hossein Saidi | Isfahan University of Technology (original) (raw)

Papers by hossein Saidi

IEICE Transactions on Information and Systems, 2019

Device-to-device (D2D) communication in cellular networks is defined as direct communication betw... more Device-to-device (D2D) communication in cellular networks is defined as direct communication between two mobile users without traversing the base station (BS) or core network. D2D communication can occur on the cellular frequencies (i.e., inband) or unlicensed spectrum (i.e., outband). A high capacity IEEE 802.11-based outband device-todevice communication system for cellular networks is introduced in this paper. Transmissions in device-to-device connections are managed using our proposed medium access control (MAC) protocol. In the proposed MAC protocol, backoff window size is adjusted dynamically considering the current network status and utilizing an appropriate transmission attempt rate. We have considered both cases that the request to send/clear to send (RTS/CTS) mechanism is and is not used in our protocol design. Describing mechanisms for guaranteeing quality of service (QoS) and enhancing reliability of the system is another part of our work. Moreover, performance of the system in the presence of channel impairments is investigated analytically and through simulations. Analytical and simulation results demonstrate that our proposed system has high throughput, and it can provide different levels of QoS for its users.

Multi-constraint quality-of-service routing will become increasingly important as the Internet ev... more Multi-constraint quality-of-service routing will become increasingly important as the Internet evolves to support real-time services. It is well known however, that optimum multi-constraint QoS routing is computationally complex, and for this reason various heuristics have been proposed for routing in practical situations. Among these methods, those that use a single mixed metric are the most popular. Although mixed metric routing discards potentially useful information, this is compensated for by significantly reduced complexity. Exploiting this tradeoff is becoming increasingly important where low complexity designs are desired, such as in battery operated wireless applications. In this paper, a novel single mixed metric multi-constraint routing algorithm is introduced. The proposed technique has similar complexity compared with existing low complexity methods. Simulation results are presented which show that it can obtain better performance than comparable techniques in terms of generating feasible multi-constraint QoS routes. I.

International Journal of Ad Hoc and Ubiquitous Computing, 2015

In single channel wireless networks, concurrent transmissions at different links may interfere wi... more In single channel wireless networks, concurrent transmissions at different links may interfere with each other. To improve system throughput, a scheduling algorithm is necessary to choose a subset of links for data transmission. Throughput optimal link scheduling discipline is generally an NP-hard problem. In this paper, we utilise the concept of line graph and extend it to line multigraph to cope with the complexity issue of the maximum weight scheduling (MWS) algorithm. The necessary and sufficient conditions for reducing the complexity of MWS in terms of network topology are derived. We prove that the complexity of eLehot is polynomial time provided that conflict graph does not contain seven derived forbidden graphs as induced subgraphs. We also propose eLehot algorithm for detecting whether a graph is line multigraph and output its root graph. The results of this paper introduce a new approach in wireless topology control where the target is complexity reduction.

International Journal of Ad Hoc and Ubiquitous Computing, 2015

In single channel wireless networks, concurrent transmissions at different links may interfere wi... more In single channel wireless networks, concurrent transmissions at different links may interfere with each other. To improve system throughput, a scheduling algorithm is necessary to choose a subset of links for data transmission. Throughput optimal link scheduling discipline is generally an NP-hard problem. In this paper, we utilise the concept of line graph and extend it to line multigraph to cope with the complexity issue of the maximum weight scheduling (MWS) algorithm. The necessary and sufficient conditions for reducing the complexity of MWS in terms of network topology are derived. We prove that the complexity of eLehot is polynomial time provided that conflict graph does not contain seven derived forbidden graphs as induced subgraphs. We also propose eLehot algorithm for detecting whether a graph is line multigraph and output its root graph. The results of this paper introduce a new approach in wireless topology control where the target is complexity reduction.

2015 International Conference on Event-based Control, Communication, and Signal Processing (EBCCSP), 2015

In the past few years, as an alternative for time-triggered control, event-triggered control (ETC... more In the past few years, as an alternative for time-triggered control, event-triggered control (ETC) has been investigated for networked control systems (NCS). ETC is a control strategy where the control algorithm is executed only when a special condition is satisfied. In this paper, a solution to find an appropriate bandwidth for event-based control systems over wireless networks is proposed. Moreover, it is shown how the delay bound of network can be affected by control system. These two results are achieved by applying network calculus theorem to a control system. For efficient use of network resources, a new triggering algorithm is proposed. An advantage of proposed algorithm is that the minimum time between two consecutive events is considered as a designable control parameter and it can guarantee a lower bound on input traffic to the network. An illustrative case study of a NCS based on IEEE 802.15.4 protocol is presented to show the effectiveness of the proposed event-triggered algorithm and investigate the effect of bandwidth allocation on NCS.

