In communication systems, precisely a wireless communication system, signals can take different multiple distinct pathways to reach the receiver. In the different pathways to the receiver, the signal can easily be refracted, reflected, diffracted or even blocked hence reaching its destination, the receiver attenuated or faded. To ensure that the signal reaches the receiver just  like it departed from the transmitter to ensure some much needed fidelity, there needs some application to recover that signal originality, a point where the rake receiver is greatly called to action (Korhonen, 2003).

Ideally, the rake receiver is moreorless of a radio which helps in minimizing and countering the effects of signal distortion or fading as a result of multipath effects as the signal travels from the transmitter to the receiver. The rake receiver avoids the cancellation of signal fades in the occasion that delayed paths reach the receiver in different phases and weighs the signals that come in with various signal-to-noise ratios appropriately (Korhonen, 2003).

The rake receiver, just like the farmer’s rake achieves its function by the use of sub-receivers aka fingers which are simply several correlators, with each of them assigned to specific multipath component. Each finger decodes a specific multipath component independently with the contribution of each individual finger later getting combined to make the best use of the various transmission features of each of the individual transmission paths. The rake receiver design can be seen as a series of time delayed correlator taps receiving input from a central antenna. The outputs of every tap can be easily recombined in phase if the individual correlator taps are delayed to tally the particular transmitted signal arrival. In a nutshell, the rake receiver works just like a garden rake, gathering the signal components received over the various fingers or delayed propagation paths and combining those components from the individual fingers to avoid fading of signal distortions (Korhonen, 2003).

Reference

Juha Korhonen, (2003), Introduction to 3G Mobile Communications, Artech House.