In this paper, we introduce a VP rearrangement scheme to realize the dynamic control of ATM network. We demonstrate its effectiveness for the transport of B-ISDN traffic which is both fluctuous and hard to predict. First, we present a strategy for the ATM network provisioning, used to manage both the logical VP network and the underlying physical transport network. We then propose a VP rearrangement scheme and discuss its performance. Lastly, we analyze the proposed scheme by simulations, and confirm that its performance, in comparison to the conventional, dynamic VP bandwidth control scheme, is superior.

This paper proposes a high-speed VP bandwidth control scheme for ATM networks that utilizes a distributed control mechanism. First, the characteristics of VPs are compared with those of digital paths in STM networks. A distributed control scheme is adopted for rapid control. The basic elements and the necessary distributed function, the control algorithm, and the message transmission mechanism, are elucidated. The bandwidth alteration time with the proposed algorithm is estimated by considering network element processing and queuing delay. The proposed VP bandwidth control scheme can be applied to both public networks and leased line services. Finally, this paper focuses on its application to leased line services, and discusses the resource reduction effects of the proposed scheme.

With the rapid deployment of the Internet of Things, where various devices are connected to communication networks, remote driving applications for Unmanned Vehicles (UVs) are attracting attention. In addition to automobiles, autonomous driving technology is expected to be applied to various types of equipment, such as small vehicles equipped with surveillance cameras to monitor building internally and externally, autonomous vehicles that deliver office supplies, and wheelchairs. When a UV is remotely controlled, the control accuracy deteriorates due to transmission delay and jitter. The accuracy must be kept high to realize UV control system by a cloud server. In this study, we investigate the effectiveness of Digital Twin Computing (DTC) for path tracking control of a UV. We show the results of simulations that use transmission delay values measured on the Internet with some cloud servers. Through the results, we quantitatively clarify that application of DTC improves control accuracy on path tracking control. We also clarify that application of jitter buffer, which absorbs the transmission delay fluctuation, can further improve the accuracy.

A 10-Gbit/s-class ac-coupled average-detection-type burst-mode receiver (B-Rx) with an ultra fast response and a high tolerance to the long consecutive identical digits has been developed. Key features of the circuit design are the baseline-wander common-mode rejection technique and the inverted distortion technique adopted in the limiting amplifier to cope with both the fast response and the high tolerance. Our B-Rx with newly developed limiting amplifier IC achieved a settling time of less than 150 ns, a sensitivity of -29.8 dBm, and a dynamic range of 23.8 dB with a 231-1 pseudo random bit sequences. Moreover, we also describe several potential B-Rx applications. We achieved better performance by applying the proposed systems to our B-Rx.

This paper presents spectral multi-level (M-ary) amplitude shift keying (ASK) optical code-division-multiplexing (OCDM) as a key technology for future optical access network. A novel transmitter configuration to achieve flexible scalability that is required in future optical access network is proposed. The transmitter employs pre-biasing circuits and dummy data input. Pre-biasing circuits enable us to achieve high tolerance to multiple access interference by compensating for the nonlinearity of the M-ary ASK and increase the number of multiplexed binary data streams. By inputting the dummy data into the transmitter so that the total number of multiplexed binary data streams including those that actually accommodate users/services and the dummy streams remains constant, the number of users/services can be increased up to the total number of data streams without changing the parameters for pre-biasing. Therefore, the proposed transmitter can flexibly enhance the scalability of the spectral M-ary ASK OCDM. The formulas for calculating the bit error rate characteristics are described when using the conventional and proposed transmitters. The feasibility of the proposed transmitter is verified theoretically using the established formulas.

In order to pave the way to B-ISDN, one of the most important issues for network providers is to identify the most efficient B-ISDN introduction strategy. This paper focuses on the costs of introducing ATM transmission systems into backbone transport networks which must provide highly reliable broad band transmission capability. In this context, the main rival to ATM is Synchronous Transfer Mode (STM); recent Synchronous Digital Hierarchy (SDH) equipment supports the establishment of advanced STM-based high speed transport networks. This paper offers a cost comparison of ATM and STM based backbone transport networks. A digital path network in STM has a hierarchical structure determined by the hierarchical multiplexing scheme employed. The minimum cost STM path network can only be determined by developing a path design method that considers all hierarchical path levels and yields the optimum balance of link cost and node cost. Virtual paths have desirable features such as non-deterministic path bandwidth and non-hierarchical and direct multiplexing capability into high speed optical transmission links. These features make it possible to implement a non-hierarchical VP network with ATM cross connect systems which can handle any bandwidth VP with a universal cell switching function. This paper shows that the non-hierarchical VP routing, which strongly minimizes link cost, can be implemented without significantly increasing node cost. Network design simulations show that the virtual path scheme, possible only in an ATM network, yields the most cost effective path network configuration.

