Yansha Deng
King's College London, Informatics, Post-Doc
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http://www.yanshadeng.org/edit
—We investigate beamforming and artificial noise generation at the secondary transmitters to establish secure transmission in large scale spectrum sharing networks, where multiple non-colluding eavesdroppers attempt to intercept the... more
—We investigate beamforming and artificial noise generation at the secondary transmitters to establish secure transmission in large scale spectrum sharing networks, where multiple non-colluding eavesdroppers attempt to intercept the secondary transmission. We develop a comprehensive analytical framework to accurately assess the secrecy performance under the primary users' quality of service constraint. Our aim is to characterize the impact of beamforming and artificial noise generation (BF&AN) on this complex large scale network. We first derive exact expressions for the average secrecy rate and the secrecy outage probability. We then derive an easy-to-evaluate asymptotic average secrecy rate and asymptotic secrecy outage probability when the number of antennas at the secondary transmitter goes to infinity. Our results show that the equal power allocation between the useful signal and artificial noise is not always the best strategy to achieve maximum average secrecy rate in large scale spectrum sharing networks. Another interesting observation is that the advantage of BF&AN over BF on the average secrecy rate is lost when the aggregate interference from the primary and secondary transmitters is strong, such that it overtakes the effect of the generated AN.
Research Interests:
This paper exploits the potential of physical layer security in massive multiple-input multiple-output (MIMO) aided two-tier heterogeneous networks (HetNets). We focus on the downlink secure transmission in the presence of multiple... more
This paper exploits the potential of physical layer security in massive multiple-input multiple-output (MIMO) aided
two-tier heterogeneous networks (HetNets). We focus on the
downlink secure transmission in the presence of multiple eavesdroppers.
We first address the impact of massive MIMO on the
maximum receive power based user association. We then derive the tractable upper bound expressions for the secrecy outage probability of a HetNets user.We show that the implementation of massive MIMO significantly improves the secrecy performance, which indicates that physical layer security could be a promising solution for safeguarding massive MIMO HetNets. Furthermore, we show that the secrecy outage probability of HetNets user first degrades and then improves with increasing the density of PBSs.
two-tier heterogeneous networks (HetNets). We focus on the
downlink secure transmission in the presence of multiple eavesdroppers.
We first address the impact of massive MIMO on the
maximum receive power based user association. We then derive the tractable upper bound expressions for the secrecy outage probability of a HetNets user.We show that the implementation of massive MIMO significantly improves the secrecy performance, which indicates that physical layer security could be a promising solution for safeguarding massive MIMO HetNets. Furthermore, we show that the secrecy outage probability of HetNets user first degrades and then improves with increasing the density of PBSs.
Research Interests:
This paper develops a tractable framework for exploiting the potential benefits of physical layer security in three-tier wireless sensor networks using stochastic geometry. In such networks, the sensing data from the remote sensors are... more
This paper develops a tractable framework for exploiting the potential benefits of physical layer security in three-tier wireless sensor networks using stochastic geometry. In such networks, the sensing data from the remote sensors are collected by sinks with the help of access points, and the external eavesdroppers intercept the data transmissions.We focus on the secure transmission in two scenarios: i) the active sensors transmit their sensing data to the access points, and ii) the active access points forward the data to the sinks. We derive new compact expressions for the average secrecy rate in these two scenarios. We also derive a new compact expression for the overall average secrecy rate. Numerical results corroborate our analysis and show that multiple antennas at the access points
can enhance the security of three-tier wireless sensor networks.
Our results show that increasing the number of access points
decreases the average secrecy rate between the access point and its associated sink. However, we find that increasing the number of access points first increases the overall average secrecy rate, with a critical value beyond which the overall average secrecy rate then decreases. When increasing the number of active sensors, both the average secrecy rate between the sensor and its associated access point and the overall average secrecy rate decrease. In contrast, increasing the number of sinks improves both the average secrecy rate between the access point and its associated sink, as well as the overall average secrecy rate.
can enhance the security of three-tier wireless sensor networks.
Our results show that increasing the number of access points
decreases the average secrecy rate between the access point and its associated sink. However, we find that increasing the number of access points first increases the overall average secrecy rate, with a critical value beyond which the overall average secrecy rate then decreases. When increasing the number of active sensors, both the average secrecy rate between the sensor and its associated access point and the overall average secrecy rate decrease. In contrast, increasing the number of sinks improves both the average secrecy rate between the access point and its associated sink, as well as the overall average secrecy rate.
