Increased capacity communication links with spectrum sharing

Due to a great demand of higher capacity in various applications, there is a need for increasing the capacity of communications links without a significant increase in the required resources. Many techniques have been introduced to increase the capacity; however, they cannot be successfully applied without a significant increase in the transmitted power. Spectrum sharing is a technique to increase the capacity in communication links that has been invented by Dr. Rajendra Kumar. The details of this technology is explained in the patent application 20110216810A1, September 2011 and the US Patent 008767845B2, July 2014. In this technique one wideband signal will be overlapped with one or more narrowband signals in spectrum. The narrowband signals are shifted from the center frequency of the wideband signal. This method provides an increase in the capacity, compared to the traditional systems. Moreover, using spectrum sharing does not have the drawbacks of other commonly used techniques for increasing the capacity. This technique does not require the system to increase its transmitted power; and, therefore, unlike other techniques, the issues regarding power constraints in some applications and nonlinearity in power amplifiers will not arise. The simulation results presented in patent application 20110216810A1, and the US Patent 008767845B2, are for the case that one wideband signal is overlapped by one narrowband signal. To further evaluate the performance of spectrum sharing technique, this thesis presents some results obtained by computer simulations in terms of capacity increase obtained by the spectrum sharing technique, for the case that two narrowband signals are overlapping the wideband signal.