CDMA works by having the tower send control information to the phone to ensure that each handset produces the same RF field strength at the receiving antenna. If you're a long distance from the tower or inside a building that attenuates the signal, the phone transmitter has to be run at a higher power level to achieve the expected strength at the tower. The rough value is set using the GPS location of the tower and the calculated GPS location of the handset. That coarse setting is then fine tuned based on the observed RF level arriving. A high gain antenna helps by directing the RF to the tower and reducing the amount of power required to achieve the required RF field strength.
TDMA/GSM doesn't have that same equal field strength constraint. It isn't trying to pick out a signal by correlation of a pseudo-random number stream unique to the handset. It does have other impairments. The stream is time sensitive and subject to Rayleigh fading when reflected multi-path signals mixed 180 degrees out of phase and cause signal dropout. Multipath actually helps CDMA by comparison.The multiple correlators expect out of phase arrival and leverage it as the PN streams are correlated and summed. I haven't looked at how LTE is implemented, but the move to 700 MHz should significantly improve penetration of signals into buildings.
We're being shifted from CDMA to GSM phones at the end of the month. 850 and 1900 Mhz, according to what they are licensed to use. How will that affect reception at a distance from the towers?
If it is too negative, I may have to change carriers.