A distributed control strategy for wireless ATM networks

Cellular networks are expected to be upgraded to offer Personal Communication Services (PCS). The mobility management and wireless call control approach used in cellular networks are currently being proposed for use in PCS networks. Recent work indicates that both the signaling load and database update rates caused by these mobility management and call control procedures will increase significantly in next generation PCS networks. In this paper, we propose and analyze a new cluster-based architecture and define algorithms to effectively handle mobility management and call control functions for PCS. We assume an ATM network infrastructure. Some of the key aspects of our proposal include simplifying the mobile location and tracking function, performing connection setup in segments, eliminating the need for user service profile downloads between networks, and more efficient routing of connections by removing the need for an anchor switch. Advantages of this approach include a reduction in signaling traffic load, improved call/connection setup delays, and more efficient routing of connections. We carry out an analysis of our solution for high-tier PCS applications.     

Performance analysis of cache strategy for signaling traffic management in a wireless ATM network

In a wireless ATM network for mobile multimedia services, conventional signaling protocols generate heavy traffic because the signaling load must be handled in a HLR (Home Location Register). This centralized structure of the wireless ATM network causes critical connection setup delays. Thus, distributed processing based on a reduction of the connection setup delays is needed in wireless ATM networks. A cache strategy for call delivery with cache updates of registration based on ATM multicasting is introduced with a comparison of the cost of cache scheme with the cost of a conventional scheme. Results show that the cache scheme has better performance than conventional methods when portable mobility is low with large traffic density. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the distribution of routing computation in hierarchical ATMnetworks

ATM private network-to-network interface (PNNI) is a hierarchical and dynamic link-state routing protocol, designed to scale to the largest possible ATM networks, encompassing thousands of nodes. This paper investigates the route computation load imposed by the PNNI routing scheme, and shows that this load is unevenly distributed among the network nodes. More specifically, the routing computation load associated with the setup of a single virtual path grows exponentially with the hierarchy level. As a result, some of the network nodes-mainly those that function as border nodes of high levels-may be overloaded with route computation, while other nodes are rarely involved in this process. This paper also proposes a possible scheme for spreading the route computation burden more evenly. According to this scheme, heavily loaded nodes transfer route computation tasks to lightly loaded nodes     

SSCOP信令传输时延分析与检测

SSCOP协议是ATM宽带网络信令系统数据链路层的一部分,SSCOP信令链路为ATM网络元素之间提供可靠的信令信息传输。信令链路传输时延是ATM网络传输质量的一个重要参数,SSCOP协议的很多重要参数的取值都依赖于传输时延的大小。介绍一种SSCOP信令链路传输时延的检测方法,通过构造一种特殊的SSCOP报文来测试信令网络的传输质量,并计算信令报文的传输时延。对提高ATM信令系统的网络质量和优化SSCOP协议参数具有一定的现实意义。     

Applying ATM to mobile infrastructure networks

In response to the explosive increase in the number of mobile subscribers and the ever stronger demand for mobile multimedia services, the authors propose introducing the ATM technique for next-generation mobile network infrastructures in order to handle a high volume of traffic and develop multimedia communications. First, this article clarifies mobile-specific requirements for and advantages of applying ATM to mobile infrastructure networks. However, it is risky for network operators en bloc to replace the conventional STM-based infrastructure by ATM. Therefore, this article shows a smooth evolution path for the mobile network infrastructure to convert from conventional STM to ATM as mobile multimedia services mature. Even in future mobile networks, the main traffic may still be voice communications, whose bit rate is too low for efficient use of the radio frequency band. Applying ATM to such very-low-bit-rate mobile voice streams is inefficient due to the delay in filling out the payload of an ATM cell; this “packetization delay” degrades the quality of service. This problem can be solved by using a layered cell structure for the mobile ATM network. This cell structure enables the efficient transfer of voice signals ranging from very-low-bit-rate signals to high-speed multimedia signals with little delay. Standardization of this cell structure is progressing in ITU-T and the ATM Forum. Transmission efficiency is estimated by simulation     

