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Related Concept Videos

Downsampling01:20

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When considering a sampled sequence with zero values between sampling instants, one can replace it by taking every N-th value of the sequence. At these integer multiples of N, the original and sampled sequences coincide. This process, known as decimation, involves extracting every N-th sample from a sequence, thereby creating a more efficient sequence.
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The Discrete-Time Fourier Series (DTFS) is a fundamental concept in signal processing, serving as the discrete-time counterpart to the continuous-time Fourier series. It allows for the representation and analysis of discrete-time periodic signals in terms of their frequency components. Unlike its continuous counterpart, which utilizes integrals, the calculation of DTFS expansion coefficients involves summations due to the discrete nature of the signal.
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Properties of Fourier Transform II01:24

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Updated: May 10, 2026

Continuous-Wave Propagation Channel-Sounding Measurement System - Testing, Verification, and Measurements
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Published on: June 25, 2021

Covert communications in a downlink time division multiple access system.

Jihwan Moon1, Taehoon Kim2, Inkyu Bang3

  • 1Department of Mobile Convergence Engineering, Hanbat National University, Daejeon, 34158, Republic of Korea.

Scientific Reports
|May 8, 2026
PubMed
Summary
This summary is machine-generated.

This study enhances covert communications in time division multiple access systems by optimizing power allocation to maximize secure data rates. The proposed method effectively balances covert rates against detection error probabilities for improved performance.

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Area of Science:

  • Electrical Engineering
  • Computer Science
  • Information Theory

Background:

  • Covert communication systems aim to transmit information undetected by eavesdroppers.
  • Time division multiple access (TDMA) systems sequentially allocate time slots to users.
  • Embedding secret data within public transmissions presents unique challenges in wireless networks.

Purpose of the Study:

  • To investigate and enhance covert communication capabilities within a downlink TDMA system.
  • To maximize the achievable sum covert rate by optimizing power allocation strategies.
  • To ensure reliable reception of covert messages while minimizing detection probability by legitimate users.

Main Methods:

  • A novel two-layer optimization framework is proposed to address the non-convex problem.
  • The gradient projection method is employed for efficient power allocation across time slots.
  • Analysis focuses on balancing transmit power distribution for optimal covert communication performance.

Main Results:

  • The proposed optimization framework effectively maximizes the sum covert rate.
  • Numerical simulations demonstrate the approach's efficiency in power allocation.
  • Key system parameters significantly impact the achievable covert communication performance.

Conclusions:

  • The developed method provides an effective solution for enhancing covert communication rates in TDMA systems.
  • Optimized power allocation is crucial for achieving high covert rates under detection constraints.
  • The study offers valuable insights into the design and performance of secure wireless communication systems.