BTInfinity 'upto' 40Mbps. What speed can we really expect?'

BTInfinity 'upto' 40Mbps. What speed can we really expect?'

Summary: So is BTInfinity/FTTC (Fibre to the Cabinet) a viable practical technology for rural Communities?Well it really depends on how close you are to the newly laid fibre optic and the new roadside cabinet containing newly installed DSLAMs (the bit that converts the fibre into a copper connection to your premises)Live over 1km (as the crow flies) from your roadside cabinet (1.

TOPICS: Tech Industry

So is BTInfinity/FTTC (Fibre to the Cabinet) a viable practical technology for rural Communities?

Well it really depends on how close you are to the newly laid fibre optic and the new roadside cabinet containing newly installed DSLAMs (the bit that converts the fibre into a copper connection to your premises)

Live over 1km (as the crow flies) from your roadside cabinet (1.5km by cable) - There is not much chance of BTInfinity.

It really does depend on how many new cabinets containing fibre (in addition to the existing ones) are actually deployed 'next to where you live'. The roadside cabinet is what is important here - the nearer the better.

The technology used by BT for BTInfinity is FTTC (Fibre to the cabinet) The technology implemented (modem protocols etc), is VDSL2, this is a copper based technology, like ADSL and ADSL2+. Its copper based? - YES. BT utilise this between the Premises/Home and Cabinet.

Existing ADSL2+ is limited to speeds of approximately 24Mbps and 2.2Mbps, downstream and upstream, respectively. ADSL/ADSL2+ beyond 3.5Km are approx the same in terms of speed - upto 5Mbps, downstream. Therefore ADSL2+ would not provide much improvement outside this distance, ie. beyond 3.5km from the exchange.

VDSL2 can provide theoretical speeds of 100Mbps over copper, both downstream and upstream within 300m from the cabinet containing the backhaul fibre (the technology is also better able to cope with poor lines and offers a more stable connection speed, as it can adapt to line fluctuations better than ADSL).

Note the distance: 300m though- very close to the cabinet, the maximum is 1.5km, it drops off quickly - from 100Mbps theoretical max to 10Mbps at 2km from the cabinet. ADSL2+ is 10Mbps at 2km from the exchange. BT therefore realistically quote upto 40Mbps, because the chance of higher is very slim.

The Roadside Cabinet: The fibre optic cable deployment (FTTC) is extended from the exchange to the cabinet, and the DSLAMs are fitted in the cabinet rather than the exchange, so its a similar technology to ADSL - just where the kit is placed and a better, copper transmitting technology to deliver the final part of the signal, with significantly better upload speeds.

VDSL2 appears to be backwards compatible with ADSL/ADSL2+, whether that is implemented by BT - unsure, but if they did, ADSL2+ seems to be 15% more efficient using this VDSL2 protocol to the roadside cabinet. Whether this is due to the shorter distance because its to the cab, and not the exchange - unsure.

Data rates in excess of 25 Mbps are available for distances up to 1.2Km (by cable) from cabinet, but tail off quickly after this, minimum guaranteed deployment BT offer is 'upto' 15Mpbs/1.5km from the cabinet, below this speed BT don't deploy BTInfinity. Aluminum Cabling as opposed to Copper will affect things a lot too.

In this case, existing technologies will be deployed instead like ADSL2+ and might actually work as well at this distance as VDSL In terms of download speed (10Mbps) you receive, (not what you can upload) and are improved because we're talking distance to the roadside cabinet, not back to your exchange.

To summarise - BTInfinity's potential is looking at between 'upto' 15Mbps (distance 1.5km from cab) and a max of 'upto' 50Mbps (distance-300 metres from the cab), beyond 1.5km from the cabinet- ADSL2+/ADSL will still be deployed.

Problem is FTTC/VDSL2 - beyond 2km, from the cabinet the download speed is similar to ADSL2+ from the exchange - upto 10Mbps. ADSL, ADSL2+ are pretty much identical after 3.5km from the exchange - upto 5Mbps.

I've also read that where speeds likely to be obtained are less than 15Mbps, BT won't accept an FTTC order on that line (approx 1.5km) from the cabinet - so this maybe the current physical limit to its deployment, but might have been imposed to prevent you paying extra for something you couldn't receive in terms of service.

