Verizon coming out with TWO WAY RADIOS?

[Platinum]

I have heard around that Verizon Wireless might be coming out with two-way radios. I hope they do cause that will be really sweet.

[northform]

Yes and no. Verizon, Sprint PCS, T-Mobile, AT&T and Alltel are all planning services that emmulate Nextel's push to talk system (PTT). They will be based around the GPRS and 1xRTT equipment that the networks already have in place, but it will not be compatable with current phones. The service won't be instant like Nextel's, though. Nextel's system uses circuit switched data while technologies like GPRS and 1xRTT are packet switched. There is a big difference. Circuit switched means that there is dedicated bandwidth and guarentees a certain speed. Packet switched means that the connection isn't dedicated. The best example of this is the difference between a phone call and the internet. With a phone call, you have a dedicated connection that no one else is using that connectes you to the person you are calling. It is a very reliable way of communicating. With the internet, you are being queued up, tossed around and different pieces are transmitted at different times over different connections. The connection is communal and other people are using the connection inbetween your usage (ie. connect to wirelessadvisor.com, someone else connects after me before I download image a, then I download image a, etc.). This isn't as reliable as a circuit switched system if you need to guarentee a minimum speed in real time (ie. if you need to transmit 8kbps constantly like you do for voice). If the server is under heavy load, you will connect slower. With the internet, it really doesn't matter how quickly you connect, but with real time applications like voice, it does. I'm sure you've used QuickTime on a slow connection and seen that it drops frames, blanks out, etc. when it can't obtain a consistant connection. This is what could happen to 1xRTT and GPRS based PTT systems. Most people have anticipated that those systems would be more like instant messaging than Nextel's direct connect. It is believed that they the phones will record the message and then transmit it rather than attempting to do it in real time and dropping too much data. Oh, there is also a high latency when using wireless packet switched services (around 800ms).

So far, only GPRS has been proven to handle this, but there is no reason that 1xRTT cannot either and the details around the GPRS test are sketchy at best. Suffice it to say, carriers will use this technology to bleed Nextel of their customers and by the time that their contracts are up and they can go back to Nextel (because the other PTT systems worked so poorly), Nextel will be bankrupt. GSM carriers should have gone with HSDSC (high speed data switched circuit - it runs from 20kbps to 43kbps without any fear of going below that because it is circuit switched) or simply regular switched voice. CDMA carriers likewise whould have gone with CDMAOne's 14kbps data option or switched voice. But both wanted to be able to charge for minutes without equivalent network usage so they decided on packet data. This way, the phone isn't transmitting most of the time, while they can charge like it is transmitting the entire time. That is to say, since voice only takes up 8kbps, the phone can record the statement that you make (let's say 10 sec), and then send it using less resources since packet data allows for greater efficiency (40-60kbps) than switched voice. This way the carrier is able to make you pay for a full 10 sec of airtime while you used less than that ammount of network resources. To a point Nextel has exploited this as well. With their direct connect feature, only one person is able to speak at once and so they are only using half of the network resources to complete your connection. Not that CDMA and GSM don't lower the bitrate to almost nothing when the other person isn't talking.

I'm done.