# Development of Intelligent Core Network for Tactile Internet and Future Smart Systems
## 3 System Structure  
Tactile Internet system requires a very high availability and reliability, and ultra-low latency. This put high constraints on system components in terms of context, content, and mobility. Tactile Internet system requires an end-to-end latency of millisecond. This contains both the transmission delay (including reaction transmission (feedback)) and the processing delay. The time between stimulation and response should be in one millisecond. In another word, the end-to-end latency should be less than the human reaction time [28]. In this work, we provide a frame work for the Tactile Internet system, which can solve the problem of millisecond latency and achieves other requirements from the Tactile Internet system. Our Tactile Internet system may be generally viewed as a three layer system that is based on the proposed 5G system structure, as suggested by Next Generation Mobile Networks (NGMN) [6]. As illustrated in Figure 2, the three layer system is based on the three main technologies; MEC, SDN, and NFV. The whole structure is based on the 5G cellular system, which decouples the hardware and software, and provides an APIs to facilitate the control and management of the system. The first layer is the physical hardware resource layer, which includes the cellular network infrastructure (5G/Tactile user devices, fiber cables, cloud units, and networking nodes). User devices may be a master robot or a 5G smart phone that have enough capabilities to be configured in the network [29]. The master robot is a haptic device that represents the human interface system. Haptic device has the ability to translate the human input to a haptic input by means of coding techniques [30]. Using haptic devices users can feel and touch objects in remote environments and also can control them. Cloud units are employed at the edge of the network based on the concept of MEC. We built a multi-level cloud based Tactile Internet system in [5; 31], which can be used as the cloud part in this layer. The multi-level cloud system moves from the idea of centralized cloud to the heterogeneous distributed cloud units. Cloud units are employed in levels, the first level includes Micro-clouds with small storage and processing capabilities connected to each cellular base station (eNB) [5]. The second level employs more efficient cloud units with higher processing and storage capabilities, known as Mini-clouds. Each Mini-cloud unit connects and controls a group of Micro-cloud units through a very high speed fiber connections. The final level of cloud units is the main cloud unit with powerful storage and processing capabilities centered at the core network. Main cloud unit connects, controls, and monitors all Mini-cloud units connected to the core network. Also it acts as the gateway to the huge central cloud units that are employed faraway. Figure 3 illustrates the different levels of cloud units [5]. Figure 2: System structure viewed as a three layer system. Introducing multi-level cloud units to the Tactile Internet infrastructure, achieves variety of benefits that can be summarized in the following points [31]:  
1. provides the offloading for the workload of the end user,
2. reduces the traffic load flow to the core network,
3. achieves better efficiency in terms of network congestion,
4. provides new services by accessing the network parameters through the BS,
5. provides higher security, and
6. reduces the end-to-end latency. Reducing the end-to-end latency is achieved by reducing the communication path, as the cloud is one hop away from the user's equipment. The time passed in the core of the network has not existed, as there is no data passed to the core network. The second layer is the software deployment layer, which maintains libraries for all of the functions that are needed in the network. These libraries are software functions and modules that can be used in the desired location in the network. Also, the radio access parameters and other configuration parameters of the network are located in this layer.