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The 5G is increasingly taking place in the market, as the traffic between the radio units and baseband units is on the advancement. Since the traffic is increasing, there is a demand for higher bandwidth as well. For which, the 5G will play an important role in accomplishing the demands of people. In the current networking that is LTE, CPRI has a significant role in connectivity and controlling communications between the BBUs (baseband units) and RRUs (remote radio units). However, as the 5G is going to deliver the higher-bandwidth network, the CPRI and eCPRI would play an important role in the connectivity of 5G as well. So, as these are two, that is, CPRI that is currently in use, and eCPRI, which is new in the market, there are differences in them both. To know the differences between them both, and to know what they mean to 5G, read the entire post.
Introduction To CPRI & eCPRI
CPRI: The CPRI stands for the Common Public Radio Interface. The CPRI standards define the interface between the Radio Equipment Control (REC) and Radio Equipment (RE) that are connected through the fibers. The CPRI is used to carry the data between cell stations and radio base stations that are used for cellular wireless networks. The CPRI allows I/Q data interface for numerous standards like WCDMA, GSM, LTE, and more, efficiently and flexibly. So, CPRI is used in the structure of current networking, which is spread all over.
eCPRI: eCPRI stands for the Enhanced Common Public Radio Interface. The eCPRI is the successor of the CPRI and is becoming an essential part of the new technology to get a better understanding of the 5G and to get the enhanced speed of the 5G network too.
Purpose Of Development Of eCPRI
Before we dive into what eCPRI is, it is necessary that we know what the topology of the cellular network that is using the CPRI currently is.
At the outer circle of the topology of the cellular network, the (RRUs) Remote Radio Units are fielded at fewer miles in the cities or the populated areas. These RRUs have the antennas and the functionality of computing.
Now, these RRUs have to be connected to the centralized baseband units. So, to connect the RRUs to the centralized baseband units, the fiber from the cluster of RRUs is run to the centralized baseband units. The centralized baseband unit is called by other names, too, that are baseband units and the central processing units. So you can use all these three words for addressing baseband units, and should not get confused and tangled in these words too.
These baseband units are distributed typically within 10-miles of the circle to make the networks right coverage in the densely populated areas.
When we connect the RRUs and the baseband units to the baseband station, the connection between the RRUs and the base station is called “fronthaul.”
Now, we know the topology of the cellular network, which is using CPRI currently. But to enhance the current networking systems, to make it work efficiently and flexibly, the communication interface is shifting to the eCPRI. Let’s know the purpose of bringing in the eCPRI.
The CPRI is an interface between the RRU and the baseband units, which is a serial interface that is quite a fast high-speed connection. But now, as there is more traffic on the network, there are more people out there who are demanding the high-speed network. To get a higher-speed network and to make the reach of the same to every corner, the shift from 4G to 5G is being made. While we are shifting to 5G, the fibers connecting the RRUs and basebands will have to carry more traffic to transfer the data sufficiently. Carrying more traffic makes the serial interface more challenging. So, the requirement of 5G is to stretch the limits of fiber bandwidth, to work efficiently.
To put up less stress on the fibers, by splitting the BS functionality into two parts that are, enhanced REC (eREC) and enhanced RE (eRE), the networking is being simplified by the eCPRI.
Both these parts that are, eREC, and eRE are kept separately. The eRE is installed near the RF (radio frequency) antennas, and eREC is installed at a distant location, but they both are connected through a transport network. The functionality has been divided. So, the eREC has the parts of the PHY layer (Physical layer) functions and the function of the upper layer of the air interface. While the eRE has the rest of the parts of the PHY layers functions and the functions of analogue radio frequency (ARF).
Now, as the functionality has been divided and they have different functions, the eCPRI, compared to the CPRI, reduces the data rate requirements between the eREC and eRE and works more flexibly while maintaining the complexities of the eRE, very efficiently.
The eCPRI
As the 5G application requires the flexible fronthaul necessarily, with the eCPRI that has the connecting specification of eREC and eRE via fronthaul transport network are quite suitable for the application of the 5G system, LTE-advanced, and LTE-Advanced Pro as well. So, as the eCPRI is one of the best for the 5G and other system’s applications, it reduces loads of the fibers and also will support the 5G application by its increased efficiency.
So, as the eCPRI is best for the 5G, and other networks, and is also the successor of the CPRI, that is also a high-speed interface, not so suitable for 5G but is used in the application of the same too. So, let’s see what the differences between the CPRI and eCPRI are.
Differences Between CPRI & eCPRI
- Ports Classifications –
The CPRI has two ports that are master ports and slave ports. These ports are directly connected with the help of electrical or optical cables. When we talk about eCPRI, it does not support any physical level ports.
- Logical Connections
The CPRI supports the following logical connections:
- Point to Point: One REC with one RE
- Point to Multi-Points: One REC with several REs
The eCPRI supports the following logical connections:
- Point to Point
- Point to Multi-points
- Multi-points to Multi-points
- Network Topology
The network topology is the combination of links, nodes, etc. to make the arrangements of a communication network. In CPRI, the network topology relies upon the REC/RE functions. Whereas, the eCPRI’s network topology includes eRECs/eREs nodes, transport network (fronthaul network) and more networking elements, like GM/BC for timing, and EMS/NMS for the management of the network is used.
- CPRI and eCPRI for 5G Application
In the 4G that is LTE, the fronthaul network depended on the semi-proprietary protocols, such as CPRI and OBSAI (Open Base Station Architecture Initiative).
Since the 5G requires tremendously extended bandwidth expansion, only the newest CPRI standard might meet the requirement. Also, if the CPRI protocols are used for the 5G, these protocols will not be able to be cost-effective for 5G, as they use larger spectral bands that are hundreds of MHz and MIMOs.
So, seeing these things, it’s doubtful if CPRI can provide the 5G stability and cost-affectivity or not. Moreover, even if the CPRI is used in the application of 5G, it can support the advanced standards in a very limited way, because if they are compared to other protocols, they have limited mainstream packet transport standards. And the eCPRI was introduced at first, addressing the limitations of CPRI only. So, having CPRI for 5G is not so cost-effective, might not have the stability and also will have fewer packet network transport standards.
If we talk about the application of 5G with the eCPRI, the eCPRI helps to reduce the latency of the network and also reduces the jitter even for heavy traffic. The eCPRI helps to improve the efficiency of 5G fronthaul. eCPRI uses ten times less bandwidth than the CPRI, or we can say, eCPRI is ten folds efficient than the CPRI. In the eCPRI, the traffic can be transported on the Ethernet along with other traffic in the same network. Along with all these features, eCPRI has the function of splitting in the PHY layer, which helps keep most of the function in the BBU. Thus, the eCPRI requires fewer transport resources or the radio equipment on the tower and allows acknowledgment of advanced network features without changing the radio equipment.
Endnote
There are significant differences in the CPRI and eCPRI, and especially for the 5G fronthaul. The CPRI was made especially for the LTE, which was in use, in a ubiquity, while eCPRI is made keeping the future growth of the technology in mind. The eCPRI has the capacity to optimize the radio performances as it can analyse traffic and prioritize traffic in real-time using the coordination algorithm. So, after reading the above post, it is clear that eCPRI is better than CPRI, as eCPRI provides the greater flexibility and reliability of the network too. Now, CPRI is in use generally, but eCPRI, which is new and latest in the market, will shortly be used for the application of the 5G network.
