Benefits or Advantages of eCPRI | disadvantages of eCPRI 5G NR

This page covers advantages and disadvantages of eCPRI interface used in 5G NR (New Radio). It mentions eCPRI advantages or benefits and eCPRI disadvantages or drawbacks.

What is eCPRI interface?

Introduction:
• eCPRI stands for Enhanced Common Public Radio Interface.
• The basic idea is to divide functionalities of BS (Base Station) into two blocks viz. REC (Radio Equipment Control) and RE (Radio Equipment) and connect them via packet based fronthaul transport network such as Ethernet or IP. This is shown in the figure-1. Both REC and RE are usually connected using optical fiber link. REC and RE terms are used with CPRI where as same terms are renamed as eREC and eRE in eCPRI interface.
• Group of companies Ericsson, Huawei, NEC and NOKIA are developing and maintaining eCPRI specifications.
• eCPRI handles following service points viz. User Plane Traffic, Synchronization and Control & Management.
• eCPRI can be used between 1 eREC and 1 eRE as well as between 2 eRECs and 2 eREs.

• Both eREC and eRE are physical separated where in eRE is kept near to antenna and eREC at far end.
• eREC handles part of PHY functions and upper layer functions. eRE handles other part of PHY layer functions, DAC (Digital to Analog conversion) and other analog radio frequency functions before connecting the signal to the antenna.

• The figure-2 depicts various functional decomposition and their mapping to eREC and eRE elements of eNB/gNB at RAN (Radio Access Network) layer level.
• The physical layer (PHY) has been splitted and named as {I_D, II_D, I_U} to achieve many benefits of eCPRI interface as mentioned below.
• eCPRI can be interfaced with electrical cable, electrical backplane and optical fiber. Ethernet types used with eCPRI include 10G, 25G, 40G and 100G.

Benefits or advantages of eCPRI

Following are the benefits or advantages of eCPRI:
➨Electronics hardware components are reduced at antenna side and hence reduces expenditure to maintain the site as air conditioning is not required. Moreover power consumption will reduce which leads to saving on electricity.
➨As the base station architecture is divided into BBU (Base band Unit) and RRH (remote radio head), it is simple to troubleshoot any issues at the lower layers (i.e. at BBU) at remote end rather than at antenna side. BBU and RRH used in CPRI interface is known as eREC and eRE respectively in eCPRI interface.
➨In CPRI, high bandwidth was needed to transport I/Q samples between REC and RE. eCPRI has reduced this bandwidth requirement to a great extent. Required bandwith can scale as per user plane traffic.
➨The interface can be software upgradable and hence new features can be added in the future as per requirements.
➨Ethernet can carry eCPRI traffic as well as other traffic types simultaneously. eCPRI traffic from different vendors can also be carried simultaneously over ethernet. Same ethernet OAM can be used for Operational and Maintenance of eCPRI interface.
➨It uses IEEE 802.1 CM standard which helps in reducing jitter and latency for high priority traffic.
➨The advantages of intra-PHY split in eCPRI interface include features such as CA (Carrier Aggregation), Downlink CoMP, Network MIMO, Uplink L1 Comp. Joint Processing etc. Some of these features might also be supported by other splits.

Drawbacks or disadvantages of eCPRI

Following are the drawbacks or disadvantages of eCPRI:
➨Though both CPRI and eCPRI can co-exist in a single system, eCPRI has no backward compatibility.
➨The disadvantages of intra-PHY split are as follows. A fronthaul network with "high capacity" and "low latency" is needed compare to upper layer splits.