Common Channel Signaling Research Articles

Service-Oriented Multigranular Optical Network Architecture for Clouds

This paper presents a novel service-oriented network architecture to bridge the informational gap between user applications and optical networks providing technology-agnostic multigranular optical network services for clouds. A mediation layer (service plane) between user applications and network control is proposed to facilitate a mapping process between user application requests and the network services. At the network level, a multigranular optical network (MGON) is proposed and implemented to support dynamic wavelength and subwavelength granularities with different transport formats [optical burst switched (OBS), optical burst transport (OBT)], reservation protocols (one-way, two-way), and different quality-of-service (QoS) levels per service type. The service-oriented multigranular optical network has been designed, implemented, and demonstrated on an experimental testbed. The testbed consists of service and network resource provisioning, service abstraction, and network resource virtualization. The service-to-network interoperation is provided by means of a gateway that maps service requests to technology-specific parameters and a common signaling channel for both service and network resource provisioning.

Pilot power optimization and coverage control in WCDMA mobile networks

In mobile networks using wideband code division multiple access (WCDMA), common pilot channel (CPICH) signals are used by mobile terminals for channel quality estimation, cell selection, and handover. The strength of the CPICH signal determines the coverage area of the cell, impacts the network capacity, and thereby the quality of service, and is therefore a crucial parameter in network planning and optimization. Pilot power is the most important parameter that allows us to control the strength of the CPICH signal. The more power is spent for pilot signals, the better coverage is obtained. On the other hand, a higher value of the pilot power level in a cell means higher pilot pollution in the network and less power available to serve user traffic in the cell. In this paper, we consider the problem of minimizing the total amount of pilot power subject to a coverage constraint. Our modeling and solution approaches are based on mathematical programming techniques. We present a basic model for pilot power optimization subject to a full coverage constraint as well as its extended version which allows us to study various coverage levels and to consider user traffic distribution over the network. We also propose an efficient algorithm that gives near-optimal solutions to the problem within a reasonable amount of time. We report our numerical experiments for three WCDMA networks of various sizes based on realistic planning scenarios and examine the effect of different levels of the required coverage degree on the total amount of pilot power.

CPICH power optimisation by means of simulated annealing in an UTRA-FDD environment

In the framework of an UTRA-FDD system, simulated annealing is used to optimise the values of powers assigned to common pilot channel (CPICH) signals in order to force mobiles to transmit to the best option cell. Results show the existence of optimal configurations that decrease the cells load. Consequently, capacity can be increased.

The Influence of Short Error Clusters on CCS No 7 Link Availability

Summary We observe the Common Channel Signaling (CCS) No 7 link availability under short error bursts or clusters with high bit error rate (BER), and compare it to the availability of CCS No 7 link under equivalent random errors. It is shown that the mean time to changeover of the CCS No 7 link in the case of error clusters is greater than in the case of random errors of same intensity. The reason for this positive impact of short clusters with high BER is the concentration of more than one errored bits in one errored signal unit. In the same time the mean alignment time of CCS No 7 link (that is out of service) is shortest if errors are grouped in rare short error clusters. Hence, the availability of CCS No 7 link increases and frequency of CCS No 7 link oscillations decreases, if errors are grouped.

Detecting and Preventing Routing Problems in the Planning Process ofCCSS n7 Networks

Common Channel Signalling System n7 (CCSSn7) has become nowadays widely used by most of the operators which are strongly dependant on its performance. This paper develops next issues. First, usual problems with routing in CCSSn7 networks that can not be solved by the protocol are described, and a checking algorithm based on modified dynamic programming techniques is proposed. And secondly, the problem of updating routing tables of nodes and several alternatives to solve it, are presented and compared. Two kind of solutions to solve this second problem are proposed and tested. Conclusions are presented.

