Nima Namvar | North Carolina Agricultural and Technical State University (original) (raw)

Papers by Nima Namvar

In this paper we propose a novel context-aware approach for resource allocation in device to devi... more In this paper we propose a novel context-aware approach for resource allocation in device to device (D2D) communication networks which exploits context information about the users velocity and size of their demanded data to decide whether their traffic load can be transferred to D2D tier and which D2D users should be paired. The problem is modeled as a matching game with externalities and a novel algorithm is proposed to solve the game which converges to a stable matching between the D2D users. Simulation results demonstrate the effectiveness of our model in offloading the cellular networks traffic to the D2D tier.

The deployment of small cell networks is seen as a major feature of the next generation of wirele... more The deployment of small cell networks is seen as a major feature of the next generation of wireless networks. In this paper, a novel approach for cell association in small cell networks is proposed. The proposed approach exploits new types of information extracted from the users ’ devices and environment to improve the way in which users are assigned to their serving base stations. Examples of such context information include the devices ’ screen size and the users ’ trajectory. The problem is formulated as a matching game with externalities and a new, distributed algorithm is proposed to solve this game. The proposed algorithm is shown to reach a stable matching whose properties are studied. Simulation results show that the proposed context-aware matching approach yields significant performance gains, in terms of the average utility per user, when compared with a classical max-SINR approach.

IEEE Access, 2019

This paper develops an effective approach for the 3D deployment of a heterogeneous set of unmanne... more This paper develops an effective approach for the 3D deployment of a heterogeneous set of unmanned aerial vehicles (UAVs) acting as aerial base stations that provide maximum wireless coverage for ground users in a given geographical area. This problem is addressed in two steps. First, in order to maximize the utilization of each UAV, its optimal flight altitude is found based on the UAV’s transmit power which provides maximum coverage radius on the ground. The UAVs are classified into separate groups based on their transmit powers and optimal flight altitudes. Next, given a repository of UAVs belonging to different classes, the proposed technique finds an optimal subset of the available UAVs along with their optimal 3D placement to provide the maximum network coverage for a given area on the ground with the minimum power consumption. This optimization problem is proved to be NP-hard, for which a novel algorithm is proposed to solve the problem. Simulation results demonstrate the eff...

In this paper, a cognitive radio network is considered in which the secondary network (SN) consis... more In this paper, a cognitive radio network is considered in which the secondary network (SN) consists of a source, a buffer-aided full-duplex decode-and-forward relay, and a destination, underlaid over a primary network (PN). An imperfect self-interference (SI) cancellation is assumed at the secondary relay (SR), such that the SI power is proportional to the transmit power of the SR. For the SN with limited power expenditure, a novel joint mode selection and power allocation policy is proposed to maximize the secondary throughput under the constraints of secondary power consumption and a limited average induced interference power at the primary destination. For delay sensitive SN applications, a statistical delay constraint is imposed in which the queue length at the SR can only exceed a specified threshold with a limited probability. In the two proposed policies, the SN decides optimally when to operate in half duplex mode and/or in full duplex mode, and be silent. To avoid data loss...

Small cell networks are seen as a promising technology for bo sting the performance of future wir... more Small cell networks are seen as a promising technology for bo sting the performance of future wireless networks. In this paper, w propose a novel context-aware user-cell association approach f r small cell networks that exploits the information about the veloc ity and trajectory of the users while also taking into account their quality of service (QoS) requirements. We formulate the problem in t he framework of matching theory with externalities in which th e agents, namely users and small cell base stations (SCBSs), have stri ct interdependent preferences over the members of the opposite s et. To solve the problem, we propose a novel algorithm that leads to a stable matching among the users and SCBSs. We show that the proposed approach can better balance the traffic among the cells whi e also satisfying the QoS of the users. Simulation results sho w t at the proposed matching algorithm yields significant performanc e advantages relative to traditional context-unaware approaches .

2018 Wireless Telecommunications Symposium (WTS), Apr 1, 2018

In spite of its potential advantages, the large-scale implementation of the device-to-device (D2D... more In spite of its potential advantages, the large-scale implementation of the device-to-device (D2D) communications has yet to be realized, mainly due to severe interference and lack of enough bandwidth in the microwave (µW) band. Recently, exploiting the millimeter wave (mmW) band for D2D communications has attracted considerable attention as a potential solution to these challenges. However, its severe sensitivity to blockage along with its directional nature make the utilization of the mmW band a challenging task as it requires line-of-sight (LOS) link detection and careful beam alignment between the D2D transceivers. In this paper, we propose a novel distributed mechanism which enables the D2D devices to discover unblocked LOS links for the mmW band communication. Moreover, as such LOS links are not always available, the proposed mechanism allows the D2D devices to switch to the µW band if necessary. In addition, the proposed mechanism detects the direction of the LOS links to perform the beam alignment. We have used tools from stochastic geometry to evaluate the performance of the proposed mechanism in terms of the signal-to-interferenceplus-noise ratio (SINR) coverage probability. The performance of the proposed algorithm is then compared to the one of the single band (i.e., µW/mmW) communication. The simulation results show that the proposed mechanism considerably outperforms the single band communication.

Encyclopedia of Wireless Networks

2015 49th Annual Conference on Information Sciences and Systems (CISS), 2015