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The role of open ims testbeds in complex service delivery platforms 开放式ims测试平台在复杂服务交付平台中的作用
AFRICON 2007 Pub Date : 2007-12-12 DOI: 10.1109/AFRCON.2007.4401492
F.C. de Gouveia, T. Magedanz, R. Good, N. Ventura
{"title":"The role of open ims testbeds in complex service delivery platforms","authors":"F.C. de Gouveia, T. Magedanz, R. Good, N. Ventura","doi":"10.1109/AFRCON.2007.4401492","DOIUrl":"https://doi.org/10.1109/AFRCON.2007.4401492","url":null,"abstract":"Network convergence and the multimedia service provisioning platforms within next generation networks (NGN) are subjects of huge complexity and the required architecture is extremely expensive to implement. Network operators will find it difficult to commit the necessary capital expenditure unless the NGN architecture has been thoroughly tried and tested. To ensure early adoption of this convergence platform, low cost testbeds are needed to bring together various parties to research and develop the necessary architectures. The IP multimedia subsystem (IMS), defined by the 3rd Generation Partnership Project (3GPP) represents today the global service delivery platform (SDP) standard for providing multimedia applications in NGN. Knowing that the full potential of the IMS can only be revealed by the early non-discriminant provisioning of IMS know-how and related technologies to the different market players the Fraunhofer Institute FOKUS launched the \"Open Source IMS Core\" in November 2006, which is based on extensions to the SIP express router (SER) that cope with the SIP extensions specified by 3GPP. This paper describes the Open IMS Playground and the activities in progress and cooperation works between FOKUS and the University of Cape Town for establishing joint works on open issues within IMS research and development.","PeriodicalId":112129,"journal":{"name":"AFRICON 2007","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122497953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
Power sector in Tanzania: Performance, trends and reforms 坦桑尼亚电力部门:绩效、趋势和改革
AFRICON 2007 Pub Date : 2007-12-12 DOI: 10.1109/AFRCON.2007.4401511
H.A. Mwasumbi, R. Tzoneva
{"title":"Power sector in Tanzania: Performance, trends and reforms","authors":"H.A. Mwasumbi, R. Tzoneva","doi":"10.1109/AFRCON.2007.4401511","DOIUrl":"https://doi.org/10.1109/AFRCON.2007.4401511","url":null,"abstract":"The United Republic of Tanzania is currently facing energy problems that have seriously affected its socio-economic development and environment. To solve these problems, the country is striving to exploit its renewable energy potential, among other efforts. This paper highlights the prevailing energy situation in Tanzania and provides a short review of potential energy resources. It then discusses current institutional efforts and capabilities in development, and commercialization of renewable energy technologies. The paper also identifies some barriers to promotion of renewable energy technologies as well as actions taken by the government of Tanzania to promote renewable energy technologies.","PeriodicalId":112129,"journal":{"name":"AFRICON 2007","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127063612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
A post-modulation scheme to correct insertion/deletion/substitution errors using the Dc2-balanced codes 一种使用dc2平衡码纠正插入/删除/替换错误的后调制方案
AFRICON 2007 Pub Date : 2007-12-12 DOI: 10.1109/AFRCON.2007.4401549
Ling Cheng, H. C. Ferreira
{"title":"A post-modulation scheme to correct insertion/deletion/substitution errors using the Dc2-balanced codes","authors":"Ling Cheng, H. C. Ferreira","doi":"10.1109/AFRCON.2007.4401549","DOIUrl":"https://doi.org/10.1109/AFRCON.2007.4401549","url":null,"abstract":"The runlength-limited Levenshtein code property of a dc2-balanced code allows the code words to be protected from multiple types of errors, including insertion, deletion and substitution errors. In this paper, a post-modulation scheme, in conjunction with the interleaving techniques, can correct burst substitution errors and random insertion or deletion errors, by using the dc2-balanced codes.","PeriodicalId":112129,"journal":{"name":"AFRICON 2007","volume":"259 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124034831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Investigating performance of neural networks in authentication using keystroke dynamics 利用按键动态研究神经网络在身份验证中的性能
AFRICON 2007 Pub Date : 2007-12-12 DOI: 10.1109/AFRCON.2007.4401575
N. Pavaday, K. Soyjaudah
