Why eCPRI is used in 5G and Open RAN?

  • My friend: Hi Ibrahim, I need you support.

    • Me: You’re welcome, please tell me.
  • My friend: I was wondering what is the difference between CPRI and eCPRI?

    • Me: CPRI (Common Public Radio Interface) and eCPRI (Enhanced CPRI) are two technologies that are used over the fronthaul interface between the RU and the DU. Each technology has its own characteristics, so CPRI is using TDM serial interface, while eCPRI is using packet technology by utilizing an Ethernet/IP. Currently telcos use CPRI interface as fronthaul connection mainly in 2G, 3G, and 4G, while eCPRI is used as fronthaul connection in 5G.
  • My friend: So, why eCPRI is used in 5G and not CPRI?

    • Me: Actually, eCPRI interface is more bandwidth efficient than CPRI, so while in 4G we have low bandwidths up to 20MHz for one carrier, in 5G the situation is different as we can go for 100MHz for one carrier in FR1 and even for 400MHz at FR2. So, with higher BW in 5G and by introducing massive MIMO as well, we are expecting higher traffic at 5G compared with 4G. So, the fronthaul interface, using CPRI, will require capacity up to TB/s in 5G compared with Gb/s in 4G, and this is not realistic for 5G. But if you know that the bandwidth requirement of eCPRI is about one-tenth of CPRI which makes it more suitable for 5G, so we can have a fronthaul with Gb/s in 5G using eCPRI. Also, compared to CPRI, eCPRI reduces both latency and jitter for high-priority traffic and improves the efficiency of 5G fronthaul networks.
  • My friend: But why eCPRI is used in Open RAN?

    • Me: eCPRI is an open interface which makes it easy for MNOs to select different vendors for RUs and DUs, unlike CPRI which is considered as proprietary as each vendor would have its own implementation of CPRI and as you know openness is the basis of Open RAN. And, unlike CPRI, eCPRI’s traffic can be moved on Ethernet, an important attribute for the rise of open RAN as Ethernet enables virtualization by allowing fronthaul traffic to switch between physical nodes using common off-the-shelf networking equipment.
  • My friend: Thank you so much. You made it very clear.

    • Me: You are most welcome.

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