This paper presents an adaptive control design for the ABR traffic congestion control in ATM networks. Firstly, we consider a control-based mathematical model to the ABR traffic congestion control problem. Then the feedback pole placement control design is applied to the ATM ABR traffic congestion control problem for the case of known delays. Finally, by using the online plant parameter estimation algorithm and modifying the controller parameters adaptively in real time, a method to treat the case of unknown time-varying delays is proposed. Several design modifications are introduced to solve practical control issues such as bounded command rate constraint, output buffer saturation and bounded values to the plant parameter estimation algorithm. Simulations are implemented to verify the proposed control design. It is shown that while considering these practical control issues, the control method satisfies the requirements of fairness to users, network efficiency, unknown time-varying delays, queue length control and good convergence performance at an acceptable computation effort.

The authors present a shaper for handling non-real time cell traffic which can avoid the cell loss caused by the policing function at the next hop. A state-dependent probabilistic scheduling algorithm which selects a proper queue for cell transmission is introduced. For the purpose of performance evaluation, the cell loss ratio of the proposed shaper is evaluated by simulation.

This paper proposes a stable rate allocation algorithm for ABR service in ATM networks. The main goals in designing this algorithm are to speed up the convergence according to the max-min fairness criterion and to maximize the network utilization while the switch queue length can be properly controlled. Importantly, the set goals should be achieved in a wide range of network conditions without the need for adjusting the algorithm parameters. The algorithm is targeted to work in various networking environments with additional criteria as extended from the work of E-FMMRA (Enhanced Fast Max-Min Rate Allocation) and ERICA+ (Explicit Rate Indication for Congestion Avoidance) . The additional design criteria include the ability to enhance a large number of ABR connections and staggered TCP connections as well as to perform an accurate traffic averaging. The algorithm is analytically proved to be convergent. Simulation results indicate that the proposed algorithm achieves the goals in all evaluated configurations. However, it has some limitations when working in the large-scale network due to its per-connection accounting. It is not recommended to implement the algorithm with a switch that has a small buffer size due to its relatively long averaging interval.

The IEEE 1394 is a standard for the high performance serial bus interface. This standard has the isochronous transfer mode that is suitable for real-time applications and the asynchronous transfer mode for delay-insensitive applications. It can be used to construct a small-size local area network. We propose a queueing model for a network with this standard under some assumptions, and calculate the average waiting time of an asynchronous packet in the buffer in the steady state. We give some numerical results, along with validation by simulation, in order to evaluate its performance.

We have developed a new scheme to provide Diffserv-based QoS over ATM access networks. Well-known Diffserv over ATM scheme requires some extension for conventional routers with ATM interfaces. The routers must map their Diffserv classes of services into ATM QoS classes and forward IP packets into prioritized VCs based on DSCP (DiffServ Code Point). The purpose of this work is to provide Diffserv-based QoS over ATM network using conventional IP over ATM interfaces on routers. We propose DSCP snooping at ATM edge nodes, which differentiates services over a single VC between two IP domains. A prototype circuit was used to evaluate this scheme.

In this paper, we proposed two models, the full multiple MCS (Multicast Server) model and the hybrid multiple MCS model to support multiple MCS over a single large cluster in ATM (Asynchronous Transfer Mode) networks. Also, we presented two methods for MCS assignment which are known as 2PSPMT (2 Phase Shortest Path based on Multicast tree) and hybrid-2PSPMT, and evaluated its performance by simulation. When an ATM host requests joining a specific multicast group, the MARS (Multicast Address Resolution Server) designates a proper MCS among the multiple MCSs for the group member to minimize the average path delay between the sender and the group members. Each method for MCS assignment construct a 2-phase partial multicast tree based on the shortest path algorithm. We reduced the average path delay in the multicast tree using these methods with various cluster topologies and MCS distribution scenarios in addition to distributing the load among multiple MCSs.

In this paper, we first investigate the problems of the existing branch point algorithms for available bit rate (ABR) multicast connections in ATM networks, and then propose various solutions for resolving those problems. By combining these solutions, we also propose a new efficient and scalable branch point algorithm. In the proposed algorithm, each branch point stores the feedback information on a per-branch basis for each virtual connection and only passes BRM cells returning from the farthest destination. Simulation results show that the proposed algorithm can provide a good fairness, a higher efficiency and an excellent scalability, compared with the existing algorithms.

In this paper, we present a new network design problem that is applicable for designing virtual paths (VP's) in an asynchronous transfer mode (ATM) network to efficiently support multicast applications, especially real-time multimedia applications. We first address several alternatives for the solution and compare their properties. Then we focus on a new solution which sets up a semi-permanent VP layout (VPL) and constructs VC trees for different multicast traffic demand patterns based on the constructed VPL. A three-phase heuristic solution is proposed for designing a good virtual-path layout for a given set of multicast traffic demand patterns. By varying the design parameters, we can obtain different VPLs which possess different tradeoffs among some important criteria, namely, the network overhead for a connection setup, routing table resources and control and management cost. Simulations are performed on randomly generated networks to demonstrate the performance and scalability of our solution. To the best of our knowledge, there is no prior known work which takes the multicast connection traffic into account for the VP layout design.

