Change search
Link to record
Permanent link

Direct link
BETA
Phan, Hoc
Publications (10 of 27) Show all publications
Phan, H., Zepernick, H.-J., Duong, Q. T., Tran, H. & Chu, T. M. (2015). Cognitive amplify-and-forward relay networks with beamforming under primary user power constraint over Nakagami-m fading channels. Wireless Communications & Mobile Computing, 15(1), 56-70
Open this publication in new window or tab >>Cognitive amplify-and-forward relay networks with beamforming under primary user power constraint over Nakagami-m fading channels
Show others...
2015 (English)In: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, Vol. 15, no 1, p. 56-70Article in journal (Refereed) Published
Abstract [en]

In this paper, we analyze the performance of cognitive amplify-and-forward (AF) relay networks with beamforming under the peak interference power constraint of the primary user (PU). We focus on the scenario that beamforming is applied at the multi-antenna secondary transmitter and receiver. Also, the secondary relay network operates in channel state information assisted AF mode, and the signals undergo independent Nakagami-m fading. In particular, closed-form expressions for the outage probability and symbol error rate (SER) of the considered network over Nakagami-m fading are presented. More importantly, asymptotic closed-form expressions for the outage probability and SER are derived. These tractable closed-form expressions for the network performance readily enable us to evaluate and examine the impact of network parameters on the system performance. Specifically, the impact of the number of antennas, the fading severity parameters, the channel mean powers, and the peak interference power is addressed. The asymptotic analysis manifests that the peak interference power constraint imposed on the secondary relay network has no effect on the diversity gain. However, the coding gain is affected by the fading parameters of the links from the primary receiver to the secondary relay network.

Place, publisher, year, edition, pages
Wiley, 2015
Keywords
Cognitive radio, Beamforming, Amplify-and-forward relaying, Outage probability, Symbol error rate, Nakagami-m fading
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-6429 (URN)10.1002/wcm.2317 (DOI)000345984800005 ()oai:bth.se:forskinfo8C92EC981AF0EA69C1257AC5006ABBA3 (Local ID)oai:bth.se:forskinfo8C92EC981AF0EA69C1257AC5006ABBA3 (Archive number)oai:bth.se:forskinfo8C92EC981AF0EA69C1257AC5006ABBA3 (OAI)
Available from: 2015-01-20 Created: 2012-11-29 Last updated: 2017-12-04Bibliographically approved
Phan, H., Chu, T. M., Zepernick, H.-J. & Arlos, P. (2015). Packet Loss Priority of Cognitive Radio Networks with Partial Buffer Sharing. In: 2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC): . Paper presented at IEEE International Conference on Communications (ICC), JUN 08-12, 2015, London, ENGLAND (pp. 7646-7652). IEEE Computer Society
Open this publication in new window or tab >>Packet Loss Priority of Cognitive Radio Networks with Partial Buffer Sharing
2015 (English)In: 2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), IEEE Computer Society, 2015, p. 7646-7652Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we consider the application of partial buffer sharing to an M/G/1/K queueing system for cognitive radio networks (CRNs). It is assumed that the CRN is subject to Nakagami-m. fading. Secondary users are allowed to utilize the licensed radio spectrum of the primary users through underlay spectrum access. A finite buffer at the secondary transmitter is partitioned into two regions, the first region serves both classes of packets while the second region serves only packets of the highest priority class. Therefore, the examined CRN can be modeled as an M/G/1/K queueing system using partial buffer sharing. An embedded Markov chain is applied to analyze the queueing behavior of the system. Utilizing the balance equations and the normalized equation, the equilibrium state distribution of the system at an arbitrary time instant can be found. This outcome is utilized to investigate the impact of queue length, arrival rates, and fading parameters on queueing performance measures such as blocking probability, throughput, mean packet transmission time, channel utilization, mean number of packets in the system, and mean packet waiting time for each class of packets.

