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- 저자 : Steven Freear (검색결과 3 건)
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Ho-Van, Khuong,Sofotasios, Paschalis C.,Freear, Steven The Korea Institute of Information and Commucation 2014 Journal of communications and networks Vol.16 No.1
This work investigates two important performance metrics of underlay cooperative cognitive radio (CR) networks: Interference cumulative distribution function of licensed users and outage probability of unlicensed users. These metrics are thoroughly analyzed in realistic operating conditions such as imperfect fading channel information and strict transmit power constraint, which satisfies interference power constraint and maximum transmit power constraint, over Nakagami-m fading channels. Novel closed-form expressions are derived and subsequently validated extensively through comparisons with respective results from computer simulations. The proposed expressions are rather long but straightforward to handle both analytically and numerically since they are expressed in terms of well known built-in functions. In addition, the offered results provide the following technical insights: i) Channel information imperfection degrades considerably the performance of both unlicensed network in terms of OP and licensed network in terms of interference levels; ii) underlay cooperative CR networks experience the outage saturation phenomenon; iii) the probability that the interference power constraint is satisfied is relatively low and depends significantly on the corresponding fading severity conditions as well as the channel estimation quality; iv) there exists a critical performance trade-off between unlicensed and licensed networks.
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Khuong Ho Van,Paschalis C. Sofotasios,Steven Freear 한국통신학회 2014 Journal of communications and networks Vol.16 No.1
This work investigates two important performance metricsof underlay cooperative cognitive radio (CR) networks: Interferencecumulative distribution function of licensed users andoutage probability of unlicensed users. These metrics are thoroughlyanalyzed in realistic operating conditions such as imperfectfading channel information and strict transmit power constraint,which satisfies interference power constraint and maximum transmitpower constraint, over Nakagami−m fading channels. Novelclosed-form expressions are derived and subsequently validated extensivelythrough comparisons with respective results from computersimulations. The proposed expressions are rather long butstraightforward to handle both analytically and numerically sincethey are expressed in terms of well known built-in functions. Inaddition, the offered results provide the following technical insights:i) Channel information imperfection degrades considerablythe performance of both unlicensed network in terms of OP and licensednetwork in terms of interference levels; ii) underlay cooperativeCR networks experience the outage saturation phenomenon;iii) the probability that the interference power constraint is satis-fied is relatively low and depends significantly on the correspondingfading severity conditions as well as the channel estimation quality;iv) there exists a critical performance trade-off between unlicensedand licensed networks.
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Bit Error Rate of Underlay Decode-and-Forward Cognitive Networks with Best Relay Selection
Khuong Ho-Van,Paschalis C. Sofotasios,George C. Alexandropoulos,Steven Freear 한국통신학회 2015 Journal of communications and networks Vol.17 No.2
This paper provides an analytic performance evaluation of the bit error rate (BER) of underlay decode-and-forward cognitive networks with best relay selection over Rayleigh multipath fading channels. A generalized BER expression valid for arbitrary operational parameters is firstly presented in the form of a single integral, which is then employed for determining the diversity order and coding gain for different best relay selection scenarios. Furthermore, a novel and highly accurate closed-form approximate BER expression is derived for the specific case where relays are located relatively close to each other. The presented results are rather convenient to handle both analytically and numerically, while they are shown to be in good agreement with results from respective computer simulations. In addition, it is shown that as in the case of conventional relaying networks, the behaviour of underlay relaying cognitive networks with best relay selection depends significantly on the number of involved relays.
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