CDMA is NOT the speed of your connection, it's the type of technology that is used with the mobile carrier.
Sprint, Verizon, Cricket use CDMA. AT&T, T-Mobile and some others use GSM.
There is a hidden option in some devices that allow GSM & CDMA. But, that is irrelevant with Sprint, because they're only CDMA. Theoretically, if you can unlock the phone, it can be used with a GSM carrier, such as AT&T or T-mobile.
With Sprint looking to buy T-Mobile, I'm not sure how they will switch the two technologies.
At my house, I barely get 3G with 0 or 1 bar. At work, I'm about 1/2 mile from a tower and I get 6 bars at 4G. I have an LG Optimus G.