An ATM queue manager handling multiple delay and loss priorities

The asynchronous transfer mode (ATM) technique has been widely accepted as a flexible and effective scheme to transport various traffic over the future broadband network. To fully utilize network resources while still providing satisfactory quality of service (QOS) to all network users, prioritizing the user's traffic according to their service requirements becomes necessary. During call setup or service provisioning, each service can be assigned a service class determined by a delay priority and a loss priority. A queue manager in ATM network nodes will schedule ATM cells departing and discarding sequence based on their delay and loss priorities. Most queue management schemes proposed so far only consider either one of these two priority types. The queue manager handles multiple delay and loss priorities simultaneously. Moreover, a cell discarding strategy, called push-out, that allows the buffer to be completely shared by all service classes, has been adopted in the queue manager. We propose a practical architecture to implement the queue manager by using available VLSI sequencer chips     

Interaction of call blocking and cell loss in an ATM network

The introduction of broadband ATM networks and services will raise new operational issues. An area of significant challenge to the network operators will be network dimensioning. ATM networks differ from today's STM networks in that they will have to provide acceptable performance with respect to not only call blocking, but also cell loss and cell delay. Consequently, it is important to understand the interaction of call blocking and cell loss/delay in ATM networks. The paper presents a method of exploiting the interaction of call blocking and cell loss performance in order to efficiently operate the ATM networks. Specifically, the paper demonstrates that when the network is dimensioned or engineered to meet an appropriate call blocking objective, the cell loss performance perceived by the accepted calls can be significantly better than the cell loss objective set for the connection admission control (CAC) to admit or deny a call     

SDRAM: a SD channel-based multicast scheme on ATM networks for multimedia transmissions

Multicast delivery has become more and more important in modern multimedia applications. VoD and videoconferences are two examples. Multimedia integrates texts, audios, videos and still images in a variety of applications. The data in this media can be time critical in terms of maximum delay and delay jitter. In order to satisfy all these applications, the network needs to have an efficient multicasting mechanism using the true capability of ATM networks. In the native solution, a separate connection can be set up from the source to each group node, also called full connectivity. The full connectivity needs O(N/sup 2/) connections, where N is the number of nodes in a group. Instead, we can have one tree spanning all the participants. Multicast using a single shared tree has become the trend. In this paper, we propose a bi-directional multipoint-to-multipoint multicast scheme, a SD channel-based Multicast with Round-robin Access (SDRAM), for ATM networks, which uses a single tree for a multicast group consisting of multiple participants that are either senders, receivers, or a mix of both. We first discuss why the resequencer model will not be suitable for multimedia traffic, then propose the SDRAM scheme to solve the problems, and finally compare our scheme with the resequencer model through simulation. Results show the mean queuing delays and mean inter-PDU delays of our scheme are not sensitive to mean PDU size while the mean queuing delays and mean inter-PDU delays of the resequencer scheme are very sensitive to mean PDU size.     

Performance Benefits of Virtual Path Tunneling for Control and Management Flows in the Broadband ATM Networks

In this paper, we analyze the performance benefits of broadband ATM networks when the call control and management flows are separated from user data flows. The virtual path tunneling concept for control and management flows are applied to the same physical ATM networks. The behaviors of channel throughput and transfer delay are analyzed. It results that the proposed virtual short-cut paths can maintain the network being stable with acceptable bandwidth. They are very useful to provide the stable control and management capabilities for Internet and mobile applications in the broadband ATM networks. In our numerical results, the effective throughputs of the proposed virtual short-cut channel are about three times than those of end-to-end user data channels with hop distances of 10, and about two times than those with hop distance of 5 when the link blocking probability increases to 0.1. It concludes that the effective channel bandwidth are greatly reduced down while physical links are not stable and user traffic flows are occasionally overflowed.     

