A connection admission control (CAC) that guarantees a negotiated cell-loss ratio for all cell-streams passing through the usage parameter control (UPC) in ATM networks is proposed. In particular, the cases in which a jumping-window, sliding-window, or continuous-leaky-bucket scheme are used for peak-cell-rate policing are discussued, and the upper bound for cell-loss ratio of the cell-streams passing through each type of UPC is derived. The CACs based on the derived cell-loss-ratio upper bounds ensure the quality of service in all cases by combining the relevant UPCs. There are three possible combinations of CAC and UPC, depending on the UPC mechanism used. The impact of the choice of CAC and UPC combination on bandwidth utilization is discussed using several numerical examples.

The asynchronous transfer mode (ATM) provides efficient switching capability for various kinds of communication services. To guarantee the minimum quality of services in the ATM networks, the bandwidth allocation setup procedure between the network nodes and users is very important. However, most of call admission control (CAC) methods which have been proposed so far are not fully appropriate to apply to real environments in terms of the complexity of the hardware implementation or the accuracy of assumptions about the cell-arrival processes. In addition, the success of broad bandwidth applications in the future multimedia environments will largely depend on the degree to which the efficiency in communication systems can be achieved, so that establishing high-speed CAC schemes in the ATM networks is an indispensable subject. This paper proposes a new cell-loss rate estimation method for the real time CAC in ATM networks. A neural network model using the Kalman filter algorithm was employed to improve the error minimizing process for the cell-loss estimation problem. In the process of optimizing the three-layer perceptron, the average, the variance, and the 3rd central moment of the number of cell arrivals were calculated, and cell-loss rate date based on the non-parametric method were adopted for outputs of the neural network. Evaluation results concerned with the convergence using the sum of square errors of outputs were also discussed in this paper. Using this algorithm, ATM cell-loss rates can be easily derived from the average and peak of cells rates coming from users. Results for the cell-loss estimation process suggest that the proposed method will be useful for high-speed ATM CAC in multimedia traffic environments.

In this paper, algorithms for resource allocation in an ATM node that serves heterogeneous traffic sources subject to varying Quality of Service (QoS) requirements are proposed. The node can be either a switch port or a multiplexer. Each connection is first individually treated as logical queue. Quick and efficient algorithms allocating service rate and buffer space to each connection based on traffic characteristics and QoS requirement are developed. In order to improve link and buffer utilization, the aggregate traffic is next replaced by an appropriately parameterized new traffic source that still preserves the key characteristics of the aggregate traffic. The most stringest QoS requirement among all connections is selected to be the QoS target of the new traffic source to assure that QoS of each individual connection is satisfied. Resource allocation for the aggregate traffic is determined based on the traffic parameters and QoS target of the new source. Each individually determined service rate and buffer space can be used in cell transmission scheduling and selective cell discarding. In other words, resource allocation together with two related side problems: cell transmission and cell discarding, are treated in this paper in an integrated and efficient manner. The resource allocation algorithms proposed in this paper can also be used to support Call Admission Control (CAC) in ATM networks.

Superposed ATM cell streams have burstiness and strong autocorrelation properties. This paper investigates traffic measurement-based modeling method for superposed ATM cell streams. We develop a new measurement method based on monitoring both the waiting time distribution in a monitoring queue and the autocorrelation of cell interarrival times. Through the monitoring queue, we directly observe the queueing effect of superposed cell flows on ATM multiplexers. The measured traffic is modeled as the two-state MMPP. With the measured traffic, we estimate the cell loss probability in ATM multiplexers from the MMPP/D/1/K queue. Our method successfully works with homogeneous and heterogeneous superposition of traffic sources including voice, data, and video. These results can be applied to the evaluation of ATM multiplexers, traffic engineering, and network performance monitoring.

In the proposed architecture, switching system hardware resources are allocated at the equipment level rather than at the component level of LSI chips. Equipment using these resources can thus be shared between independent systems. The efficiency of system development is improved by using structural elements called functional blocks (FBs). The hardware in each FB consists of a shared part (amicroprocessor, its peripheral circuitry, and memory) and a dedicated part that implements the specific functions of the FB. Firmware loaded into the microprocessor consists of a shared part and a dedicated part that corresponds to the hardware parts. Each FB also has its own built-in autonomous testing function to test the reliability of that FB and has its own identification function. By combining these FBs, this approach can flexibly cope with various switching system configurations for plain old telephone service (POTS), integrated services digital network (ISDN), and broad-band ISDN (B-ISDN). Tests using several types of FBs showed that the shared hardware and firmware parts of an FB can be shared between blocks. An architecture based on FBs results in a platform that can handle the hardware for various systems, making it easy to construct new switching systems.

