Determination of Optimum Number of Trunk Lines for Corporate Network Backbone in Nigeria

The problem of determining the optimum number of telecommunication trunk lines subscribers' common equipment) for a given average traffic intensity is contributory, among other things, to the problem encountered in providing cost effective and high quality telecommunication services to corporate network users. Therefore, an accurate means of determining the optimum number of trunk lines required to be leased from public network backbone is vital. It is usual, in the developed countries, to assume a reliable public network while determining the optimum number of trunk lines required to be leased. In most developing countries, this assumption will lead to errors in determining the number of trunk lines required to be leased. In this paper, therefore, a template is developed for corporate network providers in Nigeria for the determination of the precise number of required trunk lines based on the concept of equipment failure and restoration

Resource Allocation Methodology for Internet Heterogeneous Traffic

The mode of operation of internet can lead to congestion which, in turn, leads to degradation in the quality of service (QoS). Congestion can be seen as overflow in the input and/or output buffers of switches at a node. Research issue relating to internet services is determining the optimum network resources - in terms of transmission link bandwidth and buffer capacity in switches - that are required for heterogeneous internet traffic which guarantees a given QoS, even under high network loading conditions.This paper, therefore, presents a method for determining the optimum internet resources required for heterogeneous (data and voice only) traffic services to guarantee given QoS requirement

Point Coordination Function WLAN Traffic Loadings

The current proliferation of Internet and the advancements in its technology contributed significantly in the gradual shift from wired LANs to wireless LANs (WLANs). WLAN’s ability to provide high capacity links, mobility and low acquisition cost played considerable positive role in its popularity. The operation of WLAN in Nigeria is associated with excessive traffic loading that adversely influence its performance since bandwidth is usually very limited. Achievement of satisfactory performance standard under this condition requires thorough analysis of traffic loadings on WLAN. Therefore, in this work, WLAN performance analysis under traffic loadings is presented. Influence of traffic loadings on WLAN quality of service (QoS) parameters was analyzed using computer simulation modeling technique. It was shown that the operation of WLAN is highly influenced by the intensity of traffic that it supports. The relationships between the network quality of service (QoS) parameters and traffic loading for specified values of resources were determined. A useful control tool was derived from the relationships for the determination of the optimum traffic loadings in a point coordination function (PCF) WLAN

Effect of Data Traffic Patterns on QoS Parameters

In the design and management of data communication networks the appropriate choice of traffic model that would reflect the exact pattern of the users’ traffic has always been an issue of study. In the literatures different models have been presented. This work presents the comparison of several data traffic models (most popularly used in the literatures) on the basis of their influence on the quality of service (QoS) parameters. It is intended that this comparison would place at the disposal of researchers the data traffic models that would assist in making effective worse-case or best-case analysis of data communication systems. Object oriented computer simulation modeling technique provided the general platform necessary for such level of comparison. In this work MATLAB simulink simevent simulation environment was employed. The results present exponential distribution as the traffic model to be employed for worst-case analysis while Gamma distribution is for best-case communication systems analysis

Application of integrated modeling technique for data services resource allocation in atm based private wan

Computer simulation modelling has the advantage of flexibility and modelling accuracy. However, it has limitations in its ability to be used to simulate cell loss rate when deriving the optimum resources required for data services to guarantee specific Quality of Service (QoS) requirement. Cell loss rates are simulated with excessive and unacceptable computer simulation run times. This limitation was overcome in an earlier publication by the author using an integrated simulation technique. This paper, therefore, describes the application of the integrated simulation technique for deriving the optimum resources required for data services in an asynchronous transfer mode (ATM) based private wide area network (WAN) to guarantee specific QoS requirement. The simulation tool drastically cuts the simulation run-time and is much more accurate. The effectiveness of the technique with data services is demonstrated by the simulation of an ATM switching node and in comparison with traditional approach.Keywords: Asynchronous transfer mode node; integrated modelling; simulation; Cell los

A Comparative Study of Prioritized Handoff Schemes with Guard Channels in Wireless Cellular Networks

Mobility management has always been the main challenge in most mobile systems. It involves the management of network radio channel resource capacity for the purpose of achieving optimum quality of service (QoS) standard. In this era of wireless Personal Communication Networks such as Global System for Mobile Communication (GSM), Wireless Asynchronous Transfer Mode (WATM), Universal Mobile Telecommunication System (UMTS), there is a continuous increase in demand for network capacity. In order to accommodate the increased demand for network capacity (radio resource) over the wireless medium, cell sizes are reduced. As a result of such reduction in cell sizes, handoffs occur more frequently, and thereby result in increased volume of handoff related signaling. Therefore, a handoff scheme that can handle the increased signaling load while sustaining the standard QoS parameters is required.This work presents a comparative analysis of four popular developed handoff schemes. New call blocking probability, forced termination probability and throughput are the QoS parameters employed in comparing the four schemes. The four schemes are:RCS-GC,MRCS-GC, NCBS-GC, and APS-GC. NCBS-GChas the leased new call blocking probability while APS-GC has the worst. In terms of forced termination probability, MRCS-GC has the best result, whileRCS-GChas the worst scheme.MRCS-GC delivers the highest number of packets per second while APS-GC delivers the least. These performance metrics are computed by using the analytical expressions developed for these metrics in the considered models in a Microsoft Excel spreadsheet environment.http://dx.doi.org/10.4314/njt.v34i3.2

