Interference Analysis in the LTE and NB-IoT Uplink Multiple Access with RF impairments

Narrowband internet of things (NB-IoT) considers the connection of thousands of devices to a single LTE base station (BS). To make possible the coexistence with classic LTE user equipements (UE)s, the BS allocates several IoT UEs into special physical resource blocks (PRB)s. These special PRBs reduce the IoT transmitter complexity but make the LTE signal interfere with the IoT PRBs. IoT nodes are in general low-cost and therefore prone to suffer from RF impairments. The LTE interference and the RF impairments compromise the performance of IoT nodes. In this paper, we analyze the coexistence of LTE and IoT in the multiple access uplink, considering RF impairments. We analyze the use of guard bands to reduce the interference from LTE in IoT. Also, we evaluate the allowable carrier frequency offset (CFO) and I/Q imbalance levels that ensures a reasonable system performance.