One of the reasons that the ATT network performs so poorly in many places is because it uses the UMTS version of CDMA, also called WCMDA that is asynch. It uses 5 MHz channels to transmit both data and voice. So, within a cell or sector, if there are people using a lot of data, there is not enough capacity to transmit voice. So calls get dropped, or no coverage.
VZ uses the CDMA/EVDO. Basically voice goes on separate 1.25 MHz channels. Data goes, mostly, on the DO 1.25 MHz channels. So a lot of data usage will slow the data rate like in cable network in a neighborhood in the evening. However, voice will be unaffected by data usage.
QCOM, the original implementer of CDMA has patents on UMTS/WCDMA. They do make chip sets that work on multiple standards like CDMA, GSM, UMTS, etc. The just cost a low of money and the implementation costs too with more complex power amps and antenna design.
The only reason we got the UMTS/WCDMA is because Nokia and Ericsson wanted to dilute QCOM patents... and came with a solution where everybody got to thrown their patents in to reduce QCOM typical 5.5% royalties. Well, it barely works well with voice... drains too much battery due to its wide rake receivers, asynch tech. Hand-offs are a problem too.
As any wireless network engineer will tell, implementing any new tech like 4G that is a based on OFMD will be quite complex. Antenna spacing will be different. New fiber backbone or major upgrades will be needed along with routers, and switches to hand the traffic. At network is as good as the weakest link. Handset chipsets will have to developed, tested, extensively... then sampled. Manufacturers go through a complex approval process as well. The network upgrades is what is called "truck load upgrades". Costs $Billions for a nationwide foot print.
I would not be holding my breath hoping ATT or anybody else will have a nation wide working 4G real network going next year. Making a CDMA/EVDO iPhone is no big deal. I think it all depends if VZ is willing to give the control that Apple wants. Without that control, it may be better for Apple to push ATT to upgrade the 3G capacity.
+1. ATnT has to do something to catch up with Verizon in the 4G race.
Comments
One of the reasons that the ATT network performs so poorly in many places is because it uses the UMTS version of CDMA, also called WCMDA that is asynch. It uses 5 MHz channels to transmit both data and voice. So, within a cell or sector, if there are people using a lot of data, there is not enough capacity to transmit voice. So calls get dropped, or no coverage.
VZ uses the CDMA/EVDO. Basically voice goes on separate 1.25 MHz channels. Data goes, mostly, on the DO 1.25 MHz channels. So a lot of data usage will slow the data rate like in cable network in a neighborhood in the evening. However, voice will be unaffected by data usage.
QCOM, the original implementer of CDMA has patents on UMTS/WCDMA. They do make chip sets that work on multiple standards like CDMA, GSM, UMTS, etc. The just cost a low of money and the implementation costs too with more complex power amps and antenna design.
The only reason we got the UMTS/WCDMA is because Nokia and Ericsson wanted to dilute QCOM patents... and came with a solution where everybody got to thrown their patents in to reduce QCOM typical 5.5% royalties. Well, it barely works well with voice... drains too much battery due to its wide rake receivers, asynch tech. Hand-offs are a problem too.
As any wireless network engineer will tell, implementing any new tech like 4G that is a based on OFMD will be quite complex. Antenna spacing will be different. New fiber backbone or major upgrades will be needed along with routers, and switches to hand the traffic. At network is as good as the weakest link. Handset chipsets will have to developed, tested, extensively... then sampled. Manufacturers go through a complex approval process as well. The network upgrades is what is called "truck load upgrades". Costs $Billions for a nationwide foot print.
I would not be holding my breath hoping ATT or anybody else will have a nation wide working 4G real network going next year. Making a CDMA/EVDO iPhone is no big deal. I think it all depends if VZ is willing to give the control that Apple wants. Without that control, it may be better for Apple to push ATT to upgrade the 3G capacity.
+1. ATnT has to do something to catch up with Verizon in the 4G race.