Friday, July 21, 2023

Doing a little digging on 5G and 4G infrastructure. OpenRAN

Trying to make sense of the Open RAN initiative, and it's not directly FOSS. Although there are Free Open Source Solutions. 

Open Radio Access Network (Open RAN) is a concept in network engineering that involves the design and implementation of radio access networks (RANs) using open and interoperable protocols and interfaces, which allows for increased flexibility and diversity in network deployments.

Traditionally, the elements of a radio access network - such as the baseband unit, remote radio head, and the various functions and applications that run on them - have been provided by a single vendor in a closed system. These elements have typically been custom designed, with proprietary interfaces between them, meaning that network operators have had to rely on a single vendor for their equipment and upgrades.

Open RAN changes this by standardizing the protocols and interfaces between these elements. This means that they can be provided by different vendors and still work together. This opens up the market to more competition, potentially leading to innovation, reduced costs, and the ability for operators to more easily customize their networks to suit their needs.

Open RAN can be used in 5G networks in the same way as previous generations. However, 5G presents new demands for connectivity, capacity, latency, and more - which makes the flexibility, scalability, and cost-effectiveness of Open RAN particularly beneficial.

Open RAN is supported by several industry groups, such as the O-RAN Alliance and the Telecom Infra Project (TIP), which work to define and promote open and interoperable standards. However, the implementation of Open RAN requires advanced network management and orchestration capabilities and will be a significant change for network operators used to working with traditional, single-vendor RAN systems. As of my knowledge cut-off in September 2021, Open RAN is in the early stages of deployment in many parts of the world.

Home | Open RAN Global Forum 2023 (

In the context of O-RAN or Open RAN interfaces (like A, E, O, and eCPRI), the physical transport medium would typically be fiber-optic cables, due to their high data capacity and low latency characteristics, which are crucial for the high bandwidth and real-time requirements of 5G networks.

  1. eCPRI Interface (between CU/DU and RU): The physical transport of the eCPRI (enhanced Common Public Radio Interface) typically relies on Ethernet carried over fiber-optic cables. This is due to the high bandwidth requirements of the fronthaul link, which can reach up to 25 Gbps or even higher depending on the number and bandwidth of the radio channels, and the radio interface technology (e.g., MIMO configurations).

  2. A, E, and O Interfaces: For the A, E, and O interfaces, the physical transport medium could also be Ethernet over fiber, but it could potentially also be other high-speed digital communication lines, depending on the specific requirements of the network. These interfaces typically don't have as stringent latency and bandwidth requirements as the eCPRI interface, so there could be more flexibility in the transport medium.

However, the specific transport medium used can depend on a number of factors, including the existing infrastructure, the specific requirements of the interfaces and network, and the cost and feasibility of installing new infrastructure.

Open5GS is an open-source project that provides implementations for the protocols that form the core network in 4G and 5G systems, based on the 3GPP (3rd Generation Partnership Project) specifications.

These protocols define the behavior of the network components that handle tasks like authentication, mobility management, session management, and interfacing with the packet data network. In a 5G context, Open5GS would provide the software necessary to implement the 5G core network, including elements like the Access and Mobility Management Function (AMF), Session Management Function (SMF), and User Plane Function (UPF).

Open5GS is designed to support both 4G and 5G systems, meaning it can be used to build a network that supports these different generations of mobile technology. It could be particularly useful for anyone looking to experiment with 5G network deployments or develop new 5G services, given its open-source nature and implementation of 5G core functions.

Remember that, while a project like Open5GS can provide the software needed to run a 5G network, deploying a real-world mobile network would also require compatible hardware and spectrum, and would need to meet any relevant regulatory requirements.

"OpenCore" in the context of 5G usually refers to the concept of an open-source implementation of the core network protocols specified by 3GPP for 5G networks. These protocols define the behavior of the network components that handle tasks such as authentication, mobility management, session management, and interfacing with the packet data network.

One of the primary examples of an open-source 5G core network implementation is the Open5GS project that I mentioned earlier. The "open" aspect refers to the fact that the source code is freely available and can be modified and distributed under the terms of its respective license, which in the case of Open5GS is the Apache License 2.0.

OpenCore in 5G provides opportunities for operators and organizations to experiment with 5G network deployments, develop new 5G services, and potentially reduce costs by avoiding the licensing fees associated with proprietary software solutions.

eCPRI (enhanced Common Public Radio Interface) standard specifies the use of Ethernet as the physical transport layer. This is a change from the original CPRI standard, which used a dedicated serial interface.

Beyond Ethernet over fiber-optic cables, several other high-speed communication lines are commonly used in networking and telecom infrastructure, depending on the requirements of the specific network, interface, and use case. Here are a few examples:

  1. SONET/SDH: These are standard synchronous fiber-optic networking technologies used for high-speed data transfer. They have traditionally been used in telecom backbone networks, but have more recently been replaced by more modern technologies in many cases.

  2. DWDM (Dense Wavelength Division Multiplexing): This technology is used to increase the bandwidth of optical fiber networks by transmitting multiple signals at different wavelengths (colors) simultaneously on the same fiber.

  3. OTN (Optical Transport Network): This is a set of optical network standards that allow efficient transport of data traffic over optical fiber. It's often used in conjunction with DWDM systems for long-distance, high-capacity networks.

  4. MPLS (Multiprotocol Label Switching): While not a physical line in itself, MPLS is a protocol that can enhance data transmission over various types of physical lines. It's often used in high-performance networks due to its ability to handle different types of data streams (like Ethernet, SONET, etc.) and its capabilities for managing quality of service (QoS) and traffic engineering.

  5. xDSL Lines: For shorter distances or last-mile connectivity, different types of DSL (Digital Subscriber Line) technologies can be used, such as ADSL, VDSL, etc.

  6. Coaxial Cable: Coaxial cable, while not as commonly used for high-speed backbone networks, is still used in certain applications and last-mile connections, particularly in cable broadband networks (DOCSIS technology).

Please note that for the transport of RAN traffic, especially for 5G networks, high-speed, low-latency connections are crucial. Therefore, options like Ethernet over fiber-optic cable, DWDM, and OTN are most commonly used.

UDPCP Communication Protocol

UDPCP is a communication protocol specified by the Open Base Station
Architecture Initiative Special Interest Group (OBSAI SIG). The
protocol is based on UDP and is designed to meet the needs of "Mobile
Communication Base Station" internal communications. It is widely used by
the major networks infrastructure supplier.

The UDPCP communication service supports the following features:

-Connectionless communication for serial mode data transfer
-Acknowledged and unacknowledged transfer modes
-Retransmissions Algorithm
-Checksum Algorithm using Adler32
-Fragmentation of long messages (disassembly/reassembly) to match to the MTU
 during transport:
-Broadcasting and multicasting messages to multiple peers in unacknowledged
 transfer mode