Analyzing Telephone Network Data

As our reliance on computer networks grows, it becomes increasingly important that we understand the behavior of the traffic that they carry. Because of the speeds and sizes involved, working with traffic collected from a computer network usually means working with large datasets. This article describes our experience with traffic collected from the common channel signaling (CCS) network. I will briefly describe the data and how they are collected and discuss similarities with and differences from other large datasets. Next, I will describe our analysis tools and outline the reasons that they have been found useful. Finally, I will discuss the challenges facing us as we strive for a better understanding of more data from faster networks. Although my emphasis in this article is on the CCS network, it has been my experience that both the problems and the solutions generalize to data from other networks.

Performability analysis of common-channel signaling networks, based on signaling system 7

Within integrated services digital networks (ISDN), all inter-change signaling messages for ISDN and intelligent network (IN) call controls are carried through a common channel signaling network (CCSN) as a backbone signaling network. Since CCSN usually have very strict reliability requirements as well as good performance objectives, performance and reliability of CCSN need to be jointly analyzed. This paper evaluates the mean end-to-end delay of a single-mated pair (SMP) CCSN for various call-arrival rates in a normal state and several failure states, as a performance index. As a performability index, this paper also analyzes the mean time to unreliable operation (MTUO) of a given network for various call-arrival rates at each signaling end point (SEP) and the failure rate of each signaling transfer point (STP). These results can be used in the design of common-channel signaling networks. This performability evaluation can be further studied for varying the failure rates of SEP and linksets, and the various threshold values of the unreliable operation.

Intelligent recognition of speech signals using caller demographics

In a switching system for connecting a call between a calling station and a called station, a system and method of voice recognition using a concentrated or distributed multiplicity of voice recognition and other resources with a facility for selecting an initial resource on the calling station going off-hook by accessing a demographic database using common channel signaling and selecting a prompt to be delivered to the caller from a multiplicity of preselected prompts and reacting to a response by the caller with further addressing of database information to continue to select from said multiplicity of resources the most appropriate resource or resources in reaction to caller utterances. According to another feature the selection of resources is aided by optical means at the calling station delivering information regarding characteristics of the caller including lip movement to permit lip reading.

Use of SS7 in D-AMPS-based PCS: orthodoxy vs. heterodoxy

D-AMPS, the digital version of the Advanced Mobile Phone System (AMPS), is among the key technologies for providing personal communications services (PCS). The bulk of signaling in D-AMPS-based PCS, as, in most modern telecommunication systems, is based on Signaling System No. 7 (SS7). SS7 is a general-purpose common channel signaling (CCS) system specified by the International Telecommunication Union Telecommunications Standardization Sector (ITU-T) and adapted to North American needs by the American National Standard Institute (ANSI). Besides the orthodox use for signaling, SS7 is used in D-AMPS-based PCS for operation, administration, maintenance, and provisioning (OAM&P) of the D-AMPS-based PCS network and for the short message service (SMS). This article reviews the use of SS7 in D-AMPS-based PCS. It motivates the need for a gradual return to orthodoxy where this use is confined to signaling. It also proposes alternatives to the current heterodox use. The alternatives the authors suggest are all rooted in orthodoxy.

Design and performance evaluation of intelligent multimedia services

Telecommunications networks are evolving globally to keep pace with rapid technological, regulatory and market changes. This is particularly evident in the introduction of intelligent network (IN) capabilities by network providers around the world. These IN capabilities will augment the network “intelligence” via the common channel signaling network and distributed service control points allowing users to gain access to advanced communications services. In this paper, we present the results of our research in the area of intelligent multimedia services. One of the main results has been the design of novel multimedia services operating over different network platforms. One of the new services being designed is an intelligent multimedia gateway, providing interconnectivity between the public service telephone network and the Internet. The design of this service has proved useful in gaining insight into the way novel intelligent multimedia services across network platforms will benefit from the use of IN technology. A performance evaluation of the service has also proved valuable to identify the major system and traffic parameters to consider when designing and deploying IN multimedia services across multiple networks.