IEEE Transactions on Wireless Communications, 2017

In this paper, the problem of random access contention between machine type devices (MTDs) in the... more In this paper, the problem of random access contention between machine type devices (MTDs) in the uplink of a wireless cellular network is studied. In particular, the possibility of forming cooperative groups to coordinate the MTDs' requests for the random access channel (RACH) is analyzed. The problem is formulated as a stochastic coalition formation game in which the MTDs are the players that seek to form cooperative coalitions to optimize a utility function that captures each MTD's energy consumption and time-varying queue length. Within each coalition, an MTD acts as a coalition head that sends the access requests of the coalition members over the RACH. One key feature of this game is its ability to cope with stochastic environments in which the arrival requests of MTDs and the packet success rate over RACH are dynamically time-varying. The proposed stochastic coalitional is composed of multiple stages, each of which corresponds to a coalitional game in stochastic characteristic form that is played by the MTDs at each time step. To solve this game, a novel distributed coalition formation algorithm is proposed and shown to converge to a stable MTD partition. Simulation results show that, on the average, the proposed stochastic coalition formation algorithm can reduce the average fail ratio and energy consumption of up to 36% and 31% for a cluster-based distribution of MTDs, respectively, compared to a noncooperative case. Moreover, when the MTDs are more sensitive to the energy consumption (queue length), the coalitions' size will increase (decrease).

IEEE Access, 2020

Low-power Wireless Sensor Networks (WSNs) play a key role in realization of the Internet-of-Thing... more Low-power Wireless Sensor Networks (WSNs) play a key role in realization of the Internet-of-Things (IoT). Among others, Time Slotted Channel Hopping (TSCH) is a Medium Access Control (MAC) operational mode of the IEEE 802.15.4 standard developed for communications in short range IoT networks. TSCH provides high level reliability and predictability by its channel hopping mechanism and time division channel access nature. In many applications, a number of TSCH networks may coexist in the same neighborhood. Several vehicles close to one another, each including a TSCH network for its in-vehicle communications, serve as an example. Since such networks are running independent of one another, they are not expected to be synchronized in time, and they are not scheduled to operate in exclusive frequency channels. This may lead to inter-TSCH interferences deteriorating the reliability of the networks, which is an important requirement for many IoT applications. This paper analyzes the impact of multiple asynchronous TSCH networks on one another. An analytical model is developed that estimates the chance of such interferences, and the expectation of the number of affected TSCH channels when a number of them are in the vicinity of one another. The developed model is verified using extensive simulations and real-world experiments. Also, a scalable and fast multi-TSCH coexistence simulator is developed that is used to get insight about coexistence behaviors of any number of TSCH networks with various configurations. INDEX TERMS Internet-of-Things, wireless sensor networks, coexistence, IEEE 802.15.4, TSCH. I. INTRODUCTION As a major building block of the Internet-of-Things (IoT), a number of low-power wireless devices communicate with one another to sense and deliver sensor data, forming a Wireless Sensor Network (WSN). The IEEE 802.15.4 [1] standard is one of the most widely used communication technologies in WSNs, providing the physical and Medium Access Control (MAC) layers' specifications. This standard operates in the unlicensed 2.4 GHz ISM frequency band and is basically designed for low-power, low-cost, and low data rate applications. Time Slotted Channel Hopping (TSCH) is one of the MAC operational modes of this standard, which is mainly developed for industrial applications in which higher communication reliability and predictability is required. The main features of this mode are the use of Time Division Multiple Access (TDMA) together with a frequency channel hopping. The TDMA mechanism of TSCH makes the communications more efficient and predictable by avoiding The associate editor coordinating the review of this manuscript and approving it for publication was Hongwei Du.

Journal of Network and Computer Applications, 2017

Software Defined Networking paves the way for simplifying network management. This is achieved th... more Software Defined Networking paves the way for simplifying network management. This is achieved through the separation of control plane and data plane in a network. In Software Defined Networks (SDN), the network control functions are removed from the data forwarding nodes and placed into a logically centralized controller. So, these functions can be updated with a cost of a simple software change and without any changes in the hardware modules. But an important question arises about the performance of SDNs. This question becomes more serious regarding the central control unit as a probable obstacle to the scalability of SDNs. To have a precise image of this problem, in this paper an analytical model is provided for SDNs implemented based on pure OpenFlow standard. This model which is based on the network calculus framework, computes the worst case delay bound of such SDNs. The delay bound is estimated according to the similarities between the caches and flow tables in OpenFlow switches. The results show the interaction of different parameters such as network size, flow table size, traffic characteristics and the delay of SDNs. This can be used to evaluate SDN prototypes in the early stages of the design phase. Also, it affirms the importance of proposing scalable architectures for SDNs, such as deploying distributed controllers. Additionally, some points about using distributed controllers are discussed based on the provided results.