ATM网络中语音编码和传输的新方案

本文针对未来新的ＡＴＭ通信方式,提出了一种新的语音可变速率编码和可变时延传输系统方案,为了将信号源和人耳听觉的特征,与ＡＴＭ网络的统计复用性相结合,实现语音的码率在缩和低时延传输,该方案将ＡＴＭ网络环境和语音编码系统中最优信号分析区间的选取、编码系统参数的确定相结合。文中基于一种新的分布熵进行信号特征判断,对输入信号构成不同的处理系统,具体编码由小波变换分带、多带二进树ＶＱ构成,输出码率可调,改变     

The Effects of Management Traffic on the Local Call Processing Performance of ATM Switches Using Queue Network Models and Jackson's Theorem

This paper considers a TMN‐based management system for the management of public ATM switching networks using a four‐level hierarchical structure consisting of one network management system, several element management systems, and several agent‐ATM switch pairs. Using Jackson's queuing model, we analyze the effects of one TMN command on the performance of the component ATM switch in processing local calls. The TMN command considered is the permanent virtual call connection. We analyze four performance measures of ATM switches—utilization, mean queue length and mean waiting time for the processor directly interfacing with the subscriber lines and trunks, and the call setup delay of the ATM switch—and compare the results with those from Jackson's queuing model.     

Survey of error recovery techniques for IP-based audio-visualmulticast applications

IP-based audio-visual multicast applications are gaining increasing interest since they can be realized using inexpensive network services that offer no guarantees for loss or delay. When using network services that do not guarantee the quality of service (QoS) required by audio-visual applications, recovery from losses due to congestion in the network is a key problem that must be solved. This survey gives an overview of existing transport-layer error control mechanisms and discusses their suitability for use in IP-based networks. Additionally, the impact of IP over ATM on the requirements of error control mechanisms is discussed. Different network scenarios are used to assess the performance of retransmission-based error correction and forward error correction     

Survey of switching techniques in high-speed networks and their performance

One of the most promising approaches for high speed networks for integrated service applications is fast packet switching, or ATM (asynchronous transfer mode). ATM can be characterized by very high speed transmission links and simple, hard-wired protocols within a network. To match the transmission speed of the network links, and to minimize the overhead due to the processing of network protocols, the switching of cells is done in hardware switching fabrics in ATM networks. A number of designs have been proposed for implementing ATM switches. Although many differences exist among the proposals, the vast majority of them are based on self-routeing multistage interconnection networks. This is because of the desirable features of multi-stage interconnection networks such as self-routeing capability and suitability for VLSI implementation. Existing ATM switch architectures can be classified into two major classes: blocking switches, where blockings of cells may occur within a switch when more than one cell contends for the same internal link, and non-blocking switches, where no internal blocking occurs. A large number of techniques have also been proposed to improve the performance of blocking and non-blocking switches. In this paper, we present an extensive survey of the existing proposals for ATM switch architectures, focusing on their performance issues.     

Securing multimedia services over satellite ATM networks

In recent years there has been increasing interest in interconnecting satellite and ATM networks, because both share common characteristics of the ability to provide bandwidth-on-demand and flexibility of integrating voice, video and data services. There are several new satellite constellation proposals that support multimedia service and transport ATM traffic. For a successful implementation of such systems it is essential to address the security requirements of users, satellite ATM network operators and multimedia service providers. In order to minimize delay and the cost of implementing security systems for satellite ATM networks, the network operator role (in security services) can be limited to the mutual authentication with satellite users during call set-up periods. In this paper a mutual authentication protocol between the user and the satellite network is presented using digital signature and public key systems. Also, another mutual authentication protocol between the user and the service provider is presented to provide end-to-end authentication and negotiation of security options such as selecting a secret key system and the key length. Finally, a detailed hardware implementation of ATM cell payload encryption is presented using the DES/TripleDES secret key system. © 1998 John Wiley & Sons, Ltd.     