{"title":"Investigating performance of neural networks in authentication using keystroke dynamics","authors":"N. Pavaday, K. Soyjaudah","doi":"10.1109/AFRCON.2007.4401575","DOIUrl":"https://doi.org/10.1109/AFRCON.2007.4401575","url":null,"abstract":"Biometrics technology has emerged as the desired solution for a range of secure applications where a person's identity must be determined. Biometrics is currently controlling network and physical access in numerous high risk areas, including airport customs and immigration desks, financial malls among others. This paper compares applications of neural networks to the field of hardened password mechanism in a typical workplace environment.","PeriodicalId":112129,"journal":{"name":"AFRICON 2007","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126530125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 22
A Multi-dimensional super-orthogonal modulation alternative to M-QAM WCDMA for next generation wireless applications 用于下一代无线应用的M-QAM WCDMA的多维超正交调制替代方案
AFRICON 2007 Pub Date : 2007-12-12 DOI: 10.1109/AFRCON.2007.4401467
L. Linde, J. D. Vlok
{"title":"A Multi-dimensional super-orthogonal modulation alternative to M-QAM WCDMA for next generation wireless applications","authors":"L. Linde, J. D. Vlok","doi":"10.1109/AFRCON.2007.4401467","DOIUrl":"https://doi.org/10.1109/AFRCON.2007.4401467","url":null,"abstract":"This paper presents bit-error-rate (BER) performance results of an upwards-expandable Multidimensional super-orthogonal modulation alternative to M-ary quadrature amplitude modulation wideband code- division-multiple-access (M-QAM WCDMA), suitable for application in next generation WLAN and wireless cellular systems. The unique combination of a M=4-dimensional WCDMA modem configuration and super-orthogonal families of quasi-complementary root-of-unity filtered (RUF) near constant-envelope generalized-chirp-like complex spreading sequences (SO-CE-GCL-CSS), renders a spectrally and power efficient output signal with a data throughput rate equivalent to that of M=16-ary quadrature amplitude modulated (16-QAM) WCDMA, but with the BER performance equivalent to that of BPSK/QPSK in both additive white Gaussian noise (AWGN) and fading multipath channel scenarios, given identical spreading factors and bandwidths.","PeriodicalId":112129,"journal":{"name":"AFRICON 2007","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127867419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Performance of super-orthogonal space-time trellis code in a multipath environment 超正交空时格码在多径环境下的性能
AFRICON 2007 Pub Date : 2007-12-12 DOI: 10.1109/AFRCON.2007.4401542
O. Sokoya, B. Maharaj
{"title":"Performance of super-orthogonal space-time trellis code in a multipath environment","authors":"O. Sokoya, B. Maharaj","doi":"10.1109/AFRCON.2007.4401542","DOIUrl":"https://doi.org/10.1109/AFRCON.2007.4401542","url":null,"abstract":"This paper investigates the performance of super-orthogonal space-time trellis code (SOSTTC) designed primarily for non-frequency selective (i.e. flat) fading channel but now applied to a frequency selective fading channel. A new decoding trellis is proposed for the SOSTTC in frequency selective fading environment. It was apparent that the number of state of the decoding trellis of the SOSTTC in a frequency selective channel is a function of the number of divergent paths per state, the multipath ray and the original number of states of the SOSTTC. Simulation result (i.e. frame error rate) shows that the SOSTTC in such environment (i.e. frequency selective) could not take full advantage of the multipath environment to increase coding advantage (i.e. shift of error rate curve) due to increase in parallel path of the decoding trellis. However the diversity order (i.e. slope of the error rate curve) performance is equivalent to that obtained in flat fading channel.","PeriodicalId":112129,"journal":{"name":"AFRICON 2007","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127414153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 7
Comparison of principal component analysis and linear discriminant analysis for face recognition (March 2007) 主成分分析与线性判别分析在人脸识别中的比较(2007年3月)
AFRICON 2007 Pub Date : 2007-12-12 DOI: 10.1109/AFRCON.2007.4401538
P. E. Robinson, W. Clarke
{"title":"Comparison of principal component analysis and linear discriminant analysis for face recognition (March 2007)","authors":"P. E. Robinson, W. Clarke","doi":"10.1109/AFRCON.2007.4401538","DOIUrl":"https://doi.org/10.1109/AFRCON.2007.4401538","url":null,"abstract":"In this paper two face recognition techniques, principal component analysis (PCA) and linear discriminant analysis (LDA), are considered and implemented using a nearest neighbor classifier. The performance of the two techniques is then compared in facial recognition and detection tasks. The comparisons are done using a facial recognition database captured for the project that contains images captured over a range of poses, lighting conditions and occlusions.","PeriodicalId":112129,"journal":{"name":"AFRICON 2007","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132765003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
