Re: [MEXT] [dmm?] Surprising assertion about make-before-break handover prevalance

Hi Charlie,

I guess you are referring to handovers across different access types
(wifi<->3G) etc.

Whether you can accomplish a make-before-break handover in such scenarios
depends on the device in many cases. So there is no black-or-white answer
to your question at the present time.

Will devices keep multiple radios powered on simultaneously in the future?
It depends.
Battery technology still lags the advances of radio, processors and
displays on devices. And hence it generally boils down to optimizing
battery in handheld devices which implies that you would not want to
always keep multiple radios switched "On" all the time. You could if you
were willing to carry around a battery backpack all the time :)
Or keep your device plugged into a power source or charge it every few
hours...

Algorithms will/may help a device to turn on/off various radios to enable
better handover performance. And multiple radios could be simultaneously
operational for brief periods of time to enable the make-before-break
handover scenarios.

DMM design should not be overly concerned about the make-before-break
handovers IMO. DMM is focused on optimizing the latency, reducing backhaul
traffic etc. I don¹t believe DMM is a way to enable handovers with better
performance. It would be a benefit if performance of even the
break-before-make handover scenario improves as a result of DMM.

W.r.t devices a couple of examples:
1. On my Nokia N900 (Maemo), I can operate both the wifi and 3G radios
simultaneously (requires an update to the software that ships on the
device). Normal operation however is either wifi or 3G.
2. On my N8 (S^3), I can have cellular data (PDP context) and wifi
connectivity running in parallel all the time. But there is no good reason
to do that. And hence the setting is to have either 3G or Wifi data
connectivity. 

-Basavaraj

On 8/4/11 3:52 PM, "ext Charles E. Perkins"
<[email protected]> wrote:

>
>Hello folks,
>
>Sorry if this is considered to be imperfectly relevant,
>but I'm curious whether or not handovers in the future
>would be typically make-before-break.  Or [even "worse"],
>in terms of radio interfaces, whether typically wireless
>devices in the future will keep multiple radios powered
>on all the time.
>
>This might well have an impact on assumptions about
>dmm.  It was claimed that, for instance, iPad and iPhone
>usually have both interfaces active.  I know that when
>I'm using my iPad I do not keep both radios turned on,
>but I do not claim to be a typical user, and anyway I
>do not have an iPhone.
>
>Comments will be appreciated!
>
>Regards,
>Charlie P.
>
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