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An Opportunistic Channel Access Scheme for Interweave Cognitive Radio Systems
Senthuran, Sivasothy,Anpalagan, Alagan,Kong, Hyung Yun,Karmokar, Ashok,Das, Olivia The Korea Institute of Information and Commucation 2014 Journal of communications and networks Vol.16 No.1
We propose a novel opportunistic access scheme for cognitive radios in an interweave cognitive system, that considers the channel gain as well as the predicted idle channel probability (primary user occupancy: Busy/idle). In contrast to previous work where a cognitive user vacates a channel only when that channel becomes busy, the proposed scheme requires the cognitive user to switch to the channel with the next highest idle probability if the current channel's gain is below a certain threshold. We derive the threshold values that maximize the long term throughput for various primary user transition probabilities and cognitive user's relative movement.
Nitin Sharma,Alagan Anpalagan 한국통신학회 2014 Journal of communications and networks Vol.16 No.5
Orthogonal frequency divisionmultiple access (OFDMA)is a promising technique, which can provide high downlink capacityfor the future wireless systems. The total capacity of OFDMAcan be maximized by adaptively assigning subchannels to the userwith the best gain for that subchannel, with power subsequentlydistributed by water-filling. In this paper, we propose the use ofcomposite differential evolution (CoDE) algorithm to allocate thesubchannels. The CoDE algorithm is population-based where a setof potential solutions evolves to approach a near-optimal solutionfor the problem under study. CoDE uses three trial vector generationstrategies and three control parameter settings. It randomlycombines them to generate trial vectors. In CoDE, three trial vectorsare generated for each target vector unlike other differentialevolution (DE) techniques where only a single trial vector is generated. Then the best one enters the next generation if it is betterthan its target vector. It is shown that the proposed method obtainshigher sum capacities as compared to that obtained by previousworks, with comparable computational complexity.
An Opportunistic Channel Access Scheme for Interweave Cognitive Radio Systems
Sivasothy Senthuran,Alagan Anpalagan,공형윤,Ashok Karmokar,Olivia Das 한국통신학회 2014 Journal of communications and networks Vol.16 No.1
We propose a novel opportunistic access scheme for cognitiveradios in an interweave cognitive system, that considers thechannel gain as well as the predicted idle channel probability (primaryuser occupancy: Busy/idle). In contrast to previous workwhere a cognitive user vacates a channel only when that channelbecomes busy, the proposed scheme requires the cognitive user toswitch to the channel with the next highest idle probability if thecurrent channel’s gain is below a certain threshold. We derive thethreshold values that maximize the long term throughput for variousprimary user transition probabilities and cognitive user’s relativemovement.
Multi-Hop Cooperative Transmission Using Fountain Codes over Rayleigh Fading Channels
Tran Trung Duy,Alagan Anpalagan,Hyung-Yun Kong 한국통신학회 2012 Journal of communications and networks Vol.14 No.3
In this paper, we study multi-hop cooperative transmission protocols using fountain codes. The proposed protocols can reduce the end-to-end delay and number of stages compared to those in conventional multi-hop transmission. VariousMonte-Carlo simulations are presented to evaluate and compare performance of the protocols over Rayeigh fading channels.
Multi-Hop Cooperative Transmission Using Fountain Codes over Rayleigh Fading Channels
Duy, Tran Trung,Anpalagan, Alagan,Kong, Hyung-Yun The Korea Institute of Information and Commucation 2012 Journal of communications and networks Vol.14 No.3
In this paper, we study multi-hop cooperative transmission protocols using fountain codes. The proposed protocols can reduce the end-to-end delay and number of stages compared to those in conventional multi-hop transmission. VariousMonte-Carlo simulations are presented to evaluate and compare performance of the protocols over Rayeigh fading channels.
