Introduction

Alef Connect is a Mobile Network as a service (MNaaS) that allows enterprises to create, connect to, and manage private mobile wireless networks within enterprise IT to securely and seamlessly run their business workflows over a private edge network on near-prem “Edge points”.

Thanks to our suite of Open Edge APIs, all this is achieved without the dependency on mobile network operators and the knowledge of the intricacies of mobile system specifications. Enterprises will have the freedom to choose their on-site mobile APs, and use standard and secure transport mechanisms to connect them to our managed mobile network infrastructure.

Before we get into the details of our private mobile edge solution, you should understand the basics of two key mobile networking concepts; spectrum and the EPC.


Key mobile concepts

What is spectrum?

Spectrum sharing is what makes private edge mobile networking possible. It is revolutionizing mobile networking due to sharing frameworks that have been put in place to assign certain frequencies to certain entities at certain locations.

Many countries have opened up a band of frequencies for private use, and specific frequencies within this band are assigned to private organizations in given locations either statically by arrangement with the local regulator, or dynamically via automated systems such as the Spectrum Access System (SAS) in the US. This means that although the available spectrum of frequencies is limited, each frequency can be used many times by many enterprises in different locations. The mobile (4/5G) access points you will use in your private mobile network will be using a frequency that has been assigned to them via such a spectrum sharing initiative.

The general availability of these broadband frequencies is a major step towards making 4G and 5G technology accessible to a wide audience and decoupling 5G access from major cellular network providers.

The United States is currently leading the way in spectrum sharing, with the Citizen’s Broadband Radio Service (CBRS).

CBRS
CBRS is a band of frequencies between 3550 MHz and 3700 MHz that the US Federal Communications Commission (FCC) has recently opened up to general users in the US. This is managed by a network of Spectrum Access Systems (SAS) that communicates with all CBRS mobile APs, instructing them in real-time which frequency they can use ensuring that each enterprise has interference free use of a given frequency in a given location. This means that as an enterprise CBRS user, you do not need to be concerned with RF management of your CBRS APs, as this is taken care of by the SAS. There are several SAS operators, the choice of which will be up to your CBRS AP vendor.

What is the EPC?

In modern mobile networks, the mobile packet core is referred to as the Evolved Packet Core (EPC).

The EPC consists of multiple orchestrated elements that are responsible for the user authentication, session management, and mobility management for mobile networks. Mobile APs need to communicate with the EPC to complete the installation of the private mobile network. You will need to configure your mobile APs to communicate with our EPC - but that’s it - we’ll take it from there.


The Alef Connect private edge mobile network

Network elements

Managed by Customer/AP vendor:

Mobile (4/5G) APs

Provided and managed by enterprise customer. The enterprise will engage a vendor to supply, and if required manage, these devices.

Spectrum

The range of frequencies that the enterprise’s mobile APs can use in a given location.

Mobile Device (UE)

The device where you will install a SIM/eSIM that will use your private mobile network.

Tip

The formal mobile networking terminology for a mobile device is ‘User Equipment’ (UE). You will see the term UE used in our API, it just means mobile device.

Provided and Managed by Alef:

Alef Edge point

The Edge point is the nearby Point of Presence (POP) that hosts Alef’s Edge platform and software stack. It will usually be located in a colo facility close to the enterprise to provide the low latency connectivity required by enterprise applications.

This enhanced, low latency mobile connectivity experience is made possible by two main factors in play at the Edge Point:

  • Seamless mobility within a mobile network is achieved by keeping a mobile device’s data session anchored to a fixed PDN Gateway (PGW) while the mobile device roams between mobile APs. Alef Connect provides PGW functions at the Edge point, anchoring the mobile device’s continuous data session and hence improving the connectivity experience as the device moves around.

  • Local breakout of user traffic at the Edge Point places the mobile device’s original IP packets on the wire at the Edge Point so they can be routed back into the enterprise network, and vice versa.