The technology is potentially, capable of faster speeds than the up to 40Mbps (Advertised by BTInfinity)- near to the cabinet (within 300m) but as always its very dependent on distance from the cabinet and realistically 40Mbps-50Mbps is the max. Its the same method BT describe ADSL2+ as an upto 20Mbps technology, though some users could get higher very close to the exchange (upto 24Mbps)

It really depends on how BTOpenreach deploy things - ie. If more roadside cabinets containing fibre are installed nearer to Villages outside the town containing the exchange, then it might be worthwhile method of delivering High Speed Broadband.

If BTOpenreach keep the infrastructure the same, then it is not that good for areas outside the town away the exchange/roadside cab itself - areas more than 1.5km from the roadside cabinet - these will be the new BTInfinity NOTSPOTs.

Topic: Tech Industry

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  • Comments welcome, both negative and good!
  • great article, just need to get it out into the media then people understand the con. Many councils are handing over public money in the belief that fttc will help the notspots - we know it won't. if you are a notspot with adsl chances are you still will be with infinity. In fact I can see there being even more notspots and crapspots in the future if we don't stop this hype from BT.
  • I don't see why this is a con. It's all down to the location of cabinets and villages away from the exchange will have cabinets so those people would be fine with FTTC.

    Clearly there is an issue with those a long distance from their cabinet. But how many (%) are there? Is there a cabinet and a non-spot map?
  • Hi

    I currently get a solid 13mb download speed at different times of the day over a period of several weeks. Does this mean my line has been upgraded as I know a lot of people in Colchester only get 3mb - 6mb?
  • @digitalark26
    Here is the info for the Colchester Exchange by
    The Colchester exchange shows that is ADSL2+ (upto 20Mbps) enabled (ISP/BT Wholesale products) + number of LLU ISPs - Orange, TalkTalk, Sky. The exchange is not enabled for FTTC/BTInfinity products through either BT or TalkTalk.

    Without knowing your ISP, it can be the result of several scenarios:
    The simplest:
    Assuming BT/plusnet or other ISP IPStream/BTWholesale product- the router would reconnect using the newer ADSL2+ protocol. ADSL2+ is a software upgrade to the exchange DSLAMs.
    @13Mbps, your line is now using ADSL2+,(upto 20Mbps as marketed by BT/theoretically 24Mbps) Note:This is not FTTC/BTInfinity.

    Newer Standard ADSL Wireless Routers are capable of both connecting ADSL and ADSL2+ signals, so the switch over would be seamless, once the router was cycled off/on.

    A BTInfinity switchover requires a completely new router based on VDSL2 (still a copper 2 wire connection though) rather than ADSL (normally supplied as part of BTInfinity)

    Neighbours still receiving 3-6Mbps, should check their ADSL Router, and make sure its capable of connecting both ADSL and ADSL2+ signals. Replacing the older router might all that is needed to upgrade to a faster connection, though your ISP would know whether they offered ADSL2+ (upto 20Mbps) their end, and whether it was worth replacing the router to get the additional speed.

    There is very little benefit of ADSL2+ over ADSL once distances from the exchange reach 3.5km, At these distances ADSL can be marginally slower, but more reliable in terms of connection speed.

    As stated their are several scenarios as to why your line has changed to ADSL2+.
    The exchange shows AOL (now Talktalk), C&W/BullDog, Orange, Sky/Easynet, Talktalk, Tiscali (now Talktalk) and WBInternet(Colchester is their only exchange) as having LLU (Local Loop Unbundling), which means they have their own ADSL2+ equipment installed in the exchange with speeds upto 20Mbps.

    If you use one of these ISPs, you line may have been moved over from a previous BTWholesale product to the ISPs own LLU service, which would result in the increase in speed. Virtual all LLU Services provide upto 20Mbps ADSL2+, rather than ADSL.

    The only disadvantage of being on a LLU service is moving provider, you can't migrate your connection as easily, often the fee is much higher than switching between BTWholesale products which is generally free.
  • With all the current BT 'marketing' over substance, of Superfast Broadband. I thought it was best to highlight this blog post again.