Multi-channel switching has been suggested as a means of alleviating the speed limitation of the ... more Multi-channel switching has been suggested as a means of alleviating the speed limitation of the electronics in broadband networks. The processing speed of electronic switches, which run at a substantially slower rate compared with lightwave transmission technology, is a natural bottleneck; this disparity is likely to worsen in the coming years. By exploiting the concept of channel grouping, multi-channel switches can provide higher performance and reduced hardware complexity. The proposed thesis work is one of the first comprehensive studies in multi-channel switching. Some nonblocking conditions for multi-channel switching are characterized, along with crosspoint and control complexities. Assuming the broadband communication environment using ATM technology, potential benefits of multi-channel switching over traditional point-to-point switching are analyzed. Performance objectives in multi-channel switches are determined and implementable multi-channel switching architectures that satisfy the objectives are presented. A comprehensive study of the efficacy of the proposed architectures is conducted. At the conclusion of this thesis, we hope to have ignited interest in multi-channel switching within the broadband communication community by suggesting methods to alleviate the bottleneck in the processing speed of electronic switches and by proposing simple, inexpensive switching architectures that can support very high bandwidth in ATM networks.

2019 IEEE Wireless Communications and Networking Conference (WCNC)

Wireless Body Area Networks (WBANs) have made their way into many smart and ubiquitous healthcare... more Wireless Body Area Networks (WBANs) have made their way into many smart and ubiquitous healthcare and wellness applications. A low-power, efficient, and reliable communication protocol is of paramount importance for the success of WBANs in satisfying the requirements of the health applications. The IEEE 802.15.4 standard is always one of the main options due to its efficiency and low-complexity. However, it suffers from the impact of other wireless technologies using the same frequency band such as WiFi and Bluetooth. Time Slotted Channel Hoping (TSCH) is an operational mode of the IEEE 802.15.4e standard, which is originally developed for reliable industrial wireless networks. TSCH has Time Division Multiple Access (TDMA) and frequency hopping features, which increase the network robustness against effects such as noise, interference, and multi-path fading. This paper proposes to exploit TSCH for communications in WBANs, and studies its performance. The features of TSCH like power efficiency, TDMA-based operation, and heterogeneity support fit very well with the requirements of many health monitoring applications. The performance of the TSCH standard for WBAN communications is investigated through real-world experiments in various conditions. The results show that TSCH outperforms the basic IEEE 802.15.4 standard in terms of communication reliability against interferences from coexisting wireless devices.

In this paper we introduced two types of common household demand, time limited and controlling de... more In this paper we introduced two types of common household demand, time limited and controlling demands. In this model based on the idea of mutual interaction between these two demands, we propose a new model for home load management. After assigning an innovative concave utility-function model for each demand, we change the common method of summing up the individual utility-functions with multiplication. The introduced model is developed as an MINLP problem that can be successfully handled by available commercial software. The analysis of the numerical examples indicates that they are acceptable in terms of optimality and compliance with actual conditions in human experience.

2016 IEEE Globecom Workshops (GC Wkshps), 2016

In this paper, a novel framework for power-efficient, cluster-based machine-to-machine (M2M) comm... more In this paper, a novel framework for power-efficient, cluster-based machine-to-machine (M2M) communications is proposed. In the studied model, a number of unmanned aerial vehicles (UAVs) are used as aerial base stations to collect data from the cluster heads (CHs) of a set of M2M clusters. To minimize the CHs' transmit power while satisfying the rate requirements of M2M devices, an optimal scheduling and resource allocation mechanism for CH-UAV communications is proposed. First, using the queue rate stability concept, the minimum number of UAVs as well as the dwelling time that each UAV must spend for servicing the CHs are computed. Next, the optimal resource allocation for the CH-UAV communication links is determined such that M2M devices rate requirements are satisfied with a minimum transmit power. Simulation results show that, as the packet transmission probability of machines increases, the minimum number of UAVs required to guarantee the queue rate stability of CHs will also significantly increase. Our results also show that, compared to a case with pre-deployed terrestrial base stations, the average transmit power of CHs will decrease by 68% when UAVs are used.

