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Uplink Multiple Access with Heterogeneous Blocklength and Reliability Constraints: Discrete Signaling with Treating Interference as Noise

Min Qiu, Yu-Chih Huang, Jinhong Yuan

TL;DR

It is demonstrated theoretically and numerically that the proposed scheme employing quadrature amplitude modulations and TIN decoding can perform very close to the benchmark scheme based on Gaussian signaling with perfect SIC decoding.

Abstract

We consider the uplink multiple access of heterogeneous users, e.g., ultra-reliable low-latency communications (URLLC) and enhanced mobile broadband (eMBB) users. Each user has its own reliability requirement and blocklength constraint, and users transmitting longer blocks suffer from heterogeneous interference. On top of that, the decoding of URLLC messages cannot leverage successive interference cancellation (SIC) owing to the stringent latency requirements. This can significantly degrade the spectral efficiency of all URLLC users when the interference is strong. To overcome this issue, we propose a new multiple access scheme employing discrete signaling and treating interference as noise (TIN) decoding, i.e., without SIC. Specifically, to handle heterogeneous interference while maintaining the single-user encoding and decoding complexities, each user uses a single channel code and maps its coded bits onto sub-blocks of symbols, where the underlying constellations can be different. We demonstrate theoretically and numerically that the proposed scheme employing quadrature amplitude modulations and TIN decoding can perform very close to the benchmark scheme based on Gaussian signaling with perfect SIC decoding. Interestingly, we show that the proposed scheme does not need to use all the transmit power budget, but also can sometimes even outperform the benchmark scheme.

Uplink Multiple Access with Heterogeneous Blocklength and Reliability Constraints: Discrete Signaling with Treating Interference as Noise

TL;DR

It is demonstrated theoretically and numerically that the proposed scheme employing quadrature amplitude modulations and TIN decoding can perform very close to the benchmark scheme based on Gaussian signaling with perfect SIC decoding.

Abstract

We consider the uplink multiple access of heterogeneous users, e.g., ultra-reliable low-latency communications (URLLC) and enhanced mobile broadband (eMBB) users. Each user has its own reliability requirement and blocklength constraint, and users transmitting longer blocks suffer from heterogeneous interference. On top of that, the decoding of URLLC messages cannot leverage successive interference cancellation (SIC) owing to the stringent latency requirements. This can significantly degrade the spectral efficiency of all URLLC users when the interference is strong. To overcome this issue, we propose a new multiple access scheme employing discrete signaling and treating interference as noise (TIN) decoding, i.e., without SIC. Specifically, to handle heterogeneous interference while maintaining the single-user encoding and decoding complexities, each user uses a single channel code and maps its coded bits onto sub-blocks of symbols, where the underlying constellations can be different. We demonstrate theoretically and numerically that the proposed scheme employing quadrature amplitude modulations and TIN decoding can perform very close to the benchmark scheme based on Gaussian signaling with perfect SIC decoding. Interestingly, we show that the proposed scheme does not need to use all the transmit power budget, but also can sometimes even outperform the benchmark scheme.

Paper Structure

This paper contains 21 sections, 3 theorems, 60 equations, 7 figures, 1 table.

Table of Contents

  1. Introduction
  2. Notations
  3. System Model
  4. The Deterministic Channel and Achievable Schemes with TIN
  5. Deterministic MAC under Heterogeneous Interference
  6. The Two-User Case
  7. The $K$-User Case
  8. Proposed Coded Modulation Scheme With TIN
  9. Proposed Achievable Scheme
  10. Encoding
  11. Constellation Symbol Mapping
  12. Constellation Design
  13. TIN Decoding
  14. Mutual Information and Minimum Distance Analysis
  15. Finite Blocklength Coding Analysis and Design
  16. ...and 6 more sections

Key Result

Theorem 1

Let $\epsilon_k$ be the upper bound on the average TIN decoding error probability of user $k$. For the $K$-user MAC with heterogeneous blocklength constraints $(N_1,\ldots,N_k)$ and error probability constraints $(\epsilon_1,\ldots,\epsilon_K)$, the rate of user $k$ with TIN decoding, i.e., $R_k$, i where are the mutual information and dispersion, respectively, and $Q^{-1}(x)$ is the inverse of $

Figures (7)

  • Figure 1: $K$ users send their packets with different lengths to the receiver.
  • Figure 2: The two-user deterministic model with $(n_1,n_2)=(10,8)$ and $(m_1,m_{2,1},m_{2,2})=(6,4,8)$.
  • Figure 3: Two users send their coded symbols with different lengths to the receiver.
  • Figure 4: The receiver performs parallel TIN decoding on two users' transmitted blocks.
  • Figure 5: Achievable rate pairs of two users in bits/s/Hz.
  • ...and 2 more figures

Theorems & Definitions (11)

  • Remark 1
  • proof
  • Remark 2
  • proof
  • Remark 3
  • proof
  • Theorem 1
  • Remark 4
  • proof
  • Lemma 1
  • ...and 1 more