In upgrading wireless cellular networks for personal communication services (PCS), it is anticipated that the signaling load caused by mobility management and wireless call control functions will be significant using current techniques. We propose and analyze a new cluster-based architecture and define distributed servers and algorithms to effectively handle mobility management and call control functions for PCS. We assume an ATM network infrastructure. By separating the functions of mobile location, call control and connection control, several advantages can be gained over the current cellular call control and mobility management approach. These advantages include a reduction in signaling traffic load, improved call/connection setup delays, and more efficient usage of bandwidth. We carry out an analysis of our solution for PCS applications.

A distributed control strategy for wireless ATM networks

Summary IP-based networks grow rapidly and coexist with other universal basic telecommunication infrastructures, namely with the ISDN, mobile networks and ATM networks. Since all infrastructures are capable of carrying all applications and services, there is a growing need for interworking. To be able to transfer signaling traffic originating in the other networks via IP networks, a family of protocols is being defined based on SCTP, a new end-to-end transport protocol. This paper describes some features of SCTP in detail and highlights some advantages over TCP. In addition, a modification of SCTP is proposed and evaluated which significantly enhances the performance in long delay environments.

SCTP – A Multi-link End-to-end Protocol for IP-based Networks

An overview of Signaling System No.7 (SS7) is presented. The salient features of SS7's network services part (NSP) are described. Functionally, NSP corresponds to the first three layers of the Open System Interconnection (OSI) reference model. The signaling network structures that, in conjunction with the NSP, provide integrated services digital network (ISDN) nodes with a highly reliable and efficient means of exchanging signaling messages are discussed. The nodal capabilities of call control and remote process invocation and management, part of the SS7 user parts, are described. The very stringent performance requirements of signaling systems and their reflection on the critical nature of signaling functions and their real-time exigencies are discussed. The likely evolution of network signaling in the remaining years of the 20th century is discussed. >

An overview of Signaling System No.7

Simulation plays an important role in computer-aided modeling, analysis and design of communication networks and related systems. A number of approaches based on Queueing models, Petri nets and Fin...

A Block-Oriented Network Simulator (BONeS)™:

Internet telephony is viewed as an emerging technology not only for wireline networks, but also for third-generation wireless networks. Although IP end to end is considered the ultimate approach to future wireless voice services, there is still a long way to go before IP voice packets can be effectively transported over the air. Therefore, Internet telephony and today's circuit-switched wireless network will coexist for years to come, and it is essential to effectively perform interworking between these networks. This article proposes the Unified Mobility Manager (UMM) that achieves efficient interworking between traditional wireless networks and Internet telephony networks. The main characteristic of the UMM is that it combines UMTS HLR and SIP proxy functionality in one logical entity, which helps eliminate the performance degradation due to interworking between SIP and UMTS. This article identifies seven potential network architectures with and without the UMM and with varying degrees of IP penetration in the wireless core networks, and performs comparative analysis in terms of their call setup signaling latency. Our performance results show that for SIP originated calls, the architecture with the UMM can achieve better performance than existing UMTS networks without the UMM. Our results further show that when the backbone network is fully IP-enabled, dramatic performance gains can be accomplished with the UMM for PSTN originated calls as well as for SIP originated calls. The article also demonstrates that the UMM allows graceful migration from today's circuit-switched wireless networks to hybrid SIP/circuit-switched wireless networks, and toward the IMS architecture for all-IP UMTS networks in the future.

http://www.cse.psu.edu/~tfl12/paper/wcom.pdf

Unified Mobility Manager: enabling efficient SIP/UMTS mobile network control

The layered performance modeling approach is refined and extended to cover the latest CCITT Blue Book specifications. Specific submodels for the higher-level functional blocks, such as the message transfer part (MTP) level 3, the signaling connection control part (SCCP), the ISDN user part (ISDN-UP), and the transaction capabilities application part (TCAP), are given in a generic way, explicitly. With these submodels, generic models for signaling points and signaling transfer points are constructed. The major functional parts of the layered protocol architecture of SS7 are modeled in a generic way by extended queuing network elements such as full duplex flow controlled links, priority processors, multiple-chain multiple-class traffic streams, or elements for segmenting and reassembling of messages. The analysis of the whole network starts from a global traffic flow analysis, which takes all the different signaling message types, their paths through the network, and the load into account. The overall performance measures, such as end-to-end transfer times, are found from all the component delays. The analytical results have been validated by simulation, revealing a high degree of accuracy. >

G. Willmann

Papers

Performance modeling of Signaling System No.7