2017 IEEE 13th Malaysia International Conference on Communications (MICC), 2017
In this work, we consider a joint power allocation and bit loading problem in an orthogonal frequ... more In this work, we consider a joint power allocation and bit loading problem in an orthogonal frequency division multiplexing (OFDM) based cognitive radio (CR) network. The objective is to maximize the end-to-end rate in a relay aided dual hop transmission subject to individual power constraints at each transmission node. More specifically, an underlay CR transmission is considered, where the secondary nodes transmit simultaneously with the primary nodes subject to an interference protection criteria. An efficient algorithm is proposed which maximizes the overall throughput while meeting all the constraints. Simulations results are presented to validate the performance of our proposed scheme.
2017 International Conference on Frontiers of Information Technology (FIT), 2017
A channel amplitude quantization method that can effectively quantize the channel response using ... more A channel amplitude quantization method that can effectively quantize the channel response using just one single threshold value is proposed in order to extract a random manipulating sequence with good secrecy properties. Specifically, a Time Division Duplex (TDD) wireless system is considered over independent identical distributed (i.i.d.) Rayleigh fast fading channel, where potential passive eavesdroppers (Eves) can only estimate their own channel and have no knowledge about CSI between legitimate communication parties. The transmitter (Alice) is only aware of the CSI of the legitimate user (Bob). Particularly, the proposed security technique takes the bits of the transmitted data packets and manipulate them with a logical vector that characterizes the channel randomness based on the estimated CSI gain. The process of manipulation is implemented on a bit level basis using an XOR operation exactly before modulation process. The same XOR operation is implemented after demodulation process on the detected bits to extract the concealed bits. The obtained simulation results show that the employment of such mechanism can ensure data confidentiality. Furthermore, the simulation results are extended to include the effect of the selected quantization threshold on the BER performance of Eve as well as the amount of information leakage to its side. It is shown that security gap region between Bob and Eve is made very large over all expected Signal to Noise ratio (SNR) values despite the small degradation in the bit error rate (BER) performance of Bob because of the expected channel estimation errors due to noise.
This work aims to achieve fairness among secondary users (SUs) in IoT cooperative NOMA-based CR t... more This work aims to achieve fairness among secondary users (SUs) in IoT cooperative NOMA-based CR transmission. We design a power allocation algorithm for secondary IoT network that ensures protection of primary system. Further, an independent battery constraint at each node is considered, and power gap among transmissions of two NOMA users is applied for successive interference cancellation. Our extensive simulation results show that the proposed framework provides excellent performance and for sufficient available transmission power perfect fairness is achieved in the rate of both the users.
2017 International Conference on Frontiers of Information Technology (FIT), 2017
In this study, we first quantify the secrecy performance achieved by employing precoded orthogona... more In this study, we first quantify the secrecy performance achieved by employing precoded orthogonal space time block coding (POSTBC) in order to use it as a benchmark for comparison purposes with a new proposed security scheme. In POSTBC, space time codewords are precoded before being transmitted with an optimum pre-coding matrix based on the main channel of the legitimate parties. The obtained results demonstrate a considerable secrecy gap region in the resulting bit error rate (BER) performance due to using POSTBC. Afterwards, a new method called pre-equlicodization (precoding along with semi pre-equalization) is proposed to further enhance the secrecy performance. In pre-equlicodization scheme, the transmitted symbols are precoded by a new modified matrix called pre-equalicodizing matrix. This matrix is built by manipulating each row element in the optimal selected precoding matrix by the corresponding amplitude square inverse of the estimated channel gain over each data stream. T...
