Enabling mURLLC Under κ-μ Shadowed Fading by Cell-Free mMIMO

It is challenging to meet the requirement for massive ultra-reliable low-latency communications (mURLLC) under complex environments as well as diverse fading channels in the sixth-generation (6G) mobile communication system. In the 6G, user-centered cell-free (CF) architecture equipped with massive multiple input multiple output (mMIMO) technology breaks through the traditional cellular system design concept and is a promising research direction. Based on the CF mMIMO uplink system, we investigate how to implement mURLLC. Firstly, we use the least-squares estimation (LSE) method for channel estimation and obtain the channel estimation matrix which is utilized for obtaining user’s post-processing signal-to-noise ratio (PPSNR) under κ-μ shadowed fading. Secondly, we deduce the probability density function (PDF) of PPSNR. Lastly, an expression for the relationship between the length of pilots (LoP) and the error probability (EP) is available using the information theory of the finite blocklength (FBL). Furthermore, for a given delay condition, we apply the golden section search algorithm (GSSA) to find the optimal LoP. The results of the simulations demonstrate that when the system is configured with appropriate parameters, the mURLLC will be enabled. Moreover, the κ-μ shadowed fading model can characterize almost all classic fading models.