The latest findings and trends in packet fronthaul – Ericsson
For the past decade, I had the privilege to work at Ericsson as a product manager bringing WDM optical fronthaul product portfolio plus, recently, packet fronthaul portfolio to the market. A lot of learning over the years, and I continue to learn as we prepare and start deploying the first packet fronthaul networks.
Since the introduction of eCPRI specification in 2017 and within Ericsson RAN products a few years ago, Ericsson has seen an uptick in the interest in packet-based fronthaul solutions from operators all over the world. In this blog, I will give a quick update on the latest trends and findings in this area.
For a quick refresh, majority associated with the current WENT deployments have radio units on top of the tower or rooftop with the associated baseband processing units located in close proximity. The connectivity between the radios plus baseband digesting units is via a fiber-based CPRI or even eCPRI interface. CPRI interface is TDM based and is implemented in many existing radios. eCPRI, on the other hand, will be Ethernet based and currently mostly applied in MIMO AAS (for more info please see Embark the particular evolution to Packet Fronthaul paper), and all new Ericsson radios will support eCPRI.
eCPRI, being an Ethernet dependent interface, makes it possible to use a packet network to transport eCPRI between radio plus baseband processing units. This packet fronthaul transport system can facilitate the deployment of centralized RAN and Cloud LEAPED (see Cloud RAN weblog ), allowing HAPPENED TO RUN functions in order to be deployed in different physical locations within the network. In addition , the flexibility introduced by box fronthaul system facilitates the particular ability to introduce automation to allow resource pooling plus better life cycle management.
Now, let’s go straight into some of the styles and results we possess seen recently in packet fronthaul.
1. Radio more than Ethernet is usually a niche solution
Currently, there are a couple of options in the industry in order to transport CPRI over the packet fronthaul network. One solution is Radio Over Ethernet (RoE), where CPRI are usually encapsulated over the transportation network and regenerated around the other end. The some other option would be a conversion associated with CPRI to eCPRI by distributing some of the particular baseband digesting functions in order to the converter. What we have found is that dense radio configurations commonly found in urban macro sites make RoE-based solution mostly infeasible for Centralized RAN deployments due to the amount of transport bandwidth required. Using RoE, a 100GE interface does not have got sufficient bandwidth to transport fronthaul traffic among a C-RAN hub site and its macro antenna web site. Additionally , RoE solution introduces additional latency, which limits the distance in between a C-RAN hub plus macro websites as RoE function is definitely needed at the hub site. On the particular other hand, a solution that will converts CPRI to eCPRI allows the same city macro sites to use up to a single 100GE interface with regard to transport between a C-RAN hub web site and its macro antenna site along with no latency overhead.
2 . Proper synchronization solution can be not just about Class C PTP T-BC
Radios depend on accurate sync information so they can transmit/receive signals without causing interference and assistance advanced WENT coordination features. In box fronthaul, the particular synchronization information is distributed using Precision Time Protocol (PTP) and associated ITU-T telecom profiles. Router/switch vendors have through the years implemented PTP with enough accuracy (e. g., Class C), allowing them to be used in a packet fronthaul network. However , inaccuracy in synchronization distribution can be launched from additional areas. For example, asymmetry in transmit/receive fiber length of just the few meters may cause synchronization error greater than synchronization error released in router/switches. BiDi optics can be used to address this latency asymmetry issue and also reduce the number of fiber strands needed.
3. Increasing Impair RAN/O-RAN activities are driving more attention toward packet fronthaul
With Cloud RAN/O-RAN activities at many providers, packet fronthaul naturally is a topic being heavily discussed. This is certainly because Cloud RAN/O-RAN is about distributing LEAPED functions that used to exist in the Baseband processing unit across various platforms and different physical areas. The box network is the glue that will connects them all together so the solution can function as a system. We see that areas such as security and management are introducing new requirements into packet fronthaul networks. z
In summary, while the journey of packet fronthaul has started, its make use of for central RAN plus Cloud HAPPENED TO RUN deployments is still evolving. From the technology perspective, new RAN features and new devices will place new needs on the network. Operationally, brand new methods plus procedures in order to allow application, monitoring, and troubleshooting of these disaggregated system solutions are to be developed. Different operators have different strategies regarding evolving their networks. At Ericsson, all of us possess all the necessary pieces to support our customers in the path these people choose, regardless if it is Distributed WENT, Centralized LEAPED, or Impair RAN/O-RAN.