Call Setup Delay Research Articles

On overlapping resource management and call setup signaling: a new signaling approach for internet multimedia applications

Interactive multimedia applications combine requirements of traditional telephony services and Internet applications. This requires call setup, call signaling, negotiation, routing, and network resources. However, in dynamic network environments resources are not protected unless the applications reserve them for the multimedia session. To provide quality of service (QoS) control, the subject of the interaction of call signaling and resource management have addressed resource reservation during the call setup phase. Usually, the rule is to use the traditional telephony-style call setup model (i.e. users are only alerted after all resources have been successfully reserved for the call). In the Internet, however, this may incur in long call setup delays and a high call blocking rate (‘no QoS/no call’). In order to provide users with a practical and fast way to reserve resources during session setup, we investigate a different call setup model than that of traditional telephony. Our model allows users to be alerted while the resource reservation takes place, thus, taking advantage of parallel user answering delays and reservation delays. For this to occur efficiently, we use existing elements of the Session Initiation Protocol (SIP) to provide means for independent call setup and resource management transactions and flow negotiation. Based on experimental comparisons obtained in a multimedia call, we demonstrate that the proposed approach reduces the impact of the reservation delays, with maximum call setup delay improvements when we have approximate values of reservation and answering delays.

Environment‐adaptive personal communications realizing ubiquitous computing networks

AbstractThis paper is concerned with the realization of a ubiquitous computing network designed to improve the reachability of communications and to eliminate complex setup and manipulation related to communications. The new communication system EAPEC (environment‐adaptive personal communications) is proposed. The communications context of the user, which changes from time to time, is automatically acquired. Based on that information, the communications terminal and the communications service/medium that are optimal for the receiver to receive the message are automatically selected. Then, according to the selection, the communications service or the communications medium is automatically converted. It is shown in this paper that EAPEC can be realized under the 3GPP (third‐generation partnership project) IP network architecture. Placement of five functional modules in the network and the automatic acquisition procedure for communications context are described. As a means of performance evaluation, the call setup delay is evaluated by simulation, and guidelines for network design are obtained. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(1): 34–47, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10087

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.

Two-level pointer forwarding strategy for location management in PCS networks

For a IPCS network to effectively deliver services to its mobile users, it must have an efficient way to keep track of the mobile users. The location management fulfills this task through location registration and paging. To reduce the signaling traffic, many schemes such as a local anchor (LA) scheme, per-user caching scheme and pointer forwarding scheme have been proposed in the past. In this paper, we present a new location management scheme which intends to mitigate the signaling traffic as well as reduce the tracking delay in the PCS systems. In this strategy, we choose a set of visitor location registers (VLRs) traversed by users as the mobility agents (MA), which form another level of management in order to make some registration signaling traffic localized. The idea is as follows: instead of always updating to the home location register (HLR), which would become the bottleneck otherwise, many location updates are carried out in the mobility agents. Thus, the two-level pointer forwarding scheme is designed to reduce the signaling traffic: pointers can be set up between VLRs as the traditional pointer forwarding scheme and can also be set up between MAs. The numerical results show that this strategy can significantly reduce the network signaling traffic for users with low CMR without increasing much of the call setup delay.

A distributed overload control algorithm for delay-bounded call setup

As communication networks provide newer services, signaling is becoming more and more compute intensive compared to present day networks. It is known that under overload conditions, the call throughput (goodput) and the network revenue drops to zero even when transport resources are available. A distributed overload control algorithm for delay-bounded call setup is proposed. The end-to-end delay bound is budgeted among the switching nodes involved in call setup, and these nodes apply a local overload control with a deterministic delay threshold and drop call requests experiencing higher delays. This algorithm does not depend on feedback on network conditions and makes use of only parameters that can be instrumented locally by the switching node. Using an M/M/1 queueing model with first-in-first-out (FIFO) service discipline at a switching node, two optimized control schemes are considered for local overload control and compared their performance through analysis: one with arrival rate limit and the other with buffer size limit. Though both the schemes minimize the unproductive call processing at heavy load, the latter is found to yield higher call throughput and lower average call setup delays compared to the former. Also, the buffer size required for the scheme with buffer size limit is typically small and call throughput close to the server capacity can be achieved during overload. The performance of the distributed overload control algorithm in a network is evaluated through simulation experiments, using the scheme with buffer size limit for the local overload control. It shows that the average end-to-end delay could be much less than the end-to-end delay bound, providing room for overprovisioning of the delay bounds. The tradeoff between the number of nodes, call throughput, and average end-to-end delay needs to be considered while deciding the route budgeting the end-to-end delay bound among different nodes along the route. These performance results are expected to serve as lower bounds to more sophisticated local call rejection mechanisms such as push-out or time-out along with a last-in-first-out (LIFO) service discipline.

