74 research outputs found
Joint Spatial and Spectrum Cooperation in Wireless Network.
PhDThe sky-rocketing growth of multimedia infotainment applications and broadband-hungry
mobile devices exacerbate the stringent demand for ultra high data rate and more spectrum resources. Along with it, the unbalanced temporal and geographical variations
of spectrum usage further inspires those spectral-efficient networks, namely, cognitive
radio and heterogeneous cellular networks (HCNs). This thesis focuses on the system
design and performance enhancement of cognitive radio (CR) and HCNs. Three different
aspects of performance improvement are considered, including link reliability of cognitive
radio networks (CNs), security enhancement of CNs, and energy efficiency improvement
of CNs and HCNs.
First, generalized selection combining (GSC) is proposed as an effective receiver design
for interference reduction and reliability improvement of CNs with outdated CSI. A uni-
ed way for deriving the distribution of received signal-to-noise ratio (SNR) is developed
in underlay spectrum sharing networks subject to interference from the primary trans-
mitter (PU-Tx) to the secondary receiver (SU-Rx), maximum transmit power constraint
at the secondary transmitter (SU-Tx), and peak interference power constraint at the
PU receiver (PU-Rx), is developed. Second, transmit antenna selection with receive
generalized selection combining (TAS/GSC) in multi-antenna relay-aided communica-
tion is introduced in CNs under Rayleigh fading and Nakagami-m fading. Based on
newly derived complex statistical properties of channel power gain of TAS/GSC, exact
ergodic capacity and high SNR ergodic capacity are derived over Nakagami-m fading.
Third, beamforming and arti cial noise generation (BF&AN) is introduced as a robust
scheme to enhance the secure transmission of large-scale spectrum sharing networks
with multiple randomly located eavesdroppers (Eves) modeled as homogeneous Poisson
Point Process (PPP). Stochastic geometry is applied to model and analyze the impact of
i
BF&AN on this complex network. Optimal power allocation factor for BF&AN which
maximizes the average secrecy rate is further studied under the outage probability con-
straint of primary network. Fourth, a new wireless energy harvesting protocol is proposed
for underlay cognitive relay networks with the energy-constrained SU-Txs. Exact and
asymptotic outage probability, delay-sensitive throughput, and delay-tolerant through-
put are derived to explore the tradeoff between the energy harvested from the PU-Txs
and the interference caused by the PU-Txs. Fifth, a harvest-then-transmit protocol is
proposed in K-tier HCNs with randomly located multiple-antenna base stations (BSs)
and single antenna mobile terminals (MTs) modeled as homogeneous PPP. The average
received power at MT, the uplink (UL) outage probability, and the UL average ergodic
rate are derived to demonstrate the intrinsic relationship between the energy harvested
from BSs in the downlink (DL) and the MT performance in the UL. Throughout the
thesis, it is shown that link reliability, secrecy performance, and energy efficiency of
CNs and HCNs can be signi cantly leveraged by taking advantage of multiple antennas,
relays, and wireless energy harvesting
Secrecy Outage on Transmit Antenna Selection/Maximal Ratio Combining in MIMO Cognitive Radio Networks
This paper investigates the secrecy outage performance
of transmit antenna selection (TAS)/maximal ratio
combining (MRC) in multiple input multiple output (MIMO)
cognitive radio networks (CRNs) over Rayleigh fading channels.
In the considered system, a secondary user (SU-TX) equipped
with NA (NA 1) antennas uses TAS to transmit confidential
messages to another secondary user (SU-RX), which is equipped
with NB (NB 1) antennas and adopts MRC scheme to
process multiple received signals. Meanwhile, an eavesdropper
equipped with NE (NE 1) antennas also adopts MRC scheme
to overhear the transmitted information between SU-TX and
SU-RX. SU-TX adopts the underlay strategy to guarantee the
quality of service of the primary user without spectrum sensing.
In this paper, we derive the exact and asymptotic closed-form
expressions for the secrecy outage probability. Simulations are
conducted to validate the accuracy of the analysis.ARC Discovery Projects Grant DP150103905
Hybrid satellite–terrestrial networks toward 6G : key technologies and open issues
Future wireless networks will be required to provide more wireless services at higher data rates and with global coverage. However, existing homogeneous wireless networks, such as cellular and satellite networks, may not be able to meet such requirements individually, especially in remote terrain, including seas and mountains. One possible solution is to use diversified wireless networks that can exploit the inter-connectivity between satellites, aerial base stations (BSs), and terrestrial BSs over inter-connected space, ground, and aerial networks. Hence, enabling wireless communication in one integrated network has attracted both the industry and the research fraternities. In this work, we provide a comprehensive survey of the most recent work on hybrid satellite–terrestrial networks (HSTNs), focusing on system architecture, performance analysis, design optimization, and secure communication schemes for different cooperative and cognitive HSTN network architectures. Different key technologies are compared. Based on this comparison, several open issues for future research are discussed
- …