How green is your broadband

How green is your broadband

IrelandOffline, a leading consumer group, have studied the “green” ideal of various different broadband technologies. We have come to the conclusion that the electricity usage of mobile technologies (as used in the National Broadband Scheme) is far worse than ordinary DSL technologies. If our goal is that of a sustainable economy then excess usage of electricity must be looked at very carefully.

Green technology gone astray

A base station (where your calls and NBS comes from) are 800 Watts each for each transmitter/receiver (even though the aerial is fed 10W to 20W of RF typically) and about 5200W for the rest of the equipment at the mast. Typically there are three sets of aerials, each for about 120 degrees of coverage.
So total usage for each Base Station for 3G/HSPA is 7.6kW approx for three sectors, running for say 10 people who are streaming. You can support far more people just for web browsing, but more than 2 to 3 people per sector streaming Web video is a struggle.

Data Usage on Mobile is 100x to 400x the data rate per person of voice usage on Mobile and is 500W to 2,200W per user. A mast can usefully support about 10 simultaneous transfers at “entry level” Broadband speed (1Mbps), so power consumption assumes 10 users. The Up To speed can only be reached by having a single user in a sector with perfect signal. With all three sectors used by just three users the power consumption is over 2,200 per user. Minimum speed is “no connect” or 0.05Mbps. If no-one is using the mast Consumption can still be over 4,500W.
Watching YouTube or RTE player is easily the same power consumption as a kettle and a 2 hour show would be more electricity than a full wash.

DSL and Cable Broadband: Telephone Exchange and FTTC (Fibre to The Cabinet)

Data energy usage on DSL or FTTC is about 2W to 85W per person (85W is the consumption of a typical 48 Line Broadband interface in an Exchange or roadside FTTC system, the DSLAM).

FTTC is more efficient if you have universal BB and closedown the exchanges. Phone would be by integrated phone port on Modem as Digiweb, Magent and UPC provide and secure QOS managed VLAN to the ISP gateway switch ensuring ISDN voice quality. Basic DSL gives average of 3Mbps, ADSL2+ 7Mbps (both 1Mbps minimum) and proper FTTC minimum of 20Mbps.
The Cheapest FTTC option is simply the up to 24Mbps ADSL2+ DSLAM in a roadside Cabinet. 85W per 48 Users. VDSL2 allows 40Mbps to 100Mbps in FTTC mode. FTTC mode saves more energy than ordinary ADSL and also gives more speed because instead of fibre to DSLAM in the Exchange, the fibre (as cheap to lay as phone cable) goes to a street cabinet only a little bigger than existing street cabinet. The existing copper pair from the street can be used. The Exchange can be sold off with subsequent saving of electricity, lighting and heating. The speed is increased as the maximum distance is a few hundred metres of the length of street rather than the up to 8km of exchange (average exchange distance limits speed to 3Mbps DSL or 7Mbps ADSL2+). The fibre feeding cabinet can be 200km or more so no exchanges are needed.

Worst case the NBS is up to 4,500x less energy efficient than DSL or FTTC, for 1/3 to 1/100th of the speed. On average the NBS is probably 100x less energy efficient than DSL or FTTC.

With FTTC upgrades, even existing ADSL2+ Modems and existing copper from the street cabinet can give a real minimum 20Mbps. Upgrades from 7.2Mbps 3G/HSDPA to even 42Mbps 3G/HSPA+ or LTE on 5MHz channels only give increased speed to less than 2% of NBS or Mobile Subscribers, therefore the usage and speeds delivered are less than optimally efficient.


DSLAM: Digital Subscriber Line Access Multiplexer is a small cheap box to interface backhaul Fibre in exchange or Street cabinet to ordinary copper phone wire for high speed Broadband. Costs under $2,000 for 48 users. The same box can do ADSL, ADSL2+, VDSL2 in an Exchange or a Street Cabinet. Newer boxes do 96 lines / users in a similar size package at lower power per user.

FTTC: Fibre to the Cabinet. Move the DSLAM close to user (one or two cabinets per street) and thus have x10 to x100 speed at lower cost as the Exchanges are no longer needed.

Basestation. Costs from $100,000 to $300,000. Comprises typically 3x Node B and a Radio Network Controller This is the equipment at a 3G/HSPA mast for NBS, 3G voice and Mobile Internet. Realistically can only service about 10 simultaneous data streams at entry level Broadband Speed (1Mbps). A complete Base Station is about 19” wide, 30” deep and 72” high.

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