IEEE Transactions on Cognitive Communications and Networking, 2021
The future generation of wireless communication networks demands for high spectral efficiency to ... more The future generation of wireless communication networks demands for high spectral efficiency to accommodate a large number of devices over the limited available frequency spectrum. Device to device (D2D) systems exploit channel reuse to offer high spectral efficiency and reduce the burden on the communication infrastructure by facilitating communication between devices without involving the base station. We can further enhance the efficiency of D2D systems by employing non-orthogonal multiple access (NOMA) for the transmission of the signals. In NOMA the signals of multiple users are transmitted on the same channel, simultaneously. Deployment of relays can assist the users that do not have a reliable link of communication. A combination of these advanced technologies may offer very high spectral efficiency and a robust communication system. This article aims to design efficient resource allocation techniques for the future communication systems. We consider sum rate maximization problem subject to limited power budget at different transmitting nodes and necessary transmit power gap among users for successful NOMA implementation. Under decode and forward relaying protocol, the problem turns out to be a unique joint uplink-downlink NOMA optimization. We then propose a deep neural networks (DNN) framework to acquire a joint power loading solution at source and relaying nodes. To obtain reliable data for DNN training and testing, we also derive an optimal solution of the problem through convex optimization paradigm, which is used later as a bench mark to verify the performance of proposed DNN based solution. It is observed that DNN provides promising results both in terms of sum rate and the computational complexity.
The current study was aimed at examining the prescribing patterns of antihypertensive medications... more The current study was aimed at examining the prescribing patterns of antihypertensive medications, dispensing time, generic prescribing, drug-drug interactions and to determining whether or not prescriptions are consistent with the recommendations of the Joint National Committee (JNC-8) guidelines. A cross-sectional study was conducted in three tertiary care hospitals among patients of 30 years and more who visited the outpatient departments (OPDs) from January 2018 to September 2018. Prescription patterns were assessed by reviewing the patient’s prescriptions, who were attending the OPDs of targeted hospitals during the study duration. Drug interactions in prescriptions were checked by using Micromedex® database to detect incompatible drug combinations. A total of 500 prescriptions were collected that met the criteria for inclusion. The sample data consisted of 57% of males with an average age of 54 years. The average time spent by the patients at the dispensing area was barely 1 min, and no proper counselling had provided them how and when to take medicine. One hundred one drug interactions have been identified in prescriptions. The most frequently first line prescribed drug class was found to be calcium channel blockers 27.8%, followed by 26.1% angiotensin-converting enzyme inhibitor, and 16% vasodilators. The trend observed in double combinations was calcium channel blockers + angiotensin receptor blockers (18.6%) followed by vasodilator + Beta-blockers 14.1%, and Beta-blockers + angiotensin-converting enzyme inhibitor 7.1%. The study findings demonstrated average compliance with the JNC-8 guidelines; none of the drug was prescribed by generic name and had very short dispensing time without counselling; approximately 101 minor and major drug-drug interactions were identified. This multi-factorial phenomenon of average compliance with the guidelines must be addressed in order to ensure the rational and quality use of medicines to improve the quality of life of patients.
Wireless Communications and Mobile Computing, 2019
The issue of spectrum scarcity in wireless networks is becoming prominent and critical with each ... more The issue of spectrum scarcity in wireless networks is becoming prominent and critical with each passing year. Although several promising solutions have been proposed to provide a solution to spectrum scarcity, most of them have many associated tradeoffs. In this context, one of the emerging ideas relates to the utilization of cognitive radios (CR) for future heterogeneous networks (HetNets). This paper provides a marriage of two promising candidates (i.e., CR and HetNets) for beyond fifth generation (5G) wireless networks. More specifically, a joint power allocation and user assignment solution for the multiuser underlay CR-based HetNets has been proposed and evaluated. To counter the limiting factors in these networks, the individual power of transmitting nodes and interference temperature protection constraints of the primary networks have been considered. An efficient solution is designed from the dual decomposition approach, where the optimal user assignment is obtained for the...
Transactions on Emerging Telecommunications Technologies, 2018
Nonorthogonal multiple access (NOMA) has been recognized as a key solution to fulfill the demands... more Nonorthogonal multiple access (NOMA) has been recognized as a key solution to fulfill the demands of 5G wireless communication. In this paper, our aim is to maximize the fairness in the data rates of different users in a multiuser NOMA system. We optimize the downlink transmission subject to minimum rate requirement of each user, limited power budget at the transmitter, and the successive interference cancelation constraint. First, we solve the problem for two‐user scenario where the nonconvex problem is transformed into a standard convex minimization problem and the duality theory is exploited to find the solution. The optimal power allocation is obtained from the Karush‐Kuhn‐Tucker (KKT) conditions, whereas the dual problem is solved via subgradient algorithm. As a next step, we consider the general multiuser optimization problem where more than two users can share the same channel under NOMA transmission. We design efficient solution techniques to solve the nonconvex optimization...