2016 Annual Conference on Information Science and Systems (CISS), 2016

In a device-to-device (D2D) local area network (LAN), mobile users (MUs) must cooperate to downlo... more In a device-to-device (D2D) local area network (LAN), mobile users (MUs) must cooperate to download common real-time content from a wireless cellular network. However, sustaining such D2D LANs over cellular networks requires the introduction of mechanisms that will incentivize the MUs to cooperate. In this paper, the problem of energy-aware D2D LAN formation over cellular networks is studied. The problem is formulated using a game-theoretic framework in which each MU seeks to minimize its energy consumption while actively participating in the D2D LAN. To account for the selfish behavior of the MUs, a punishment and incentive protocol is proposed in order to ensure cooperation among MUs. Within this protocol, an estimation algorithm is proposed to simulate the process of D2D LAN formation and, then, adjust the mechanism parameters to maintain cooperation. Simulation results show that the proposed framework can improve energy efficiency up to 36% relative to the traditional multicast scenario.

2015 23rd Iranian Conference on Electrical Engineering, 2015

Software Defined Networks (SDN) are proposed as a new solution to facilitate dealing with some ma... more Software Defined Networks (SDN) are proposed as a new solution to facilitate dealing with some major network management issues. Just like other networks, SDNs are considered as a communication resource which can be shared between several tenants. However several virtualization solutions are proposed in the past to provide necessary mechanisms to slice SDN between several virtual networks, but virtualizing SDN can cause some performance degradation issues (e.g., additional packet forwarding latency). In this paper a novel network calculus based analytical model is proposed to get the upper bounds on some performance parameters of virtualized SDNs.

ABSTRACT Wireless sensor networks are widely used in many application domains. One of the well-kn... more ABSTRACT Wireless sensor networks are widely used in many application domains. One of the well-known applications of such networks is tracking of moving objects. In this paper we propose a novel algorithm in which head and members of next clusters are chosen and woken up dynamically by the current active cluster head in a grid network of wireless sensors. This dynamic algorithm is designed for target tracking applications. The proposed solution is a distributed clustering scheme, in which, head and cluster members of the next cluster are selected cooperatively. Based on the distributed solution, a semi-localized clustering scheme is also presented. Moreover, a distributed target movement history recording algorithm is proposed to reduce target misses. Simulation results show that by using the proposed method, there are significant reductions in the average number of received messages, averaged number of sent messages, and average number of samplings of the sensing subsystem. In addition, a meaningful reduction in target miss rate is achieved by using distributed target movement recording algorithm.

2011 1st International eConference on Computer and Knowledge Engineering (ICCKE), 2011

ABSTRACT In the past decade, several efforts have been taken to develop efficient yet low complex... more ABSTRACT In the past decade, several efforts have been taken to develop efficient yet low complexity link scheduling algorithms to achieve the entire or a fraction of throughput region in wireless networks. In this paper we study delay property of the throughput optimal maximum weight link scheduling algorithm. Specifically, the impact of Edge-Chromatic number of the network graph on average delay of the packets is derived analytically. The results of this paper show that how bound of average delay is affected by network topology in the order sense. Simulation results confirm our analytical findings.

ArXiv, 2012

In single channel wireless networks, concurrent transmission at different links may interfere wit... more In single channel wireless networks, concurrent transmission at different links may interfere with each other. To improve system throughput, a scheduling algorithm is necessary to choose a subset of links at each time slot for data trasmission. Throughput optimal link scheduling discipline in such a wireless network is generally an NP-hard problem. In this paper, we develop a poylnomial time algorithm for link scheduling problem provided that network conflict graph is line multigraph. (i.e. line graph for which its root graph is multigraph). This result can be a guideline for network designers to plan the topology of a stationary wireless network such that the required conditions hold and then the throughput optimal algorithm can be run in a much less time.

Abstract. Due to the increasing size of IP routing table and the growing rate of their lookups, m... more Abstract. Due to the increasing size of IP routing table and the growing rate of their lookups, many algorithms are introduced to achieve the required speed in table search and update or optimizing the required memory size. Many of these algorithms are suitable for IPv4 but cannot be used for IPv6. Nevertheless new efforts are going on to fit the available algorithms and techniques to the IPv6 128 bits addresses and prefixes. The challenging issues in the design of these prefix search structures are minimizing the worst case memory access, processing and pre-processing time for search and update procedures, e.g. Binary Tries have a worst case performance of O(32) memory accesses for IPv4 and O(128) for IPv6. Other compressed Tries have better worst case lookup performance however their update performance is degraded. One of the proposed schemes to make the lookup algorithm independent of IP address length is to use a binary search tree and keep the prefix endpoints within its nodes....