Impact of the location area structure on the performance of signaling channels in wireless cellular networks

The authors consider connection-oriented wireless cellular networks such as IS-54, IS-95, GSM, and wireless ATM networks. These are connection-oriented digital networks which employ separate radio channels for the transmission of signaling information. A forward signaling channel is a common signaling channel assigned to carry the multiplexed stream of paging and channel-allocation packets from a base station to mobile stations. For wireless ATM networks, paging and virtual-circuit (VC) allocation packets are multiplexed across the forward signaling channels as part of the VC setup phase. A reverse signaling channel, which employs a contention-oriented medium access algorithm, is used by mobile stations to send channel-request and location-update packets. A location area is a region which includes a specified set of adjacent cells; it is used to track the location of mobile stations. Mobile units must reregister as they cross the boundary of a location area. The channel setup and paging response times are critical performance factors in the design of the signaling subsystem. A location area structure must be suitably selected to ensure that acceptable levels of such performance functions are achieved. A network which employs small location-areas will experience a high rate of location updates, while larger location areas lead to higher traffic intensities of paging messages. The authors overview a method for calculating the performance behavior of signaling messages. Subsequently the impact of the location area structure on the performance of the signaling system is investigated.

Delay analysis for forward signaling channels in wireless cellular network

We consider connection-oriented wireless cellular networks. Such second generation systems are circuit-switched digital networks which employ dedicated radio channels for the transmission of signaling information. A forward signaling channel is a common signaling channel assigned to carry the multiplexed stream of paging and channel-allocation packets from a base station to the mobile stations. Similarly, for ATM wireless networks, paging and virtual-circuit-allocation packets are multiplexed across the forward signaling channels as part of the virtual-circuit set-up phase. The delay levels experienced by paging and channel-allocation packets are critical factors in determining the efficient utilization of the limited radio channel capacity. A multiplexing scheme operating in a "slotted mode" can lead to reduced power consumption at the handsets, but may in turn induce an increase in packet delays. Focusing on forward signaling channels, we present schemes for multiplexing paging and channel-allocation packets across these channels, based on channelization plans, access priority assignments and paging group arrangements. For such multiplexing schemes, we develop analytical methods for the calculation of the delay characteristics exhibited by paging and channel-allocation packets. The resulting models and formulas provide for the design and analysis of forward signaling channels for wireless network systems.

A comparison of CCS tandem overload controls

In this paper we analyse issues associated with overloads in tandem switching systems in Common Channel Signalling (CCS) networks. In particular, we examine the need for, and effectiveness of, Automatic Congestion Control (ACC), a CCS mechanism which allows a congested switching system to inform adjacent CCS nodes of its level of overload, and subsequently controls the rate at which traffic is sent to the congested node. We demonstrate the critical need for end-offices and tandem switching systems to implement some form of ACC if network performance is to be maintained during congestion, especially in tandem exchanges. In addition, we find that the presently defined ACC should be expanded to allow more levels of congestion to be reported to adjacent nodes, so that a more effective, finer grained control is produced.

Signaling System Number 7

In a public switched telephone network (PSTN), the control information is exchanged among the network elements by signaling. The early telephone system used circuit associated signaling or inband signaling where the same transmission channel was shared by both signaling and user information (voice or data). Another signaling method is common channel signaling (CCS). Unlike the circuit associated signaling, CCS uses a separate out-of-band signaling network to carry signaling messages. CCS consists of supervisory functions, addressing, and providing call information. A CCS channel conveys messages to initiate and terminate calls, check on the status of some part of the network, and control the amount of traffic allowed. Signaling System No. 7 (SS7) is a CCS system developed to satisfy the telephone operating companies' requirements for an improvement to the earlier inband signaling systems. The advantages of CCS are listed.