Research Interests:
In this paper, we present an analytical model for a diffusive molecular communication (MC) system with a reversible adsorption receiver in a fluid environment. The time-varying spatial distribution of the information molecules under the... more
In this paper, we present an analytical model for a
diffusive molecular communication (MC) system with a reversible adsorption receiver in a fluid environment. The time-varying spatial distribution of the information molecules under the reversible adsorption and desorption reaction at the surface of a bio-receiver is analytically characterized. Based on the spatial distribution, we derive the number of newly-adsorbed information molecules expected in any time duration. Importantly, we present a simulation framework for the proposed model that accounts for the diffusion and reversible reaction. Simulation results show the accuracy of our derived expressions, and demonstrate the positive effect of the adsorption rate and the negative effect of the desorption rate on the net number of newly-adsorbed information molecules expected. Moreover, our analytical results simplify to the special case of an absorbing receiver.
diffusive molecular communication (MC) system with a reversible adsorption receiver in a fluid environment. The time-varying spatial distribution of the information molecules under the reversible adsorption and desorption reaction at the surface of a bio-receiver is analytically characterized. Based on the spatial distribution, we derive the number of newly-adsorbed information molecules expected in any time duration. Importantly, we present a simulation framework for the proposed model that accounts for the diffusion and reversible reaction. Simulation results show the accuracy of our derived expressions, and demonstrate the positive effect of the adsorption rate and the negative effect of the desorption rate on the net number of newly-adsorbed information molecules expected. Moreover, our analytical results simplify to the special case of an absorbing receiver.
Research Interests:
Wireless energy harvesting is regarded as a promising energy supply alternative for energy-constrained wireless networks. In this paper, a new wireless energy harvesting protocol is proposed for an underlay cognitive relay network with... more
Wireless energy harvesting is regarded as a promising energy supply alternative for energy-constrained wireless networks. In this paper, a new wireless energy harvesting protocol is proposed for an underlay cognitive relay network with multiple primary user (PU) transceivers. In this protocol, the secondary nodes can harvest energy from the primary network (PN) while sharing the licensed spectrum of the PN. In order to assess the impact of different system parameters on the proposed network, we first derive an exact expression for the outage probability for the secondary network (SN) subject to three important power constraints: 1) the maximum transmit power at the secondary source (SS) and at the secondary relay (SR), 2) the peak interference power permitted at each PU receiver, and 3) the interference power from each PU transmitter to the SR and to the secondary destination (SD). To obtain practical design insights into the impact of different parameters on successful data transmission of the SN, we derive throughput expressions for both the delay-sensitive and the delay-tolerant transmission modes. We also derive asymptotic closed-form expressions for the outage probability and the delay-sensitive throughput and an asymptotic analytical expression for the delay-tolerant throughput as the number of PU transceivers goes to infinity. The results show that the outage probability improves when PU transmitters are located near SS and sufficiently far from SR and SD. Our results also show that when the number of PU transmitters is large, the detrimental effect of interference from PU transmitters outweighs the benefits of energy harvested from the PU transmitters.
Research Interests:
We consider transmit antenna selection with receive generalized selection combining (TAS/GSC) for cognitive decodeand- forward (DF) relaying in Nakagami-m fading channels. In an effort to assess the performance, the probability density... more
We consider transmit antenna selection with receive
generalized selection combining (TAS/GSC) for cognitive decodeand-
forward (DF) relaying in Nakagami-m fading channels. In
an effort to assess the performance, the probability density
function and the cumulative distribution function of the endto-
end SNR are derived using the moment generating function,
from which new exact closed-form expressions for the outage
probability and the symbol error rate are derived. We then
derive a new closed-form expression for the ergodic capacity.
More importantly, by deriving the asymptotic expressions for
the outage probability and the symbol error rate, as well
as the high SNR approximations of the ergodic capacity, we
establish new design insights under the two distinct constraint
scenarios: 1) proportional interference power constraint, and 2)
fixed interference power constraint. Several pivotal conclusions
are reached. For the first scenario, the full diversity order of the
outage probability and the symbol error rate is achieved, and
the high SNR slope of the ergodic capacity is 1/2. For the second
scenario, the diversity order of the outage probability and the
symbol error rate is zero with error floors, and the high SNR
slope of the ergodic capacity is zero with capacity ceiling.
generalized selection combining (TAS/GSC) for cognitive decodeand-
forward (DF) relaying in Nakagami-m fading channels. In
an effort to assess the performance, the probability density
function and the cumulative distribution function of the endto-
end SNR are derived using the moment generating function,
from which new exact closed-form expressions for the outage
probability and the symbol error rate are derived. We then
derive a new closed-form expression for the ergodic capacity.