Generalized Processor Sharing (GPS) Techniques

In this era of service integration and proliferation of value-added services, ICT networks have traffic volume that tends to overwhelm network resources. Satisfaction of quality of services (QoS) is usually difficult especially with static network resources. A flexible and popular technique, Generalized Processor Sharing (GPS), provided an effective and efficient utilization of the available resources at the face of stringent and varied QoS requirements. This paper, therefore, presents the comparison of two GPS techniques – PGPS and CDGPS – based on performance with limited resources in an isolated node. The better performing PGPS technique was further investigated under varying QoS, resources and traffic load. PGPS resource utilization behaviors for given QoS parameters (delay, and reliability) were presented and applied in the realization of a network performance management system at the ETF centre of excellence in Communication Networking, University of Nigeria, Nsukka

COMPARATIVE ANALYSIS OF THE PERFORMANCE OF RESOURCE ALLOCATION ALGORITHMS IN LONG TERM EVOLUTION NETWORKS

The growth in the good number of real-time and non-real-time applications has sparked a renewed interest in exploring resource allocation schemes that can be efficient and fair to all the applications in overloaded scenarios. In this paper, the performance of six scheduling algorithms for Long Term Evolution (LTE) downlink networks were analyzed and compared. These algorithms are Proportional Fair (PF), Exponential/Proportional Fair (EXP/PF), Maximum Largest Weighted Delay First (MLWDF), Frame Level Scheduler (FLS), Exponential (EXP) rule and Logarithmic (LOG) rule.  The performances of these algorithms were evaluated using an open source simulator (LTE simulator) and compared based on network parameters which include: throughput, delay, Packet Loss Ratio (PLR), and fairness. This work aims at giving insight on the gains made on radio resource scheduling for LTE network and to x-ray the issues that require improvement in order to provide better performance to the users. The results of this work show that FLS algorithm outperforms other algorithms in terms of delay, PLR, throughput, and fairness for VoIP and video flow. It was also observed that for Best Effort (BE) flows, FLS outperforms other algorithms in terms of delay and PLR but performed least in terms of throughput and fairness. http://dx.doi.org/10.4314/njt.v36i1.2

REVIEW OF WIRELESS MIMO CHANNEL MODELS

The need to increase spectral efficiency has led to the design of multiple antenna systems for both transmit and receive sides otherwise known as MIMO. Channel modeling forms an integral part of this design. Therefore it is very important to investigate and understand existing MIMO channel models. This paper provides a detailed review of existing MIMO channel models, their characteristics, tradeoffs and challenges. As with most models in the scientific and technical fields, open issues in MIMO channel modeling have also been enumerated. http://dx.doi.org/10.4314/njt.v35i2.2

3066 consecutive Gamma Nails. 12 years experience at a single centre

<p>Abstract</p> <p>Background</p> <p>Fixation of trochanteric hip fractures using the Gamma Nail has been performed since 1988 and is today well established and wide-spread. However, a number of reports have raised serious concerns about the implant's complication rate. The main focus has been the increased risk of a subsequent femoral shaft fracture and some authors have argued against its use despite other obvious advantages, when this implant is employed.</p> <p>Through access to a uniquely large patient data base available, which is available for analysis of trochanteric fractures; we have been able to evaluate the performance of the Gamma Nail over a twelve year period.</p> <p>Methods</p> <p>3066 consecutive patients were treated for trochanteric fractures using Gamma Nails between 1990 and 2002 at the Centre de Traumatologie et de l'Orthopedie (CTO), Strasbourg, France. These patients were retrospectively analysed. Information on epidemiological data, intra- and postoperative complications and patients' outcome was retrieved from patient notes. All available radiographs were assessed by a single reviewer (AJB).</p> <p>Results</p> <p>The results showed a low complication rate with the use of the Gamma Nail. There were 137 (4.5%) intraoperative fracture-related complications. Moreover 189 (6.2%) complications were detected postoperatively and during follow-up. Cut-out of the lag screw from the femoral head was the most frequent mechanical complication (57 patients, 1.85%), whereas a postoperative femoral shaft fracture occurred in 19 patients (0.6%). Other complications, such as infection, delayed healing/non-union, avascular femoral head necrosis and distal locking problems occurred in 113 patients (3.7%).</p> <p>Conclusions</p> <p>The use of the Gamma Nail in trochanteric hip fractures is a safe method with a low complication rate. In particular, a low rate of femoral shaft fractures was reported. The low complication rate reported in this series can probably be explained by strict adherence to a proper surgical technique.</p