A dual bandwidth estimation method for wireless mobile ad hoc networks 一种无线移动自组网双带宽估计方法
AFRICON 2007 Pub Date : 2007-12-12 DOI: 10.1109/AFRCON.2007.4401603
B. Nyambo, J. Mugumba, G. Janssens
{"title":"A dual bandwidth estimation method for wireless mobile ad hoc networks","authors":"B. Nyambo, J. Mugumba, G. Janssens","doi":"10.1109/AFRCON.2007.4401603","DOIUrl":"https://doi.org/10.1109/AFRCON.2007.4401603","url":null,"abstract":"In recent years we have seen a great interest in wireless mobile ad hoc networks (MANETs) and multimedia technologies. However, MANETs face a lot of technical changes which make it almost impossible to merge the two technologies. Therefore, providing quality of service in mobile ad hoc networks is a very important research issue. To have proper traffic management in MANETS, we should be able to effectively determine the available resources at our disposal. Therefore a quality of service framework for MANETs should be equipped with reliable bandwidth estimation method. In this paper we propose a bandwidth estimation technique called dual bandwidth estimation method. It uses two common techniques to estimate the available bandwidth. These are the listening method and the hello messages technique. The weaknesses of each of the two methods are solved by the other, thereby making the method so robust and reliable.","PeriodicalId":112129,"journal":{"name":"AFRICON 2007","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122235408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 10
Excluding some weak keys in the mceliece cryptosystem 排除mcelelece密码系统中的一些弱密钥
AFRICON 2007 Pub Date : 2007-12-12 DOI: 10.1109/AFRCON.2007.4401626
J. A. Ryan
{"title":"Excluding some weak keys in the mceliece cryptosystem","authors":"J. A. Ryan","doi":"10.1109/AFRCON.2007.4401626","DOIUrl":"https://doi.org/10.1109/AFRCON.2007.4401626","url":null,"abstract":"A Goppa code which has a non trivial automorphism group is a weak key for the McEliece cryptosystem. A quasicyclic code clearly has a non trivial automorphism group. Hence any quasicyclic code is a weak key. Some new classes of quasicyclic irreducible Goppa codes have recently been established and it is conjectured that, in the binary case, these new classes contain all binary quasicyclic ireducible Goppa codes. Using simple numerical conditions on the parameters of a Goppa code, we show that if we adopt the parameters as suggested by McEliece himself for choosing Goppa codes in the implementation of his cryptosystem, then some such codes are weak keys. We suggest other parameters which we claim would reduce the probability of choosing a weak key.","PeriodicalId":112129,"journal":{"name":"AFRICON 2007","volume":"08 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116609079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
Design of a power factor correction ac-dc converter 功率因数校正ac-dc变换器的设计
AFRICON 2007 Pub Date : 2007-12-12 DOI: 10.1109/AFRCON.2007.4401519
P. N. Ekemezie
{"title":"Design of a power factor correction ac-dc converter","authors":"P. N. Ekemezie","doi":"10.1109/AFRCON.2007.4401519","DOIUrl":"https://doi.org/10.1109/AFRCON.2007.4401519","url":null,"abstract":"The need to keep EMI emissions by electronic power supplies below the limit specified by international standards have dictated that any new power supply design must include active power factor correction at the front end. The modern trend in power supply designs is towards digital control. This paper reports an effort to design a power factor correction AC-DC converter that is geared towards digital control. The power factor correction circuit employs zero voltage transition arrangement to minimize switching losses. Calculations that led to the selection of the circuit components are presented. Interface requirements between the power converter stage and the digital control processor are tackled. Average current mode control method is employed in the controller. The complete design has been tested by means of Powersim power electronics simulation software. The resulting input voltage and current waveforms show that the design is successful.","PeriodicalId":112129,"journal":{"name":"AFRICON 2007","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131394393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 37
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