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Why Verizon Doesn't Want You To Buy an iPhone
Hugh Pickens writes "Sascha Segan writes that although Verizon adamantly denies steering customers away from Apple's iPhones in favor of 4G LTE-enabled Android devices, he is convinced that Verizon has a strong reason to push buyers away from the iPhone. 'Here's the problem,' writes Segan. 'Verizon has spent millions of dollars rolling out its massive LTE network' but the carrier can't easily add capacity on its old 3G network. Since the iPhone isn't a 4G phone, sales of Verizon iPhones just crowd up their already busy 3G network while their 4G network has plenty of space. 'The iPhone is a great device. But it's making a crowded network more crowded. Until the LTE iPhone comes along, to rebalance its network, Verizon may quietly push Android phones.'"
Doesn't LTE actually converge these 2 standards - CDMA and GSM into one?
Nope. LTE is part of the GSM family - CDMA has functionally dead-ended (at least in the US) with EVDO Rev B. It seems like it's a convergence because you will eventually finally have all four major US carriers using a single 4G technology. But having LTE on a phone doesn't make 2G/3G CDMA and GSM technologies any more compatible.
This is especially important because in the US right now, none of the major carriers have implemented Voice over LTE (VoLTE), so when you use a data connection it's routed over the LTE network... but your voice calls use the 3G circuit-switched network instead. No compatible 3G = no phone calls. Also remember that the US carriers are all deploying LTE on different bands so an LTE phone designed for one won't necessarily work with the other.
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The attempts by people to badmouth CDMA never cease to amaze me. The original GSM was based on the horribly inefficient TDMA. Basically, the phones took turns talking to the tower, even if they had nothing to say. You got the same limited bandwidth whether you were the only phone connected to the tower, or if the tower were at capacity. If there were more phones than timeslices, you couldn't connect, period.
CDMA allows all phones to transmit simultaneously, they just use orthogonal codes which allow the tower to decipher which signal came from which phone. It's computationally more expensive, but it allows a single phone to use all the bandwidth if there are no other phones, while distributing the bandwidth equally if there are multiple phones. If there are more phones transmitting than bandwidth, you start getting dropouts (the volatility of SNR means there's no hard limit at which this happens, as with TDMA).
When carriers started adding data services, GSM was borked due to TDMA's inefficiency. That's why CDMA carriers rolled out 2G and 3G service about a year sooner than GSM carriers. GSM was forced to graft on a separate non-TDMA radio just to handle data traffic. (This is also why you can talk and use data simultaneously on GSM - the phones have two radios, one for voice, one for data. It's not a feature; it's a side-benefit to a fix which CDMA never needed. Most CDMA phones just have one radio which handles both voice and data.) The later GSM 3g data protocols used wideband CDMA. That's right, CDMA won - it was the better technology for data. GSM just incorporated it into their standard so it was still called GSM. If LTE is CDMA functionally dead-ending, then GSM dead-ended way back when cellular data services were first added.
What's happening with LTE is that most implementations are opting for OFDMA. OFDMA can squeeze in more bandwidth than CDMA, but requires even more processing power. Until recently, microprocessors weren't powerful enough to decode it on a cell phone without severely impacting battery life (this is the reason early LTE implementations have a reputation for being power hogs). Because it's OFDMA, it requires a different radio. That's old hat for GSM phones - just add a third radio for LTE. But it's something new for CDMA phones - CDMA radio for voice and 3g data, add a second radio for LTE. (And yes, this means you can talk and use LTE data simultaneously on a CDMA phone.)
GSM and CDMA have nothing to do with LTE technologically; it is just the standard they've decided to use for 4g data. In both cases, a completely new radio has to be added to the phone to handle LTE traffic. GSM using LTE is not a concession to CDMA, and CDMA using LTE is not a concession to GSM. Theoretically, if you expanded the operating frequencies, an LTE tower should be able to service 4g data for both GSM and CDMA phones (the whole point of LTE was to standardize a lot of the underlying technologies for compatibility). But until GSM ditches TDMA for voice and/or CDMA ditches CDMA for voice, there will be no convergence.