Demonstration of network technology that automatically guarantees low latency and high-efficiency accommodation for first time in world

--Accommodating 1,000 IoT devices while meeting latency requirement of 5G fronthaul in network without operator control--

Tokyo - May 27, 2021 - Nippon Telegraph and Telephone Corporation (headquartered in Chiyoda-ku, Tokyo; Jun Sawada, President & CEO; hereinafter referred to as "NTT") has undertaken research and development of "Wired-and-Wireless Converged Radio Access Network for Massive IoT¹ Traffic　(JPJ000254)," which is funded by the Ministry of Internal Affairs and Communications (MIC) in Japan. Through these activities, NTT has developed network technology that automatically guarantees low latency and high-efficiency accommodation without any operator control with the cooperation of Fujitsu Limited. NTT demonstrated the technology in experiments and succeeded in accommodating a massive 1,000 IoT devices while meeting the latency requirement of 5G mobile fronthaul for the first time in the world.

1. Background

The mobile fronthaul (MFH) between a central/distributed unit and remote unit in a mobile network is currently connected by point-to-point optical fiber links. As MFH traffic is packetized in the 5th Generation Mobile Communication System (5G), it can be efficiently accommodated by using network equipment. As shown in Fig. 1, by accommodating MFH traffic with a wide-area access network that currently accommodates services including wired and Wi-Fi internet services, more efficient and cost-effective networks are expected. There are two issues to consider in realizing such networks.

However, the conventional technology for guaranteeing low latency is very complicated since the network operator should manually set the bandwidth for guaranteeing low latency to each piece of network equipment considering fiber delay. Moreover, the guaranteed bandwidth is preset as a larger amount than actually needed, which thus degrades the efficiency of accommodating IoT traffic. Therefore, for future wide-area access networks, autonomous technology that increases the number of IoT devices that can be accommodated while guaranteeing low MFH latency is essential.

Fig. 1: Accommodation of MFH traffic in wide-area access network.

2．Content and results of research and development

Our developed technology makes it possible to realize high-efficiency accommodation of traffic while guaranteeing low latency. Low latency is automatically guaranteed by utilizing the periodicity of traffic, and bandwidth is minimized in accordance with the amount of the traffic so that both low latency and high-efficiency accommodation are realized. As these operations are automatically performed in network equipment, the need for network operator settings is eliminated.

The following shows the results obtained by using the technology.

2.1 Experiments on accommodating both MFH and massive amount of IoT traffic

We constructed a network with the technology, and we succeeded in accommodating a massive 1,000 IoT devices while meeting the latency requirement of 5G MFH in the network for the first time in the world. This was done with the cooperation of the Graduate School for the Creation of New Photonics Industries, Osaka City University, and National Institute of Information and Communications Technology. The results were presented as a post deadline paper² at an international conference, ECOC 2020. The paper reported that the MFH latency was reduced below the required latency of 100 us for 5G fronthaul by our technology. The paper also reported that our technology improved the number of IoT devices that can be accommodated from 240 to 1,000.

2.2 Control of transmission routes in network

For more highly efficient accommodation, we succeeded in demonstrating that transmission routes can be controlled on the basis of prediction with the cooperation of Tokyo University, which owns technology for predicting the amount of traffic by monitoring the amount of traffic in a network in real time. A massive amount of IoT traffic can cause a sudden increase in traffic, namely a microburst. In this case, the conventional technology for route control cannot follow the sudden increase, causing IoT packets to be discarded. The FLARE switch³ owned by Tokyo University is able to monitor the traffic per application such as for IoT. This switch performs machine learning by using the monitored traffic as training data, and it predicts the amount of the traffic per application. Through this cooperation, discarding of packets due to microbursts is eliminated, and thus, even more efficient accommodation of IoT traffic is made possible.

3．Future prospects

We will study the accommodation of a higher number of services among which the latency requirement is different and aim to apply the technology more widely.

¹IoT: Internet of Things.

²Post deadline papers: a technical paper that is received after the regular submission deadline. In the optical communication research field, research groups from around the world submit their best results. A limited number of papers that receive an extremely high evaluation in a selection meeting held during the conference period are accepted for presentation in the post deadline session.

³FLARE switch: a programmable network node developed by Tokyo University that is able to monitor the traffic per application.

About NTT

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