( Yuli Zhang ),( Yuhua Xu ),( Qihui Wu ),( Alagan Anpalagan ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.8
We study the problem of optimal opportunistic spectrum access with unknown and heterogeneous channel dynamics in cognitive radio networks. There is neither statistic information about the licensed channels nor information exchange among secondary users in the respective systems. We formulate the problem of maximizing network throughput. To achieve the desired optimization, we propose a win-shift lose-stay algorithm based only on rewards. The key point of the algorithm is to make secondary users tend to shift to another channel after receiving rewards from the current channel. The optimality and the convergence of the proposed algorithm are proved. The simulation results show that for both heterogeneous and homogenous systems the proposed win-shift lose-stay algorithm has better performance in terms of throughput and fairness than an existing algorithm.
Analysis of Joint Parallelism in Wireless and Cloud Domains on Mobile Edge Computing over 5G Systems
Glaucio H.S. Carvalho,Isaac Woungang,Alagan Anpalagan,Muhammad Jaseemuddin 한국통신학회 2018 Journal of communications and networks Vol.20 No.6
The realization of mobile edge computing (MEC) overemerging fifth (5G) generation of wireless systems arises as adriving-force in the future of cloud computing. In order to copewith the volume, variety, and velocity of the IoT traffic while makingoptimal use of the network infrastructure, a synergistic exploitationof MEC and 5G should be put forward to support advancedresource management applications. In this paper, we proposethe use of joint parallelism between wireless and cloud domainsto efficiently respond to mobile data deluge. We review theliterature, discuss the enabling network architecture, potentials,challenges, and open issues related to the realization of such levelof parallelism.We present and evaluate two design examples – parallelcomputation offload method (PCOM) and parallel transmissionand storage method (PTSM)—which outline the benefits ofparallelism for computation-hungry and storage-hungry applications,respectively. Results of our optimization formulation showthat PCOM and PTSM are able to make an efficient use of the networkresources and support a heavy instantaneous workload bymeans of the parallelism.
Exploiting Multichannel Diversity in Spectrum Sharing Systems Using Optimal Stopping Rule
Yuhua Xu,Qihui Wu,Jinlong Wang,Alagan Anpalagan,Yitao Xu 한국전자통신연구원 2012 ETRI Journal Vol.34 No.2
This letter studies the problem of exploiting multichannel diversity in a spectrum sharing system, where the secondary user (SU) sequentially explores channel state information on the licensed channels with time consumption. To maximize the expected achievable throughput for the SU, we formulate this problem as an optimal stopping problem, whose objective is to choose the right channel to stop exploration based on the observed signal-to-noise ratio sequence. Moreover, we propose a myopic but optimal rule, called one-stage look-ahead rule, to solve the stopping problem.
Biologically Inspired Cooperative Spectrum Sensing Scheme for Maritime Cognitive Radio Networks
Ejaz, Waleed,Hasan, Najam ul,Shah, Ghalib A.,Kim, Hyung Seok,Anpalagan, Alagan IEEE 2018 IEEE systems journal Vol.12 No.3
<P>Spectrum sensing is imperative to the success of maritime cognitive radio networks (MCRNs). Spectrum sensing in MCRNs is challenging because of the sea surface movement, the channel interference, and the unstable link quality. Recent research reveals that existing spectrum sensing schemes work well for lower sea states; however, they have failed to perform effectively at higher sea states. There are two disadvantages of performing spectrum sensing at higher sea states: 1) low probability of detection may also cause interference with primary system and 2) energy wastage. In this paper, a biologically inspired cooperative spectrum sensing scheme (BIC3S) is proposed to deal with the reliability and energy consumption challenges associated with the sea environment. It is based on the task allocation model of an insect colony. The proposed BIC3S chooses participating secondary users for cooperative spectrum sensing according to their given sea state. Further, it enables the secondary users to decide whether or not to perform spectrum sensing based on their sea state. Simulation results are presented to demonstrate the performance of the proposed scheme in terms of energy consumption, detection performance, and throughput. It is shown that the proposed BIC3S consumes less energy and, at the same time, achieves higher detection probability and fewer probability of false alarms compared to the existing schemes. Moreover, BIC3S provides better adaptation capabilities for the sea environment.</P>