For a closed park or enterprise network, the MEC solution can be used to offload the internal network traffic within a park or an enterprise to achieve local management and operation of the enterprise network, thus meeting the real-time, high-bandwidth, and high-security requirements for mobile office, video monitoring, and on-site data collection inside the enterprise.
How to deploy MEC NEs conveniently and quickly, and realize flexible and efficient traffic offloading without impacting the existing network is a key issue to consider in MEC deployment.
At present, there are two mainstream offloading technologies for 4G: TOF+ and CUPS and three mainstream offloading technologies for 5G: LADN solution, UL-CL solution and multi-homing solution.
4G MEC Offloading Technology
This solution has the least impact on the existing network. The SGW can be deployed with the MEC platform to implement local breakout (LBO) function through the SGW enhancement.
As shown in Fig. 1, the combination of SGW and LBO (enhanced SGW function) supports detecting IP address of uplink data packets, thus realizing data steering and local offloading.
The SGW provides the following functions: Identifying the IP address of the uplink data packets; diverting the traffic that can be broken out locally; integrating the downlink data from LBO with the downlink data from the PGW; implementing the charging function as well as the lawful interception function for locally offloaded traffic.
LBO functions include: Offloading the data forwarded by the SGW to a local data network; encapsulating the downlink data flow received from the local network to the corresponding bearer, and transmitting the data to the SGW as GTP-U tunnel packets.
In the control and user plane separation (CUPS) solution, GW-C is deployed in the core equipment room, and GW-U is deployed in the edge equipment room. The GW-U has the traffic offloading function to realize MEC offloading.
In the CUPS solution (Fig. 2), NE functions and external service interfaces of the gateway (GW-C+GW-U) after a CP-UP split are not changed. Without transforming adjacent NEs (such as UE and RAN), they can be interconnected with each NE in the existing network. The GW-C is connected with the adjacent equipment through the unified outgoing signaling interface to simplify network deployment.
5G MEC Offloading Technology
Based on the C/U separation architecture of 5G core network, the UPF needs to be deployed at the network edge to reduce the transmission latency and perform local traffic offload. Control plane NEs, such as SMF, are deployed in central DC in a centralized manner to control UPFs deployed in the MEC and configure traffic steering rules in UPF (Fig. 3).
A local MEC AF informs the PCF of the UPF traffic steering rules via N5/N33 interface. The PCF configures the traffic steering rules in SMF, and the SMF performs centralized scheduling of all traffic. It uses such solutions as local area data network (LADN), uplink classifier (UL-CL) or multi-homing to support the (re) selection of a local UPF for local traffic offload. All other traffic is sent to a central UPF through the local UPF for processing. This avoids all traffic to transverse the central network, reducing the pressure on backbone network transmission and network construction costs and improving on-net packet data bearing efficiency and user experience.
LADN is designed with respect to regional services or applications. When a user uses the application, the user accesses the application through LADN. When the user is not located within the LADN service area, the user cannot access the LADN. The access to a DN through the LADN PDU session is only valid in a specific LADN service area, defined as a set of tracking areas (TAs). LADN is a 5G session management mechanism in support of edge computing. When LADN is used for edge computing traffic offload, the service areas of the LADN correspond to those of the single edge computing platform.
When the type of PDU session type is IPv4, IPv6, IPv4v6 or Ethernet, the SMF may decide to insert an uplink classifier (UL-CL) into the data path of a PDU session. The UPF supporting UL-CL functionality diverts some traffic by matching the traffic filters provided by SMF.
A single PDU session associated with multiple IPv6 prefixes is the multi-homed PDU session. A multi-homed PDU session provides access to the DN through multiple PDU session anchors. Different user plane paths leading to different PDU session anchors form branches at a "common" UPF. The public UPF is the UPF that supports a "branching point" functionality. The branching point forwards the uplink traffic to different PDU session anchors and aggregates the downlink traffic towards the UE i.e. aggregating the traffic from different PDU session anchors to the UE.
As shown in Table 1, 5G mobile communication technology naturally better supports the MEC in terms of architecture, UPF can be flexibly inserted into each node of the network, making the architecture more flexible and dynamic. The coordination of MEC and network slicing enables end-to-end SLAs for different service scenarios or industrial customers, and realizes enterprise-customized virtual private networks.
ZTE's flexible and efficient MEC offloading solution covering 4G and 5G offloading technologies provides different offloading strategies for different scenarios. It can provide virtual private network services that features high performance, high confidentiality, low latency and low cost with no need for construction and maintenance, thus meeting the demands of "lightweight assets" in closed parks or enterprise parks. Together with other government and enterprise service products, ZTE provides a full range of services from fixed network to mobile network and from PC to mobile, improving satisfaction of industrial customers, their network availability, and service usage.