6 research outputs found
Performance study of an underlay cognitive radio network in the presence of co-channel interference
PhD ThesisMassive innovation in all aspects of the wireless communication network
has been witnessed over the last few decades. The demand for data
throughput is continuously growing, as such, the current regulations for
allocating frequency spectrum are not able to respond to this exponential growth. Cognitive radio (CR), has been proposed as a solution to
this problem. One of the possible scenarios of the implementation of CR
is underlay cognitive radio. In this thesis the performance of an underlay cognitive radio network (UCRN) in the presence of the co-channel
interference (CCI) is assessed.
Firstly, the impact of CCI on the dual-hop cooperative UCRN is investigated over Rayleigh fading channels. In order to do this, the exact outage
probability (OP), average error probability (AEP) and the ergodic capacity (EC) are studied. In addition, simple and asymptotic expressions
for the OP and AEP are derived. Furthermore, the optimal power allocation is investigated to enhance the network performance. Moreover,
the performance of a multi-user scenario is studied by considering the
opportunistic SNR-based selection technique.
Secondly, the effect of both primary network interference and CCI on
the dual-hop UCRN over Rayleigh fading channels are studied. The
equivalent signal-to-interference-plus-noise ratio (SINR) for this network
scenario is obtained by considering multi-antenna schemes at all receiver
nodes. The different signal combinations at the receiver nodes are investigated and compared, such as selection combining (SC) and maximum
ratio combining (MRC) techniques. Then, the equivalent probability
density function (PDF) and cumulative distribution function (CDF) of
the networkās equivalent SINR are derived and discussed. Furthermore,
expressions for the exact OP, AEP, and EC are derived and reviewed.
In addition, asymptotic OP expressions are obtained for different case
scenarios to gain an insight into the network parameters.
Thirdly, multiple-input multiple-output (MIMO) UCRN is investigated
under the influence of primary transmitter interference and CCI over
Rayleigh fading channels. The transmit antenna selection and maximum
ratio combining (TAS/MRC) techniques are considered for examining
the performance of the secondary network. At first the equivalent SINR
for the system is derived, then the exact and approximate expressions
for the OP are derived and discussed.
Fourthly, considering Nakagami-m fading channels, the performance of
the UCRN is thoroughly studied with the consideration of the impact
of primary network interference and CCI. The equivalent SINR for the
secondary system is derived. Then, the system equivalent PDF and CDF
are derived and discussed. Furthermore, the OP and AEP performances
are investigated.
Finally, for the cases mentioned above, numerical examples in conjunction with MatLab Monte Carlo simulations are provided to validate the
derived results. The results show that CCI is one of the factors that
severely reduces the UCRN performance. This can be more observable
when the CCI power increases linearly with the transmission power of
the secondary transmitter nodes. Furthermore, it was found that in
a multi-user scenario the opportunistic SNR-based selection technique
consideration can improve the performance of the network. Moreover,
adaptive power allocation is found to give better results than equal power
allocation. In addition, cooperative communication can be considered to
be an effective way to combat the impact of transmission power limitation of the secondary network and interference power constraint. The
multi-antenna schemes are another important consideration for enhancing the overall performance. In fact, despite the interference from the
CCI and primary user sources, the multi-antennas scheme does not lose
its advantage in the UCRN performance improvementHigher Committee for Education Development in Iraq (HCED). I am also grateful to
the Ministry of Transportation and Communication, Kurdistan Regional
Government-Iraq
A novel mobile communication system using Pulse Position based Chirp Spread Spectrum modulation
The paper presents a new mobile communication system based on Chirp Spread Spectrum (CSS) transmission. The downlink modulation scheme is extended with Pulse Position Modulation (PPM) to carry data for multiple mobile terminals simultaneously. The described novel mechanism ensures reliable and robust communication between the parties, especially for terminals moving with high speeds or at long range. Furthermore, the proposed system take care of the uplink communication as well, where Closed-Loop Power Control (CLPC) is applied to handle the near-far problem and improve the performance of the system. Based on the attributes of the proposed system the application area covers sensor networks, IoT applications and Industry 4.0 as general field of LPWAN, however, mobility of terminals also considered.Analytical investigations for downlink communication are described focusing on the instantaneous symbol-error rate and average SER in Rayleigh fading channel. The results show that the proposed Pulse Position based Chirp Spread Spectrum technique for Multiple Access (shortly PP-CSS-MA) allows higher data rates that is used for the multiple access feature. In addition, numerical results are presented as well, and they point out the benefits of the applied CLPC mechanism. Finally, considerations regarding to the implementation of the proposed communication system are described
A novel mobile communication system using Pulse Position based Chirp Spread Spectrum modulation
The paper presents a new mobile communication system based on Chirp Spread Spectrum (CSS) transmission. The downlink modulation scheme is extended with Pulse Position Modulation (PPM) to carry data for multiple mobile terminals simultaneously. The described novel mechanism ensures reliable and robust communication between the parties, especially for terminals moving with high speeds or at long range. Furthermore, the proposed system take care of the uplink communication as well, where Closed-Loop Power Control (CLPC) is applied to handle the near-far problem and improve the performance of the system. Based on the attributes of the proposed system the application area covers sensor networks, IoT applications and Industry 4.0 as general field of LPWAN, however, mobility of terminals also considered.Analytical investigations for downlink communication are described focusing on the instantaneous symbol-error rate and average SER in Rayleigh fading channel. The results show that the proposed Pulse Position based Chirp Spread Spectrum technique for Multiple Access (shortly PP-CSS-MA) allows higher data rates that is used for the multiple access feature. In addition, numerical results are presented as well, and they point out the benefits of the applied CLPC mechanism. Finally, considerations regarding to the implementation of the proposed communication system are described
Recent Advances in Wireless Communications and Networks
This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters