[AusNOG] wifi phone calls

[John Edwards]

Hi Ross,

Standards-based WiFi has been handling multi path just like LTE since
802.11n-2009. LTE's preferred method for shifting data - OFDM - was in
WiFi long before it was in cellular. Today, you can buy off-the-shelf
WiFi products with QAM-256 modulation, which won't be seen in LTE
until 2016.

Range in cellular networks is a function of output power and RF
management. There isn't anything particularly special about LTE's use
of RF, other than the removal of previous clocking/synchronisation
requirements that limited physical cell size.
Multiple-carrier-aggregation could make a difference, but probably not
to voice.

WiFi is restricted to low power as part of the class licence it
leverages. This is why you don't (usually) see WiFi macrocells
designed for long range.

The primary drawback to using WiFi for Voice is the client devices,
many of which have WiFi has a gimmick that hasn't been designed to
work outside of the home/office. Out in the street where your receiver
may inadvertently pick up the signals of 100 other users, you may have
issues with SNR. The handset manufacturer probably doesn't want you to
complain about battery life, so they use a transmit power that is
better suited to indoor applications, further limiting your ability to
send a signal at a level higher than the background noise.

Most of us buy our portable voice devices from a phone company that
operates cellular networks, it shouldn't be a surprise that these
operators sell devices that are optimised for their own networks.

I find the parallels between LTE and WiFi similar to the historical
argument of ATM vs Ethernet. One is beautifully over-engineered, and
the other gets the job done - we know how it turned out for ATM.

John






On 17 February 2015 at 09:50, Ross Annetts
<ross.annetts at digitalpacific.com.au> wrote:
> LTE (4G) is already all IP and as already mentioned is better suited for
> long distances as it handles diffraction, reflection and refraction of
> signals better than all 802.11 technologies at the moment. The main benefit
> of using Wifi as a supplement to Mobile networking is due to the limited
> sprectrum and ever growing devices and needs of users for bandwidth.
>
> Regards,
> Ross
>
>
>
> On 17/02/2015 10:08 am, Scott Wilson wrote:
>
> Telstra are trialling voice over LTE with their "4GX" (700mhz LTE-A)
> product.
>
> On 17 February 2015 at 09:06, Scott Howard <scott at doc.net.au> wrote:
>>
>> Mobile networks have ranges measured in up to (10's of) kilometres.  Wifi
>> networks have ranges measured in hundreds of metres - presuming these's
>> nothing too solid to block them.
>>
>> Providers like Republic Wifi work well simply because the majority of the
>> time most people are around good wifi signals, but they still need to fill
>> the holes of coverage - which basically starts the moment you walk out of
>> the front door.  I have multiple friends that use Republic and couldn't be
>> happier - they generally say that the quality isn't quite as good as
>> standard mobile, but for the price they are happy.  (FreedomPop is a
>> different story, and not a company I'd recommend going near)
>>
>> However as far as "VOIP" for mobile call, that's happening.  In the US,
>> Verizon has been doing Voice-over-LTE (VoLTE) for some time, and others will
>> likely follow.  For Verizon this is a big win as it allows devices on their
>> CDMA network to handle "voice" and data simultaneously (as it's all data) -
>> something they haven't been able to do before now.  The LTE spec fully
>> supports voice-over-data, and it's expected all carriers will move to it
>> eventually.
>>
>>  Scott
>>
>>
>>
>> On Mon, Feb 16, 2015 at 2:45 PM, Alex Samad - Yieldbroker
>> <Alex.Samad at yieldbroker.com> wrote:
>>>
>>> Hi
>>>
>>> So I saw this whilst I was reading Slashdot.
>>>
>>>
>>> http://mobile.slashdot.org/story/15/02/16/1627240/cellphone-start-ups-handle-calls-with-wi-fi
>>>
>>>
>>> This got me thinking, if you took money out of the equation and politics
>>> (sic).  Would it be better for use to have a completely wifi wireless
>>> network, get rid of the mix of technology and just have devices that do some
>>> sort of VOIP.  I am presuming running an IP network is better than a
>>> GSM/3g/4g.
>>>
>>> How much better would that be ?
>>>
>>> A
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>>
>>
>>
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>
>
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>
> --
> Regards,
> Ross Annetts
>
>
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