Synchronization method for long-term evolution-based machine-type communication in low-power cellular Internet of Things

Rothna Pec,Chang-Hwan Park,Joo-Hyung Choi,Yong Soo Cho

doi:10.1177/1550147716662774

Abstract

The significant growth of machine-to-machine applications for low-power cellular Internet of Things has compelled 3rd Generation Partnership Project to ensure that the future release of long-term evolution can support massive transfer of small, infrequent packets using ultra-low-power and low-cost devices. The 3rd Generation Partnership Project version of machine-to-machine, called “machine-type communication,” is currently being standardized for low-cost machine-type communication operations. In this article, a complete synchronization and cell search procedure is described for machine-type communication devices in long-term evolution systems. Low-complexity algorithms for primary synchronization signal and secondary synchronization signal detection, which requires the highest computational complexity in synchronization and cell search period, are also proposed for low-power machine-type communication devices. Through simulation under long-term evolution-based machine-type communication environments, we show that the proposed methods for primary synchronization signal and secondary synchronization signal detection require six and five times less computational complexity than the conventional methods, respectively, while their performance is similar. The proposed algorithms allow machine-type communication devices in a discontinuous reception cycle to resynchronize quickly with less power when synchronization is lost during a deep sleep period.

Highlights

The master information block (MIB) that consists of 24 bits is the most important broadcast information, which is transmitted on physical broadcast channel (PBCH) that occupies the resource grid of 72 subcarriers in the frequency domain and four orthogonal frequencydivision multiplexing (OFDM) symbols in the time domain.[23]
MIB baseband processing is performed as follows: the 24 bits are attached with cyclic redundancy check (CRC) bits, encoded with tail biting convolutional coding, interleaved with rate matching, scrambled, mapped with quadrature phase shift keying (QPSK) modulation, precoded by a diversity precoder, mapped to the resource grid of subframe 0 for each antenna port.[24,26]
A complete synchronization and cell search procedure was described for machine-type communication’’ (MTC) devices in long-term evolution (LTE) systems

Summary

Introduction

The growing pervasiveness and ubiquity of small and cheap computing devices is paving the way for the realization of the Internet of Things (IoT) vision.[1,2] Several billions of such devices that use machine-to-machine (M2M) communication are predicted to come into existence over the few years, and the majority of them are expected to be wireless sensors.[2,3,4] A large variety of communication technologies that connect such devices have emerged to support a large diversity of applications: Bluetooth in personal area networks, Zigbee in home automation systems, WiFi in local area networks, and cellular networks.[5,6,7]. The MIB that consists of 24 bits is the most important broadcast information, which is transmitted on PBCH that occupies the resource grid of 72 subcarriers in the frequency domain and four OFDM symbols in the time domain.[23] MIB baseband processing is performed as follows: the 24 bits are attached with cyclic redundancy check (CRC) bits, encoded with tail biting convolutional coding, interleaved with rate matching, scrambled, mapped with quadrature phase shift keying (QPSK) modulation, precoded by a diversity precoder, mapped to the resource grid of subframe 0 for each antenna port.[24,26] For a normal CP type, the number of bits increases from 24 to 1920 after interleaving, rate matching, and 16 repetitions.

Method

Conclusion