Rollout of next-generation "5G" mobile services is set to start soon. 5G aims to provide on-demand services and applications at high speed and high reliability with low latency to multiple users simultaneously.
This document describes which technologies and measurements are needed to develop faster, low-latency mobile networks.
New 5G Network Services
Achieving faster communications is the main issue for 4G networks today. As well as upgrading to faster and larger capacity, 5G networks also feature support for new network requirements using ultra-high-reliability low latency and multi-connectivity. Based on these features, 5G deployment is expected to be the foundation for new services, including IoT-based sensor business, self-driving automobiles, etc.
Usage image of 5G Mobile Network
Implementing faster, large-capacity communications with ultra-high-reliability low latency over multiple simultaneous connections on the same communications network infrastructure not only requires 5G wireless interfaces but also requires major developments at the wired network side, particularly integration of the mobile fronthaul (MFH) and mobile backhaul (MBH).
- MFH Interface Changes: Switch from CPRI to eCPRI or RoE
- MFH and MBH One-Way Delay Times: Cut to 100 µs max.
- Time Synchronization: Achieve even higher measurement accuracy
The Anritsu Network Master Pro MT1000A is the ideal quality evaluation solution as mobile networks progress from 4G to 5G.
Mobile Fronthaul and Backhaul Development and Issues
Example of 4G Mobile Network
Example of 5G Mobile Network
Key Points in Development from 4G to 5G Mobile Networks
- Switch communications between Antennas (RRH) and signal processing unit (BBU) from CPRI to eCPRI/RoE
Currently, CPRI technology is used to connect the RRH and BBU. However, CPRI has a data transmission efficiency of about 6%, making how to speed-up networks an important issue. The division of functions between the RRH and BBU as well as the communications protocols are being re-examined to help solve this issue. Division of functions by keeping one part of the modulation functions at the RRH side is expected to play a key role in suppressing the communications band. In addition, the potential of the Ethernet-based eCPRI and RoE protocols is being examined. While eCPRI/RoE improves the transmission rate by using Ethernet, it also plays a role in cutting the cost of base-station infrastructure because it can use the 25 and 100GbE high-speed interfaces that are common in many world markets.
- Minimize network latency by implementing high-accuracy low-latency measurements
5G mobile networks require an end-to-end latency of within 1 ms, including the wireless section; the required one-way latency of the wired section, particularly in 5G mobile networks, is about 100 µs. Consequently, communications equipment vendors must measure latency with high accuracy when evaluating devices on networks.
- Emphasize importance of time synchronization
At present, time synchronization between base stations commonly uses GPS time data, but this method is limited by the ability of GPS radio waves to reach some locations where base stations are installed, such as inside buildings and underground shopping malls, etc. To remedy this problem, PTP-based time synchronization is being deployed at some locations. Since PTP is unaffected by installation location, it is being proposed for 5G, making it more important than previously.
5G mobile networks are developing from 4G mobile networks based on these types of new technologies. However, although these developments will not occur overnight, construction of future networks will emphasize upgradability to 5G.
Anritsu 5G Mobile Network Evaluation Solutions
In addition to conventional throughput and BER measurements, 5G mobile network evaluations will focus on eCPRI/RoE, high-accuracy latency, and time synchronization measurements. The MT1000A supports every measurement function required for 5G mobile network deployment.
Instead of using the conventional CPRI technology, 5G mobile networks are expected to adopt the eCPRI and RoE frame technologies. Naturally, the MT1000A supports BER communications tests and latency measurements using eCPRI and RoE frames.
Both BER and latency can be measured via the WDM circuit.
High-Resolution Latency (Delay) Measurements
The stipulated maximum one-way latency for 5G mobile networks is 100 µs. However, minimizing the latency of network devices is a key point because actual optical-fiber networks must reach speeds of 5 μs per km.
The one-way latency between two separate points can be measured using two MT1000A units.
In addition, the high-resolution and high-accuracy latency measurements required by the 5G mobile standards are supported by MT1000A options.
PTP-based Time Synchronization Measurement
5G mobile networks perform time synchronization using PTP, and frequency synchronization using SyncE. Time synchronization evaluates whether the time difference (Time Error) from the distributed Grand Master Clock (GM) is within the permissible range, and plays a key role in overall network evaluation.
Installing the GPS Disciplined Receiver MU100090A with built-in high-accuracy rubidium clock in the MT1000A supports this time synchronization accuracy evaluation (Time Error measurement).
- The phase error of the measurement-target 1 pps signal vs reference 1 pps signal can be measured.
- The one-way latency can be measured based on the time stamp in the IEEE1588 packet using the time synchronization data from the GPS. This supports the Time Transfer Error measurement specified by ITU-T G.8273.
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