New communication systems via chaotic modulations are experimentally, demonstrated. They contain the wellknown chaotic circuits as its basic elements--Chua's circuits and canonial Chua's circuits. The following advantage is found in our laboratory experiments: (a) Transmitted signals have broad spectra. (b) Secure communications are possible in the sense that the better parameter matching is required in order to recover the signal. (c) The circuit structure of our communication system is most simple at this stage. (d) The communication systems are easily built at a small outlay.

This paper discusses a way of identifying the network configuration of ATM-LANs, which are composed of a number of ATM hubs. In general, a Network Management System (NMS) sets and gets the necessary data to and from the network elements. In managing an ATM-LAN, the ATM connection between the NMS and each network element, namely the ATM hub, must be established in order to get and set the necessary data. This forms a remarkable contrast with conventional LANs such as the IEEE802.3 LAN, which is a shared media network and enables broadcast communication without setting up any connection. This paper proposes a new protocol and a procedure that establishes the ATM connection between the NMS and each ATM hub, while identifying the overall network configuration. First, this paper makes clear the peculiarity of the ATM-LAN in terms of automatically identifying the network configuration. Next, the identification protocol that achieves the required properties is precisely explained. Then, the proposed identification protocol is evaluated in terms of required bandwidth and identification time.

Recently, there has been increasing interest in Code Division Multiplex (CDM) systems. We reported the CDM system using the -chip shift multiplex operation. So far the performance of this system evaluated under the optimum . In this letter, we evaluate an influence of the phase difference between the groups on BER performance in 2M-plex system.

Asynchronous Transfer Mode (ATM) is an information transport technique that well supports Broadband ISDN (B-ISDN). One unsolved problem to the perfection of ATM networks is to provide a testing environment that conforms to some standardized network management scheme. From this point of view, remotely controlled virtual path testing is considered in this paper. Remotely controlled virtual path testing should be executed through the standardized Telecommunications Management Network (TMN) model, which employs the OSI systems management concept as the basis of information exchange. Thus, this paper addresses the two issues that arise when OSI systems management standards are applied to virtual path testing. One issue is to define relevant information models. The other issue is to provide test resources with a concurrency control mechanism that guarantees a consistent test environment without causing deadlocks. To resolve these issues, technical requirements are clarified for the remote control of test resources. Next, alternatives to the concurrency control mechanism are shown and compared through computer simulations. A method of defining information models is then proposed. The proposed method ensures the easy storage and retrieval of intermediate test results as well as permitting the effective provision of concurrency control for test resources. An application scenario is also derived. The scenario shows that tests can be executed by using standardized communication services. These results confirm that virtual path testing can be successfully achieved in conformance with the OSI systems management standards.

For the connection request procedure in mobile communication systems, a previous study had shown that the 3-channel systems provide the haighest maximum of stable per channel throughput. In this paper, we propose and study a new algorithm, called the Parallel Collision Resolution Algorithm, which can be implemented in a Q-channel connection request environment, where Q3. For the implementation, the channels are arranged in R groups, where R is a positive integer. The collision resolution scheme distributes the collided messages over all the groups so that throughput and delay measures can be improved. At any point in time, there can be a maximum of R collision resolution schemes operational irrespective of the channel or the group number over which collisions occurred. The performance measures are estimated by computer simulation. Under the new algorithm, almost the same level of the perchannel stable throughput measure of a 3-channel network can be achieved in networks for which Q3. This feature allows freedom to the network designer to employ a higher number of connection request channels without forfeiting high channel utilization rates. When Q is an integral multiple of 3, the maximum stable per channel throughput level achieved can be the same as that achieved by the 3 channel system, if the grouping of channels is such that each group consists of 3 channels. When Q is not an integral multiple of 3, the intuitive strategy of organizing the channels in such a way that Q/3 groups consist of 3 channels each and one group consists of (Q mod 3) channels, may result in much degraded performance. It is found that, if the channels are so organised that no group is composed of (Q mod 3) channels, the performance levels can be substantially enhanced. Also, under the new algorithm, the delay measure is significantly improved, particularly in schemes like the mobile satellite systems with high propagation delays. We conclude that the new scheme presents a promising collision resolution methodology for connection request procedures.

Subscriber network opticalization is the key issue for the next generation network. Fiber-optic systems have been limited to mainly big business applications, so far. Massive opticalization including home and small business customers remains the ultimate goal. Opticalization of the subscriber network needs an enormous investment and a long construction period. In order to achieve smooth evolution towards B-ISDN, the subscriber network must be effectively opticalized well in advance of full B-ISDN deployment. This paper presents the development concept of optical subscriber network. It also describes the design concept and configuration of fiber-optic subscriber systems. Deployment strategies and the developing technologies for the future subscriber network are also addressed.