Autonomous driving technology is expected to be applied to various applications with unmanned vehicles (UVs), such as small delivery vehicles for office supplies and smart wheelchairs. UV remote control by a cloud server (CS) would achieve cost-effective applications with a large number of UVs. In general, dead time in real-time feedback control reduces the control accuracy. On remote path tracking control by the CS, UV control accuracy deteriorates due to transmission delay and jitter through the Internet. Digital twin computing (DTC) and jitter buffer are effective to solve this problem. In our previous study, we clarified effectiveness of them in UV remote control by CS. The jitter buffer absorbs the transmission delay jitter of control signals. This is effective to achieve accurate UV remote control. Adaptive buffering time optimization according to real-time transmission characteristics is necessary to achieve more accurate UV control in CS-based remote control system with DTC and jitter buffer. In this study, we proposed a method for the adaptive optimization according to real-time transmission delay characteristics. To quantitatively evaluate the effectiveness of the method, we created a UV remote control simulator of the control system. The results of simulations quantitatively clarify that the adaptive optimization by the proposed method improves the UV control accuracy.

This paper presents a newly developed analytical method which evaluates the virtual path bandwidth control effects for a general topology ATM (Asynchronous Transfer Mode) transport network. The virtual path concept can enhance the controllability of path bandwidth. Required link capacity to attain a specified call blocking probability can be reduced by applying virtual path bandwidth control. This paper proposes an analytical method to evaluate the call blocking probability of a general topology ATM network, which includes many virtual paths, that is using virtual path bandwidth control. A method for the designing link capacities of the network is also proposed. These methods make it possible to design an optimum transport network with path bandwidth control. Finally, a newly developed approximation technique is used to develop some analytical results on the effects of dynamic path bandwidth control are provided to demonstrate its effectiveness.

A Wavelength division multiplexing passive optical network (WDM-PON) system that uses spectrum-sliced broadband incoherent light is attractive because it avoids the cost of operating/administering wavelengths in optical network units (ONU) at customer premises. However, it is difficult to enhance the spectrum efficiency to ensure a sufficient signal to noise ratio because it would demand broad channel width. To overcome this problem, we proposed a spectrum-interleaved duplex technique. It enables upstream and downstream communications to share one channel by using a cyclic filter. This sharing of one channel eliminates the need for a guard interval between signal lights duplexed in the channel. One residual issue regarding single band transmission is its robustness to reflection in the transmission medium. To increase the reflection robustness of the spectrum-interleaved duplex scheme, we propose a reflection remover based on an optical code division multiplexing technique. We also evaluate the extent to which capacity of the spectrum efficiency of the spectrum-interleaved duplex WDM-PON system that uses spectrum-sliced broadband incoherent light can be increased.

We propose frequency-domain optical code-division-multiplexing (CDM) employing quadrature-amplitude-modulation (QAM) using two of multi-level (M-ary) data generated based on electrical-domain spatial code spreading. Its spectral efficiency is enhanced compared to the conventional scheme with amplitude-shift-keying (ASK) using only one of M-ary data. Although it demands the recovery of amplitude and optical phase information, the practicality of the receiver is retained with self-homodyne detection using a phase-shift-keying (PSK) pilot light. Performance is theoretically evaluated and the optimal parameters are derived. Finally, the feasibility of the proposed technique is experimentally confirmed.

This paper shows new techniques to construct a service network which realizes responsive large-size data transmission for widely distributed mass users. We set our service target as transferring mega-byte scale data from a server to a client within one second. ATM is recognized as a powerful technology with which to construct a wide area network infrastructure that supports multiple bandwidth services. Our fundamental principles in developing such a service network are as follows: a) The bandwidth sharing mechanism should be of the best effort rather than resource reservation type. This is because only best effort schemes remove bandwidth reservation/release overheads. b) More than a 100 Mb/s data transmission rate should be supported throughout data transfer. c) Data transfer should be completed within the round trip through the network (or a small multiple thereof). This is necessary to minimize the effect of transmission time in large-scale networks. d) The user network interface should be simply defined to allow independent evolution of both network and terminal technologies. e) Congestion control must block the spread of congestion within the network. Based on these principles, we propose the "ATM superpacket network (ATM-SN)" as the service network to realize our target service. Key techniques are as follows. (1) Best effort and cut-through transmission of superpackets whose length reaches ten mega-bytes. (2) Network nodes with large-capacity buffer memories that prevent superpacket collisions. (3) Superpacket admission control at network nodes to prevent cell overflow. (4) Superpacket-based congestion control. Our proposal assumes the existence of a high-quality ATM infrastructure that can provide a large bandwidth with a high-quality DBR cell transmission capability (cell loss ratio is less than 10E-7) and small bit error ratios (less than 10E-10). First, we detail our proposal of the ATM-SN. Next, we propose a superpacket-based congestion control technique coupled with a simple Usage Parameter Control function. We then show the evaluation results of those key techniques to confirm the effectiveness of the superpacket network.