IEICE Transactions on Information and Systems, 2019

Device-to-device (D2D) communication in cellular networks is defined as direct communication betw... more Device-to-device (D2D) communication in cellular networks is defined as direct communication between two mobile users without traversing the base station (BS) or core network. D2D communication can occur on the cellular frequencies (i.e., inband) or unlicensed spectrum (i.e., outband). A high capacity IEEE 802.11-based outband device-todevice communication system for cellular networks is introduced in this paper. Transmissions in device-to-device connections are managed using our proposed medium access control (MAC) protocol. In the proposed MAC protocol, backoff window size is adjusted dynamically considering the current network status and utilizing an appropriate transmission attempt rate. We have considered both cases that the request to send/clear to send (RTS/CTS) mechanism is and is not used in our protocol design. Describing mechanisms for guaranteeing quality of service (QoS) and enhancing reliability of the system is another part of our work. Moreover, performance of the system in the presence of channel impairments is investigated analytically and through simulations. Analytical and simulation results demonstrate that our proposed system has high throughput, and it can provide different levels of QoS for its users.

Multi-constraint quality-of-service routing will become increasingly important as the Internet ev... more Multi-constraint quality-of-service routing will become increasingly important as the Internet evolves to support real-time services. It is well known however, that optimum multi-constraint QoS routing is computationally complex, and for this reason various heuristics have been proposed for routing in practical situations. Among these methods, those that use a single mixed metric are the most popular. Although mixed metric routing discards potentially useful information, this is compensated for by significantly reduced complexity. Exploiting this tradeoff is becoming increasingly important where low complexity designs are desired, such as in battery operated wireless applications. In this paper, a novel single mixed metric multi-constraint routing algorithm is introduced. The proposed technique has similar complexity compared with existing low complexity methods. Simulation results are presented which show that it can obtain better performance than comparable techniques in terms of generating feasible multi-constraint QoS routes. I.

International Journal of Ad Hoc and Ubiquitous Computing, 2015

In single channel wireless networks, concurrent transmissions at different links may interfere wi... more In single channel wireless networks, concurrent transmissions at different links may interfere with each other. To improve system throughput, a scheduling algorithm is necessary to choose a subset of links for data transmission. Throughput optimal link scheduling discipline is generally an NP-hard problem. In this paper, we utilise the concept of line graph and extend it to line multigraph to cope with the complexity issue of the maximum weight scheduling (MWS) algorithm. The necessary and sufficient conditions for reducing the complexity of MWS in terms of network topology are derived. We prove that the complexity of eLehot is polynomial time provided that conflict graph does not contain seven derived forbidden graphs as induced subgraphs. We also propose eLehot algorithm for detecting whether a graph is line multigraph and output its root graph. The results of this paper introduce a new approach in wireless topology control where the target is complexity reduction.

International Journal of Ad Hoc and Ubiquitous Computing, 2015

In single channel wireless networks, concurrent transmissions at different links may interfere wi... more In single channel wireless networks, concurrent transmissions at different links may interfere with each other. To improve system throughput, a scheduling algorithm is necessary to choose a subset of links for data transmission. Throughput optimal link scheduling discipline is generally an NP-hard problem. In this paper, we utilise the concept of line graph and extend it to line multigraph to cope with the complexity issue of the maximum weight scheduling (MWS) algorithm. The necessary and sufficient conditions for reducing the complexity of MWS in terms of network topology are derived. We prove that the complexity of eLehot is polynomial time provided that conflict graph does not contain seven derived forbidden graphs as induced subgraphs. We also propose eLehot algorithm for detecting whether a graph is line multigraph and output its root graph. The results of this paper introduce a new approach in wireless topology control where the target is complexity reduction.

2015 International Conference on Event-based Control, Communication, and Signal Processing (EBCCSP), 2015

In the past few years, as an alternative for time-triggered control, event-triggered control (ETC... more In the past few years, as an alternative for time-triggered control, event-triggered control (ETC) has been investigated for networked control systems (NCS). ETC is a control strategy where the control algorithm is executed only when a special condition is satisfied. In this paper, a solution to find an appropriate bandwidth for event-based control systems over wireless networks is proposed. Moreover, it is shown how the delay bound of network can be affected by control system. These two results are achieved by applying network calculus theorem to a control system. For efficient use of network resources, a new triggering algorithm is proposed. An advantage of proposed algorithm is that the minimum time between two consecutive events is considered as a designable control parameter and it can guarantee a lower bound on input traffic to the network. An illustrative case study of a NCS based on IEEE 802.15.4 protocol is presented to show the effectiveness of the proposed event-triggered algorithm and investigate the effect of bandwidth allocation on NCS.

