SDR implementation of the receiver of adaptive communication system

Abstract

The paper presents software implementation of a receiver forming a part of an adaptive communication system. The system is intended for communication with a satellite placed in a low Earth orbit (LEO). The ability of adaptation is believed to increase the total amount of data transmitted from the satellite to the ground station. Depending on the signal-to-noise ratio (SNR) of the received signal, adaptive transmission is realized using different transmission modes, i.e., different modulation schemes (BPSK, QPSK, 8-PSK, and 16-APSK) and different convolutional code rates (1/2, 2/3, 3/4, 5/6, and 7/8). The receiver consists of a software-defined radio (SDR) module (National Instruments USRP-2920) and a multithread reception software running on Windows operating system. In order to increase the speed of signal processing, the software takes advantage of single instruction multiple data instructions supported by x86 processor architecture.

Verifying a concept of adaptive communication with LEO satellites using SDR-based simulations

“…The set of available modulation schemes is assumed to include BPSK, QPSK, 8-PSK, and 16-APSK (after the DVB-S2 standard [7]), whereas the convolutional code rate can be selected from 1/2, 2/3, 3/4, 5/6, or 7/8 (after the DVB-S standard [8]). The receiver measures the current SNR level, compares it with a number of predefined thresholds, selects the best transmission mode to be used [6], and sends the transmission mode change request to the satellite via the return channel. The threshold levels were determined experimentally so as to provide BER not higher than 10 −6 at the output of the channel decoder.…”

“…For these reasons, in [5] we proposed a system intended for providing an adaptive communication between a small, low cost, low Earth orbit (LEO) satellite and a ground station (GS). The laboratory model of the system was set up using the transmitter operating as a LEO satellite, the satellite channel simulator, and the receiver representing a ground station, described in details in [6]. This paper is focused on the reception process.…”

A Carrier Synchronization Algorithm for SDR-based Communication with LEO Satellites

“…A simple carrier synchronization method for an adaptive LEO satellite system was presented in [7]. The authors run a number of tests in a set-up consisted of SDR modules acting as a LEO satellite, a channel simulator and an SDR receiver.…”