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Closed-Loop Binary Media-Based Modulation

Majid Nasiri Khormuji, Branislav M. Popovic

TL;DR

The paper addresses the limitations of open-loop Binary MBM by introducing a closed-loop scheme with feedback that uses optimally chosen complex weights to maximize constellation distance under a power constraint. The main result is that closed-loop Binary MBM achieves diversity order $2$ and, with optimal weights, matches the performance of Alamouti-coded BPSK using a single RF chain, while a unit-amplitude phase-only variant remains near-optimal. The findings show a substantial BER improvement over open-loop MBM and establish a practical path for MBM deployment in fading channels. The work also clarifies the connection to classic space-time coding and highlights significant SNR gains that support MBM as a viable transmit-diversity technique for future networks.

Abstract

Presenting analytical results for Binary Media-Based Modulation (B-MBM) over fading channels for single-antenna receivers. Illustrating that open-loop B-MBM, in the absence of feedback, only achieves a diversity order of one. However, with feedback and optimal weight selection in closed-loop configurations, a diversity order of two becomes achievable. Notably, the closed-loop B-MBM, with analytically computed optimal weights, performs equivalent to Alamouti-coded BPSK transmission, demonstrating feasibility even with just one radio frequency chain when feedback is available.

Closed-Loop Binary Media-Based Modulation

TL;DR

The paper addresses the limitations of open-loop Binary MBM by introducing a closed-loop scheme with feedback that uses optimally chosen complex weights to maximize constellation distance under a power constraint. The main result is that closed-loop Binary MBM achieves diversity order and, with optimal weights, matches the performance of Alamouti-coded BPSK using a single RF chain, while a unit-amplitude phase-only variant remains near-optimal. The findings show a substantial BER improvement over open-loop MBM and establish a practical path for MBM deployment in fading channels. The work also clarifies the connection to classic space-time coding and highlights significant SNR gains that support MBM as a viable transmit-diversity technique for future networks.

Abstract

Presenting analytical results for Binary Media-Based Modulation (B-MBM) over fading channels for single-antenna receivers. Illustrating that open-loop B-MBM, in the absence of feedback, only achieves a diversity order of one. However, with feedback and optimal weight selection in closed-loop configurations, a diversity order of two becomes achievable. Notably, the closed-loop B-MBM, with analytically computed optimal weights, performs equivalent to Alamouti-coded BPSK transmission, demonstrating feasibility even with just one radio frequency chain when feedback is available.
Paper Structure (8 sections, 6 theorems, 44 equations, 4 figures, 1 table)

This paper contains 8 sections, 6 theorems, 44 equations, 4 figures, 1 table.

Table of Contents

  1. Background and Outline
  2. Open-Loop Binary MBM
  3. Closed-Loop Binary MBM
  4. Performance of Closed-Loop B-MBM
  5. Connection to Alamouti Code
  6. Closed-Loop B-MBM with Unit- Amplitude Weights
  7. Performance Evaluations
  8. Conclusions

Key Result

Proposition 1

Bit Error Rate (BER) of the open-loop B-MBM is where ${\rm snr }:=N_0^{-1}$ for unit power transmitter, unit-variance Rayleigh fading and AWGN with variance of $N_0$ at the receiver. Hereafter, $f(x) = O (g(x))$ means that there exists $\Omega,M \in R$ such that $\left|\frac{f(x)}{g(x)}\right| \leq M$ whenever $x> \Omega$.

Figures (4)

  • Figure 1: B-MBM transmission link with a single RF chain, a two-state RF connected to a controller and a single-antenna receiver.
  • Figure 2: Closed-loop B-MBM transmission link with a single RF chain, a two-state mirror and complex weight $w$ adjusted by feedback.
  • Figure 3: Closed-loop B-MBM received constellation points with rotation.
  • Figure 4: Performance of BPSK of SISO (black) and MRC (red) for $2\times 1$ link and B-MBM for open-loop (blue), closed-loop with optimal weights (orange) and closed-loop with optimal unit-amplitude weights (green) with analytical (solid lines) and simulation (dots) results over Rayleigh fading channels.

Theorems & Definitions (11)

  • Proposition 1
  • proof
  • Proposition 2
  • proof
  • Proposition 3
  • proof
  • Proposition 4
  • proof
  • Proposition 5
  • proof
  • ...and 1 more