Wifi Phone?

There is a bunch of talk going around about cities hosting publicly available wifi.  While I am hessitant to ditch my ISP with plans to tap the public internet access, I’m optimistic that one day (perhaps years from now), we will live in a society where a person can get wifi access everywhere in the country.  I like to think of it like electricity; there was once a point where electricity was only available in the homes of the rich who lived in urban centers. The middle class and the rual population, however, were not included in the service area.  About sixty years ago, however, the US made a big push to get electric service to all homes.  My mom, who grew up in a small farm town in the middle of Nowhere, Minnesota, talks about getting electricity when she was 13 and how different life was before electricity versus after electricity.  I figure if the US can successfully implement the initiative of distributing electricity to all homes, distributing WiFi across the country can’t be that challenging sixty years later.

Consider cellular networks: twenty-five years ago, we didn’t have cell phones, but now the majority of the US is covered in 3G access.  I admit that a 3G signal can travel further than a WiFi signal and therefore the 3G model requries fewer towers to cover the same amount of area, but it can be considered a proof of concept that we can blanket the country with a form of wireless network access.

The question could be asked, “Why should we consider covering the country, or the globe for that matter, with WiFi access if we can already do it with 3G?”  My answer is simple; 3G is slow and expensive compared to WiFi.  Wifi has a speed of roughly 54 Mbps compared to roughly 21 Mbps over 3G.  With 3G, you need to purchase a plan from a cellular provider, versus the ad-hoc nature of Wifi.  While I expect that a publicly provided wifi would not be free, I suspect it would be cheaper than the total cost of ownership of a 3G hotspot device.

Being that publicly provided, wide spread wifi would be cheaper and faster than the current 3G model, it seems natural to want to develop this solution.  If this were to happen, however, how would it affect cellular providers?  If a faster, cheaper wireless connection exists, could the current cellular model be overthrown?

With this question in mind, I sat down and designed a model of how I would build a wifi-enabled mobile phone.  The idea is to use existing IP-based networks along with Wifi, whether it is publicly provided or by using existing wifi providers (i.e. coffee shops, hotels).  The solution would include a hand held device similar to that of a common cell phone plus a VOIP bridge (more about this later).  I came up with an interesting solution.

In this scenario, audio (voice)  coming into the handheld device is processed by an audio to digital converter.  I’ve picked the VS1053 only because I’m familiar with it, but I’m sure there are others that could do just as well.  The digital signal is transfered to a micro processor which routes it out via wifi to the internet.  The handheld device not only manages its wifi connection, but also stores the configuration to connect via the internet to the user’s home network in order to route the data of the audio signal back to the VOIP bridge (home network device as noted in the image).  The bridge is merely the inverse of the handheld.  It takes the IP data and produces serialized data that can be decoded by the VS1053 into a regular audio signal.  This audio is fed into the home computer, which utilizes a VOIP solution for telephone access.  To hear the user on the other end, the whole process works in reverse.  The audio out of the home computer routes into the home network device / VOIP bridge, out through the internet to the handheld which decodes it and plays the audio back to the user.

There are plenty of details to work out, but it is a model that can be leveraged.  Imagine the paradigm shift of mobile phones if the phone service were to be decoupled from the phone vendors.  Instead of a handheld device being paired to a provider’s network via a sim card, any phone could could be used by any user regardless of the ultimate phone provider.  Instead of matching the phone to the service semi-perminently, a phone could log into any individual’s home device, thus allowing it to be used on any VOIP provider.  Say I forget my phone at home.  I could borrow my friend’s handset and log it into my service instead of his.

If this model were to gain strength, the role of the VOIP bridge could be centralized, easing the use of the system for the less technically-minded users.  This would probably be the future for Sprint, AT&T, Verizon, and the rest of the cellular crew if WiFi does go global.


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