# mIoT Slice for 5G Systems: Design and Performance Evaluation
## 1 Introduction  
Upon completion of use cases and requirements analysis, telecommunication industry is now moving towards developing 5G solutions to deploy from 2020 onwards. Leveraging on architecture modularization, service-oriented interfaces and end-to-end (E2E) network slicing, 5G systems are expected to enable the integration of vertical industries, thus aiming at creating an ecosystem able to efficiently support the heterogeneous features of tree use case categories [1; 2], namely enhanced Mobile Broadband (eMBB), massive Internet of Things (mIoT) and Critical Communications (CriC). Architecture modularization and network slicing [3; 4] will allow the design, deployment and management of specific E2E communication systems, featuring ad-hoc Control Plane (CP) and User Plane (UP) solutions conceived and optimized around the performance and functional requirements of related use cases. In this scenario, the attention devoted to mIoT has been constantly increasing over the past years [5]. Market reports and data traffic forecasts predicted the proliferation of a wide variety of applications and services, where the massive deployment of, e.g., sensors, meters, actuators, wearables and connected appliances, will lead to a 75% increase of mobile connectivity request by the end of the decade [6]. In parallel, research and standardization communities are focusing on the challenges of mIoT, specifically in terms of device energy consumption, scalability and ubiquity of access, communication security, mobility and Quality of Service (QoS). Notably, the great majorityof contributions put emphasis on access network and physical layer [7; 8; 9; 10]. Hence, a key research and standardization challenge, addressed by this paper, is to design an E2E architecture targeting mIoT specific requirements, overcoming the key limitations of E2E 4G systems, to become a suitable candidate solution for 5G mIoT network slice. Quite unique compared to all related prior work (always focusing on Access Network improvements), to the best of authors' knowledge, this paper proposes and evaluates a 5G E2E network slice solution for the mIoT use case. To address the challenge of massive access in the mIoT scenarios, numbers of research works have proposed novel scheduling algorithms [11]. Furthermore, scalability of solutions is one of the major challenges in solutions proposed for mIoT [12], which is well addressed in this paper. The closest to the contribution of this paper, a connection-less transmission concept, is in [13], where devices transmit packets without any bearer establishment. However, this solution also focuses solely on radio access network (RAN) rather than an E2E approach including the mobile core network. Furthermore, the solution in this paper has been designed around the 5G reference architecture recently finalized by the 3 rd Generation Partnership Project, i.e., 3 GPP [14]. Specifically, in E2E perspective, we identify limitations relating to core network (CN) and hence we focus on novel solutions to handle massive connectivity at CN, on both CP and UP sides, ensuring an efficient resource utilization and satisfying the diverse QoS required by different device categories. The proposed solution challenges the 4G \"Always-ON\" connectivity model, and proposes an alternative for 5G mIoT network slice, still connection oriented. Concisely, our proposal is based on the introduction of Virtual Devices, aggregating the CP and UP in the CN of multitudes of physical devices (PhDs) with homogeneous QoS requirements and traffic patterns characteristics. Our solution is able to drastically reduce the CP signaling load and also improve the UP resource utilization as it requires fewer UP resources in the CN to handle mIoT traffic.