A Novelistic GSA and CSA Based Optimization for Energy-Efficient Routing Using Multiple Sinks in HWSNs Under Critical Scenarios

Asynchronous transfer mode (ATM) tends to be the most mature infrastructure to serve the imminent media broadband networks and is intended to eliminate network latency and improve traffic output versatility. In Weighted Round Robin (WRR) scheme, the main cause of concern is the delay that is being caused by high volumes of workloads at the wireless source nodes. In this paper, proposed an efficient intelligent time slice based round Robin scheduling algorithm for ATM with the use of integrated speed bit protocol (ISBP). The intelligent time slice offers priority, the blast of the CPU, and the time meaning transfer. The speed bit manager is maintained by the ISBP that contains prioritized objects. Then the intelligent time slice is done to generate the quantum time value. The purpose of this paper to enhance network performance in ATM networks by improving the throughput and average end-to-end delay. The new proposed scheme also offers a significant reduction in the average end-to-end delay when compared to the existing WRR scheme.

     

Broadband satellite networks-the global IT bridge

Next-generation broadband satellite networks are being developed to carry bursty Internet and multimedia traffic in addition to the traditional circuit-switched traffic (mainly voice) on a global basis. These satellites provide direct network access for personal applications as well as interconnectivity to the terrestrial remote network segments. The main requirement in success of these networks is that they should be able to transmit high data rate traffic with prescribed quality of service (QoS). Thus, the broadband satellite network has no choice other than the rise of ATM technology and to be optimized for Internet-based traffic. ATM is the promising technology for supporting high-speed data transfer potentially suitable for all varieties of private and public telecommunications networks. IP, on the other hand is the fast-growing Internet layer protocol that is applicable over any data link layer Internet-based applications are the emerging source of traffic in the future wireless networks and broadband satellite networks should consider Internet as the primary service. In this paper, we discuss the traditional ATM and wireless ATM networks and explain the characteristics of the wireless IP networks. The paper then uses those concepts in defining the criteria for the broadband satellite networks such as the QoS and traffic management. Application of the broadband satellite networks is also proposed     

A lossless handover method for video transmission in mobile ATMnetworks and its subjective quality assessment

Cell loss is one of the major causes of degradation in quality of service in ATM mobile communication systems. It can be suppressed by employing buffer memories in the network; however, cell delay occurs as a consequence. This article proposes a lossless handover method for mobile ATM communication networks that both prevents cell loss and can suppress cell delay variation. The method was simulated on an experimental system to subjectively evaluate MPEG2 images relative to buffer memory size and the results obtained are presented     

Minimizing call setup delay in ATM networks via optimal processingcapacity allocation

This paper considers the problem of process allocation in designing real-time call setup for asynchronous transfer mode (ATM) networks. With the constraint of finite processing capacity in a realistic ATM switching system, we aim to minimize the call setup delay by avoiding the potential bottleneck process. Our approach is to distribute and balance the processing loads among call control processes via optimal capacity allocation. The derived results can provide important and useful guidelines in system design and performance evaluation     

Performance evaluation — Test configurations and results

In this paper experimental designs for investigating performance parameters and their corresponding experimental results on the EXPLOIT testbed facilities are given. In an exemplary way the performance evaluation of a switch and an ATM network is described. These designs and results can be used in two ways: firstly in determining the network performance of already existing equipment and networks and secondly in designing new equipment by modelling the described scenarios within simulations. As important network performance parameters under study have been identified cell delay, cell loss and cell delay variation. These will be investigated together with some techniques for assessing those. Initially the question, whether the occurring delays in successive switches are independent, is tackled. If the independence assumption holds true or the correlation can be quantified, then out of measurements at a single switch the delay behaviour after having passed a number of switches can be determined, thus extrapolation from a small network to a larger one becomes possible. Afterwards the fairness of the switch design with respect to multiplexing traffic sources while being in an overload state are discussed. For being able to predict delays in the future the suitability of traditional queueing models will be checked. Out of this, forecasts on cell losses can be gained as well. For this investigation specific traffic mixes have been chosen, which are representative of the predicted traffic for future ATM networks. Also some results on the end-to-end cell delay variation are given.