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Papers by Kamran Sayrafian
IEEE Conference Proceedings, 2016
A virtualization platform is responsible for allocation and/or aggregation of radio resources fro... more A virtualization platform is responsible for allocation and/or aggregation of radio resources from different access technologies owned by the Infrastructure Providers (InPs). It is also responsible for the distribution of the total capacity among Virtual Network Operators (VNOs). This distribution should comply with requirements specified in the Service Level Agreements (SLAs) of each VNO. The admission control process ensures adherence to the minimum service level requirements during network operation i.e. users' arrivals/departures. A joint resource management and admission control methodology is proposed in this paper that achieves optimality with respect to the aggregate system utility. The proposed approach is evaluated by simulating a sequence of scenarios with increasing number of arrivals. The results confirm maximal utilization of the available capacity in the system while all SLAs are satisfied.
IEEE Conference Proceedings, 2020
PubMed, 2014
A Body Area Network (BAN) is a wireless network of wearable or implantable computing devices. A B... more A Body Area Network (BAN) is a wireless network of wearable or implantable computing devices. A BAN typically consists of several miniaturized radio-enabled body sensor/actuator that communicate with a single coordinator. Medical applications usually impose stringent constraints on the BAN operational reliability, quality of service, and power consumption. However, as there is no coordination among multiple co-located BANs, cross-interference could make achieving these objectives a challenging problem. Assuming Time Division Multiple Access (TDMA) at each BAN, this paper investigates the ability of regret matching based transmission scheduling algorithm to ease the impact of inter-BAN interference. This scheduling algorithm uses pattern of past interference for implicit coordination between different BAN transmissions. Simulation results demonstrate potential benefits of the proposed scheme for inter-BAN interference mitigation.
Human Body Communication (HBC) is an attractive low complexity technology with promising applicat... more Human Body Communication (HBC) is an attractive low complexity technology with promising applications in wearable biomedical sensors. In this paper, a simple parametric model based on the finite-element method (FEM) using a full human body model is developed to virtually emulate and examine the HBC channel. FEM allows better modeling and quantification of the underlying physical phenomena including the impact of the human body for the desired applications. By adjusting the parameters of the model, a good match with the limited measurement results in the literature is observed. Having a flexible and customizable simulation platform could be very helpful to better understand the communication medium for capacitively coupled electrodes in HBC. This knowledge, in turn, leads to better transceiver design for given applications. The platform presented here can also be extended to study communication channel characteristics when the HBC mechanism is used by an implant device.
A Body Area Network (BAN) is a wireless protocol for connectivity of wearable and implantable sen... more A Body Area Network (BAN) is a wireless protocol for connectivity of wearable and implantable sensors located inside, on the surface or near the human body. Medical applications requirements impose stringent constraints on the reliability, and quality of service (QoS) performance in these networks. Interference from other co-located BANs or nearby devices that share the same spectrum could greatly impact the communication link reliability in these networks. Link adaptation (LA) schemes can be an efficient alternative to preserve link quality in high interference environments. This paper proposes a low complexity link adaptation strategy to mitigate cross-interference in scenarios where multiple BANs are operating adjacent to each other. Each BAN is assumed to be using the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol as outlined by the IEEE 802.15.6 Standard, where different modulation schemes are available at the physical layer. Each node selects the appropriate modulation scheme based on the experienced channel quality indicated by the received Signal-to-Interference and Noise Ratio (SINR). System performance is evaluated in terms of Packet Delivery Ratio (PDR) per link. Simulation results demonstrate significant improvement in the performance and highlight potential benefits of using link adaptation schemes for BAN applications.
IEEE Access, 2023
This work involved human subjects or animals in its research. Approval of all ethical and experim... more This work involved human subjects or animals in its research. Approval of all ethical and experimental procedures and protocols was granted by Concordia University under Application No. 30013664, and NIST under Application No. ITL-2021-0273. ABSTRACT Energy harvesting (EH) is the process of capturing and storing energy from external sources or the ambient environment. The EH devices have found various emerging applications, particularly, in healthcare sector. Kinetic-based micro energy-harvesting is a promising technology that could prolong the lifetime of batteries in small wearable or implantable devices. In this paper, using a mathematical model of a Coulomb-force parametric generator, we analyze the dependency of the output power on the electrostatic force in this micro-harvester. We propose a low complexity strategy to adaptively change the electrostatic force in order to maximize the harvested power. Simulation results using the human acceleration measurements confirm the effectiveness of the proposed strategy.
