Message 3 of 12

Re: HH6 and 2.4 GHz Wireless N speed issue

Most of those links don't go into the detailed specs sufficiently, but the Wikidevi link suggests that the Smart Hub operates 2.4 GHz in 3x3 MIMO config and the 5 GHz band in 4x4 config, which ties in with more basic info elsewhere that says the Smart Hub has 7 antennae. That would mean it should be capable of supporting up to 450 Mbps on the 2.4 GHz band for 802.11n. The 600N and 900N come about because 802.11n can operate on 2.4 GHz and 5 GHz bands, so if the hardware is true dual band which can run both frequencies together, then you can get 300 (2x2) Mbps or 450 (3x3) Mbps on each band thus giving the 600N and 900N rates (ie 2 x 300 and 450). However, in practice it might be more common for the 5 GHz band to be used for 802.11ac in which case the 2.4 GHz band would be the only one used for 802.11n resulting in 150, 300 and 450 Mbps for 1x1, 2x2 and 3x3 setups.

 

Clearly the BT Smart Hub is not implementing this correctly, or I have one of the many faulty hubs in circulation.

 

I had looked at the BT test report some time ago but hadn't noticed the specs they give for the various hubs tested which confirm the Smart Hub is 3x3 for the 2.4 GHz band and 4x4 for the 5 GHz band. However, I think the data rates they give for 2.4 GHz 802.11n are suspect (290 Mbps for 3x3 and 144 Mbps for 2x2) as I have read elsewhere that 1x1 = 150 Mbps (I think 144 vs 150 might be due to what the M represents, 1 million or 1024x1024 as with HDDs), 2x2 = 300 Mbps and 3x3 = 450 Mbps ie these are multiples of 150, whereas for 802.11ac the different antenna numbers give multiples of 433 Mbps yielding 433, 866 and 1300 Mbps for 1x1, 2x2 and 3x3 setups, which do agree with the numbers in the BT test report.

 

So it seems that the BT interpretation of the 2.4 GHz 802.11n spec in regards to the speeds for the numbers of antennae is different to everyone else and is also inconsistent in itself, if 144 Mbps was indeed 2x2, then 1x1 would be 72 Mbps meaning 3x3 would be 3 x 72 = 216 Mbps and not 290 Mbps.

 

This is further backed up by figures for other manufacturers hubs, such as the Netgear D7000 which uses the same Broadcom chip for the 2.4 GHz 802.11n The D7000 quoted by Netgear as as an AC1900 route with 600 Mbps on 2.4 GHz band + 1300 Mbps on the 5 GHz band.

 

So again I say either BT is telling porkies or their hubs are faulty.

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Message 4 of 12

Re: HH6 and 2.4 GHz Wireless N speed issue

I'm not including your message quote, for simplicity.

 

Out of curiosity, I opened up Inssider 3, which has shown in the past to be reasonably accurate.

It shows 216 mbps, for the HH6 2.4GHz signal.

Channel 11 is set., wireless N.

There are no others on that channel. (others occupy channels 1 & 6).

Signal strength varies between -50 to -60.

Adaptor is inbuilt Intel Centrino Wireless - N0030. (2.4GHz only).

Distance to hub ~ 15 ft, one wall between.

 

However in the past, a netgear, dual band plug in usb wireless - N adapator has shown speeds of up to 300 mbps.

I know this because in the early days the pc would not connect to hub, using the inbuilt adaptor, for longer than 1 minute.

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brookheather
Expert
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Message 5 of 12

Re: HH6 and 2.4 GHz Wireless N speed issue

You will be limited to around 216 Mbps for a 3 stream 2.4GHz connection (this will be slightly higher if the guard inteval is reduced) with 20MHz.  In order to use 40MHz to get up to 450 Mbps it will need to overlap with Channel 6 in addition to Channel 11 but you have a neighbouring signal on Channel 6 so the router is being "neighbourly" and only using 20MHz channel width.  A 20 MHz signal on channel 11 will actually use channels 9-13 and channel 6 will use channels 4-8.

 

https://en.wikipedia.org/wiki/List_of_WLAN_channels

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Message 6 of 12

Re: HH6 and 2.4 GHz Wireless N speed issue


@brookheather wrote:

You will be limited to around 216 Mbps for a 3 stream 2.4GHz connection (this will be slightly higher if the guard inteval is reduced) with 20MHz.  In order to use 40MHz to get up to 450 Mbps it will need to overlap with Channel 6 in addition to Channel 11 but you have a neighbouring signal on Channel 6 so the router is being "neighbourly" and only using 20MHz channel width.  A 20 MHz signal on channel 11 will actually use channels 9-13 and channel 6 will use channels 4-8.

