Recently standardized New Radio (NR) technology supports both ultra-reliable low-latency (URLLC) service and conventional enhanced mobile broadband (eMBB) service. Owing to extreme latency and reliability requirements an explicit prioritization needs to be provided to URLLC service when these traffic types are mixed up at the air interface. In this work, we consider simultaneous support of these two services in an industrial environment, where production line equipment utilizes URLLC service for reorganization and synchronous operation while eMBB service is used for remote monitoring. By utilizing the tools of stochastic geometry and queuing theory, we formalize the model with pre-emptive priority service at NR base station (BS) with and without direct device-to-device (D2D) communications. Our numerical results indicate that the priority-based implementation of URLLC and eMBB coexistence allows us to isolate the former traffic efficiently and requires no external control. D2D-aware strategy, where the BS explicitly reserves some resources for direct communications, drastically outperforms those, where no explicit reservation is utilized, as well as the baseline strategy where all the traffic goes through the BS. This strategy can achieve 10 ⁻⁵ of URLLC drop probability when the baseline strategy produces just $5\times 10^{-3}$ , leading to three orders of magnitude reduction in drop probability and without significant impact produced on eMBB session drop probability. The developed model can be utilized to estimate the NR BS density required to support prescribed performance guarantees for all the considered strategies.

5G New Radio (NR) systems promise to expand offered services to enable industrial automation scenarios. To enable ultra-low latency at the air interface and to exploit spatial redundancy for applications such as synchronization and motion control, user equipment (UE) will naturally require device-to-device (D2D) and base station (BS) to UE communications and directional transmissions provided by millimeter wave (mmWave) frequencies. However, the performance of such systems is affected by the blockage phenomenon. In this paper, we propose a simple line-of-sight (LoS) blockage model for Industrial mmWave-based industrial Internet of Things (IIoT) deployments. The model is based on two sub-models, where each part can be changed/replaced to fit the scenario of interest. The first part is based on photogrammetry and provides the transparency probability for a single element on the factory floor. The second one utilizes these models of industrial elements to form the deployment and then applies stochastic geometry to derive the blockage probability. The proposed model can be utilized for any type of industrial machine, accounts for their inherent regular deployments on the factory floor, and provides the final results in an easy-to-compute form. Our results indicate that direct UE-UE communications are feasible in sparse deployments (less than 0.1 machine/m²) or at small communications distances (less than 5–10 m) or in deployments with highly transparent machines (machine transparency less than 0.5). Otherwise, BS-UE communications need to be utilized. In this case, BS height becomes a critical parameter affecting the LoS probability. Specifically, using a BS height of 10 m allows blockage probability to be improved by 20–30% as compared to a BS of height 4 m. Finally, as UE height produces more impact on the blockage probability as compared to a machine height, in real deployments, one needs to ensure that the height of communications modules at UEs are maximized.

Fifth-generation (5G) New Radio (NR) systems are expected to support multiple traffic classes including enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC) at the same air interface. This functionality is assumed to be implemented by utilizing the network slicing concept. According to the 3rd Generation Partnership Project (3GPP), the efficient support of this feature requires statistical multiplexing and, at the same time, traffic isolation between slices. In this paper, we formulate and solve a mathematical model for a class of Radio Access Network (RAN) slicing algorithms that simultaneously include resource reservation and a priority-based service discipline allowing us to incur fine granularity in the service processes of different traffic aggregates. The system is based on a queueing model and allows parametrization by accounting for the specifics of wireless channel impairments. As metrics of interest, we utilize K-class session drop probability, K-class session pre-emption probability, and system resource utilization. To showcase the capabilities of the model, we also compare performance guarantees provided for URLLC, eMBB, and mMTC traffic when multiplexed over the same NR radio interface. Our results demonstrate that the performance trade-off is dictated by the offered traffic load of the highest priority sessions: (i) when it is small, mixed reservation/priority scheme outperforms the full reservation mechanism; (ii) for overloaded conditions, full reservations provides better traffic isolation. The mixed strategy is beneficial to traffic aggregates with short-lived lightweight sessions, such as URLLC and mMTC, while the reservation only scheme works better for elastic eMBB traffic. The most important feature is that the mixed strategy allows resource utilization to be improved up to 95%, which is 10–15% higher compared to the reservation-only scheme while still providing isolation between traffic types.

Enabling efficient traffic coexistence between ultra-reliable low-latency (URLLC) and enhanced mobile broadband (eMBB) services at the 5G New Radio (NR) air interface using the concept of network slicing requires careful tuning of session and medium access control (MAC) layer parameters. The studies performed so far addressed only one of these layers concentrating either on resource allocation or packet scheduling. The aim of this paper is to propose a joint model for performance analysis and optimization of session and MAC layer parameters jointly. To this aim, by accounting for wireless channel characteristics and arriving traffic specifics at both session andMAC layers, we utilize the tools for stochastic geometry and queuing theory to formulate a joint performance model. The model has a two-level structure, where the solution of the session level sub-model provides the input to the MAC one. As the intermediate parameters connecting two levels we consider the URLLC and eMBB drop and preemption probabilities that allows us to characterize the input traffic at the MAC layer. The ultimate metric of interest is the delay of the URLLC and eMBB packets experienced in the MAC buffer. Our numerical results show that the use of strict connection admission control at the session layer leads to the pessimistic system behavior at the MAC layer making the system overprovisioned in terms of packet loss probabilities, that is, the worse case packet loss probability for eMBB traffic is 10⁻⁴. While it ensures close to 1 ms packet latency for URLLC traffic over 90% admitted range of session arrival intensities, it is still violates it at the maximal admitted rates increasing the URLLC packet delay up to ≈ 3 ms. Thus, additional degree of overprovisioning is required on top of conventional prioritization at the session level.