IEEE Transactions on Wireless Communications, 2017

In this paper, the problem of random access contention between machine type devices (MTDs) in the... more In this paper, the problem of random access contention between machine type devices (MTDs) in the uplink of a wireless cellular network is studied. In particular, the possibility of forming cooperative groups to coordinate the MTDs' requests for the random access channel (RACH) is analyzed. The problem is formulated as a stochastic coalition formation game in which the MTDs are the players that seek to form cooperative coalitions to optimize a utility function that captures each MTD's energy consumption and time-varying queue length. Within each coalition, an MTD acts as a coalition head that sends the access requests of the coalition members over the RACH. One key feature of this game is its ability to cope with stochastic environments in which the arrival requests of MTDs and the packet success rate over RACH are dynamically time-varying. The proposed stochastic coalitional is composed of multiple stages, each of which corresponds to a coalitional game in stochastic characteristic form that is played by the MTDs at each time step. To solve this game, a novel distributed coalition formation algorithm is proposed and shown to converge to a stable MTD partition. Simulation results show that, on the average, the proposed stochastic coalition formation algorithm can reduce the average fail ratio and energy consumption of up to 36% and 31% for a cluster-based distribution of MTDs, respectively, compared to a noncooperative case. Moreover, when the MTDs are more sensitive to the energy consumption (queue length), the coalitions' size will increase (decrease).

IEEE Access, 2020

Low-power Wireless Sensor Networks (WSNs) play a key role in realization of the Internet-of-Thing... more Low-power Wireless Sensor Networks (WSNs) play a key role in realization of the Internet-of-Things (IoT). Among others, Time Slotted Channel Hopping (TSCH) is a Medium Access Control (MAC) operational mode of the IEEE 802.15.4 standard developed for communications in short range IoT networks. TSCH provides high level reliability and predictability by its channel hopping mechanism and time division channel access nature. In many applications, a number of TSCH networks may coexist in the same neighborhood. Several vehicles close to one another, each including a TSCH network for its in-vehicle communications, serve as an example. Since such networks are running independent of one another, they are not expected to be synchronized in time, and they are not scheduled to operate in exclusive frequency channels. This may lead to inter-TSCH interferences deteriorating the reliability of the networks, which is an important requirement for many IoT applications. This paper analyzes the impact of multiple asynchronous TSCH networks on one another. An analytical model is developed that estimates the chance of such interferences, and the expectation of the number of affected TSCH channels when a number of them are in the vicinity of one another. The developed model is verified using extensive simulations and real-world experiments. Also, a scalable and fast multi-TSCH coexistence simulator is developed that is used to get insight about coexistence behaviors of any number of TSCH networks with various configurations. INDEX TERMS Internet-of-Things, wireless sensor networks, coexistence, IEEE 802.15.4, TSCH. I. INTRODUCTION As a major building block of the Internet-of-Things (IoT), a number of low-power wireless devices communicate with one another to sense and deliver sensor data, forming a Wireless Sensor Network (WSN). The IEEE 802.15.4 [1] standard is one of the most widely used communication technologies in WSNs, providing the physical and Medium Access Control (MAC) layers' specifications. This standard operates in the unlicensed 2.4 GHz ISM frequency band and is basically designed for low-power, low-cost, and low data rate applications. Time Slotted Channel Hopping (TSCH) is one of the MAC operational modes of this standard, which is mainly developed for industrial applications in which higher communication reliability and predictability is required. The main features of this mode are the use of Time Division Multiple Access (TDMA) together with a frequency channel hopping. The TDMA mechanism of TSCH makes the communications more efficient and predictable by avoiding The associate editor coordinating the review of this manuscript and approving it for publication was Hongwei Du.

Journal of Network and Computer Applications, 2017

Software Defined Networking paves the way for simplifying network management. This is achieved th... more Software Defined Networking paves the way for simplifying network management. This is achieved through the separation of control plane and data plane in a network. In Software Defined Networks (SDN), the network control functions are removed from the data forwarding nodes and placed into a logically centralized controller. So, these functions can be updated with a cost of a simple software change and without any changes in the hardware modules. But an important question arises about the performance of SDNs. This question becomes more serious regarding the central control unit as a probable obstacle to the scalability of SDNs. To have a precise image of this problem, in this paper an analytical model is provided for SDNs implemented based on pure OpenFlow standard. This model which is based on the network calculus framework, computes the worst case delay bound of such SDNs. The delay bound is estimated according to the similarities between the caches and flow tables in OpenFlow switches. The results show the interaction of different parameters such as network size, flow table size, traffic characteristics and the delay of SDNs. This can be used to evaluate SDN prototypes in the early stages of the design phase. Also, it affirms the importance of proposing scalable architectures for SDNs, such as deploying distributed controllers. Additionally, some points about using distributed controllers are discussed based on the provided results.

