Performance Comparison of Dynamic Guard Channel Assignment with Buffered Prioritized Scheme for Mobile WiMAX Network

Abstract—Priority is usually given to handover traffic in mobile communication but doing so has the tendency of increasing call blocking probability. It was said previously that non-prioritized call traffic channel assignment scheme reduces call blocking probability more than other basic channel assignment schemes at high handover traffic intensities. A comparison of channel assignment schemes by analysis and MATLAB simulation in this research has shown that dynamic guard channel assignment scheme based on channel utilization minimizes call blocking probability better than non-prioritized, prioritized guard channel and prioritized guard channel with queue/buffer. The wireless technology used was Mobile WiMAX with mobile assisted handover (MAHO) and the queueing policy employed was M/M/C/Q with FCFS service discipline

Improving Prioritized Handover Performance for Mobile WiMAX by Dynamic Guard Channel Allocation and RSS Quality Factor

In cellular communication, guard channel has been used to provide priority to ongoing call traffic crossing cell boundaries in handover process but the major concern is that most guard channel allocation scheme are fixed channels. System congestion problems arising from traffic pattern in the real world is another major concern relating to fixed allocation of guard channels let alone the huge traffic that will emanate from user mobility in the envisaged converged traffic of 4G networks. Hence, dynamic guard channel (DGC) allocation based on traffic intensity or channel utilization of each traffic type was used in this research and it reduced the new call blocking probability better than the fixed prioritized guard channel (PGC) and non-prioritized channel allocation scheme. Its performance in terms of call dropping probability reduction is comparable with the PGC and slightly better off at poor signal condition. It was revealed that DGC averaged QoS better than the existing channel assignment schemes. An investigation into the RSS quality factor (QF) proposed also, showed that at high quality RSS the blocking and dropping probability of the traffic were reduced for the Mobile WiMAX wireless technology network with mobile assisted handover

A Comparative Simulation Study of IP, MPLS, MPLS-TE for Latency and Packet Loss Reduction over a WAN

The need for improved network performance towards providing reliable services in the face of growing demand on enterprise network and internet service across all sectors of the economy has become very paramount. Latency and packet loss as quality of service (QoS) metrics are issues of concern since different multimedia applications, voice and data packets have to be delivered to end systems over long distances. This study investigated the technology behind the delivery of the packets by comparing the performance of each of IP, MPLS and MPLS-TE on the same congested WAN design. The results showed that MPLS-TE had the least latency and barely any packet los

Effect of Increasing Buffer Size on Prioritized Guard Channels with Queue during Call Traffic Congestion

Prioritized guard channel (PGC) assignment with queue was designed to reduce call dropping probability associated with a base station congested with handover call traffic. The Markov chain was used in the analysis of the PGC scheme and queuing discipline was FIFO for a PGC+MAHO scheme. Simulation was carried out using MATLAB. The results showed that increasing buffer size reduces call dropping probability which becomes discontinuous at some value of traffic arrival rate for each buffer size. It was found out that some queuing parameters such as queue product form becomes undefined at an arrival rate for a large buffer size. This limits the extent to which buffer size can be increased. System computational speed was also a contributory facto

Performance Evaluation of Dynamic Guard Channels Assignment with Queue and Prioritized Schemes

It has been said that dynamic guard channel (DGC) assignment scheme based on traffic intensities averages QoS and performs better than the prioritized guard channel assignment scheme with queue (QPGC) during traffic congestion. This work has extended the investigation to DGC with queue (QDGC) and carried out its comparison with other call traffic channel assignment schemes. Mathematical analysis of the models was done using Markov chain and simulation was carried out in MATLAB. When traffic arrival rates were symmetric, the QPGC had the lower call blocking probability than the QDGC but became the same when the system was congested. However, the performance of the two queuing schemes was the same when handover call traffic was more than new calls traffic

A Decision Support System for Information Technology Policy Formulation

The implementation of an effective ICT policy requires the development of material and intellectual resources to support good decision making by humans.   In this paper, we examined and analysed Information Technology (IT) policy development process with a view to developing automated system supporting such process.  The data used for this work were obtained through purposeful interview of five professionals and experts who are familiar with IT policy formulation in Nigerian environment.  Some of the experts had earlier participated in policy design and formulation process at national level.     The Hierarchical Input Process Output (HIPO) model was used to analyse various input (contributions of professionals and experts) and output (agreed resolution of the professionals and experts) of the system.  The information obtained from the experts was represented using rule base techniques.  The overall system was designed using the Unified Modelling Language (UML) and implemented using the Visual Prolog version 7.0.  The metrics used for evaluating the system includes: processing time, decision process efficiency and cost effectiveness.   We compared the result of our system with that of the traditional manual system in use.  Our result showed that the DSS for policy formulation process enhances the decision output significantly when compared to the manual process where no DSS is used.  Moreover, the quality of policy produced by our DSS system is more consistent when compared with the manual process.

RADIOACTIVITY CONCENTRATION AND DOSE ASSESSMENT OF SOIL SAMPLES IN CEMENT FACTORY AND ENVIRONS IN OGUN STATE, NIGERIA

The main natural radioactive materials that contribute externally and internally to man and his environs are radionuclides emanating from gamma series of 238U, 232Th, as well as 40K isotope, alpha and beta sources. Also, human activities such as mining and milling of uranium and phosphate, tobacco smoking, oil exploration, air transportation, coal-fired power station, and so on can trigger The technologically Enhanced Naturally Occurring Radioactive Materials (TENORMs). It is imperative to monitor the terrestrial background radiation of radionuclides emanating from these sources in order maintain a safe environment for humans. This study measured the activity concentration of 238U, 40K and 232Th in soil samples from cement factory and environs using the NaI(TI) detector, in three zones in Ogun State, Nigeria. The activity concentrations obtained for the three zones are in the order 238U < 232Th < 40K respectively. The radiological parameters estimated from the activity measured were all within the recommended permissive limit except for the annual gonadal doses from the cement factory and its environs, which are higher than the global standard by the factors of 1.03 and 1.07 respectively. This study therefore concludes that people living and working in these areas might be exposed to high radiation burden as a result of cumulative effect of the emission from the factory

Theory, practice and policy: An inquiry into the uptake of HCI practices in the software industry of a developing country

With almost four decades of existence as a community, human–computer interaction (HCI) practice has yet to diffuse into a large range of software industries globally. A review of existing literature suggests that the diffusion of HCI practices in software organizations lacks theoretical guidance. Although many studies have tried to facilitate HCI uptake by the software industry, there are scarce studies that consider HCI practices as innovations that software organizations could or should adopt. Furthermore, there appears to be a lack of structure in the facilitation of HCI methodological development within the specialized emerging regions field such as Sub-Saharan Africa. In order to address this gap, an exploratory investigation regarding the state of uptake of HCI practices in Nigeria is conducted. The aim of this article is to improve our understanding regarding the state of HCI uptake in developing countries and the challenges prevailing. The findings show that HCI practice still remains within its infancy stage in most software companies. Universities are also lacking the required knowledge transfer of HCI to the students, and in effect themselves contributing to the lack of HCI skills in industry. Furthermore, government policies are in need of refinement and end-users’ involvement in software development is not prioritized