Why frequency hopping is used in gsm

For clarity, consider an sector with channels A and B. Hardly all slots of all channels are in use all the time. Even if a particular slot of channel A is also in use in another sector - co-channel interference, chances are that another slot of channel B are not!

In other words, a channel can be suffering interference, but we have other channels in the sequence of jumps that may be no interference! When the network uses FH, and moves our call slot to slot, and frequency to frequency, the interference is turns into a random effect. We still, as we speak, the problems of multipath. And the idea is basically the same.

By jumping from one frequency to another, the user suffers the effects of multipath problem by a very small periods of time. Remember we use narrow bands! In both cases, whether co-channel interference or multipath fading, there are the error correction algorithms, which achieve the most efficient way to clean and recover the original signal. Finally, we see a simplified diagram showing the steps involved in establishing a communication using FH. First, the transmitter sends a request 1 to start the FH through the control channel.

The receiver, after receiving this request sends a base number 2 back. The transmitter then uses that number, calculates and sends the series of frequencies 3 to be used. In Fast Frequency Hopping FFH , the carrier frequency is allowed to change more than once during a bit duration, but this is not implemented in GSM At first, the frequency hopping was used in military applications in order to improve the secrecy and to make the system more robust against jamming.

In cellular network, the frequency hopping also provides some additional benefits such as frequency diversity and interference diversity. Google serves cookies to analyze traffic to this site and for serving personalized ads.

IEEE 4th Internat. Nielsen, J. Wigard and P. Download references. You can also search for this author in PubMed Google Scholar. Reprints and Permissions. Bourjolly, JM. Telecommunication Systems 21, — Download citation. The results show that the performance of frequency hopping surpasses that of intra-timeslot handover as more hopping channels are deployed. Technology in Motion. Article :.