A Body Area Network (BAN) is a radio standard for wireless connectivity of wearable and implantab... more A Body Area Network (BAN) is a radio standard for wireless connectivity of wearable and implantable sensor nodes that are located inside or in proximity to the human body. Many applications of BANs (e.g. physiological monitoring) require reliable communication of information between the sensor nodes and their controller. As there are currently no coordinating mechanisms among multiple co-located BANs, interference caused by co-channel transmission in adjacent BANs could impact the reliability and in general quality of the service experienced by a receiver node within an individual BAN. Here, we present a simulation platform that allows for statistical evaluation of interference in multi-BAN scenarios and performance of possible mitigation algorithms. Currently, there are no mechanisms for interfering BANs to explicitly coordinate their transmissions. As our analysis show, this may result in unacceptably high interference; and therefore, high link outage probability by the intended receiver. We propose uncoordinated approaches that could help to ease cross-interference among multiple adjacent BANs. Simulation results in our preliminary studies support the effectiveness of our approach.
Wearable medical sensors are one of the key components of remote health monitoring systems which ... more Wearable medical sensors are one of the key components of remote health monitoring systems which allow patients to stay under continuous medical supervision away from the hospital environment. These sensors are typically powered by small batteries which allow the device to operate for a limited time. Any disruption in the battery power could lead to temporary loss of vital data. Kinetic-based micro-energy-harvesting is a technology that could prolong the battery lifetime or equivalently reduce the frequency of recharge or battery replacement. Focusing on a Coulomb-Force Parametric Generator (CFPG) micro harvesting architecture, several machine learning approaches are presented in this paper to optimally tune the electrostatic force parameter; and therefore, maximize the harvested power.
IEEE802.15.6 is a radio interface standard for wireless connectivity of wearable and implantable ... more IEEE802.15.6 is a radio interface standard for wireless connectivity of wearable and implantable sensors and actuators located inside or in close proximity to the human body i.e., Body Area Network (BAN). Medical applications impose stringent requirements on BAN Quality of Service (QoS), including reliability and on-time availability of data. However, interference from other co-located BANs or other nearby devices sharing the same spectrum, e.g., due to BAN mobility, may cause unacceptable QoS degradation. This paper suggests that the impact of such QoS degradations can be minimized with a queue-size and channel quality based adaptation of the Energy Detection Threshold (EDT) at the transmitting nodes. Guided by known results for Q-CSMA/CA, we propose an adaptive EDT algorithm for use in the IEEE 802.15.6 BAN standard. Our preliminary simulation results demonstrate the performance gain of our algorithm compared to using a fixed EDT, and thus warrant future efforts in the adaptive EDT optimization as a mechanism to maintain QoS in various interference scenarios.
IEEE Internet of Things Journal, 2023
2022 IEEE Sensors, Oct 30, 2022
Wearable sensors are considered to be a key component of cognitive infocommunications systems. Th... more Wearable sensors are considered to be a key component of cognitive infocommunications systems. These sensors, which are basically enabler of inter-cognitive communication, will provide physical interfaces between humans and future information and communication technology (ICT) devices. Due to their small size, such sensors are often powered by small batteries which might necessitate frequent recharge or even sensor replacement. Energy harvesting can reduce the charging frequency of these sensors. Longer operational lifetime can simplify the everyday use of wearable sensors in many of their applications. In this paper, our objective is to estimate the average amount of kinetic energy that can be harvested to power a wearable device. To obtain this estimate, we have measured typical acceleration of the human body through the use of a triaxial accelerometer placed at various locations on the body surface. These locations are assumed to be associated with the typical placement of a wearable sensor. Using a mathematical model of a micro energy-harvester, instantaneous harvested power can be generated, and target statistics such as average can be calculated. Our results show that kinetic-based micro harvesters could be a promising technology for prolonging the operational lifetime of wearable sensors.
IEEE802.15.6 is a radio interface standard for wireless connectivity of wearable and implantable ... more IEEE802.15.6 is a radio interface standard for wireless connectivity of wearable and implantable sensors and actuators located inside or in close proximity to the human body i.e., Body Area Network (BAN). Medical applications impose stringent requirements on BAN Quality of Service (QoS), including reliability and on-time availability of the sensors data. However, interference from other co-located BANs or other nearby devices sharing the same spectrum may cause unacceptable QoS degradation. The impact of such degradations can be minimized by using adaptive schemes that intelligently adjust relevant parameters at the transmitting or receiving nodes of a BAN. This paper provides a framework for low complexity regret minimization based algorithms for Energy Detection Threshold (EDT) adaptation in the transmitter node of a BAN. The nodes are assumed to be using the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol according to the IEEE 802.15.6 BAN standard. Our preliminary simulation results demonstrate the performance gain of our algorithm compared to using a fixed EDT, and thus warrant future efforts in the adaptive EDT optimization as a mechanism to maintain QoS in various interference scenarios.