Multi-channel switching has been suggested as a means of alleviating the speed limitation of the ... more Multi-channel switching has been suggested as a means of alleviating the speed limitation of the electronics in broadband networks. The processing speed of electronic switches, which run at a substantially slower rate compared with lightwave transmission technology, is a natural bottleneck; this disparity is likely to worsen in the coming years. By exploiting the concept of channel grouping, multi-channel switches can provide higher performance and reduced hardware complexity. The proposed thesis work is one of the first comprehensive studies in multi-channel switching. Some nonblocking conditions for multi-channel switching are characterized, along with crosspoint and control complexities. Assuming the broadband communication environment using ATM technology, potential benefits of multi-channel switching over traditional point-to-point switching are analyzed. Performance objectives in multi-channel switches are determined and implementable multi-channel switching architectures that satisfy the objectives are presented. A comprehensive study of the efficacy of the proposed architectures is conducted. At the conclusion of this thesis, we hope to have ignited interest in multi-channel switching within the broadband communication community by suggesting methods to alleviate the bottleneck in the processing speed of electronic switches and by proposing simple, inexpensive switching architectures that can support very high bandwidth in ATM networks.

2019 IEEE Wireless Communications and Networking Conference (WCNC)

Wireless Body Area Networks (WBANs) have made their way into many smart and ubiquitous healthcare... more Wireless Body Area Networks (WBANs) have made their way into many smart and ubiquitous healthcare and wellness applications. A low-power, efficient, and reliable communication protocol is of paramount importance for the success of WBANs in satisfying the requirements of the health applications. The IEEE 802.15.4 standard is always one of the main options due to its efficiency and low-complexity. However, it suffers from the impact of other wireless technologies using the same frequency band such as WiFi and Bluetooth. Time Slotted Channel Hoping (TSCH) is an operational mode of the IEEE 802.15.4e standard, which is originally developed for reliable industrial wireless networks. TSCH has Time Division Multiple Access (TDMA) and frequency hopping features, which increase the network robustness against effects such as noise, interference, and multi-path fading. This paper proposes to exploit TSCH for communications in WBANs, and studies its performance. The features of TSCH like power efficiency, TDMA-based operation, and heterogeneity support fit very well with the requirements of many health monitoring applications. The performance of the TSCH standard for WBAN communications is investigated through real-world experiments in various conditions. The results show that TSCH outperforms the basic IEEE 802.15.4 standard in terms of communication reliability against interferences from coexisting wireless devices.

In this paper we introduced two types of common household demand, time limited and controlling de... more In this paper we introduced two types of common household demand, time limited and controlling demands. In this model based on the idea of mutual interaction between these two demands, we propose a new model for home load management. After assigning an innovative concave utility-function model for each demand, we change the common method of summing up the individual utility-functions with multiplication. The introduced model is developed as an MINLP problem that can be successfully handled by available commercial software. The analysis of the numerical examples indicates that they are acceptable in terms of optimality and compliance with actual conditions in human experience.

2016 IEEE Globecom Workshops (GC Wkshps), 2016

In this paper, a novel framework for power-efficient, cluster-based machine-to-machine (M2M) comm... more In this paper, a novel framework for power-efficient, cluster-based machine-to-machine (M2M) communications is proposed. In the studied model, a number of unmanned aerial vehicles (UAVs) are used as aerial base stations to collect data from the cluster heads (CHs) of a set of M2M clusters. To minimize the CHs' transmit power while satisfying the rate requirements of M2M devices, an optimal scheduling and resource allocation mechanism for CH-UAV communications is proposed. First, using the queue rate stability concept, the minimum number of UAVs as well as the dwelling time that each UAV must spend for servicing the CHs are computed. Next, the optimal resource allocation for the CH-UAV communication links is determined such that M2M devices rate requirements are satisfied with a minimum transmit power. Simulation results show that, as the packet transmission probability of machines increases, the minimum number of UAVs required to guarantee the queue rate stability of CHs will also significantly increase. Our results also show that, compared to a case with pre-deployed terrestrial base stations, the average transmit power of CHs will decrease by 68% when UAVs are used.