 

https://en.wikipedia.org/wiki/List_of_WLAN_channels


Yes we are all "neighbourly", here. Fortunately it's not a congested area, as the HH6 can only use 1,6 and 11 as fixed channels

I caught on to this with the HH3, (seems years ago now), where my hub was in competition with a nearby Sky hub.

We chased each other for a day or two, continually swapping channels on the auto select. Like Tom chasing Jerry.

I put my foot down and fixed channel 11 (standard bandwidth). Channel 1 is poor here.

The channel swapping has stopped here, although Sky hub changes from channel 1 to 6 occasionally.

216 mbps is adequate.

Remember, for those who use a USB wireless adaptor though:

USB2 speeds are 480 mbps max.

 

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ByJings
Aspiring Contributor
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Message 7 of 12

Re: HH6 and 2.4 GHz Wireless N speed issue

I appreciate all the comments and find other's experience to be a useful guide. However, in my OP I stated that I was using channel 6 (fixed) for 2.4GHz band and a couple of weak neighbour signals were found on channels 1 and 11 (all BT hubs I think).

 

To summarise;

a) I believe that the HH6 using 3x3 MIMO for 11n on 2.4 GHz band should support up to 450 Mbps. Is that right or wrong ?

b) The Intel AC 7265 2x2 dual band wireless adapter in my Dell laptop, not only should support up to 300 Mbps for 11n on 2.4 GHz, but actual connection to my 6 year old Netgear DGN2200 300N wireless ADSL2+ router confirms this to be the case.

c) My Dell laptop will only connect to the HH6 on 2.4 GHz channel 6 (fixed and unused by any neightbours) at 144 Mbps, even when only 3 or 4 feet apart.

 

Update: the driver for the Intel AC 7265 allows the 802.11n 2.4 GHz channel width to be set to either 20 MHz or Auto. Mine is set to Auto, and I assume that when connecting to the Netgear 300N hub it uses 40 MHz to achieve the 300 Mbps connection.

 

Replies above suggest HH5 has provided connections of 200 Mbps and above, depending on signal strength, so has the HH6 been downgraded in some way or do I have a faulty hub ?

 

Can anyone confirm if they have managed to get a 2.4 GHz 11n connection to a HH6 with a link speed in excess of 144 Mbps ?

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3,774 Views
Message 8 of 12

Re: HH6 and 2.4 GHz Wireless N speed issue


@ByJings wrote:

I appreciate all the comments and find other's experience to be a useful guide. However, in my OP I stated that I was using channel 6 (fixed) for 2.4GHz band and a couple of weak neighbour signals were found on channels 1 and 11 (all BT hubs I think).

 

To summarise;

a) I believe that the HH6 using 3x3 MIMO for 11n on 2.4 GHz band should support up to 450 Mbps. Is that right or wrong ?

b) The Intel AC 7265 2x2 dual band wireless adapter in my Dell laptop, not only should support up to 300 Mbps for 11n on 2.4 GHz, but actual connection to my 6 year old Netgear DGN2200 300N wireless ADSL2+ router confirms this to be the case.

c) My Dell laptop will only connect to the HH6 on 2.4 GHz channel 6 (fixed and unused by any neightbours) at 144 Mbps, even when only 3 or 4 feet apart.

 

Update: the driver for the Intel AC 7265 allows the 802.11n 2.4 GHz channel width to be set to either 20 MHz or Auto. Mine is set to Auto, and I assume that when connecting to the Netgear 300N hub it uses 40 MHz to achieve the 300 Mbps connection.

 

Replies above suggest HH5 has provided connections of 200 Mbps and above, depending on signal strength, so has the HH6 been downgraded in some way or do I have a faulty hub ?

 

Can anyone confirm if they have managed to get a 2.4 GHz 11n connection to a HH6 with a link speed in excess of 144 Mbps ?


 Not sure of your case, exactly.

With the HH6 set in wireless mode 1 the throughput is the maximum.

I think that the 20 MHz is fixed for the HH6 in mode 1. There's no auto mode. But there are modes 1,2 and 3.

It's strange that your HH6 is rebooting, on wifi drops.

