Time-Sensitive Networking (TSN) provides deterministic communication with bounded delay guarantees and zero jitter through precise scheduling mechanisms. However, when TSN is deployed in Service Provider Networks (SPNWs), online scheduling approaches encounter significant scheduling slot fragmentation, substantially reducing network resource utilization efficiency. This paper proposes an interswitch coordination scheduling method to address the fundamental challenge where short-path flows prevent the schedulability of long-path flows in online environments. The proposed method strategically coordinates short-path flows while considering future coordination with long-path flows, thereby maintaining global temporal structure and mitigating fragmentation risks. Simulation evaluations demonstrate that the proposed approach improves bandwidth utilization efficiency by 16.9% on average compared to conventional methods and achieving 51.5% utilization compared to 12.5% for conventional methods in worst-case scenarios. The method maintains practical computation times of 4.34 seconds per flow while consistently achieving bandwidth utilization rates exceeding 50%, establishing the technical foundation for practical TSN deployment in SPNWs.

This study presents a real-time quality control architecture that integrates network and computing domain monitoring for stable and responsive remote robot operation over best-effort networks. The proposed architecture performs real-time end-to-end (E2E) latency monitoring and dynamically adjusts robot motion and feedback according to E2E quality levels. Field experiments over a 400-km remote strawberry-harvesting demonstrated real-time control within the robot's 100ms cycle, a twofold improvement in operability, and a 13 % reduction in task completion time under fluctuating network conditions. These findings demonstrate the proposal's capability to maintain stable control and improve the user experience under variable network latency, offering practical benefits for remote operation.

Factories have strict latency requirements and a large number of IoT devices, both of which are challenges when implementing software-based motion control systems. This paper proposes a new packet sequencing method for real-time level control of a large number of IoT devices with latency of better than 10 ms via the network by suppressing the congestion and jitter at the physical interface. The proposed method can guarantee real-time services of multiple devices from a single server by controlling the timing of transmission and reception. We develop a new driver for real-time industrial protocols and verify the effectiveness of the proposed method. An experiment confirms real-time response by successful controlling a motor with control cycle of 8 ms. Also, the proposed method is confirmed to connect 100 IoT devices with less jitter and packet loss compared to the conventional method.

In factory networks, various network protocols are used to meet strict requirements for accuracy and latency. The controllers that use these protocols are built with dedicated equipment, making it difficult to mix them with other protocols. Moreover, these controllers often rely on specialized software, complicating the integration of innovative technologies like AI. In this paper, we propose a versatile control system by implementing one of the industrial protocols, EtherCAT, on a general-purpose server. This system can control multiple protocols, allowing new protocols to be added without changing existing equipment. Experiments demonstrated that the system reliably operates multiple devices in a daisy-chain configuration, a characteristic feature of EtherCAT.

In order to improve the flexibility and compatibility of industrial networks, there is ongoing research on their software-based implementation. In this study, we propose a virtualized method for industrial networks that require periodic communication; we adopt a PON system to increase the flexibility and set end-to-end paths to ensure low latency for packets related to industrial protocols and improve overall communication efficiency. The proposed method links the PON system with industrial networks, manages VLANs and T-CONT/LLID, ensures low-latency communication, and allows the system to be managed as an industrial low-latency software switch. An actual device experiment confirms that the proposed method reduces latency in bandwidth-rich environments by allocating fixed bandwidth for industrial protocols and using priority control. In a bandwidth-rich environment experiencing congestion, the delay using the conventional method is 19.8 ms, but only 237 us with the proposed method.

In order to improve the flexibility and compatibility of industrial networks, there is ongoing research on the software-based implementation of industrial networks. The coexistence of multiple industrial protocols on the same industrial network is a challenge due to differences in QoS requirements and scheduling algorithms. In this study, we propose a method for the coexistence of multiple industrial protocols by introducing a protocol management application that manages the sending and receiving of packets in control from general-purpose computing resources. The proposed method is implemented and tested in a robot arm-based experiment. The proposed method achieved simultaneous operation of the robot arm and motor using different protocols. The proposed method could complete to control in 6.6 s even in a high-network-load environment, compared to the benchmark method, which took 256 s. In addition, a protocol switching experiment confirms that control could be continued without interruption even when the protocol was switched.

