Abstract
Successive interference cancelation (SIC) has been considered widely for the detection of downlink nonorthogonal multiple access (NOMA) signals. However, the sequential detection inherent to SIC process may introduce additional time delay for certain users, making the SIC unsuitable for communication systems with time delay constraints such as wireless networks that utilize unmanned aerial vehicles or low earth orbit satellites. Therefore, this article considers the performance of NOMA systems using a joint multiuser detector (JMuD), which can detect the signals of all users simultaneously and, hence, reduce the detection time requirements. The performance of the JMuD is evaluated in terms of bit error rate (BER), computational complexity, and processing time and compared to the SIC detector (SICD). The exact BER of the JMuD is derived analytically using quadrature phase shift keying modulation where closed-form expressions are derived for the two- and three-user scenarios for the air-to-ground channel, which is modeled as a Rician fading channels with order statistics. The obtained analytical results corroborated by Monte Carlo simulation confirm that the BERs of the JMuD and SICD are identical; however, the processing time of the SICD is 51% more than the JMuD for several cases of interest.
Highlights
T HE utilization of unmanned aerial vehicles (UAVs) and small low Earth orbit satellites (LEOSs), such as CubeSat, for various applications has witnessed a significant increase in the last few years
Unlike the work of [33] which presents an upper bound on the bit error rate (BER) and compares the complexity of the SIC detector (SICD) and joint multiuser detector (JMuD) for the two-user scenario, the aim of this article is to derive the exact BER of nonorthogonal multiple access (NOMA) systems using JMuD, evaluate its computational time and complexity, and compare them to the SICD for the two- and three-user scenarios
We present the analytical and Monte Carlo simulation results for the JMuD and SICD over Rician channel
Summary
T HE utilization of unmanned aerial vehicles (UAVs) and small low Earth orbit satellites (LEOSs), such as CubeSat, for various applications has witnessed a significant increase in the last few years. Unlike the work of [33] which presents an upper bound on the BER and compares the complexity of the SICD and JMuD for the two-user scenario, the aim of this article is to derive the exact BER of NOMA systems using JMuD, evaluate its computational time and complexity, and compare them to the SICD for the two- and three-user scenarios. Such comparison enables the system designer to optimize the system.
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