TABLE OF CONTENTS Frequency diversity is the process of receiving a radio signal or components of a radio signal on multiple channels (different frequencies) or over a wide radio channel (wide frequency band) to reduce the effects of radio signal distortions (such as signal fading) that occur on one frequency component but do not occur (or not as severe) on another frequency component.
Because the CDMA radio channel provides communication over a relatively wide 1.23 MHz radio channel (compared to the 30 kHz analog channel), it is less susceptible to signal fading. When radio signal fades occur (due to signal combining and canceling), they generally occur over a narrow frequency range. This means a signal fade only affects the reception of some of the chips that represent each bit of information that is transmitted. If a majority of the remaining chips can be successfully received, this results in the successful transfer of information, even in the presence of radio signal fades. Figure 1.7 shows how a wideband radio channel offers the capability of frequency diversity. This example shows that only a portion of the wideband CDMA radio channel is affected by the radio signal fade. As a result, only a few of the chips are lost and a majority of chips are successfully transmitted.