We experimentally demonstrate real-time end-to-end (E2E) uplink video streaming with our proposed jitter reduction technique for the use case of remote operation. One challenge is that the uplink video quality for remote operation is degraded by jitter due to the radio transmission scheme, such as time division duplexing (TDD), retransmission of lost data units, and data unit concatenation. The proposed technique executes traffic shaping at a router behind a next generation node B (gNB) in a mobile network by using the traffic information obtained from the gNB to calculate the optimal shaping rate. To evaluate the application-level performance of the jitter reduction technique, we carried out E2E uplink video streaming experiments using actual user equipment (UE), gNB, core node, and video server, including actual radio transmission and traffic shaping with the jitter reduction technique at an actual router. Experimental results of evaluating video frame intervals with real-time transport protocol (RTP) header information show that the ratio of video frame intervals that fell within ±5% of the ideal video frame interval value improved from 8.8% without shaping to 20.8% with shaping. These results experimentally demonstrate that jitter due to radio transmission actually degrades video quality in terms of video frame intervals and that the proposed jitter reduction technique effectively reduces it.

Because factory networks have strict requirements in terms of accuracy and latency, they are implemented using dedicated network protocols. However, these protocols tie the factory to specific equipment vendors, making it difficult to introduce to other protocols. In this paper, we propose a novel architecture that softwarizes the conventional industrial Ethernet protocol to replicate the functions of conventional industrial machines on a general-purpose server. Moreover, we first demonstrate the motion control from a softwarized control system using industrial Ethernet protocol and verify the effectiveness of the proposed architecture. Our proposal allows existing industrial protocols to be recreated in the software, making it possible to realize software-defined factory networks without changing the system configuration or the applications. The experiment confirms that the PROFINET software-based motion control system is implemented.

Although demand has been increasing for accurate remote motion control of IoT devices, jitter can negatively impact control performance. Jitter buffering has been studied as a solution, but it is necessary to obtain delay values in real-time. In this study, we propose an architecture that uses collected network information to realize jitter buffering suitable for user-managed IoT device control applications in the All-Photonics Network. The architecture collects end-to-end delay values in real-time, implements jitter buffer based on the obtained values, and performs more detailed delay compensation control based on fixed delay values. This allows network conditions, which are normally out of user's control, to optimize the user's IoT device control application. We construct a basic motor-based experimental system around an FPGA and verify the effectiveness of the proposed architecture. An experiment shows that the proposed architecture holds jitter to any practical set value and achieves successful motor control within 0.62 s, whereas it cannot be controlled when there is no jitter buffer.

We propose a novel technique for the accommodation of mobile base stations (BSs) and a secondary system with a time division duplex (TDD) frame monitor. By increasing the number of BSs accommodated in a passive optical network (PON), the cost of mobile fronthaul (MFH) can be reduced. To realize even further cost reduction, a secondary system is accommodated in the PON with the MFH while the mobile signal is transferred with low latency. We propose a technique for overlapping the signal of the secondary system on the signals of the TDD mobile BSs by using a function for distinguishing the unallocated interval of TDD uplink signals. We evaluate the improvement in the optical uplink bandwidth efficiency with a numerical calculation. By employing the proposed technique, in a numerical simulation we greatly increase the optical bandwidth of the secondary system compared with that without a TDD frame monitor. For the uplink of the mobile system, the MFH latency is kept at a low value regardless of TDD frame monitoring.

In 5th generation mobile communications systems (5G), the number of small cells with centralized-radio access network (C-RAN) architecture is expected to increase greatly. Time division multiplexing-passive optical networks (TDM-PON) are promising transmission systems for networks between a baseband unit (BBU) and a remote radio head (RRH). However, there is a challenge as regards the ultra-low latency requirements of 5G including less than 1 ms for end-to-end communication, because a TDM-PON generally transmits using time division multiple access (TDMA) as a basis. In this paper, we derive the achievable latency and the number of RRHs accommodable by TDM-PON, and analyze the applicable range of a TDM-PON for mobile use. Our analysis shows that it is possible to design a PON application in accordance with the latency requirements of mobile systems.

Recently, various architectures for future networks have been researched and discussed. In one of these approaches, we assume the deployment of an access network in which wavelength division multiplexing (WDM) and time division multiplexing (TDM) techniques will be applied to user and service multiplexing, respectively. In line with the envisioned scenario, we are studying a new access network based on a multi-stage semiconductor optical amplifier (SOA), which has a flexible transmission distance, low delay performance and low power consumption for each service. It has multi-access points supporting the dropping/adding/regenerating of signals with/without optical-electrical-optical (OEO) conversion. In this paper, we describe the configuration of this new access network. Moreover, we propose a priority control method for adding/regenerating signals designed to realize a low delay, and describe simulation results related to the number of OEO conversions. Moreover, we clarify a multi-access point traffic design for low delay performance.