INTERSYMBOL INTERFERENCE (ISI) MITIGATION SCHEMES IN IR-UWB SYSTEMS EMPLOYING ENERGY DETECTION RECEIVER

Abstract

Ultra-Wideband (UWB) is an emerging wireless technology that has attracted many applications in modern day communications. Its ability to provide high data rates at very low complexity makes the system attractive for many indoor high-speed wireless communications. UWB signal can be transmitted by either impulse radio (IR) or multicarrier techniques. Impulse radio technique in particular, is a carrier less technology using pulses in the range of nanoseconds or less providing a low complexity, low power and low interference susceptible wireless system. These features motivate the usage of energy detection based receiver structures that operates at very low power.

With the recent developments in UWB technology, a promising feature of this system is to provide high data rate with transceivers operating at very low power. High data rate on the other hand can be achieved only by using a complex modulation schemes that requires more transmitted power. As a limitation in the spectral emission associated with UWB, only low-level modulation technology can be used in UWB systems. Hence, in order to achieve high data rates using low-level modulation schemes, the Inter-symbol interference (ISI) becomes unavoidable.

Decision feedback equalization (DFE) is one of the signal process techniques that can be used to mitigate the effects of ISI. This thesis proposes an energy subtraction algorithm combining with the principles of DFE to mitigate the effects of ISI in an impulse radio UWB system employing energy detection receiver. Computer simulations have been performed to verify the operation of the new proposed algorithm under UWB channel characteristics and relevant comparisons have been made with the basic energy detection receiver. Simulation results show that the ISI can be effectively mitigated with low system complexity.