If the media driven hype around 5G is anything to go by, it’s going to be a matter of time before we’ll be queuing up to have hair transplants performed by a remote surgeon (at least I will be anyway), or having pizza delivered by a 5G connected drone. For those of us who’ve perhaps dug a little deeper into 5G, we know that although these headline-grabbing use cases MAY one day become a reality, there’s a number of technical hurdles which must be jumped before we get even close to reading the morning newspaper whilst the 5G connected car drives us to work…
Certainly, one of the key enablers for the next generation of 5G orientated services is MEC (Multi Access Edge Computing). As a one sentence description, you could say that MEC is a means by which you can provide compute/storage resources closer to the subscriber’s point of attachment to the network. So, in the case of 5G for example, it’s quite possible that the UPF (User Plane Function) is situated at the RAN site in order to provide access to MEC resources that are in close proximity to the subscriber. Ultimately, by doing this, the service provider can potentially reduce latency and avoid sending large amounts of traffic across the entire network.
So, how does MEC, which is standardized by ETSI, integrate with 5G, which is standardized by the 3GPP? Simply searching the 3GPP specifications for MEC won’t really provide a lot of answers. That said, this doesn’t mean that the 3GPP have not been thinking about support for Edge Computing in 5G. To the contrary, the 3GPP have introduced a significant number of enablers into the 5G System which, if deployed by the service provider, could directly support MEC applications. Figure 1 provides a summary of these techniques:
Figure 1 Support for MEC in 5G
If you’re unfamiliar with some of the architectural elements mentioned below, you may find this blog useful.
UPF Reselection – during PDU Session Establishment, the SMF (Session Management Function) will choose an appropriate UPF. During the lifetime of the PDU Session, the UPF may change based on the subscriber’s location. Therefore, if a local data network close to the subscriber is offering MEC services, the UPF can be reselected so that the user plane traffic is optimally routed.
Local Routing and Traffic Steering – based on techniques such as UL CL (Uplink Classifier) and IPv6 Multihoming, the device’s user plane traffic can be manipulated; some of the traffic can be filtered to be diverted to local MEC resources (termed “local access to the data network), whereas the remainder of the traffic can follow the regular path out to the Data Network.
Session and Service Continuity – when a PDU Session is established, it will be associated with one of three potential SSC Modes. These define IP address continuity for mobility scenarios and have a potentially significant impact on the mobility aspect of MEC applications.
AF Influenced Traffic Routing – by communicating with the PCF (Policy Control Function) either directly or via the NEF (Network Exposure Function), an MEC Application Function can influence how traffic is routed through the network e.g. the MEC AF can inform the 5G network that the subscriber has just launched a gaming app, with instructions for the 5G network to send gaming traffic to local MEC resources.
Network Capability Exposure – the PCF can exchange network capability information with the AF (Application Function) e.g. network events, provisioning, policy control, charging, analytics, either directly or via the NEF. This capability information could then influence the operation of MEC.
QoS and Charging – the PCF can provide QoS and Charging rules for PDU Sessions associated with MEC. This ensures the MEC related user plane traffic receives the correct QoS treatment and as such is then billed appropriately.
LADN (Local Area Data Network) – 5G supports LADN connectivity, which will be applicable to a specific geographical area. As such, the device must be in one of the collection of Tracking Areas that are serviced by the LADN to receive MEC based services which may be housed within the LADN.
Many of the techniques outlined here will require a complete 5G System, so there’s limited scope for deploying these solutions in today’s (mid 2019) largely Non-Standalone based 5G deployments. However, it’s imperative that service providers have MEC on their roadmap, since without it the next generation of 5G services that we’ve all been promised will potentially never materialize. My hair, at the very least, can’t wait much longer.