This paper outlines technical trend of multimedia mobile and broadband wireless access systems utilizing comprehensive concept and new categorization of wireless access. It is pointed out that mobile communications have much potential market in future high-speed data or IP (Internet Protocol)-based traffic. Categorization of three kinds of wireless access is presented based on the definition adopted by the Radiocommunication Sector in ITU. IMT (International Mobile Telecommunications)-2000 and broadband wireless LANs (Local Area Networks) each representing mobile and nomadic wireless access will bring about a turning point to a new era that wireless communications become dominant media in access networks. With this perspective technical subjects, spectrum consideration and deployment scenario for these systems are discussed.

This paper investigates the performance of relative rate (RR) switch algorithms for available bit rate (ABR) flow control in asynchronous transfer mode (ATM) networks. An RR switch can be implemented differently according to the congestion detection and notification methods used. This paper proposes three implementation schemes for an RR switch using various congestion detection and notification methods, and then analyzes the allowed cell rate (ACR) of a source and the queue length at a switch in steady state. The upper and lower bounds for the maximum and minimum queue lengths are also determined for each scheme, respectively, thereby investigating the effects of ABR parameter values on a queue length. Furthermore, a selection method for rate increase factor (RIF) and rate decrease factor (RDF) parameter values is suggested to prevent buffer overflow and underflow.

This letter proposes an efficient implementation method for a binary feedback switch, called EFCI/RELAY, which can reduce the feedback delay of the congestion status of a switch in multiple-hop network environments. At each transit switch, this method relays the EFCI-bit contained in an incoming data cell to the head-of-line cell with a corresponding VC which is waiting for transmission in the output buffer. Simulation results show that the proposed method can achieve a lower queue length while maintaining a higher link utilization.

An important issue in accelerating the introduction of ATM networks is to offer more convenient access to the customer and a more efficient ATM system architecture. Regarding the first point, ATM network customers are currently inconvenienced by the need to declare traffic parameters, such as peak and average cell rates to the network provider before using the network. However, it is difficult for a customer to predict traffic parameters. This paper proposes a new ATM system with a dynamic bandwidth estimation and allocation scheme. This eliminates the need for traffic parameter declaration, and realizes more convenient ATM service. The proposed ATM system is a ring network. Bandwidth estimation is carried out by the "Network Server" located on the ring network. The estimation is achieved by observing the parameters closely related to media access control (MAC) protocols of LAN/MAN systems. Based on an estimation of customer traffic, the "Network Server" effectively allocates the bandwidth to each customer. This realizes a more efficient ATM network.

In the wireless ATM network, the key issue is to guarantee various QoS (Quality of Service) under the conditions of the limited radio link bandwidth and error prone characteristics. In this paper, we show a combination method of the error correction schemes, which is suitable to establish multimedia wireless ATM Networks while keeping an efficient use of the limited bandwidth. We consider two levels of FEC; a bit-level and a cell-level to guarantee cell loss probabilities of real time applications. By combining two levels of FEC, various requirements on cell loss can be met. We then apply the bit-level FEC and ARQ protocol for the data communication; tolerant to the delay characteristics. Through the analytical methods, the required overheads of FECs are examined to satisfy the various QoS requirements of CBR connections. The mean delay analysis for the UBR service class is also presented. In numerical examples, we show how the combination scheme to guarantee various cell loss requirements affects the call blocking probability of the CBR service class and the delay of UBR service class.

Multimedia communications often require intramedia synchronization for video data to prevent potential playout discontinuity while still retaining satisfactory playout throughput. In this paper, we propose a novel intra-video synchronization mechanism, called the Video Smoother, particularly suitable for low-end multimedia applications, such as video conferencing. Generally, the Video Smoother dynamically adopts various playout rates according to the number of frames in the playout buffer in an attempt to compensate for the delay jitter introduced from networks. In essence, if the number of frames in the buffer exceeds a given threshold (TH), the Smoother employs a maximum playout rate. Otherwise, the Smoother employs linearly or exponentially reduced rates to eliminate playout pauses resulting from the emptiness of the playout buffer. To determine optimal THs achieving a minimum of playout discontinuity and a maximum of playout throughput under various bursty traffic, we propose an analytic model assuming incoming traffic following an Interrupted Bernoulli arrival Process (IBP). As a result, optimal THs can be analytically determined resulting in superior playout quality under various arrivals and loads of networks. Finally, we display simulation results which demonstrate that, compared to the playout without intra-video synchronization (instant playout), the Video Smoother achieves superior smooth playout and compatible throughput.