Architecture for restorable call allocation and fast VP restoration in mesh ATM networks

This paper presents an architecture for restorable call allocation and fast virtual path (VP) restoration in mesh ATM networks. In this architecture, virtual working and spare capacities needed for call allocation and restoration are reserved and released dynamically on a call-by-call basis at the time of call admission and termination. This obviates the need for advance assignment of spare and working capacities. To shorten the call processing delay, this is done in a parallel-distributed fashion. To provide restorable call allocation, parallel-distributed call processing algorithms of sender-chooser type are suggested. The algorithms integrate, on the call level, virtual bandwidth allocation, virtual spare-capacity assignment, and fixed, alternate, or state-dependent routing. Each routing scheme leads to a particular tradeoff between call processing complexity, call setup delay, and bandwidth efficiency. For each pair of nodes, two sets of VPs are provisioned. The first, working VP (WVP) set, is used for call allocation during the normal operation. The second, spare VP (SVP) set, is used for WVP restoration in the event of failures of network elements. Each SVP protects a preassigned subset of the node pair's WVPs. Each SVP is selected to be link/node disjoint from the WVPs that it is assigned to protect. This assures a protection of the WVP set by a small number of SVPs. Since SVPs are preset and appropriate virtual spare capacities are reserved in advance, the architecture guarantees full restorability and provides very fast restoration. The restoration is done on the VP level in a self-healing manner. The suggested architecture requires only local information to be maintained at each node.

Performance evaluation of integrated IN/B-ISDN signalling platforms

The integration of intelligent networks (IN) and B-ISDN signalling is considered as a prominent and robust solution to the rapid deployment of multimedia application services. The main advantage of this approach is that the network can offer advanced services without significant modifications to existing broadband signalling systems. The IN/IB-ISDN signalling platform will include a set of new elements as the broadband service control point (B-SCP) and the broadband service switching point (B-SSP), which will provide all the functionality required for the processing of user requests for complex multimedia services. The performance of these elements and their protocols is a crucial factor for network design as it determines the total number of calls the network can admit with acceptable call set-up delay. In this paper we study the performance of an IN/B-ISDN integrated architecture by developing a set of protocol models and analysis techniques which are also applicable to other systems. Results show that the proposed architecture constitutes a promising and robust solution that can guarantee a smooth and cost effective evolution to multimedia networks.

Minimizing call setup delay in ATM networks via optimal processing capacity 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.

A route optimization algorithm and its application to mobile location management in ATM networks

In this paper, we propose an algorithm for optimizing the route of a connection that becomes suboptimal due to operations such as handoffs and location-based reroutes, for mobile ATM (asynchronous transfer mode) networks based on the PNNI (private network-to-network interface) standard. This algorithm uses hierarchical route information of the connection and summarized topology and loading information of the network to determine a such that adjusting the connection from that crossover node results in an optimally routed connection. We then apply this algorithm to the mobile location management problem. Location management schemes have been proposed in which an incoming call to a mobile is routed to its home switch (based on summarized reachability data) and then rerouted to the mobile's current location. If we consider such rerouting a first phase of mobile connection setup, a second phase is required to optimize the paths of such rerouted connections. Such an approach is considered a two-phase mobile location/connection setup scheme. Alternatively, an incoming call to a mobile can be routed to its home switch based on summarized reachability data, and then cranked back to an optimal crossover node before rerouting the connection to the mobile's current location. Such a scheme is a one-phase mobile location/connection setup scheme since it directly results in an optimal path. A comparative performance analysis of the one- and two-phase connection setup schemes is presented. Measures of comparison are call setup delay and the amount of network resources allocated to a connection. The maximum call setup delay (worst case call setup delay) is lower in the two-phase scheme, but the average call setup delay is lower in the one-phase scheme. The amount of resources required for a connection in the two-phase scheme (prior to route optimization) is significantly greater than that in the one-phase scheme.