IEEE Conference Proceedings, 2016
A virtualization platform is responsible for allocation and/or aggregation of radio resources fro... more A virtualization platform is responsible for allocation and/or aggregation of radio resources from different access technologies owned by the Infrastructure Providers (InPs). It is also responsible for the distribution of the total capacity among Virtual Network Operators (VNOs). This distribution should comply with requirements specified in the Service Level Agreements (SLAs) of each VNO. The admission control process ensures adherence to the minimum service level requirements during network operation i.e. users' arrivals/departures. A joint resource management and admission control methodology is proposed in this paper that achieves optimality with respect to the aggregate system utility. The proposed approach is evaluated by simulating a sequence of scenarios with increasing number of arrivals. The results confirm maximal utilization of the available capacity in the system while all SLAs are satisfied.
IEEE Conference Proceedings, 2020
PubMed, 2014
A Body Area Network (BAN) is a wireless network of wearable or implantable computing devices. A B... more A Body Area Network (BAN) is a wireless network of wearable or implantable computing devices. A BAN typically consists of several miniaturized radio-enabled body sensor/actuator that communicate with a single coordinator. Medical applications usually impose stringent constraints on the BAN operational reliability, quality of service, and power consumption. However, as there is no coordination among multiple co-located BANs, cross-interference could make achieving these objectives a challenging problem. Assuming Time Division Multiple Access (TDMA) at each BAN, this paper investigates the ability of regret matching based transmission scheduling algorithm to ease the impact of inter-BAN interference. This scheduling algorithm uses pattern of past interference for implicit coordination between different BAN transmissions. Simulation results demonstrate potential benefits of the proposed scheme for inter-BAN interference mitigation.
Human Body Communication (HBC) is an attractive low complexity technology with promising applicat... more Human Body Communication (HBC) is an attractive low complexity technology with promising applications in wearable biomedical sensors. In this paper, a simple parametric model based on the finite-element method (FEM) using a full human body model is developed to virtually emulate and examine the HBC channel. FEM allows better modeling and quantification of the underlying physical phenomena including the impact of the human body for the desired applications. By adjusting the parameters of the model, a good match with the limited measurement results in the literature is observed. Having a flexible and customizable simulation platform could be very helpful to better understand the communication medium for capacitively coupled electrodes in HBC. This knowledge, in turn, leads to better transceiver design for given applications. The platform presented here can also be extended to study communication channel characteristics when the HBC mechanism is used by an implant device.
A Body Area Network (BAN) is a wireless protocol for connectivity of wearable and implantable sen... more A Body Area Network (BAN) is a wireless protocol for connectivity of wearable and implantable sensors located inside, on the surface or near the human body. Medical applications requirements impose stringent constraints on the reliability, and quality of service (QoS) performance in these networks. Interference from other co-located BANs or nearby devices that share the same spectrum could greatly impact the communication link reliability in these networks. Link adaptation (LA) schemes can be an efficient alternative to preserve link quality in high interference environments. This paper proposes a low complexity link adaptation strategy to mitigate cross-interference in scenarios where multiple BANs are operating adjacent to each other. Each BAN is assumed to be using the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol as outlined by the IEEE 802.15.6 Standard, where different modulation schemes are available at the physical layer. Each node selects the appropriate modulation scheme based on the experienced channel quality indicated by the received Signal-to-Interference and Noise Ratio (SINR). System performance is evaluated in terms of Packet Delivery Ratio (PDR) per link. Simulation results demonstrate significant improvement in the performance and highlight potential benefits of using link adaptation schemes for BAN applications.
IEEE Access, 2023
This work involved human subjects or animals in its research. Approval of all ethical and experim... more This work involved human subjects or animals in its research. Approval of all ethical and experimental procedures and protocols was granted by Concordia University under Application No. 30013664, and NIST under Application No. ITL-2021-0273. ABSTRACT Energy harvesting (EH) is the process of capturing and storing energy from external sources or the ambient environment. The EH devices have found various emerging applications, particularly, in healthcare sector. Kinetic-based micro energy-harvesting is a promising technology that could prolong the lifetime of batteries in small wearable or implantable devices. In this paper, using a mathematical model of a Coulomb-force parametric generator, we analyze the dependency of the output power on the electrostatic force in this micro-harvester. We propose a low complexity strategy to adaptively change the electrostatic force in order to maximize the harvested power. Simulation results using the human acceleration measurements confirm the effectiveness of the proposed strategy.
