Waveform optimization using trapezoidal pulses for 5G random access with short message support

It is well-known that sporadic traffic will be an increasing demand in the 5G market. Obviously, bulky synchronization procedure of the current 4G LTE cellular systems is not a viable option. Transmission of control signaling and payload “in one shot” in physical layer random access channel is an interesting direction. A major challenge is to cope with highly asynchronous access as well as high carrier frequency offsets of low-cost IoT devices. We address this challenge by using a waveform design approach based on a (tail-biting) bi-orthogonal frequency division multiplexing approach (at non-critical density). More specifically, we introduce a 2-parameter trapezoidal pulse family and investigate their properties both by analysis and simulations. In particular, we reveal surprising favorable properties like excellent time domain localization measured in terms of their L₁-norm and relate this to “extreme” cases like the triangle pulse and the sinc pulse which appear as special cases of the trapezoidal family.