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Uplink Non-Orthogonal Multiple Access with Channel Estimation Errors for Internet of Things Applications.

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Next-generation wireless systems need efficient Internet of Things (IoT) support. This study proposes an uplink non-orthogonal multiple access (NOMA) scheme to improve performance despite channel estimation errors in high-density networks.

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Area of Science:

  • Wireless Communication Systems
  • Signal Processing
  • Internet of Things (IoT)

Background:

  • Next-generation wireless systems require efficient support for a large number of Internet of Things (IoT) connections.
  • Uplink non-orthogonal multiple access (NOMA) schemes enable superimposed pilot and data symbols on shared resources.
  • Channel estimation errors severely degrade performance in uplink NOMA, especially with many superimposed packets.

Purpose of the Study:

  • To address the performance degradation caused by channel estimation errors in uplink NOMA systems.
  • To propose a novel uplink NOMA scheme that mitigates the impact of channel estimation inaccuracies.
  • To analyze the performance of uplink NOMA with quadrature phase shift keying (QPSK) modulation under channel estimation errors.

Main Methods:

  • Investigated uplink NOMA schemes with channel estimation errors using quadrature phase shift keying (QPSK) modulation.
  • Analyzed scenarios with superimposed pilot signals and concurrent random access from numerous devices.
  • Developed and evaluated a proposed uplink NOMA scheme designed to alleviate performance degradation.

Main Results:

  • Channel estimation can be inaccurate in high signal-to-noise ratio (SNR) environments when many devices access a single base station resource concurrently.
  • Performance degradation due to channel estimation errors is a significant challenge in uplink NOMA systems.
  • The proposed uplink NOMA scheme demonstrates an ability to alleviate performance degradation.

Conclusions:

  • Accurate channel estimation is critical for uplink NOMA performance, even in high SNR.
  • The proposed uplink NOMA scheme offers a viable solution to mitigate performance issues arising from channel estimation errors.
  • This research contributes to the development of robust communication systems for dense IoT deployments.