A profile-based location strategy and its performance

Future microcellular personal communications systems (PCSs) will be characterized by high user density and high mobility. It is expected that registrations will incur a large amount of the radio link signaling traffic. A profile-based strategy (PBS) is proposed to reduce the signaling traffic on the radio link by increasing the intelligence within the fixed network. The system maintains a sequential list of the most likely places where each user is located. The list is ranked from the most to the least likely place where a user is found. When a call arrives for a mobile, it is paged sequentially in each location within the list. When a user moves between location areas in this list, no location update is required. The list may be provided by the user or may be based on each user's past calling history. The method for doing this is outside the scope of this work. This work focuses on the potential performance improvements that can result from maintaining such a list. This paper compares the performance of the proposed strategy to the typical geographic-based location-tracking schemes being implemented in evolving digital cellular and cordless standards. Key performance measures for the comparison are radio bandwidth, fixed network SS7 traffic, and call setup delay. We investigate the conditions under which the PBS performs better than the traditional scheme. Results indicate that over a wide range of parameters, it may be possible to reduce both the radio bandwidth and fixed network signaling load for a modest increase in call setup delay.

GSM signalling in prioritised LEO satellite environment

The authors discuss a number of issues concerned with the functionally efficient integration of GSM signalling and services with a low-earth orbiting (LEO) mobile communication satellite system. Modified GSM signalling procedures are introduced which provide prioritised access and call setup, and reduced call setup delays.

Provision of isochronous service on IEEE 802.6

The author concentrate on the provision of isochronous services to users via the existing IEEE 802.6 framework using Q.931 as the signalling protocol for providing call control functions. They present possible scenarios of isochronous service provisioning via the IEEE 802.6 network. Real time performance for call setup procedures is simulated and analyzed with different priority schemes for transferring signalling messages. The results show that using a prioritized queue arbitrated (QA) bandwidth to send signalling messages greatly reduces call setup delay. Call setup delays are determined using both Poisson-type and bursty type data traffic models. The positioning of the bandwidth manager, the virtual channel identifier (VCI) server and the Q.931 signalling termination is shown to influence call setup performance. >

Call control and traffic transport for connection-oriented high speed wireless personal communications over metropolitan area networks

A distributed circuit-switched approach for supporting the deployment of high speed wireless personal communication services in urban areas through the interconnection of base stations via metropolitan area networks (MANs) is proposed. Broadband MANs minimize traffic congestion by dynamic sharing of link capacity and by serving as distributed switches for partitioning call control functions. While the DQDB protocol readily supports distributed packet-switching over the IEEE 802.6 MAN, isochronous traffic such as voice and video is best supported by circuit-switched connections. The authors present an enhanced bi-state pre-arbitrated (PA) transport mechanism, and associated call control and handoff management techniques, which enable distributed circuit-switching over the MAN. These capabilities are not currently addressed in the 802.6 standards. The bi-state PA transport mechanism facilitates statistical multiplexing of variable rate isochronous traffic sources. The network capacity is constrained by the call setup delay performance, and is analyzed by simulations. Alternative signaling architectures, involving different placements of call control network elements, are evaluated. The effects of erasure nodes, and close bus versus open bus architectures, are considered. The overlap inter-MAN call setup procedure is proposed to reduce delays. Different call handoff procedures are formulated according to the type of handoff and the resulting change in call connectivity. Most handoffs are intra-MAN, requiring simple procedures with short delays.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Demand assignment multiple access and dynamic channel allocation strategies for integrating radio dispatch and telephone services over mobile satellite systems

The authors discuss the performance analyses of a novel demand assignment multiple access (DAMA) scheme addressing the special characteristics of the mobile radio service (MRS), and a new method for dynamically allocating a common pool of channels to both MRS and mobile telephone service (MTS) to improve channel utilization. The new DAMA scheme makes use of call queuing, batch processing, and pipelined signaling to minimize call setup overhead for MRS traffic. MRS call setup delays were analyzed by simulation modeling of a mobile satellite system (MSS) with many mobile voice-dispatch networks operating over a multiple spot beam satellite to investigate the effects of traffic volume, batch size, and batch service disciplines. A reserved channel margin algorithm for dynamic channel allocation was shown to be effective in harmonizing the different call setup performance requirements for MTS and MRS. Numerical results show that dynamic channel allocation applied to a common pool of 40 channels enables a 20-25% increase in the number of mobile terminals compared with a fixed allocation of 20 channels to each of the two services. >

Grade of service in the ISDN era

The grade of service (GOS) concept is explained, and effect of ISDN (integrated-service digital network) services on GOS parameters is explored. Consideration is given to quality degradation that could be caused by traffic congestion, other than effects on the existing parameters such as call setup delay and call blocking probability, and to the changes that would be induced on the existing parameters. Current studies, including CCITT standardization, are reviewed, and a direction for GOS specification methods in the ISDN era is suggested.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>