Qualcomm was the only one to create these communication chips for the CDMA Technology. Qualcomm was privy to the classified information. However once the information became public, Qualcomm claimed patents on the technology and became the first to commercialize it.

In CDMA each user is allocated the entire spectrum all the time, however as the name suggests it uses codes to identify the connections. CDMA uses a unique spreading code to spread the baseband data before transmission. Now the signal is transmitted in a channel, this is below the noise level. The receiver that this end uses a correlator to de-spread the wanted signal, which is then passed through a narrow band-pass filter. Here the unwanted signals will not be de-spread and will not pass through the filter. CDMA Codes take the form of a carefully designed sequence of one’s and zero’s which are produced at a much higher rate than the baseband data. In CDMA the rate of spreading code is referred to as chip rate and not bit rate.

CDMA codes are not required to provide call security, but create a uniqueness to enable call identification. Codes should not correlate to other codes or time shifted version of itself. WCDMA uses Direct Sequence spreading, where spreading process is done by directly combining the baseband information to high chip rate binary code.

One of the main advantages of CDMA systems is the capability of using signals that arrive in the receivers with different time delays. This phenomenon is called multi-path. As FDMA and TDMA, are narrow band systems, they cannot discriminate between the multi-path arrivals, and resort to equalization to mitigate the negative effects of multi-path. Due to its wide bandwidth and rake receivers, CDMA uses the multi-path signals and combines them to make an even stronger signal at the receivers. CDMA subscriber units use rake receivers. This is essentially a set of several receivers. One of the receivers constantly searches for different multi-paths and feeds the information to the other three receivers. Each receiver then de-modulates the signal corresponding to a strong multi-path. The results are then combined together to make the signal stronger.