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Telus To Shutter CDMA Service On January 31, 2017 (mobilesyrup.com)
An anonymous reader writes: With most Canadian mobile devices on some form of HSPA+ or LTE network, you don't hear mention of CDMA that often anymore. And for good reason; carriers like Telus, which still maintain their CDMA network for legacy customers, plan to mothball the tech over the next few years. We now have a definitive date when Telus customers will no longer be able to use their old CDMA device. Over the weekend, the company sent text messages stating, "CDMA service ends January 31, 2017. Move to our 4G network with great offers."
CDMA won the GSM vs. CDMA war. The HSPA/HSDPA 3G service in most GSM phones uses CDMA or wideband CDMA.
See, the original GSM spec used TDMA - basically each phone is assigned a timeslice and all phones take turns talking with the tower. This meant that even if the phone didn't have much data to transmit or didn't need to send any data at all, it still used a full timeslice. Couple that with time buffers to account for phones being different distances from the tower, and GSM ends up wasting a lot of bandwidth. CDMA allows all phones to transmit at the same time. The tower tells them apart by assigning an orthogonal code to each phone. Bandwidth scales automatically between phones because each phone sees the other phones' transmissions as noise, thus reducing the signal to noise ratio and reducing bandwidth. If a phone doesn't need data for a few seconds, the noise decreases, the SNR for the other phones increases, and that extra bandwidth is immediately available for all the other phones to use.
This is why CDMA carriers got 3G about a year before GSM carriers. Their towers could already provide 3G data speeds. GSM had to amend the GSM spec to specify CDMA and wideband CDMA data services, then wait for handset manufacturers and carriers to implement it. This is also why GSM phones could talk and use data at the same time. They had two separate radios - a TDMA radio for voice, a CDMA radio for data. CDMA phones only had a single radio which could be used for voice or data, but not both at the same time.
Most implementations of LTE use OFDMA. It does the same thing as CDMA, except using orthogonal frequencies instead of orthogonal codes. CDMA served as the proof of concept for widescale simultaneous orthogonal transmissions, so without it LTE probably would not exist or would not be as mature ias it is today. (OFDMA requires more processing power than CDMA, which is why it came later. WiMax used OFDMA, and my Galaxy S phone which used it would die after 3-4 hours on WiMax vs 8-12 hours on 3G CDMA.)
If the U.S. had followed the rest of the world in adopting GSM and had prohibited CDMA, our mobile data speeds today would probably be around 100-500 kbps. So be glad CDMA won, even if Qualcomm is evil.