Place, publisher, year, edition, pages
IEEE Computer Society, 2015
Series
IEEE International Conference on Communications, ISSN 1550-3607
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-11854 (URN)000371708107145 ()978-1-4673-6432-4 (ISBN)
Conference
IEEE International Conference on Communications (ICC), JUN 08-12, 2015, London, ENGLAND
Available from: 2016-05-02 Created: 2016-05-02 Last updated: 2017-03-16Bibliographically approved
Tran, H., Zepernick, H.-J., Phan, H. & Sibomana, L. (2015). Performance Analysis of a Cognitive Radio Network with a Buffered Relay. IEEE Transactions on Vehicular Technology, 64(2), 566-579
Open this publication in new window or tab >>Performance Analysis of a Cognitive Radio Network with a Buffered Relay
2015 (English)In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, no 2, p. 566-579Article in journal (Refereed) Published
Abstract [en]

In this paper, we analyze the packet transmission time in a cognitive cooperative radio network (CCRN) where a secondary transmitter (SU-Tx) sends packets to a secondary receiver (SU-Rx) through the help of a secondary relay (SR). In particular, we assume that the SU-Tx and SR are subject to the joint constraint of the timeout probability of the primary user (PU) and the peak transmit powers of the secondary users. On this basis, we investigate the impact of the transmit power of the PUs and channel mean powers on the packet transmission time of the CCRN. Utilizing the concept of timeout, adaptive transmit power allocation policies for the SU-Tx and SR are considered. More importantly, analytical expressions for the endto- end throughput, end-to-end packet transmission time, and stable condition for the SR operation are obtained. Our results indicate that the second hop of the considered CCRN is not a bottleneck if the channel mean powers of the interference links of the networks are small and the SR peak transmit power is set to a high value.

Place, publisher, year, edition, pages
IEEE, 2015
Keywords
Cognitive Radio Network, Relaying, Performance
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-6394 (URN)10.1109/TVT.2014.2323338 (DOI)000349715000013 ()oai:bth.se:forskinfo19F1B49E3EE73AA9C1257CD80024F8EA (Local ID)oai:bth.se:forskinfo19F1B49E3EE73AA9C1257CD80024F8EA (Archive number)oai:bth.se:forskinfo19F1B49E3EE73AA9C1257CD80024F8EA (OAI)
Available from: 2015-03-20 Created: 2014-05-14 Last updated: 2017-05-22Bibliographically approved
Chu, T. M., Phan, H. & Zepernick, H.-J. (2015). Performance analysis of MIMO cognitive amplify-and-forward relay networks with orthogonal space–time block codes. Wireless Communications & Mobile Computing, 15, 1659-1679
Open this publication in new window or tab >>Performance analysis of MIMO cognitive amplify-and-forward relay networks with orthogonal space–time block codes
2015 (English)In: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, Vol. 15, p. 1659-1679Article in journal (Refereed) Published
Abstract [en]

In this paper, we study the performance of multiple-input multiple-output cognitive amplify-and-forward relay networks using orthogonal space–time block coding over independent Nakagami-m fading. It is assumed that both the direct transmission and the relaying transmission from the secondary transmitter to the secondary receiver are applicable. In order to process the received signals from these links, selection combining is adopted at the secondary receiver. To evaluate the system performance, an expression for the outage probability valid for an arbitrary number of transceiver antennas is presented. We also derive a tight approximation for the symbol error rate to quantify the error probability. In addition, the asymptotic performance in the high signal-to-noise ratio regime is investigated to render insights into the diversity behavior of the considered networks. To reveal the effect of network parameters on the system performance in terms of outage probability and symbol error rate, selected numerical results are presented. In particular, these results show that the performance of the system is enhanced when increasing the number of antennas at the transceivers of the secondary network. However, increasing the number of antennas at the primary receiver leads to a degradation in the secondary system performance.