2017 IEEE 13th Malaysia International Conference on Communications (MICC), 2017
In this work, we consider a joint power allocation and bit loading problem in an orthogonal frequ... more In this work, we consider a joint power allocation and bit loading problem in an orthogonal frequency division multiplexing (OFDM) based cognitive radio (CR) network. The objective is to maximize the end-to-end rate in a relay aided dual hop transmission subject to individual power constraints at each transmission node. More specifically, an underlay CR transmission is considered, where the secondary nodes transmit simultaneously with the primary nodes subject to an interference protection criteria. An efficient algorithm is proposed which maximizes the overall throughput while meeting all the constraints. Simulations results are presented to validate the performance of our proposed scheme.
2017 International Conference on Frontiers of Information Technology (FIT), 2017
A channel amplitude quantization method that can effectively quantize the channel response using ... more A channel amplitude quantization method that can effectively quantize the channel response using just one single threshold value is proposed in order to extract a random manipulating sequence with good secrecy properties. Specifically, a Time Division Duplex (TDD) wireless system is considered over independent identical distributed (i.i.d.) Rayleigh fast fading channel, where potential passive eavesdroppers (Eves) can only estimate their own channel and have no knowledge about CSI between legitimate communication parties. The transmitter (Alice) is only aware of the CSI of the legitimate user (Bob). Particularly, the proposed security technique takes the bits of the transmitted data packets and manipulate them with a logical vector that characterizes the channel randomness based on the estimated CSI gain. The process of manipulation is implemented on a bit level basis using an XOR operation exactly before modulation process. The same XOR operation is implemented after demodulation process on the detected bits to extract the concealed bits. The obtained simulation results show that the employment of such mechanism can ensure data confidentiality. Furthermore, the simulation results are extended to include the effect of the selected quantization threshold on the BER performance of Eve as well as the amount of information leakage to its side. It is shown that security gap region between Bob and Eve is made very large over all expected Signal to Noise ratio (SNR) values despite the small degradation in the bit error rate (BER) performance of Bob because of the expected channel estimation errors due to noise.
This work aims to achieve fairness among secondary users (SUs) in IoT cooperative NOMA-based CR t... more This work aims to achieve fairness among secondary users (SUs) in IoT cooperative NOMA-based CR transmission. We design a power allocation algorithm for secondary IoT network that ensures protection of primary system. Further, an independent battery constraint at each node is considered, and power gap among transmissions of two NOMA users is applied for successive interference cancellation. Our extensive simulation results show that the proposed framework provides excellent performance and for sufficient available transmission power perfect fairness is achieved in the rate of both the users.
2017 International Conference on Frontiers of Information Technology (FIT), 2017
In this study, we first quantify the secrecy performance achieved by employing precoded orthogona... more In this study, we first quantify the secrecy performance achieved by employing precoded orthogonal space time block coding (POSTBC) in order to use it as a benchmark for comparison purposes with a new proposed security scheme. In POSTBC, space time codewords are precoded before being transmitted with an optimum pre-coding matrix based on the main channel of the legitimate parties. The obtained results demonstrate a considerable secrecy gap region in the resulting bit error rate (BER) performance due to using POSTBC. Afterwards, a new method called pre-equlicodization (precoding along with semi pre-equalization) is proposed to further enhance the secrecy performance. In pre-equlicodization scheme, the transmitted symbols are precoded by a new modified matrix called pre-equalicodizing matrix. This matrix is built by manipulating each row element in the optimal selected precoding matrix by the corresponding amplitude square inverse of the estimated channel gain over each data stream. T...
