Abstract
In this paper, the average achievable rate and error probability of a reconfigurable intelligent surface (RIS) aided systems is investigated for the finite blocklength (FBL) regime. The performance loss due to the presence of phase errors arising from limited quantization levels as well as hardware impairments at the RIS elements is also discussed. First, the composite channel containing the direct path plus the product of reflected channels through the RIS is characterized. Then, the distribution of the received signal-to-noise ratio (SNR) is matched to a Gamma random variable whose parameters depend on the total number of RIS elements, phase errors and the channels' path loss. Next, by considering the FBL regime, the achievable rate expression and error probability are identified and the corresponding average rate and average error probability are elaborated based on the proposed SNR distribution. Furthermore, the impact of the presence of phase error due to either limited quantization levels or hardware impairments on the average rate and error probability is discussed. The numerical results show that Monte Carlo simulations conform to matched Gamma distribution to received SNR for sufficiently large number of RIS elements. In addition, the system reliability indicated by the tightness of the SNR distribution increases when RIS is leveraged particularly when only the reflected channel exists. This highlights the advantages of RIS-aided communications for ultra-reliable and low-latency systems. The difference between Shannon capacity and achievable rate in FBL regime is also discussed. Additionally, the required number of RIS elements to achieve a desired error probability in the FBL regime will be significantly reduced when the phase shifts are performed without error.
Highlights
The performance loss due to the presence of phase errors arising from limited quantization levels as well as hardware impairments at the reconfigurable intelligent surface (RIS) elements is discussed
The authors in [18] considered a phase shift error in RIS elements which is distributed as von Mises or uniform random variable (RV), following which the distribution of the signal-to-noise ratio (SNR) is approximated to a Gamma RV
Even though the aforementioned studies cover the topics of RIS and short-packet communication, to the best of our knowledge, there is no previous reports on the the performance analysis of an RIS-aided transmission with/without the presence of phase noise in an finite blocklength (FBL) regime for ultra-reliable low-latency communications (URLLC) applications
Summary
The fourth industrial evolution or Industry 4.0 is aimed at digitizing industrial technology towards decentralized manufacturing of products and automation of tasks with reduced human involvement in various industrial processes. Instruments with industrial management applications through industrial control networks (ICN) [4] to enable real-time controlling of ubiquitous actuators (AC) and machines across the smart factory To this end, traditional wired connections are being replaced with wireless networks [5] to minimize the infrastructure expenditure, and achieve higher flexibility. The structure of an RIS is composed of a metasurface where a programmable controller configures and adjusts the phase and/or amplitude response of the metasurface to modify the behaviour of the reflection of an incident wave The aim of this operation is that the received signals at a particular receiver location are constructively added so that the system performance enhances in terms of increasing e.g. the signal-to-noise ratio (SNR). The RIS technology can be effectively utilized in URLLC short packet transmissions under finite blocklength (FBL) regime in order to improve the IIoT networks’ performance in terms of enhancing the received signal quality and ensuring high reliability. Our aim is to shed some light on the average achievable rate, and error probability analysis of RIS-aided IIoT networks in FBL regime that relies on only statistical measures of channel response
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