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RISS 인기검색어
- 검색키워드
- 저자 : Usman Qamar (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Muhammad Usman,Shafi Mohammad Khosa,Moinuddin Moinuddin,Hassan Osman Mehmood,Khansa Qamar 대한혈액학회 2015 Blood Research Vol.50 No.1
BackgroundThe present study is designed to evaluate the reliability and cost effectiveness of celluloseacetate Hb electrophoresis and high performance liquid chromatography (HPLC) in thedetermination of HbA2 levels. MethodsThe test population comprised 160 individuals divided into four groups: normal individuals, β-thalassemia trait (BTT) patients, iron deficiency anemia (IDA) patients, andco-morbid patients (BTT with IDA). HbA2 levels determined using cellulose acetate Hbelectrophoresis and HPLC were compared. ResultsHbA2 levels were found to be diagnostic for classical BTT using either method. In co-morbidcases, both techniques failed to diagnose all cases of BTT. The sensitivity, specificity,and Youden’s index for detection of the co-morbid condition was 69% and 66% for HPLCand cellulose acetate Hb electrophoresis, respectively. ConclusionThis study revealed that semi-automated cellulose acetate Hb electrophoresis is moresuitable for use in β-thalassemia prevention programs in low-income countries likePakistan. This technique is easily available, simple and cost effective.
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Protocol-Aware Radio Frequency Jamming in Wi-Fi and Commercial Wireless Networks
Abid Hussain,Nazar A. Saqib,Usman Qamar,Muhammad Zia,Hassan Mahmood 한국통신학회 2014 Journal of communications and networks Vol.16 No.4
Radio frequency (RF) jamming is a denial of serviceattack targeted at wireless networks. In resource-hungry scenarioswith constant traffic demand, jamming can create connectivityproblems and seriously affect communication. Therefore, the vulnerabilitiesof wireless networks must be studied. In this study, weinvestigate a particular type of RF jamming that exploits the semanticsof physical (PHY) andmedium access control (MAC) layerprotocols. This can be extended to any wireless communication networkwhose protocol characteristics and operating frequencies areknown to the attacker. We propose two efficient jamming techniques:A low-data-rate random jamming and a shot-noise basedprotocol-aware RF jamming. Both techniques use shot-noise pulsesto disrupt ongoing transmission ensuring they are energy efficient,and they significantly reduce the detection probability of the jammer. Further, we derived the tight upper bound on the durationand the number of shot-noise pulses for Wi-Fi, GSM, and WiMaxnetworks. The proposed model takes consider the channel accessmechanism employed at the MAC layer, data transmission rate,PHY/MAC layer modulation and channel coding schemes. Moreover,we analyze the effect of different packet sizes on the proposedjamming methodologies. The proposed jamming attack modelshave been experimentally evaluated for 802.11b networks on an actualtestbed environment by transmitting data packets of varyingsizes. The achieved results clearly demonstrate a considerable increasein the overall jamming efficiency of the proposed protocolawarejammer in terms of packet delivery ratio, energy expenditureand detection probabilities over contemporary jammingmethodsprovided in the literature.
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Protocol-Aware Radio Frequency Jamming inWi-Fi and Commercial Wireless Networks
Hussain, Abid,Saqib, Nazar Abbas,Qamar, Usman,Zia, Muhammad,Mahmood, Hassan The Korea Institute of Information and Commucation 2014 Journal of communications and networks Vol.16 No.4
Radio frequency (RF) jamming is a denial of service attack targeted at wireless networks. In resource-hungry scenarios with constant traffic demand, jamming can create connectivity problems and seriously affect communication. Therefore, the vulnerabilities of wireless networks must be studied. In this study, we investigate a particular type of RF jamming that exploits the semantics of physical (PHY) and medium access control (MAC) layer protocols. This can be extended to any wireless communication network whose protocol characteristics and operating frequencies are known to the attacker. We propose two efficient jamming techniques: A low-data-rate random jamming and a shot-noise based protocol-aware RF jamming. Both techniques use shot-noise pulses to disrupt ongoing transmission ensuring they are energy efficient, and they significantly reduce the detection probability of the jammer. Further, we derived the tight upper bound on the duration and the number of shot-noise pulses for Wi-Fi, GSM, and WiMax networks. The proposed model takes consider the channel access mechanism employed at the MAC layer, data transmission rate, PHY/MAC layer modulation and channel coding schemes. Moreover, we analyze the effect of different packet sizes on the proposed jamming methodologies. The proposed jamming attack models have been experimentally evaluated for 802.11b networks on an actual testbed environment by transmitting data packets of varying sizes. The achieved results clearly demonstrate a considerable increase in the overall jamming efficiency of the proposed protocol-aware jammer in terms of packet delivery ratio, energy expenditure and detection probabilities over contemporary jamming methods provided in the literature.
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