| Popis: |
In radio communication systems, when implementing coherent types of reception, it is assumed that the receiver knows information about the state of the communication channel, which is achieved by introducing signal redundancy (pilot signals). The frequency of sending pilot signals depends on factors that change the state of the communication channel, one of which is the high speed of movement of mobile stations. The use of pilot signals not only hinders the efficient use of the radio frequency resource, but also, in the case of fast fading, does not allow the channel to be estimated and tracked with the required accuracy. These disadvantages can be eliminated by using the differential transmission method, for the implementation of which there is no need to know information about the state of the channel. The application of the principles of differential transmission to space-time coding does not find sufficiently effective solutions that combine low computational complexity and energy efficiency of differential coding methods. |