A Body Area Network (BAN) is a radio standard for wireless connectivity of wearable and implantab... more A Body Area Network (BAN) is a radio standard for wireless connectivity of wearable and implantable sensor nodes that are located inside or in proximity to the human body. Many applications of BANs (e.g. physiological monitoring) require reliable communication of information between the sensor nodes and their controller. As there are currently no coordinating mechanisms among multiple co-located BANs, interference caused by co-channel transmission in adjacent BANs could impact the reliability and in general quality of the service experienced by a receiver node within an individual BAN. Here, we present a simulation platform that allows for statistical evaluation of interference in multi-BAN scenarios and performance of possible mitigation algorithms. Currently, there are no mechanisms for interfering BANs to explicitly coordinate their transmissions. As our analysis show, this may result in unacceptably high interference; and therefore, high link outage probability by the intended receiver. We propose uncoordinated approaches that could help to ease cross-interference among multiple adjacent BANs. Simulation results in our preliminary studies support the effectiveness of our approach.
Wearable medical sensors are one of the key components of remote health monitoring systems which ... more Wearable medical sensors are one of the key components of remote health monitoring systems which allow patients to stay under continuous medical supervision away from the hospital environment. These sensors are typically powered by small batteries which allow the device to operate for a limited time. Any disruption in the battery power could lead to temporary loss of vital data. Kinetic-based micro-energy-harvesting is a technology that could prolong the battery lifetime or equivalently reduce the frequency of recharge or battery replacement. Focusing on a Coulomb-Force Parametric Generator (CFPG) micro harvesting architecture, several machine learning approaches are presented in this paper to optimally tune the electrostatic force parameter; and therefore, maximize the harvested power.
IEEE802.15.6 is a radio interface standard for wireless connectivity of wearable and implantable ... more IEEE802.15.6 is a radio interface standard for wireless connectivity of wearable and implantable sensors and actuators located inside or in close proximity to the human body i.e., Body Area Network (BAN). Medical applications impose stringent requirements on BAN Quality of Service (QoS), including reliability and on-time availability of data. However, interference from other co-located BANs or other nearby devices sharing the same spectrum, e.g., due to BAN mobility, may cause unacceptable QoS degradation. This paper suggests that the impact of such QoS degradations can be minimized with a queue-size and channel quality based adaptation of the Energy Detection Threshold (EDT) at the transmitting nodes. Guided by known results for Q-CSMA/CA, we propose an adaptive EDT algorithm for use in the IEEE 802.15.6 BAN standard. Our preliminary simulation results demonstrate the performance gain of our algorithm compared to using a fixed EDT, and thus warrant future efforts in the adaptive EDT optimization as a mechanism to maintain QoS in various interference scenarios.
IEEE Internet of Things Journal, 2023
2022 IEEE Sensors, Oct 30, 2022
Wearable sensors are considered to be a key component of cognitive infocommunications systems. Th... more Wearable sensors are considered to be a key component of cognitive infocommunications systems. These sensors, which are basically enabler of inter-cognitive communication, will provide physical interfaces between humans and future information and communication technology (ICT) devices. Due to their small size, such sensors are often powered by small batteries which might necessitate frequent recharge or even sensor replacement. Energy harvesting can reduce the charging frequency of these sensors. Longer operational lifetime can simplify the everyday use of wearable sensors in many of their applications. In this paper, our objective is to estimate the average amount of kinetic energy that can be harvested to power a wearable device. To obtain this estimate, we have measured typical acceleration of the human body through the use of a triaxial accelerometer placed at various locations on the body surface. These locations are assumed to be associated with the typical placement of a wearable sensor. Using a mathematical model of a micro energy-harvester, instantaneous harvested power can be generated, and target statistics such as average can be calculated. Our results show that kinetic-based micro harvesters could be a promising technology for prolonging the operational lifetime of wearable sensors.
IEEE802.15.6 is a radio interface standard for wireless connectivity of wearable and implantable ... more IEEE802.15.6 is a radio interface standard for wireless connectivity of wearable and implantable sensors and actuators located inside or in close proximity to the human body i.e., Body Area Network (BAN). Medical applications impose stringent requirements on BAN Quality of Service (QoS), including reliability and on-time availability of the sensors data. However, interference from other co-located BANs or other nearby devices sharing the same spectrum may cause unacceptable QoS degradation. The impact of such degradations can be minimized by using adaptive schemes that intelligently adjust relevant parameters at the transmitting or receiving nodes of a BAN. This paper provides a framework for low complexity regret minimization based algorithms for Energy Detection Threshold (EDT) adaptation in the transmitter node of a BAN. The nodes are assumed to be using the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol according to the IEEE 802.15.6 BAN standard. Our preliminary simulation results demonstrate the performance gain of our algorithm compared to using a fixed EDT, and thus warrant future efforts in the adaptive EDT optimization as a mechanism to maintain QoS in various interference scenarios.