Wyniki wyszukiwania - BazTech

1

Requirements of 4G-Based Mobile Broadband on Future Transport Networks

Fricke M., Heckwolf A., Herber R., Nitsch R., Schwarze S., Voß S.

Journal of Telecommunications and Information Technology

|

2012

|

nr 2

21-28

EN

Long term evolution technologies provide new standards in mobile communications regarding available bandwidth. It is expected that users of one radio cell will share more than 100 Mbit/s in future. To take advantage of the full feature set of next generation mobile networks, transport network design has to face new requirements, caused by the architectural changes of LTE technologies. Especially the newly defined X2 interface impacts on the transport network requirements. X2 enables direct communication between evolved base stations (eNBs) and thus, enforces local solutions. At the same time a tendency of locating network elements at fewer, central sites to reduce operational expenditure can be observed, in particular concerning the transport layer. This leads to the question of how the direct X2 connection of eNBs on the logical layer can be accommodated with a general centralization of transport networks. Our considerations show that for LTE, a centralized transport network is able to realize the local meshing between eNBs. However, for LTE Advanced, the standards currently discussed by the 3GPP initiative could lead to enhanced requirements on the X2 interface latency. Consequently, the implications for the network architecture have to be analyzed in more detail.

2

Developing a Ring-Based Optical Network Structure with Glass-Through Nodes

Caserta M., Schwarze S., Voß S.

Journal of Telecommunications and Information Technology

|

2012

|

nr 2

13-20

EN

An important issue in designing optical transport networks (OTN) is security. The concept of 1+1 protection requires to connect each origin-destination(OD)-pair by at least two node-disjoint paths. In the case of a single edge or node failure, the connection of all OD-pairs is maintained under 1+1 protection. On a ring, 1+1 protection is given naturally. Moreover, on rings, the routing effort is typically decreasing. These observations motivate the investigation of ring structures for OTN. When developing a ring structure for telecommunication networks, several subtasks can be identified. Ringshave to be designed, OD-pairs have to be assigned to rings, communication among rings has to be defined, a proper flow routing has to be chosen, and rings have to be dimensioned regarding flow capacity. In this paper, we address the first two issues, namely generation of rings and assignment of OD-pairs to rings. Our approach allows to distinguish active and non-active (glass-through) nodes in OTN. Active nodes are equipped with active routing hardware that weakens the optical signal and has impact on feasible ring lengths. Non-active nodes do not influence the optical signal. Although a consideration of active/non-active nodes is important in ring design, only a few references address this issue. We propose an algorithm for generating random ring candidates. Moreover, we present a mathematical model for the assignment of OD-pairs to rings subject to a feasible choice of active nodes. We test our methods using a case of Deutsche Telekom.

3

Software tools for a multilayer network design

Höller H., Voß S.

Journal of Telecommunications and Information Technology

|

2005

|

nr 3

57-63

EN

Today's long haul and metro high-speed networks are mainly based on synchronous digital hierarchy (SDH) or its American equivalent synchronous optical network (SONET) and wavelength division multiplex (WDM). On the other hand, the large amount of traffic growth during the last years has been caused mainly by Internet protocol (IP) traffic. Traditionally, the IP-router based networks and the cross-connect based synchronous networks are often planned and operated separately. However, in line with new developments such as generalized multiprotocol label switching (GMPLS), network providers begin to realize that the convergence of these two worlds promises significant benefits. A set of software tools to support the network designer has been developed and used on various kinds of real world network planning problems arising in the SDH/WDM context. This includes, among others, 1+1 protection planning, static restoration and dual homing issues. These tools are extended with additional features to handle aspects of the IP/SDH interplay in a GMPLS environment. The two main components are an AMPL based integer model (solved via CPLEX) and a heuristic implemented in C++.