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powder puff piece on mobile bb speeds

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  • 04-12-2008 2:16pm
    #1
    bealtine
    Registered Users Posts: 4,051 ✭✭✭


    http://www.pcpro.co.uk/news/240672/mobile-broadband-to-hit-42mbsec-in-2009.html

    Mobile broadband to hit 42Mb/sec in 2009 2:11PM, Wednesday 3rd December 2008


    Mobile broadband speeds could hit a blistering 42Mb/sec as early as next year, according to Ericsson's chief technology officer.

    The idea seems far-fetched given that even the fastest dongles currently hover at around 7.2Mb/sec, but according to John Cunliffe, the technology to smash that barrier is just around the corner.

    "If you look at what's actually happening, the fastest service in the UK at the moment is 7.2Mb/sec, but we can easily see how we get to 14Mb/sec by improving the codes using the modulation," he tells PC Pro.

    "After that there are two steps that can boost speed. We go to the modulation that is 64 QAM...
    that's 64 combinations of information in the same slot as one piece of information. In other words it's massively spectrally effecient. We think that's going to give us 21Mb/sec.

    "But then there's another technique called MIMO, multiple in multiple out. What this means is you have multiple radios on a device, this is like Wi-Fi uses with the N standard.

    With MIMO we can go from 14Mb/sec to 28Mb/sec. They're two paralell paths, but we can then combine them to get 42Mb/sec. Essentially this is happening through 2009."

    Cunliffe acknowledges that while the technology to boost speeds exists, it may take another year or so for the dongles themselves to catch up. However, he doesn't think speeds will stop at 42Mb/sec.

    "We think even more in the future, we can probably squeeze that to 80Mb/sec, and that's before we even get to Long Term Evolution."


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    #2
    watty
    Registered Users Posts: 32,417 ✭✭✭✭watty


    mimo increases sector capacity, but only for 25% of area closest to mast.

    Increased QAM only possible closest to mast...

    Even 7.2Mbps needs much better signals than 3.6Mbps.

    Some a rules of thumb:

    twice distance is less than 1/5th speed.
    Double range need 4x power
    75% of users are past the 1/2 way range, i.e. need more power and can get less speed.

    You can get 80Mbps on HSDPA bandwidth, but at about 25m to 50m range from mast. If those 75% regular users are online you only have 25% of the 80Mbps available at 20m anyway...

    It's fantasy.

    LTE acheives its speed and capacity by having much more spectrum and getting rid of stupid W-CDMA for the downlink.

    HSDPA uses W-CDMA. It scales very badly. It scales worse as you make it faster.

    CDMA was invented for single user secure wireless channel. It's cheap to implement (originally) compared with GSM, EDGE or OFDM schemes. But it's rubbish for base to multiple receivers.

    The one think that NO CDMA scheme is, is spectrally efficent, ever. Cable TV is spectrally efficient. In 5Mbps of an HSDPA channel it does 27Mbps @64QAM. Cable uses 256QAM, thus about 100Mbps is possible.

    This is pure Ericsson Kit Hype aimed at operators.

    21Mbps @64QAM on HSDPA :D
    maybe on an in office Femto Cell :)


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