Looks like a problem with the hub.

As stated, can confirm that down speed is 216 Mbps.

Perhaps others will add to this.

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ByJings
Aspiring Contributor
3,749 Views
Message 9 of 12

Re: HH6 and 2.4 GHz Wireless N speed issue

Thanks Ribblelancs. I have been doing some more background reading and I now have a much clearer understanding of how the various 802.11n data rates arise and I think I have found the answer to my own question.

 

There is an excellent Buffalo technical paper available as a PDF at http://www.lmi.net/wp-content/uploads/Optimizing_802.11n.pdf

 

To summarise, a single data stream in 802.11n has a max theoretical data rate of 72 Mbps using a single 20 MHz channel. The 802.11n spec allows various methods for increasing the data rate by either merging 2 adjacent channels into a 40 MHz channel or by using additional antennas up to a maximum of 4, or a combination of both methods. The number of antennas acts as a straight multiplier of the rate for a single antenna, but a 40 MHz channel bandwidth gives slightly more than double the 20 MHz channel due to lower overheads on the combined channel.

 

The following 802.11n data rates then result from various combinations;

 

For a single 20 MHz channel; 1x1 = 72 Mbps, 2x2 = 144 Mbs, 3x3 = 216 Mbps and 4x4 (v. rare) = 288 Mbps

 

For a 40 MHz channel; 1x1 = 150 Mbps, 2x2 = 300 Mbps, 3x3 = 450 Mbps and 4x4 = 600 Mbps

 

I thinks those numbers will be recognised by most, but the significance of the 20/40 MHz channel width is what confuses most. The Buffalo paper linked above, explains that due to congestion on the 2.4 GHz band, Wi-Fi certified products are shipped in the 20 MHz configuration, and some do not allow the user to switch to 40 MHz or even Auto. I think this describes how the BT hubs are configured, whereas other more configurable hubs allow the channel width to be customised by the user. I guess the default on my Netgear hub was either Auto or 40 MHz as I don't recall having to change anything to achieve 300 Mbps with my laptop (2x2).

 

The 216 Mbps max rate shown in inSSIDer is NOT the actual link speed but is simply stating the maximum that the HUB would support, which for the HH6 (and HH5 ?) is 3x3 so 3 x 72 = 216 Mbps. I see the same 216 Mbps in inSSIDer even though my actual link speed is shown elsewhere on my laptop is only 144 Mbps, due to it being a 2x2 device. This would also confirm that the BT hubs are stuck on a 20 MHz channel width, as my location is sufficiently quiet to maintain a steady 40 MHz channel connection giving 300 Mbps if I use my Netgear hub.

 

So the the BT HH6 implementation of the 802.11n spec combined with its hardware is as follows;

 

On 2.4 GHz band: Connections are limited to a single 20 MHz wide channel with a max data rate of 72 Mbps which, with the HH6 3x3 setup, gives a theoretical max data rate of 216 Mbps. In my case, my client laptop is a 2x2 device so I only achieve a link speed of 144 Mbps (ie 2/3 of 216).

 

On the 5 GHz band my laptop uses 802.11ac, and because congestion is not an issue at 5 GHz, channel bonding is allowed. It would appear that the HH6 uses an 80 MHz channel width which then provides ac data rates of 433 Mbps (1x1), 866 Mbps (2x2), 1300 Mbps (3x3) and 1733 Mbps (4x4). Again, as my client laptop is a 2x2 device and the 5 GHz channel width is set to Auto, I get up to 866 Mbps.

 

I don't recall what the BT hub wireless mode 2 and 3 are, but I think they are to help provide stable connections under challenging conditions (range or interference ?) and so are likely to just impose a limit on the max connection speed negotiated. Feel free to correct me on that.

 

I got further hub reboots today when switching my laptop back and forth between 2.4 and 5 GHz bands while using inSSIDer to monitor. If that continues to be an issue a may ask BT for a replacement but at the moment I feel more inclined to buy a TP-Link or Asus router.

MorgaineD
Expert
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Message 10 of 12

Re: HH6 and 2.4 GHz Wireless N speed issue

A highly informational post, and very clearly written --- thank you @ByJings! That certainly earns a +1. 🙂

I avoid RF and hardwire my computing machinery to the greatest extent possible, so your writeup about how the various wifi link speeds arise was very educational.

Thanks for your link to the Buffalo document too!

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