3GPP NB-IOT Coverage Extension Using LEO Satellites

Abstract

Machine-Type Communications are meeting a growing interest on the consumer market. Dedicated technologies arise to support more robust communications involving a massive number of low cost, low energy-consuming devices This paper discusses the coverage extension of a Low-Powered Wide Area Network using a Low Earth Orbit satellite constellation, benefiting from the improved performance of a recent standard. The transmission complies with the user equipment specifications standardized as NB-IoT by 3GPP in Release 13. This radio technology is an update on LTE standard with enhanced performances: the supported path loss can be 20 dB higher than with legacy LTE. This improvement makes satellite-compatible the small and energy-constrained devices. A specific unidirectional system is defined, and a link budget is derived. Also, a receiver architecture is presented, that takes into consideration satellite channel specific impairments.

Physical Layer Abstraction for Performance Evaluation of Leo Satellite Systems for Iot Using Time-Frequency Aloha Scheme

“…Forward Error Control (FEC) is a common way to improve the global throughput of a system. Both a turbocode and a repetition code are used in the system presented in [2]. In this section, we are going to study for this specific satellite system how the repetitions impact the decoding performance.…”

“…The scrambling is performed by multiplying every repetition by a gold code, parameterized for each repetition by the frame number, the first slot number, a ID number of the cell, and an ID number of the terminal (see section 10.1.3.1 of [11]). Because of the frame numbering, the scrambling parameters will loop every 320 ms. By using 3.75 kHz subcarrier, 16 repetitions and 2 Resource Units by repetition as in [2], the scrambling is reinitialized to the same sequence every 5 repetitions, as displayed in Table 1. In this table, the scrambling parameters are presented as a function of the repetition number nrep.…”

“…LPWAN network operators try to outperform competition by having the widest coverage. Using a Low-Earth Orbit (LEO) satellite system to extend a LPWAN coverage is an attractive option, and has already been proposed [2,3]. These solutions rely on random access protocols, both in the time and the frequency domains.…”

“…This paper focuses on the use of a Low Earth Orbit (LEO) satellite constellation to extend 3GPP LTE NB-IoT. More information about the system can be found in [2] and [3], but this study can be adapted to terrestrial systems. In this system, we encounter a TFA scheme.…”

“…This paper proposes abstraction methods to compute the BER of a noncoded QPSK transmission, and the PER of a coded QPSK transmission under a TFA access scheme, for a low number of collisions. As described in [2], the transmission follows LTE NB-IoT specifications: both a turbocode and a repetition code spreading are used, as specified by 3GPP in LTE (Release 13) standard [11,12]. As the interference also follows the same transmission scheme, some common approximations, as whiteness, cannot be used.…”