A Design for Increasing the Capacity Fourfold in NB-IoT Systems using A Modified Symbol Time Compression Approach

Abstract

One of the most significant obstacles facing the Internet of Things (IoT) is how to offer support for communication to an expanding number of linked items. 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 currently exploits modulation schemes that are characterized by low order to deliver low data rate. However, as the number of applications dependent on data rate increases, NB-IoT needs to use data rate improvement technologies that do not consume additional power. This paper proposes a design for quadrupling the total number of linked items 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%). This study suggests a design that uses the MSTC method four times in orthogonal frequency division multiplexing (4-MSTC-OFDM) to take advantage of the unused bandwidth and has the capability to deliver a quadruple quantity of information in comparison to the standard OFDM system. Simulations show that the suggested design (4-MSTC-OFDM) lowers the signal-to-noise ratio (SNR) by 3.9 dB (at BER = 10-6) and 4.4 dB (at BER = 10-4) compared to the OFDM system with 16-QAM (16-QAM-OFDM) when sending the same amount of data over the Rayleigh fading channel and additive white Gaussian noise channel (AWGN). Moreover, the results of simulations indicate that the proposed design possesses an identical BER as the conventional OFDM technique, implying that using the suggested method does not degrade the BER.