Place, publisher, year, edition, pages
John Wiley & Sons, 2015
Keywords
Multiple-input multiple-output (MIMO), amplify-and-forward (AF), relay networks, orthogonal space–time block codes (OSTBCs), cognitive radio networks, outage probability, symbol error rate (SER)
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-6740 (URN)10.1002/wcm.2449 (DOI)000358447300006 ()oai:bth.se:forskinfoEC0C39AB4AC009F7C1257C4200532BB0 (Local ID)oai:bth.se:forskinfoEC0C39AB4AC009F7C1257C4200532BB0 (Archive number)oai:bth.se:forskinfoEC0C39AB4AC009F7C1257C4200532BB0 (OAI)
Available from: 2014-04-12 Created: 2013-12-15 Last updated: 2017-12-04Bibliographically approved
Chu, T. M., Phan, H. & Zepernick, H.-J. (2014). Adaptive Modulation and Coding with Queue Awareness in Cognitive Incremental Decode-and-Forward Relay Networks. In: : . Paper presented at IEEE International Conference on Communications, Sydney, Australia (pp. 1453-1459). IEEE
Open this publication in new window or tab >>Adaptive Modulation and Coding with Queue Awareness in Cognitive Incremental Decode-and-Forward Relay Networks
2014 (English)Conference paper, Published paper (Refereed)
Abstract [en]

This paper studies the performance of adaptive modulation and coding in a cognitive incremental decode-and-forward relaying network where a secondary source can directly communicate with a secondary destination or via an intermediate relay. To maximize transmission efficiency, a policy which flexibly switches between the relaying and direct transmission is proposed. In particular, the transmission, which gives higher average transmission efficiency, will be selected for the communication. Specifically, the direct transmission will be chosen if its instantaneous signal-to-noise ratio (SNR) is higher than one half of that of the relaying transmission. In this case, the appropriate modulation and coding scheme (MCS) of the direct transmission is selected only based on its instantaneous SNR. In the relaying transmission, since the MCS of the transmissions from the source to the relay and from the relay to the destination are implemented independently to each other, buffering of packets at the relay is necessary. To avoid buffer overflow at the relay, the MCS for the relaying transmission is selected by considering both the queue state and the respective instantaneous SNR. Finally, a finite-state Markov chain is modeled to analyze key performance indicators such as outage probability and average transmission efficiency of the cognitive relay network.

Place, publisher, year, edition, pages
IEEE, 2014
Series
IEEE International Conference on Communications, ISSN 1550-3607
Keywords
Adaptive Coding, Adaptive Modulation, Queue Awarness, Markov Chain, Relay Networks, Cognitive Radio
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-6565 (URN)10.1109/ICC.2014.6883526 (DOI)000366666801099 ()978-1-4799-2003-7 (ISBN)
Conference
IEEE International Conference on Communications, Sydney, Australia
Available from: 2014-11-14 Created: 2014-11-14 Last updated: 2017-03-08Bibliographically approved
Chu, T. M., Phan, H. & Zepernick, H.-J. (2014). Cognitive AF Relay Assisting both Primary and Secondary Transmission with Beamforming. In: : . Paper presented at IEEE International Conference on Communications and Electronics (ICCE), Danang, Vietnam. IEEE
Open this publication in new window or tab >>Cognitive AF Relay Assisting both Primary and Secondary Transmission with Beamforming
2014 (English)Conference paper, Published paper (Refereed)
Abstract [en]

This paper investigates the system performance of a cognitive relay network with underlay spectrum sharing wherein the relay is exploited to assist both the primary and secondary transmitters in forwarding their signals to the respective destinations. To exploit spatial diversity, beamforming transmission is implemented at the transceivers of the primary and secondary networks. Particularly, exact expressions for the outage probability and symbol error rate (SER) of the primary transmission and tight bounded expressions for the outage probability and SER of the secondary transmission are derived. Furthermore, an asymptotic analysis for the primary network, which is utilized to investigate the diversity and coding gain of the network, is developed. Finally, numerical results are presented to show the benefits of the proposed system.

Place, publisher, year, edition, pages
IEEE, 2014
Keywords
Cognitive AF Relaying, Primary Network, Secondary Network, PrimaryBeamforming
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-6535 (URN)10.1109/CCE.2014.6916692 (DOI)000366563200022 ()978-1-4799-5049-2 (ISBN)
Conference
IEEE International Conference on Communications and Electronics (ICCE), Danang, Vietnam
Available from: 2014-11-21 Created: 2014-11-20 Last updated: 2017-03-16Bibliographically approved
Chu, T. M., Phan, H. & Zepernick, H.-J. (2014). Delay Analysis for Cognitive Ad Hoc Networks Using Multi-channel Medium Access Control. IET Communications, 8(7), 1083-1093
Open this publication in new window or tab >>Delay Analysis for Cognitive Ad Hoc Networks Using Multi-channel Medium Access Control
2014 (English)In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 8, no 7, p. 1083-1093Article in journal (Refereed) Published
Abstract [en]

