Down-Link NOMA With Successive Refinement for Binary Symmetric Source Transmission

Abstract

This paper focuses on a lossy transmission of binary symmetric source (BSS) with down-link non-orthogonal multiple access (DL-NOMA). The transmitted binary sequences are lossy-compressed descriptions of the same BSS, which are overlapped in a specified signal format, corresponding to the receivers with pre-determined distortion requirements. Despite a higher spectrum efficiency achieved by DL-NOMA, redundancy may still remain if the overlapped descriptions are correlated. In this work, a system combining DL-NOMA and successive refinement, referred to as DN-SR, is proposed. Specifically, instead of re-constructing the source by a single description, the receiver can achieve a low distortion by first recovering the basic description, and then refining it with the help of another refinement description. If the two descriptions are made independent, transmission efficiency of the conventional DL-NOMA can be further improved. As the main contribution, this paper derives the outage probability of DN-SR in closedform, assuming block Rayleigh fading channels. The advantage of DN-SR is numerically studied in terms of the system outage probability, compared to both the conventional DL-NOMA, and a modified DL-NOMA which exploits the correlation between descriptions, referred to as DN-CE. Finally, the optimal power allocation to the two descriptions is investigated for DN-SR, aiming to minimize the system outage probability.

Performance analysis of one‐source‐with‐one‐helper transmission over shadowed κ$\kappa$‐μ$\mu$ fading multiple access channels

“…Since the source‐channel separation theorem holds for point‐to‐point transmission and is not optimal in general, () is only the sufficient but not necessary condition for transmitting one source with one helper over a MAC with arbitrary small error probability. This also leads to that the derived expression is the upper bound of outage probability as in [34].…”

“…Whereas, in the high SNR region, the difference between GCC and CCC becomes significant. The approximated CCC has been evaluated in [34] which demonstrates that (23) is very accurate to represent CCC.…”

“…In this section, we derived the outage probability of the one‐source‐with‐one‐helper transmission over MAC with CCC assumption. Since there is no closed‐form expression for calculating the explicit CCC, with an approximated equation of CCC [34], the relationship between the instantaneous channel SNR $$\gamma _{1} \ (i\in \lbrace \text{1},\text{2}\rbrace )$$ and the rate $$\acute{R}$$ is written as $$\begin{eqnarray} {\begin{cases} \acute{R}\times H(\text{S})= C(\gamma _1) = \log _2(1+\gamma _1) - \displaystyle\frac{1}{2}\log _2{\left[ 1 + {\left(\displaystyle\frac{\gamma _1}{{M}} \right)} \right]} \\[19pt] \acute{R}\times H(\text{H}) \hspace*{-.5pt}=\hspace*{-.5pt} C(\gamma _2) \hspace*{-.5pt}=\hspace*{-.5pt} \log _2(1\hspace*{-.5pt}+\hspace*{-.5pt}\gamma _2) \hspace*{-.5pt}-\hspace*{-.5pt} \displaystyle\frac{1}{2}\log _2{\left[ 1 \hspace*{-.5pt}+\hspace*{-.5pt} {\left(\displaystyle\frac{\gamma _2}{{M}} \right)} \right]} \end{cases}}\!\!\!\!\!\!,\nonumber\\ \end{eqnarray}$$with $${M}$$‐ary quadrature amplitude modulation(QAM) to facilitate the outage calculation. The inverse function of () is written as …”

“…In this section, we derived the outage probability of the one-source-with-one-helper transmission over MAC with CCC assumption. Since there is no closed-form expression for calculating the explicit CCC, with an approximated equation of CCC [34], the relationship between the instantaneous channel SNR 𝛾 1 (i ∈ {1, 2}) and the rate Ŕ is written as…”

Outage Analysis for Correlated Sources Coding over NOMA in Shadowed κ-µ Fading

“…A minimum mean square error (MMSE) detector was proposed in [8] for iterative joint detecting and decoding the correlated sources transmitted over asynchronous NOMA channels. Cheng et al derived the outage probability of a lossy transmission of binary symmetric source with downlink NOMA and successive refinement [9]. Zhou et al [10] and He et al [11] calculated the outage probability upper bound for a two-correlated-source-coding system and for the two hop non-orthogonal multiple access relay channel, respectively, based on the derived sufficient condition.…”