A leaky-bucket-with-gate algorithm is proposed to control connection-setup congestion in telecommunication networks providing multimedia services, in place of the call-gapping algorithm used in telephone networks. Multimedia services may use more than one connection simultaneously, while standard telephone services use only one connection at a time. A set of connections used to construct a multimedia service is called a correlated connection group, and the setup requests of such a group form correlated request group. A correlated request group is assumed to be accepted into the network only when all the connection-setup requests for the group are accepted. In this paper, the proposed leaky-bucket-with-gate algorithm, a pure leaky-bucket algorithm, and a call-gapping algorithm are evaluated by simulating traffic with a mix of correlated and uncorrelated connection-setup requests, which models setup requests for video conferencing and telephone services. The simulation results show that the proposed algorithm accepts correlated request groups more efficiently than the pure leaky-bucket and call-gapping algorithms under the simulated traffic conditions, except when the interarrival time in a correlated request group is longer than the acceptance interval. We also present queueing analysis for determining the control parameters in the proposed algorithm. Implementation of this algorithm will facilitate the handling of both setup request traffic for correlated connection groups and for uncorrelated connections in multimedia networks.

We propose two multipriority reservation protocols for wavelength division multiplexing (WDM) networks. The network architecture is a single-hop with control channel-based passive star topology. Each station is equipped with two pairs of laser and filter. One pair of laser and filter is always tuned to wavelength λ₀ for control and the other pair of laser and filter can be tuned to any of data wavelengths, λ₁, λ₂, ..., λ_N. According to the access methods of the control channel, one protocol is called slotted ALOHA-based protocol and the other protocol is called TDM-based protocol. The two protocols have the following properties. First, each of them has its own priority control scheme which easily accommodates multipriority traffics. Second, they can be employed in the network with limited channels, i.e. the number of stations in the system is not restricted by the number of data channels. Third, they are conflict-free protocols. By using a reservation scheme and a distributed arbitration algorithm, channel collision and destination conflict can be avoided. For the performance point of view, the TDM-based protocol gives an optimal solution for the priority control. However it is less scalable than the slotted ALOHA-based protocol. The slotted ALOHA-based protocol also performs good priority control even though it is not an optimal solution. We analyze their performances using a discrete time Markov model and verify the results by simulation.

This paper presents severl radio resource scheduling algorithms which aim to provide best-effort service for non-real-time unit-oriented, or message traffic. The objective of resource scheduling algorithm is to distribute radio resources between competing message traffic sources while attaining throughput as high and fair as possible for each source without any explicit quality-of-service (QoS) guarantee. Computer simulations are carried out to evaluate the performance in terms of the average of allocation plus transfer delay, the average of throughput, the variance of throughput, and the usage of resources. The message-size distributions of homepages in World-Wide-Web and e-mails obtained by actual measurement are used. Message size-based resource scheduling algorithms are found to provide high and fair throughput as well as efficient use of the resources.

This paper proposes a parallel word alignment procedure for m Binary with 1 Complement Insertion (mBlC) or Differential m Binary with l Mark Insertion (DmBlM) line code. In the proposed procedure for mBlC line code, the word alignment circuit searches (m+1) bit pairs in parallel for complementary relationships. A Signal Flow Graph Model for the parallel word alignment procedure is also proposed, and its performance attributes are numerically analyzed. The attributes are compared with those of the conventional bit-by-bit procedure, and it is shown that the proposed procedure displays superior performance in terms of False-Alignment Probability and Maximum Average Aligning Time. The proposed procedure is suitable for high speed optical data links, because it can be easily implemented using a parallel signal processor operating at a clock rate equal to 1/(m+1) times the mBlC line rate.

The designed converter has a two-input-winding transformer powered by single-phase AC voltage and an energy storage capacitor. Small size and enhanced conversion efficiency are achieved, because more than half of the energy is supplied to the load via a single conversion stage, and fast output-voltage regulation is achieved by controlling the charging and discharging of the storage capacitor. The design and control methods for the converter take into account the reset conditions of the transformer and stability in the output voltage control. An almost unity power factor and a low output voltage ripple were achieved with this converter fabricated as a breadboard circuit using small capacitors.

A 2.4 GHz band direct sequence (DS) spread spectrum (SS) radio frequency modem with a wide bandwidth of 26 MHz in half-duplex system has been newly developed using the small size (832 mm) and highly-efficient (-57 dBm) elastic type of surface acoustic wave (SAW) convolver. The size of SS modem is 905011 mm and the weight is 75 g. The power consumption of SS modem is 1.5 W and data rate is 206 kbps with 63 chips of PN code. Electrical characteristics measurements were made to evaluate the SS modem performance.

A wireless tag system has been designed and developed for maintaining and managing outdoor communication facilities. This system employs an infrared (IR) beam and an electromagnetic wave with a radio frequency (RF), and is constructed using IR-RF tags, an IR commander, and an RF receiver. The IR command radiation with strong directivity enables a maintenance operator to recognize a target facility, and the RF response without directivity enables a management system to obtain data from within a large circular area. Solar and secondary batteries are also adopted as the power module in the tag to allow easy maintenance at long intervals. IR signal communication is possible up to a distance of 9 m, and RF signal communication is possible within a circle with a radius of 9 m.