By connecting a dedicated virtual Edge platform to the enterprise private network via a private link, the Edge platform and the “attached” mobile devices anchored at the Edge platform will become an integral part of your network, fully under your control. Alef deploys Edge Points in a geographically distributed manner across many colo facilities that are easy to reach by many network carriers, enabling the Edge platform to deliver mobile device user traffic directly to your network.

In summary, the Edge point and the Edge platform within it carries out several tasks:

  • Breaks out mobile devices’ traffic and forwards it to the enterprise network.

  • Forwards mobile control plane traffic to and from the EPC for registration, authentication, authorization, mobility hand-off and other session management signaling.

  • Forwards usage information to the Alef management services for reporting and billing.

Alef Management service

The Alef Management Service communicates with all edgepoints to achieve session management, accounting and other management plane functions. It provides the management function of all Alef Connect services, including:

  • Monitoring service Monitors all services, providing health check system metrics, alarms, logs and events.

  • Proxy Service Manages and tracks Alef Connect users, creating usage records and helps to enforce policy. Exposes stats information via APIs. Interfaces with EPC for requisite information for session management.

Alef Cloud services

This is where the APIs that enable you to provision and manage your private mobile network are exposed, and a collection of services are hosted. In summary the Alef Cloud Services component:

  • Hosts the front and back end of the developer portal.

  • Manages subscriptions of Alef service(s).

  • Hosts customer lifecycle services such as license management, ordering, account management, and billing.

  • Exposes the customer facing APIs.

SIM/eSIM

These are sent to you when requested, and facilitate secure communication between the mobile devices and their EPC via mobile APs.

EPC

Responsible for the user authentication, session management, and mobility management for the private mobile network.


Setup summary

Firstly, you will acquire and install your mobile APs, ensuring they are communicating with their management services.

Once you have placed an order on the Alef cloud services API, Alef will send you:

  • The configuration details your mobile AP will need to communicate with the EPC, via the Alef Edge Point. For more information on this refer to the Edge Point - mobile AP Connectivity Options section.

  • If you do not need to specify the internal IP ranges for mobile device addressing, we will send these to you. If, however, you do wish to provide your own address ranges for your mobile devices you will need to request a dedicated APN. For more information, refer to the Do I need a dedicated APN? Section.

  • SIMs or eSIMS as ordered by you.

To enable mobile connectivity using Alef’s MNaaS, a private connection (IP/MPLS, IPSec VPN, dedicated fiber) between an Alef Edge Point and your network infrastructure is required. You will provide information about your current network infrastructure connectivity options so that Alef can provision private connectivity from our Edgepoint to your network to bring mobile devices traffic back into your network.

Once you have configured your mobile APs and installed the SIMs/eSIMS at your site, and the breakout network configuration is complete at the Alef Edge Point, your Alef Mobile Connect solution will be operational and your mobile devices will be able to connect to your private network.


Architectural overview

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Fig.2 Alef Mobile Connect operation

1. Mobile devices will communicate over the air with the mobile APs.

2. Mobile APs will send traffic on to the nearest Alef Edge point. The connectivity between the enterprise network and the nearest Alef Edge points will be provided by a dedicated managed link such as fibre (assuming the Edge point shares a colo location with enterprise network equipment), MPLS, EVPN, or any other supported secure medium.

3. Alef Edge point will forward control plane traffic to the EPC, and usage data to Alef Management Services (Billing will be based on this usage information).

4. EPC will communicate with the mobile AP via the Alef edge point, authenticating and managing the user session in real time.

5. Alef edge point will break out the mobile user traffic, which will be routed onwards to its destination. This could be one of:

  • Enterprise private network

  • Back to the customer premises

  • Customer resources at the edge Colo

  • Customer resources in public clouds

6. On an ongoing basis, customer will provision, monitor and and manage their mobile network via the Alef Cloud Services API.