316 research outputs found
Secrecy performance of TAS/SC-based multi-hop harvest-to-transmit cognitive WSNs under joint constraint of interference and hardware imperfection
In this paper, we evaluate the secrecy performance of multi-hop cognitive wireless sensor networks (WSNs). In the secondary network, a source transmits its data to a destination via the multi-hop relaying model using the transmit antenna selection (TAS)/selection combining (SC) technique at each hop, in the presence of an eavesdropper who wants to receive the data illegally. The secondary transmitters, including the source and intermediate relays, have to harvest energy from radio-frequency signals of a power beacon for transmitting the source data. Moreover, their transmit power must be adjusted to satisfy the quality of service (QoS) of the primary network. Under the joint impact of hardware imperfection and interference constraint, expressions for the transmit power for the secondary transmitters are derived. We also derive exact and asymptotic expressions of secrecy outage probability (SOP) and probability of non-zero secrecy capacity (PNSC) for the proposed protocol over Rayleigh fading channel. The derivations are then verified by Monte Carlo simulations.Web of Science195art. no. 116
Secrecy performance enhancement for underlay cognitive radio networks employing cooperative multi-hop transmission with and without presence of hardware impairments
In this paper, we consider a cooperative multi-hop secured transmission protocol to underlay cognitive radio networks. In the proposed protocol, a secondary source attempts to transmit its data to a secondary destination with the assistance of multiple secondary relays. In addition, there exists a secondary eavesdropper who tries to overhear the source data. Under a maximum interference level required by a primary user, the secondary source and relay nodes must adjust their transmit power. We first formulate effective signal-to-interference-plus-noise ratio (SINR) as well as secrecy capacity under the constraints of the maximum transmit power, the interference threshold and the hardware impairment level. Furthermore, when the hardware impairment level is relaxed, we derive exact and asymptotic expressions of end-to-end secrecy outage probability over Rayleigh fading channels by using the recursive method. The derived expressions were verified by simulations, in which the proposed scheme outperformed the conventional multi-hop direct transmission protocol.Web of Science212art. no. 21
Performance of cluster-based cognitive multihop networks under joint impact of hardware noises and non-identical primary co-channel interference
In this paper, we evaluate outage probability (OP) of a cluster-based multi-hop protocol operating on an underlay cognitive radio (CR) mode. The primary network consists of multiple independent transmit/receive pairs, and the primary transmitters seriously cause co-channel interference (CCI) to the secondary receivers. To improve the outage performance for the secondary network under the joint impact of the CCI and hardware imperfection, we employ the best relay selection at each hop. Moreover, the destination is equipped with multiple antennas and uses the selection combining (SC) technique to enhance the reliability of the data transmission at the last hop. For performance evaluation, we first derive an exact formula of OP for the primary network which is used to calculate the transmit power of the secondary transmitters. Next, an exact closed-form expression of the end-to-end OP for the secondary network is derived over Rayleigh fading channels. We then perform Monte-Carlo simulations to validate the derivations. The results present that the CCI caused by the primary operations significantly impacts on the outage performance of the secondary network
マルチホップ無線ネットワークの特性解析に関する研究
九州工業大学博士学位論文 学位記番号:情工博甲第309号 学位授与年月日:平成28年3月25日1 Introduction||2 Impact of Transceiver Hardware Impairments on Cognitive Network||3 Case study: Two-Way Cognitive Relay in RF Energy HarvestingWireless Sensor Network||4 Soft Information Relaying Protocol||5 Overall Conclusion and FutureWorkWireless communication has been considered as the most efficient mean of data
transmission. We have been witnessed the breakthrough of wireless communication
era in many manifolds, such as speech, coverage area, and stability. However,
frequency bands, the resource to convey information wirelessly, are limited and expensive
to be granted usage licenses.
Attaining the goals of ubiquitous wireless devices will require the future wireless
networks stepping forward to overcome the scarcity and expensiveness of wireless
frequency bands. Thus, the future wireless networks should evolve to utilize wireless
frequencies more efficiently, such as cognitive relay network where non-license
users are able to transmit data in the same frequency band that officially allocated to
primary users. Subsequently, the transmit power of users in a cognitive network is
limited and the performance is vulnerable to impairments of transceiver hardware.
This dissertation aims to analyze the performance of the cognitive relay network
under the impact of transceiver hardware impairments. A case study of two-way
cognitive relay network is given for further investigate the impact of transceiver
hardware impairments on end-to-end outage performance and throughput. Furthermore,
we provide a new relaying scheme in order to lessen the impact of transceiver
hardware impairment and further boost the system performance. For the purposes,
this dissertation is organized into five (5) chapters.
Chapter 1: Introduction. In this chapter, multihop wireless networks and the performance
metrics are overviewed. In particular, the relay networks and cognitive relay
networks are presented. Moreover, the general model of the practical transceiver
hardware impairment is detailed for further analysis.
Chapter 2: The impact of transceiver hardware impairments on cognitive relay networks.
By using the general hardware impairment model for the received signal, the
closed forms of outage probability of the relay network with decode-and-forward
(DF) and amplify-and-forward (AF) under the impact of transceiver hardware imperfection
are derived. Based on these results, we provide further discussion on
transceiver hardware selection guideline.
Chapter 3: Case study: two-way cognitive relaying in energy harvesting wireless
sensor networks. A two-way relay wireless sensor network equipped with
RF energy harvesting node is introduced. This network is aimed to be implemented
in hazardous or remote areas where power supply for the relay node is
difficult to maintain. In this chapter, we consider four configurations of the network
with formed by combining two bidirectional relaying protocols and two wireless
power transfer policies. The detailed performance analysis of outage probability
and throughput of the case-study network with four configurations are presented.
Based on the analysis, we provide performance comparison between the four and
suggest the network configuration with the best performance.
Chapter 4: Soft information relaying protocol. The soft information relaying protocol
is proposed and analyzed. The analysis shows that this relaying protocol can
gradually reduce the impact of transceiver hardware impairment on cognitive relay
networks. Hence, soft relaying protocol is considered as a solution for cognitive
relay network with cost-effective wireless transceiver devices.
Chapter 5: Overall conclusion. An overall summary of the works presented in
the above is provided in this chapter. Moreover, the future related work is also
discussed.
The results in this dissertation acknowledge the impact of transceiver hardware impairment
by presenting the reduction of outage probability and throughput of the
cognitive relay network. It puts forward the consideration of including the impact
of transceiver hardware impairments on wireless network performance analysis, especially
for the cognitive networks of which the transmit power is limited.
Furthermore, a new relaying protocol, namely soft information relaying protocol,
is proposed as a solution to lessen the impact of transceiver hardware impairment.
The analysis shows that the impact of transceiver hardware impairment in cognitive
relay network is reduced in compared to conventional relaying schemes.
As a final point, we have provided a full picture of performance analysis for the
cognitive relay network under the impact of transceiver hardware imperfection and
the solution to reduce the performance loss by applying soft information relaying
scheme. This research would contribute to boost the development of cognitive relay
networks where frequency bands are used more efficiently
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