More importantly, by deriving the asymptotic expressions for
the outage probability and the symbol error rate, as well
as the high SNR approximations of the ergodic capacity, we
establish new design insights under the two distinct constraint
scenarios: 1) proportional interference power constraint, and 2)
fixed interference power constraint. Several pivotal conclusions
are reached. For the first scenario, the full diversity order of the
outage probability and the symbol error rate is achieved, and
the high SNR slope of the ergodic capacity is 1/2. For the second
scenario, the diversity order of the outage probability and the
symbol error rate is zero with error floors, and the high SNR
slope of the ergodic capacity is zero with capacity ceiling.
Research Interests:
We propose transmit antenna selection with receive generalized selection combining (TAS/GSC) in dual-hop cognitive decode-and-forward (DF) relay networks with spectrum sharing for reliability enhancement and interference relaxation. In... more
We propose transmit antenna selection with receive
generalized selection combining (TAS/GSC) in dual-hop cognitive
decode-and-forward (DF) relay networks with spectrum sharing
for reliability enhancement and interference relaxation. In this
network, a single antenna which maximizes the receive signal-tonoise
ratio (SNR) is selected at the secondary transmitter and a
subset of receive antennas with the highest SNRs are combined
at the secondary receiver. To demonstrate the advantages of
our proposed framework, we derive new exact closed-form
expressions for the outage probability and the symbol error rate
of the secondary network in Rayleigh fading. We also derive easyto-
evaluate asymptotic expressions in the high SNR regime to gain
practical insights. Several important design insights are reached.
Under the proportional interference power constraint, the full
diversity gain is achieved and is entirely determined by the total
number of antennas available in the secondary network. This
result is independent of the number of receive antennas combined
and the number of primary users. The positive impact of the
number of receive antennas combined and the negative impact
of the number of primary users on the secondary network are
showcased in the SNR gain. Under the fixed interference power
constraint, error floors are displayed and the diversity gain is
lost.
generalized selection combining (TAS/GSC) in dual-hop cognitive
decode-and-forward (DF) relay networks with spectrum sharing
for reliability enhancement and interference relaxation. In this
network, a single antenna which maximizes the receive signal-tonoise
ratio (SNR) is selected at the secondary transmitter and a
subset of receive antennas with the highest SNRs are combined
at the secondary receiver. To demonstrate the advantages of
our proposed framework, we derive new exact closed-form
expressions for the outage probability and the symbol error rate
of the secondary network in Rayleigh fading. We also derive easyto-
evaluate asymptotic expressions in the high SNR regime to gain
practical insights. Several important design insights are reached.
Under the proportional interference power constraint, the full
diversity gain is achieved and is entirely determined by the total
number of antennas available in the secondary network. This
result is independent of the number of receive antennas combined
and the number of primary users. The positive impact of the
number of receive antennas combined and the negative impact
of the number of primary users on the secondary network are
showcased in the SNR gain. Under the fixed interference power
constraint, error floors are displayed and the diversity gain is
lost.
Research Interests:
We propose cognitive spectrum sharing with generalized selection combining (GSC) at the secondary user (SU) in the presence of multiple primary transceivers with outdated channel information. Our main motivation is to determine the impact... more
We propose cognitive spectrum sharing with generalized
selection combining (GSC) at the secondary user (SU)
in the presence of multiple primary transceivers with outdated
channel information. Our main motivation is to determine the
impact of GSC and outdated channel information on the outage
probabiliy of cognitive spectrum sharing subject to two practical
power constraints: 1) maximum transmit power at the SU
transmitter, and 2) peak interference temperature at the PU
receiver. We derive new closed-form expressions for the exact
and asymptotic outage probability in Rayleigh fading. Our
expressions provide concise representations of the diversity order
and the array gain. We confirm that the diversity order of
GSC is entirely dependent on the secondary network and is
equal to the available number of receive antennas at the SU.
This result is consistent with those of maximal-ratio combining
(MRC) and selection combining (SC) in cognitive spectrum
sharing. More importantly, our results show that the outage
probability decreases with increasing the correlation coefficient
of the outdated channel.
selection combining (GSC) at the secondary user (SU)
in the presence of multiple primary transceivers with outdated
channel information. Our main motivation is to determine the
impact of GSC and outdated channel information on the outage
probabiliy of cognitive spectrum sharing subject to two practical
power constraints: 1) maximum transmit power at the SU
transmitter, and 2) peak interference temperature at the PU
receiver. We derive new closed-form expressions for the exact
and asymptotic outage probability in Rayleigh fading. Our
expressions provide concise representations of the diversity order
and the array gain. We confirm that the diversity order of
GSC is entirely dependent on the secondary network and is
equal to the available number of receive antennas at the SU.
This result is consistent with those of maximal-ratio combining
(MRC) and selection combining (SC) in cognitive spectrum
sharing. More importantly, our results show that the outage
probability decreases with increasing the correlation coefficient
of the outdated channel.