Abstract

One of the most significant challenges facing the Internet of Things (IoT) is providing support for communication to an expanding number of linked devices. Narrow-band Internet of Things (NB-IoT), which is currently an aspect of fifth-generation (5G), is a new narrow-band wireless communication technology that has evolved in recent years to address this issue. To save power, NB-IoT presently supports low-data-rate services by employing low-order modulation formats. However, as the number of data rate-driven applications increases, NB-IoT may require data rate enhancement technologies that do not consume more power. This article proposes a design for quadrupling the number of linked devices in the NB-IoT system using a symbol time compression methodology. A modified symbol time compression (MSTC) approach is specifically suggested, which could preserve 75% of the bandwidth (BW) by reducing the symbol time to a quarter (25%). The suggested design in this study, which is implemented by applying the MSTC methodology four times in orthogonal frequency division multiplexing (OFDM) systems (4-MSTC-OFDM), can exploit the unused bandwidth and transfer four times as much information as compared to the standard OFDM system. Simulation results reveal that the suggested design (4-MSTC-OFDM) decreases the signal-to-noise ratio (SNR) for transmitting the same amount of data by using the additive white Gaussian noise (AWGN) channel and Rayleigh channel, respectively, by 3.9 dB (at BER = 10-6) and 4.4 dB (at BER = 10-4) when compared to the 16-QAM-OFDM system. Moreover, the results show that the proposed design has the same BER as the typical OFDM technique, implying that using the suggested method does not degrade the BER.