2016 Annual Conference on Information Science and Systems (CISS), 2016

In a device-to-device (D2D) local area network (LAN), mobile users (MUs) must cooperate to downlo... more In a device-to-device (D2D) local area network (LAN), mobile users (MUs) must cooperate to download common real-time content from a wireless cellular network. However, sustaining such D2D LANs over cellular networks requires the introduction of mechanisms that will incentivize the MUs to cooperate. In this paper, the problem of energy-aware D2D LAN formation over cellular networks is studied. The problem is formulated using a game-theoretic framework in which each MU seeks to minimize its energy consumption while actively participating in the D2D LAN. To account for the selfish behavior of the MUs, a punishment and incentive protocol is proposed in order to ensure cooperation among MUs. Within this protocol, an estimation algorithm is proposed to simulate the process of D2D LAN formation and, then, adjust the mechanism parameters to maintain cooperation. Simulation results show that the proposed framework can improve energy efficiency up to 36% relative to the traditional multicast scenario.

2015 23rd Iranian Conference on Electrical Engineering, 2015

Software Defined Networks (SDN) are proposed as a new solution to facilitate dealing with some ma... more Software Defined Networks (SDN) are proposed as a new solution to facilitate dealing with some major network management issues. Just like other networks, SDNs are considered as a communication resource which can be shared between several tenants. However several virtualization solutions are proposed in the past to provide necessary mechanisms to slice SDN between several virtual networks, but virtualizing SDN can cause some performance degradation issues (e.g., additional packet forwarding latency). In this paper a novel network calculus based analytical model is proposed to get the upper bounds on some performance parameters of virtualized SDNs.

ABSTRACT Wireless sensor networks are widely used in many application domains. One of the well-kn... more ABSTRACT Wireless sensor networks are widely used in many application domains. One of the well-known applications of such networks is tracking of moving objects. In this paper we propose a novel algorithm in which head and members of next clusters are chosen and woken up dynamically by the current active cluster head in a grid network of wireless sensors. This dynamic algorithm is designed for target tracking applications. The proposed solution is a distributed clustering scheme, in which, head and cluster members of the next cluster are selected cooperatively. Based on the distributed solution, a semi-localized clustering scheme is also presented. Moreover, a distributed target movement history recording algorithm is proposed to reduce target misses. Simulation results show that by using the proposed method, there are significant reductions in the average number of received messages, averaged number of sent messages, and average number of samplings of the sensing subsystem. In addition, a meaningful reduction in target miss rate is achieved by using distributed target movement recording algorithm.

2011 1st International eConference on Computer and Knowledge Engineering (ICCKE), 2011

ABSTRACT In the past decade, several efforts have been taken to develop efficient yet low complex... more ABSTRACT In the past decade, several efforts have been taken to develop efficient yet low complexity link scheduling algorithms to achieve the entire or a fraction of throughput region in wireless networks. In this paper we study delay property of the throughput optimal maximum weight link scheduling algorithm. Specifically, the impact of Edge-Chromatic number of the network graph on average delay of the packets is derived analytically. The results of this paper show that how bound of average delay is affected by network topology in the order sense. Simulation results confirm our analytical findings.

ArXiv, 2012

In single channel wireless networks, concurrent transmission at different links may interfere wit... more In single channel wireless networks, concurrent transmission at different links may interfere with each other. To improve system throughput, a scheduling algorithm is necessary to choose a subset of links at each time slot for data trasmission. Throughput optimal link scheduling discipline in such a wireless network is generally an NP-hard problem. In this paper, we develop a poylnomial time algorithm for link scheduling problem provided that network conflict graph is line multigraph. (i.e. line graph for which its root graph is multigraph). This result can be a guideline for network designers to plan the topology of a stationary wireless network such that the required conditions hold and then the throughput optimal algorithm can be run in a much less time.

Abstract. Due to the increasing size of IP routing table and the growing rate of their lookups, m... more Abstract. Due to the increasing size of IP routing table and the growing rate of their lookups, many algorithms are introduced to achieve the required speed in table search and update or optimizing the required memory size. Many of these algorithms are suitable for IPv4 but cannot be used for IPv6. Nevertheless new efforts are going on to fit the available algorithms and techniques to the IPv6 128 bits addresses and prefixes. The challenging issues in the design of these prefix search structures are minimizing the worst case memory access, processing and pre-processing time for search and update procedures, e.g. Binary Tries have a worst case performance of O(32) memory accesses for IPv4 and O(128) for IPv6. Other compressed Tries have better worst case lookup performance however their update performance is degraded. One of the proposed schemes to make the lookup algorithm independent of IP address length is to use a binary search tree and keep the prefix endpoints within its nodes....