In this study, the authors analyse the average end-to-end packet delay for a cognitive ad hoc network where multiple secondary nodes randomly contend for accessing the licensed bands of primary users in non-slotted time mode. Before accessing the licensed bands, each node must perform spectrum sensing and collaboratively exchange the sensing results with other nodes of the corresponding communication as a means of improving the accuracy of spectrum sensing. Furthermore, the medium access control with collision avoidance mechanism based distributed coordination function specified by IEEE802.11 is applied to coordinate spectrum access for this cognitive ad hoc network. To evaluate the system performance, the authors model the considered network as an open G/G/1 queuing network and utilise the method of diffusion approximation to analyse the end-to-end packet delay. The authors’ analysis takes into account not only the number of secondary nodes, the arrival rate of primary users and the arrival rate of secondary users but also the effect of the number of licensed bands when assessing the average end-to-end packet delay of the networks.

Place, publisher, year, edition, pages
IET, 2014
Keywords
Delay Analysis, Cognitive Radio, Ad Hoc Networks, Medium Access Control
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-6674 (URN)10.1049/iet-com.2013.0908 (DOI)000335571300013 ()oai:bth.se:forskinfo848963A8F8A80944C1257CB000532BBE (Local ID)oai:bth.se:forskinfo848963A8F8A80944C1257CB000532BBE (Archive number)oai:bth.se:forskinfo848963A8F8A80944C1257CB000532BBE (OAI)
Available from: 2014-07-17 Created: 2014-04-04 Last updated: 2017-12-04Bibliographically approved
Chu, T. M., Phan, H. & Zepernick, H.-J. (2014). Hybrid Interweave-Underlay Spectrum Access for Cognitive Cooperative Radio Networks. IEEE Transactions on Communications, 62(7), 2183-2197
Open this publication in new window or tab >>Hybrid Interweave-Underlay Spectrum Access for Cognitive Cooperative Radio Networks
2014 (English)In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 62, no 7, p. 2183-2197Article in journal (Refereed) Published
Abstract [en]

In this paper, we study a hybrid interweave-underlay spectrum access system that integrates amplify-and-forward relaying. In hybrid spectrum access, the secondary users flexibly switch between interweave and underlay schemes based on the state of the primary users. A continuous-time Markov chain is proposed to model and analyze the spectrum access mechanism of this hybrid cognitive cooperative radio network (CCRN). Utilizing the proposed Markov model, steady-state probabilities of spectrum access for the hybrid CCRN are derived. Furthermore, we assess performance in terms of outage probability, symbol error rate (SER), and outage capacity of this CCRN for Nakagami-m fading with integer values of fading severity parameter m. Numerical results are provided showing the effect of network parameters on the secondary network performance such as the primary arrival rate, the distances from the secondary transmitters to the primary receiver, the interference power threshold of the primary receiver in underlay mode, and the average transmit signal-to-noise ratio of the secondary network in interweave mode. To show the performance improvement of the CCRN, comparisons for outage probability, SER, and capacity between the conventional underlay scheme and the hybrid scheme are presented. The numerical results show that the hybrid approach outperforms the conventional underlay spectrum access.