The standards aspects of SS7 network management

Signaling System No7 (SS7) is an internationally standardized general purpose Common Channel Signaling (CCS) system. It is a key component of modern telecommunications networks. Its malfunctioning can cause major problems, as demonstrated in recent history by the spectacular breakdowns induced in public networks by its nonperformance. This paper gives an overview of SS7 management, as represented in the standards. It reviews successively the built-in management mechanisms, the Open Systems Interconnection (OSI) system management-based functions, and the emerging Telecommunications Network Management (TMN)-based approach. It shows that the TMN approach, although still in its cradle, is the most promising.

Cost of state saving & rollback

Approaches to state saving and rollback for a shared memory, optimistically synchronized, simulation executive are presented. An analysis of copy state saving and incremental state saving is made and these two schemes are compared. Two benchmark programs are then described, one a simple, all overhead, model and one a performance model of a regional Canadian public telephone network. The latter is a large SS7 common channel signalling model that represents a very challenging, practical, test application for parallel simulation. Experimental results are presented which show the necessity and sufficiency of incremental state saving for this application.

Traffic aspect of personal telecommunications in intelligent networks

Abstract This paper evaluates the traffic load for Intelligent Networks nodes and Common Channel Signaling networks (CCS), and it clarifies the impact of traffic on these resources. The main results are that: (i) CCS load is sensitive to the calling rate of personal telecommunications but largely insensitive to the proportion of radio users, the radius of the location registration zone, the distance between calling and called parties, and the size of NSPs. (ii) Large NSPs are cost-effective. Large STPs are also cost-effective except when the number of subscribers is small and the circuit cost proportional to length is more important than the node cost. (iii) The transfer delay in the CCS and in the transport network is the most important factor determining maximum end-to-end delay.

Consideration on common channel signaling evolution for global intelligent networking

With the evolution of digital networks and intelligent network (IN) capabilities, the role of common channel signaling has become more and more important. In respect to IN, common channel signaling would play a significant role not only inside one network but also over multiple networks. International credit card validation and internetworking for digital mobile services represented by GSM (Global System for Mobile Communications) are examples which utilize internetwork signaling capabilities in the framework of the initial-phase IN. Enhanced service providers (ESPs) may access the public network through the common channel signaling interface to make use of the IN capabilities, as is being discussed in terms of ONA (open network architecture) or ONP (open network provision). This paper first identifies various scenarios where internetwork signaling interactions would take place in the framework of IN in the forthcoming era. It then identifies various requirements to cope with these scenarios. It finally discusses the directions for evolution of common channel signaling toward global intelligent networking.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Deployment issues of CCS links on self-healing rings

Fiber-based self-healing rings (SHRs) are being deployed for trunking purposes for voice/data/video services because of their high reliability and survivability. To reduce deployment and maintenance costs of provisioning different facilities for these services and common channel signaling (CCS) networks, network planners have begun to deploy CCS network signaling links on SHRs. This paper examines some issues of deploying A/B/C/D link sets on SHRs. >

Error monitoring issues for common channel signaling

Motivated by field data which showed a large number of link changeovers and incidences of link oscillations between in-service and out-of-service states in common channel signalling (CCS) networks, a number of analyses of the link error monitoring procedures in the SS7 protocol were performed by the authors. This paper summarizes the results obtained thus far and include the following: (a) results of an exact analysis of the performance of the error monitoring procedures under both random and bursty errors; (b) a demonstration that there exists a range of error rates within which the error monitoring procedures of SS7 may induce frequent changeovers and changebacks; (c) an analysis of the performance of the SS7 level-2 transmission protocol to determine the tolerable error rates within which the delay requirements can be met; (d) a demonstration that the tolerable error rate depends strongly on various link and traffic characteristics, thereby implying that a single set of error monitor parameters will not work well in all situations; and (e) some recommendations on a customizable/adaptable scheme of error monitoring with a discussion on their implementability. These issues may be particularly relevant in the presence of anticipated increases in SS7 traffic due to widespread deployment of advanced intelligent network (AIN) and personal communications service (PCS) as well as for developing procedures for high-speed SS7 links currently under consideration by standards bodies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>