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Adaptive Simultaneous Multipath Transmission Schemes

Thesis Info

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External Link

Author

Khan, Samiullah

Program

PhD

Institute

Capital University of Science & Technology

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2017

Thesis Completion Status

Completed

Subject

Computer Science

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/8978/1/PhD%20Thesis%20%20%20%20%20Samiullah%20Khan%20PhD%20CS.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727693994

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The increase in the availability of multimode devices for ubiquitous network ac- cess and the need for larger bandwidth create thrust for utilization of simultaneous network connections. Unfortunately, the standard transport layer protocols like the transmission control protocol (TCP) and user datagram protocol (UDP) have architectural constraints due to which an Internet application can use only one interface at a time. The stream control transmission protocol (SCTP) provides support for concurrent multipath transfer (SCTP-CMT). Aggregated performance is analyzed with a number of experiments to measure the aggregated throughput of SCTP-CMT by using a very popular network simulator, NS-2. It is observed that the aggregated throughput is about 20% of the available aggregated band- width. The signi cant reduction in the aggregated throughput demands a careful scrutinization of its reasons. After carefully analyzing and carrying out some further experiments, it is di- agnosed that non-di erentiation of missing packets into intra and inter-path, usage of traditional congestion window management for these missing packets and using static fast retransmit threshold which is independent of available receiver bu er space, are the main reasons for the aggregated throughput degradation. Simulta- neous multipath transmission (SMT) schemes are proposed to handle the above mentioned issues with the intention to increase aggregated throughput by avoid- ing Rbuf blocking problem and e cient utilization of available Rbuf space. SMT- modi ed fast retransmit (SMT-MFR) and SMT-adaptive modi ed fast retransmit (SMT-AMFR) schemes are formulated for SCTP. To analyze the SMT-MFR in realistic network environments, a number of simulation scenarios are carried out. The initial results revealed that SMT-MFR has overcome Rbuf blocking with im- provement in aggregated throughput ranging from 164% to 72.4% (from normal to worst scenario respectively). SMT- MFR is composed of two sender side modules, i.e., inter-path missing packet di erentiation (IMPD) and multihomed congestion control (MCC). The IMPD module di erentiates the missing packets according to its cause of missing such as, packet missing due to network congestion or due to multiple path e ects. The MCC mechanism triggers the fast retransmit event with respect to the cause of the missing packet. The SMT-MFR has successfully over- come the Rbuf blocking problem, abnormal congestion window (cwnd) reduction and has improved the aggregated throughput.
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فرقت

فرقت

دل رو رو وقت گزار گیا
غم یار دا سانوں مار گیا

جدوں ماہی دے کول وسدے سی
دکھ ویکھ اسانوں نسدے سی
لوکی روندے تے اسیں ہسدے سی
کوئی دشمن دا چل وار گیا

دل یار نوں ڈھونڈن چلیا اے
کر وعدہ یار نہ ولیا اے
میرے دل وچ بھانبھڑ بلیا اے
تیر شوق دا ہو ہن پار گیا

دل یار بناء ہون رہندا نئیں
اے درد ہجر دے سہندا نئیں
دکھ درد کسے نوں اے کہندا نئیں
سکھ چین تے نال قرار گیا

عشق دے روگوں رب بچائے
یار بنا ہن چین نہ آئے
شوق سجن دا ودھدا جائے
کیوں سوہنا یار وسار گیا

قادری سائیںؔ عشق بازار نہ جاویں
جاویں تاں سچا عشق کماویں
ہک دن درشن یار دا پاویں
سوہنا ملے تاں دکھ ہزار گیا

اردو اور ہندی کا لسانی اشتراک و افتراق

اردو اور ہندی کا لسانی اشتراک و افتراق Initially was only language used to express human ideas. In every age, along with customs and traditions, language also went through stages of evaluation. That is why language of each region is unique. This uniqueness of languages is of its identity. Like human beings, languages also have their own families, and different languages grow as sub- branches of language family. They flourish and sometimes thrive and come to life through process of evolution. When some languages die out. Urdu and Hindi also belong to large languages families. They have a deep relationship. And speaking of same relationship, some tinkers do not separate them from each other. When it sometimes thinkers, there is difference between in the two. At a glance, we will mention the linguistic similarities and difference between Urdu and Hindi. Where are places and where there is difference between them, but all of them are mentioned here.