Place, publisher, year, edition, pages
IEEE, 2014
Keywords
Interweave Scheme, Underlay Scheme, Hybrid Spectrum Access, Cognitive Cooperative Radio Networks
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-6603 (URN)10.1109/TCOMM.2014.2325041 (DOI)000341571000004 ()oai:bth.se:forskinfo2AF27033F60A8702C1257CDD0032FBD6 (Local ID)oai:bth.se:forskinfo2AF27033F60A8702C1257CDD0032FBD6 (Archive number)oai:bth.se:forskinfo2AF27033F60A8702C1257CDD0032FBD6 (OAI)
Available from: 2014-10-10 Created: 2014-05-19 Last updated: 2017-12-04Bibliographically approved
Phan, H., Chu, T. M., Zepernick, H.-J. & Ngo, H. Q. (2014). Performance of Cognitive Radio Networks with Finite Buffer Using Multiple Vacations and Exhaustive Service. In: 2014 8TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ICSPCS): . Paper presented at 8th International Conference on Signal Processing and Communication Systems, (ICSPCS), gold coast, Australia. Gold Coast, Australia: IEEE
Open this publication in new window or tab >>Performance of Cognitive Radio Networks with Finite Buffer Using Multiple Vacations and Exhaustive Service
2014 (English)In: 2014 8TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ICSPCS), Gold Coast, Australia: IEEE , 2014Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we analyze the performance of a cognitive radio network where the secondary transmitter, besides its own transmission, occasionally relays the primary signal. It is assumed that the secondary transmitter employs the exhaustive service mode to transmit the secondary signal and multiple vacations to relay the primary signal. When assisting the primary transmitter, we assume that the secondary transmitter utilizes the decode-and-forward protocol to process the primary signal and forwards it to the primary receiver. Furthermore, the secondary transmitter has a finite buffer, the arriving packets of the secondary network are modeled as a Poisson process, and all channels are subject to Nakagami-m fading. Modeling the system as an M/G/1/K queueing system with exhaustive service and multiple vacations, using an embedded Markov chain approach to analyze the system, we obtain several key queueing performance indicators, i.e., the channel utilization, blocking probability, mean number of packets, and mean serving time of a packet in the system. The derived formulas are then utilized to evaluate the performance of the considered system.

Place, publisher, year, edition, pages
Gold Coast, Australia: IEEE, 2014
Keywords
Cognitive Radio Networks, Finite Buffer, Multiple Vacations, Exhaustive Service, Queueing Performance
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-6560 (URN)000380403200085 ()oai:bth.se:forskinfoA3B3019A428FEE26C1257D93004C7D32 (Local ID)978-1-4799-5255-7 (ISBN)oai:bth.se:forskinfoA3B3019A428FEE26C1257D93004C7D32 (Archive number)oai:bth.se:forskinfoA3B3019A428FEE26C1257D93004C7D32 (OAI)
Conference
8th International Conference on Signal Processing and Communication Systems, (ICSPCS), gold coast, Australia
Available from: 2014-11-18 Created: 2014-11-17 Last updated: 2018-01-16Bibliographically approved
Chu, T. M., Phan, H., Duong, Q. T., Elkashlan, M. & Zepernick, H.-J. (2013). Beamforming Transmission in Cognitive AF Relay Networks with Feedback Delay. In: : . Paper presented at International Conference on IEEE Computing, Management and Telecommunications (IEEE ComManTel). Ho Chi Minh City: IEEE
Open this publication in new window or tab >>Beamforming Transmission in Cognitive AF Relay Networks with Feedback Delay
Show others...
2013 (English)Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we investigate the effect of feedback delay on outage probability (OP) and symbol error rate (SER) of cognitive amplify-and-forward (AF) relay networks with beamforming transmission in Rayleigh fading environment. It is assumed that the secondary transmitter and the secondary receiver are equipped with multiple antennas, whereas the relay and the primary user comprise of a single antenna. Furthermore, in this system, the secondary users use the underlay scheme in which the secondary transmitter and the relay can coexist with the primary user as long as their interference caused to the primary receiver is below a predefined threshold. Through our analysis, numerical results are provided to show the level of degradation of cognitive AF relay systems in proportion to the degree of feedback delay. In addition, we also present the effect of the number of antennas at the secondary transceiver on the performance of the considered system.

Place, publisher, year, edition, pages
Ho Chi Minh City: IEEE, 2013
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-6961 (URN)000318220400022 ()oai:bth.se:forskinfo613B1F55EB77D772C1257B9400306393 (Local ID)978-1-4673-2088-7 (ISBN)oai:bth.se:forskinfo613B1F55EB77D772C1257B9400306393 (Archive number)oai:bth.se:forskinfo613B1F55EB77D772C1257B9400306393 (OAI)
Conference
International Conference on IEEE Computing, Management and Telecommunications (IEEE ComManTel)
Available from: 2013-06-24 Created: 2013-06-24 Last updated: 2017-03-16Bibliographically approved
Organisations

Search in DiVA

Show all publications