A Multicoded-PPM Scheme for High Data Rate UWB Communication Systems
A new modulation scheme called multicoded-pulse position modulation (MC-PPM) is proposed for an ultrawideband (UWB) impulse radio communication system. The multicoded signal is generated by using several orthogonal codes for transmitting data simultaneously. Then, each multi-level value of the multicoded signal is converted to pulse position which results in not only an improved data rate, but also a processing gain in reception, delivering the power-efficient benefit of PPM and guaranteeing the low pulse energy for UWB systems. We notice that the modulation of multi-level values of the multicoded signal to pulse position is more efficient in terms of achievable data rate than the modulation of transmitting data based on other PPM schemes within given bandwidth and pulse energy. Therefore, as a performance measure, we focus on the achievable data rate (link capacity) of the proposed scheme and analyze it theoretically. Through simulation, we compare the link capacity of the MC-PPM scheme and other PPM schemes, such as M-ary PPM and multiple PPM. With the fixed bandwidth and same pulse energy condition, the UWB system based on the proposed MC-PIPM scheme shows good link capacity and an increased data rate as L increases, which is contrary to other PPM schemes.
ultrawideband (uwb) multicoded signal link capacity pulse position modulation (ppm)