IEEE Transactions on Cognitive Communications and Networking, 2021
The future generation of wireless communication networks demands for high spectral efficiency to ... more The future generation of wireless communication networks demands for high spectral efficiency to accommodate a large number of devices over the limited available frequency spectrum. Device to device (D2D) systems exploit channel reuse to offer high spectral efficiency and reduce the burden on the communication infrastructure by facilitating communication between devices without involving the base station. We can further enhance the efficiency of D2D systems by employing non-orthogonal multiple access (NOMA) for the transmission of the signals. In NOMA the signals of multiple users are transmitted on the same channel, simultaneously. Deployment of relays can assist the users that do not have a reliable link of communication. A combination of these advanced technologies may offer very high spectral efficiency and a robust communication system. This article aims to design efficient resource allocation techniques for the future communication systems. We consider sum rate maximization problem subject to limited power budget at different transmitting nodes and necessary transmit power gap among users for successful NOMA implementation. Under decode and forward relaying protocol, the problem turns out to be a unique joint uplink-downlink NOMA optimization. We then propose a deep neural networks (DNN) framework to acquire a joint power loading solution at source and relaying nodes. To obtain reliable data for DNN training and testing, we also derive an optimal solution of the problem through convex optimization paradigm, which is used later as a bench mark to verify the performance of proposed DNN based solution. It is observed that DNN provides promising results both in terms of sum rate and the computational complexity.
The current study was aimed at examining the prescribing patterns of antihypertensive medications... more The current study was aimed at examining the prescribing patterns of antihypertensive medications, dispensing time, generic prescribing, drug-drug interactions and to determining whether or not prescriptions are consistent with the recommendations of the Joint National Committee (JNC-8) guidelines. A cross-sectional study was conducted in three tertiary care hospitals among patients of 30 years and more who visited the outpatient departments (OPDs) from January 2018 to September 2018. Prescription patterns were assessed by reviewing the patient’s prescriptions, who were attending the OPDs of targeted hospitals during the study duration. Drug interactions in prescriptions were checked by using Micromedex® database to detect incompatible drug combinations. A total of 500 prescriptions were collected that met the criteria for inclusion. The sample data consisted of 57% of males with an average age of 54 years. The average time spent by the patients at the dispensing area was barely 1 min, and no proper counselling had provided them how and when to take medicine. One hundred one drug interactions have been identified in prescriptions. The most frequently first line prescribed drug class was found to be calcium channel blockers 27.8%, followed by 26.1% angiotensin-converting enzyme inhibitor, and 16% vasodilators. The trend observed in double combinations was calcium channel blockers + angiotensin receptor blockers (18.6%) followed by vasodilator + Beta-blockers 14.1%, and Beta-blockers + angiotensin-converting enzyme inhibitor 7.1%. The study findings demonstrated average compliance with the JNC-8 guidelines; none of the drug was prescribed by generic name and had very short dispensing time without counselling; approximately 101 minor and major drug-drug interactions were identified. This multi-factorial phenomenon of average compliance with the guidelines must be addressed in order to ensure the rational and quality use of medicines to improve the quality of life of patients.
Wireless Communications and Mobile Computing, 2019
The issue of spectrum scarcity in wireless networks is becoming prominent and critical with each ... more The issue of spectrum scarcity in wireless networks is becoming prominent and critical with each passing year. Although several promising solutions have been proposed to provide a solution to spectrum scarcity, most of them have many associated tradeoffs. In this context, one of the emerging ideas relates to the utilization of cognitive radios (CR) for future heterogeneous networks (HetNets). This paper provides a marriage of two promising candidates (i.e., CR and HetNets) for beyond fifth generation (5G) wireless networks. More specifically, a joint power allocation and user assignment solution for the multiuser underlay CR-based HetNets has been proposed and evaluated. To counter the limiting factors in these networks, the individual power of transmitting nodes and interference temperature protection constraints of the primary networks have been considered. An efficient solution is designed from the dual decomposition approach, where the optimal user assignment is obtained for the...
Transactions on Emerging Telecommunications Technologies, 2018
Nonorthogonal multiple access (NOMA) has been recognized as a key solution to fulfill the demands... more Nonorthogonal multiple access (NOMA) has been recognized as a key solution to fulfill the demands of 5G wireless communication. In this paper, our aim is to maximize the fairness in the data rates of different users in a multiuser NOMA system. We optimize the downlink transmission subject to minimum rate requirement of each user, limited power budget at the transmitter, and the successive interference cancelation constraint. First, we solve the problem for two‐user scenario where the nonconvex problem is transformed into a standard convex minimization problem and the duality theory is exploited to find the solution. The optimal power allocation is obtained from the Karush‐Kuhn‐Tucker (KKT) conditions, whereas the dual problem is solved via subgradient algorithm. As a next step, we consider the general multiuser optimization problem where more than two users can share the same channel under NOMA transmission. We design efficient solution techniques to solve the nonconvex optimization...
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