Molecular Epidemiology and Genetic Characterization of Measles Virus in Pakistan

Measles is highly infectious and fatal viral disease still responsible for more than 150,000 annual mortalities among children in the developing countries. In Pakistan, measles is endemic for years and comprehensive data about the disease burden and the viral genotypes is not available. The objectives of this study were to investigate the molecular epidemiology and genetic diversity of measles virus causing infections in Pakistani population. A total of 15,311 samples including 15,081 serum samples, 32 oral and 198 throat swabs were collected from suspected cases during 1st January 2013 to December 2015 reported across all provinces of Pakistan. The highest disease burden was noted in 2013 due to wide-spread outbreak in the country represented by 10,890 samples. The Sindh province was severely affected with 45% of total reported cases followed by Punjab and Khyber Pakhtunkhwa (KP) with 38.15% and 7.23% cases respectively. The outbreak was contained in Sindh reflected by a significant decline in the number of cases (n=1,572) notified during 2014 and 2015 except Karachi where cases continued to appear over three years. In Punjab six (Bahawalpur, Gujranwala, Lahore, Okara, Rawalpindi and Sialkot) and in Baluchistan four districts (Lasbella, Naseerabad, Quetta and Zhob) remained infected throughout the study period. In contrast, Peshwar was the most heavily infected district in Khyber Pakhtunkhwa province with sporadic cases notified from other districts. In 2013, most of samples were received during January and February compared to 2014 and 2015 where a slight increase was reported during April to June compared to the first quarter of the year. The coverage of immunization remained suboptimal indicating a single vaccine dose received by 51% children whereas only 21.9% children received two recommended doses of vaccine. The male patients remained dominant compared to females, with male to female ratio of 1.32:1, 1.13:1 and 1.16:1 during 2013, 2014 and 2015 respectively. The laboratory testing revealed that the overall IgM positivity rate remained 64% and IgM antibodies were detected in 52%, 9.3% and 2.5% patients reported during 20132015, respectively. Out of total 15,081 samples screened for IgM antibodies, 36% male and 28% females were found positive. The rate of positivity declined with increasing age and the children below 60 months of age represented the most infected age group. A total of 230 samples, including 198 throat and 32 oral swabs, were processed for detection and genetic characterization of measles virus. Thirty two (16.16%) throat swabs that were negative for measles virus RNA on real-time PCR were cultured on Vero/SLAM cells, out of which 22 (68.75%) samples yielded typical cytopathic effect of measles virus i.e. syncytia formation within 4-6 days of inoculation. For phylogenetic analysis and genetic characterization, 208 samples (166 throat, 20 oral swabs and 22 culture isolates) were processed. The complete H-gene of 63 isolates recovered from 50 throat swabs and 22 culture isolates and partial fragment of N-gene in 171 samples including 132 throat swabs, 17 oral swabs and 22 culture isolates was successfully amplified. Sequence analysis of H-gene revealed that the PAK sequences shared 99% - 99.46% nucleotide and 99.4% - 99.1% amino acid homology with the WHO reference strains, whereas the nucleotide and amino acid homology within the study strains was found as 99.8% and 99.1% respectively. A total of 21 amino acid substitutions were found in all PAK measles virus strains identified in this study. Out of these, five substitutions were found in antigenic sites at amino acid position 178, 307, 309, 400, and the fifth one was found at amino acid position 397. Overall, the mutation rate for synonymous and non-synonymous mutations remained 0.4% and 0.1% respectively. The partial sequencing of N-gene performed on 171 samples revealed that 168 viruses belong to genotype-B3 and 3 were classified as genotype-D4. The B3 strains showed an overall heterogeneity of >1.8% at nucleotide level and 2.3% - 3.5% nucleotide divergence from WHO reference strains. On the basis of phylogenetic analysis, all B3 viruses were divided in to 2 genetic clades. Clade-1 contained seven viruses isolated during 2014-15 in Baluchistan and had 0.9% nucleotide divergence from the members of clade 2. All of the viruses isolated from other provinces during 2013-2015 grouped into clade-2 which was further subdivided into two groups. Group-1 was further subcategorized into four lineages. The nucleotide divergence between lineage 1, 11, 111, and IV was 0.7% - 0.3% whereas viruses belong to group 2 clustered with New South Wales and Stockholm strains. This is the first report on the genetic characterization and diversity of measles virus genotypes prevailing in Pakistan.The data submitted in this thesis will not only be helpful to monitor the possible changing endemic measles strains but also to map the transmission pathways to elucidate the extent of outbreak potential in the less endemic regions in future. Furthermore, it will also help to advocate implementing a robust surveillance program for measles in Pakistan including large-scale sero-survey to determine the anti-measles immunity profile in the most vulnerable population of children less than five years of age.