Análise de desempenho de sistemas MIMO-GFDM cooperativos com protocolo AF.

Abstract

The next generation of mobile telephony is being developed to provide better services in future. The fifth-generation networks will be employed in applications that will require low power consumption, providing high speed traffic in a high amount and in a way reliable. In this context, it is necessary to propose new systems or to adapt the current transmission systems, so they will be able to support the demands. The GFDM (Generalized Frequency Division Multiplexing) waveform appears in the literature as a candidate system for the fifth-generation aerial interface of the mobile telephony, being able to stabilize a communication using fragmented spaces of the spectrum, without the necessity for strict synchronism and orthogonality between the subcarries to carry the information signal. Based on this, it is necessary to analyse the performance of the GFDM system. First, an analysis of the detectors filters Matched-Filter, Zero-Forcing and Minimum Mean Square Error in the GFDM receiver. In order to obtain a clear transmission and signal reception in a medium with high concentration of users communicating with each others and transferring data’s, spatial diversity could be utilized to promote the optimization of the transmission medium through the use of cooperative communication techniques and MIMO (Multiple-In Multiple Output), achieving greater efficiency in the use of the signal. Second, it is developed a cooperative GFDM system containing multiples antennas in the transmitter, the AF relay and the receiver. For the relay MIMO-GFDM Cooperative system, a variable gain is proposed, in a way that the particularities of the GFDM system’s transmission process are used. In addition, a sub-optimal receiver is modeled using the Zero-Forcing filter to separate the flow of data at each antenna in the final destination. The performance analysis is given by computational simulations using as comparative metrics the system’s Symbol Error Ratio (SER) and the Peak-to-Average Power Ratio (PAPR) MIMO-GFDM Cooperative signal Cumulative Distribution Function (CDF).The simulations results are presented, evidencing the receiver performance and proposed gain for MIMO-GFDM Cooperative systems. Moreover, it is made a performance comparison with an equivalent OFDM system to the scheme used in this paper.