Asynchronous Transfer Mode (ATM) networks are expected to support a diverse mix of traffic sources requiring different Quality Of Service (QOS) guarantees. This paper initially examines several existing scheduling disciplines which offer delay guarantees in ATM switches. Among them, the Earliest-Due-Date (EDD) discipline has been regarded as one of the most promising scheduling disciplines. The EDD discipline schedules the departure of a cell belonging to a call based on the delay priority assigned for that call during the call set-up. Supporting n delay-based service classes through the use of n respective urgency numbers D0 to Dn-1 (D0D1 Dn-1), EDD allows a class-i cell to precede any class-j (j>i) cell arriving not prior to (Dj-Di)-slot time. The main goal of the paper is to determine the urgency numbers (Dis), based on an in-depth queueing analysis, in an attempt to offer ninety-nine percentile delay guarantees for higher priority calls under various traffic loads. In the analysis, we derive system-time distributions for both high- and low-priority cells based on a discrete-time, single-server queueing model assuming renewal and non-renewal arrival processes. The validity of the analysis is justified via simulation. With the urgency numbers (Dis) determined, we further propose a feasible efficient VLSI implementation architecture for the EDD scheduling discipline, furnishing the realization of QOS guarantees in ATM switches.

In this paper, we consider conventional signaling link fault tolerance and error correction mechanisms to provide reliable services of mobile multimedia telecommunication network based on ATM (Asynchronous Transfer Mode) technology. Also, we propose an efficient signaling protocol interworking architecture and a reliable distributed interworking network architecture between SS7 based FPLMTS and ATM networks. Besides, we evaluate the performance of proposed method through computer simulation. According to the results, proposed signaling architecture shows efficient and fast fault restoration characteristics than conventional MTP-3/3b based network. Functional signaling protocol stack and network architecture of proposed fast rerouting mechanism provide reliable and efficient restoration performance in view of interworking between SS7 based FPLMTS and ATM networks.

Connectionless data from existing network applications compose a large portion of the workload during an early ATM deployment, and are likely to make up an important portion of ATM's workload even in the long term. For providing a connectionless service over the ATM network, we compare two approaches; an indirect and a direct approaches, which are adopted by International Telecommunication Union-Telecommunication (ITU-T) as generic approaches. Our main subject of this paper is to compare network costs of two approaches by taking into account several cost factors such as transmission links, buffers, and connectionless servers in the case of the direct approach. Since the cost of the direct approach heavily depends on the configuration of a virtual connectionless overlay network, we propose a new heuristic algorithm to construct an effective connectionless overlay network topology. The proposed algorithm determines an optimal number of connectionless servers and their locations to minimize the network cost while satisfying QoS requirements such as maximum delay time and packet loss probability. Through numerical examples, we compare the indirect and direct approaches, the latter of which is constructed by means of our proposed algorithm.

This paper discribes a shared medium access control protocol for residential home and small business customer ATM network application with distributed high-speed multimedia services. This protocol offers global fairness for the whole network with a CG (Centralized Grant) signal and, at the same time, offers local fairness between nodes with DG (Distributed Grant) signals. The DG signal is only meaningful to the next neighboring node. The local fairness is kept between two nodes in distributed way, but this distributed local fairness helps to keep the global fairness. Because the DG signal is related to the passed DG signal from the neighbor node. This protocol is rather simple but shows high performance than the already announced protocols.

In this paper, we analyze the individual sojourn delay experienced by cells from each virtual channel (VC) passing through an ATM switch port. Traffic from each VC is described by a four-parameter Markov-Modulated Bernoulli process (MMBP). A switch port is assumed to receive traffic from a group of heterogeneous MMBPs and the queueing behavior is modelled by a H-MMBPs/D/1/ queue. Two service disciplines are considered: FIFO and priority. Closed-form formulas of overall as well as individual sojourn delays for both service disciplines are obtained. Although approximation is inevitable in our analysis, the accuracy is good when compare with computer simulations. As a result we provide an efficient tool to estimate cell delay for each individual VC before it is established. Our result can be applied to network resource decision or control problems such as call admission control and routing.

In this paper, a new two-level flow control scheme using VP credit-based control and stop-and-go rate control for Asynchronous Transfer Mode (ATM) networks is presented. Since the proposed scheme does not require any information on traffic characteristics, we propose to apply such a flow control scheme to the best effort traffic that requires no band-width guarantee from the network. The proposed flow control scheme can efficiently use the leftover bandwidth after the guaranteed traffic has been satisfied. Therefore, high bandwidth utilization can be achieved. Furthermore, cell loss can completely be avoided by the lower-level credit-flow control done on a per VP basis. On top of this, a higher-level Explicit Congestion Notification (ECN) rate control is employed to avoid any performance degradation. Simulations have been performed to verify the effectiveness of the proposed scheme. It is found that the average end-to-end delay of our proposed scheme is better than that of the original VCFC scheme [1]. In addition, there is also a tremendous saving in the memory required when compared with the VCFC scheme.