Browsing by Author "Abedi, Mohsen"

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Cellular Network Planning under Variable QoS Requirements Using Voronoi Algorithm
(2020-05) Abedi, Mohsen; Wichman, Risto
A4 Artikkeli konferenssijulkaisussa
We study the optimization of base station (BS) localization in cellular networks with non-uniform service demand distribution taking into account a variety of server-side and user-side requirements. To this end, we propose a power Voronoi algorithm (PVA) to obtain uniform traffic volume shares per cell while simultaneously meeting the user-side and server-side requirements of the heterogeneous devices. We describe a numerical method to solve the optimization problem by updating the weights associated to different cells in the PVA. Then, we take into account minimum signal to interference plus noise ratio at all devices as a user-side requirement. It is observed that BSs are concentrated in the areas with condensed demand and high SINR requirements. To show the advantages of the proposed method, the results are compared for different SINR requirement distributions giving insight on the performance of the algorithm.
Indoor Planning of Optical Wireless Networks for Line-of-Sight Condition in Access and Backhauling
(2024) Abedi, Mohsen; Dowhuszko, Alexis A.; Wichman, Risto
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Optical Wireless Communication (OWC) can complement wireless access services provided over Radio-Frequency (RF) bands by offering abundant additional unlicensed spectrum while enhancing privacy, security, and sustainability. This technology, however, requires Line-of-Sight (LoS) links with no obstructions between transmitter and receiver. In addition, the range of Visible Light Communication (VLC) forwireless access is limited to a few meters when using Light Emitting Diodes (LEDs). Hence, deploying VLC Access Points (APs) to prevent indoor coverage gaps is a challenging task. In this paper, we first characterize the VLC cell range in terms of the three-dimensional (3D) position, orientation, and parameters of the LEDs and the photodetector (PD). Secondly, we propose a graph model to represent the floor plan and, based on it, a clique clustering method that determines the minimum number of APs (and their locations) to ensure LoS coverage. Then, we transform this graph into a connectivity tree, such that the APs can communicate with each other via LoS infrared wireless. Based on our findings, the proposed deployment approach significantly outperforms conventional methods in terms of coverage area and required number of APs, improving the minimum/mean data rate of the VLC network when deployed to give service indoors.
Planning of Wireless Networks for 5G/6G Applications
(2024) Abedi, Mohsen
School of Electrical Engineering | Doctoral dissertation (article-based)
The rise of 6G will allow wireless communication networks to achieve unprecedented levels of connectivity, capacity, and coverage. As part of 6G, higher frequency bands such as mmWaves, Terahertz, and visible light can be utilized to provide larger capacity than sub-6 GHz b ands currently used in 4G/5G. However, as frequencies increase, the signal range and obstructions may limit the signal's coverage, creating a significant challenge when it comes to ensuring seamless coverage. Wireless network planning aims to determine the minimum number of wireless access points and their locations in the service areas. Planning is key to achieving seamless coverage, optimizing bandwidth utilization, reducing energy consumption, and ensuring sufficient quality of services. Planning is an NP-hard problem that requires an exhaustive search in order to reach the optimal solution. Due to the large dimensions, parameters, and diverse requirements of networks, it isimpossible to conduct an exhaustive search for network planning. It can, however, be made feasible by developing mathematical tools and optimization models. The purpose of this dissertation is to examine the issue of wireless network planning in light of the different wireless network requirements. Based on Voronoi diagrams and Delaunay triangulation, a regularity algorithm is proposed for planning wireless cellular networks that maximize coverage and balance cell loads outdoors. In addition, we propose a graph that models the indoor areas taking into account the propagation limits imposed by signals at higher frequencies. We then demonstrate that the deployment of access points for seamless Line-of-Sight coverage of indoor areas can be achieved by partitioning this graph into cliques, each representing a wireless access point. As a final step, we use this graph modeling to analyze network requirements to ensure that access points are deployed in a fashion that meets various operational requirements, for example, Line-of-Sight backhauling between access points and multiple Line-of-Sight coverage for positioning.
SWIPT-Enabled Multiple Access Channel: Effects of Decoding Cost and Non-linear EH Model
(2022-01) Nezhadmohammad, Pouria; Abedi, Mohsen; Emadi, Mohammad Javad; Wichman, Risto
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
We studied power splitting-based simultaneous wireless information and power transfer (PS-SWIPT) in multiple access channels (MAC), considering the decoding cost and non-linear energy harvesting (EH) constraints at the receiving nodes to study practical limitations of an EH communication system. Under these restrictions, we formulated and analyzed the achievable rate and maximum departure regions in two well-studied scenarios, i.e., a classical PS-SWIPT MAC and a PS-SWIPT MAC with user cooperation. In the classical PS-SWIPT MAC setting, closed-form expressions for the optimal values of the PS factors are derived for two fundamental decoding schemes: simultaneous decoding and successive interference cancellation. In the PS-SWIPT MAC with user cooperation, the joint optimal power allocation for users as well as the optimal PS factor are derived. This reveals that one decoding scheme outperforms the other in the classical PS-SWIPT MAC, depending on the function type of the decoding cost. Finally, it is shown that the cooperation between users can potentially boost the performance of a PS-SWIPT MAC under decoding cost and non-linear EH constraints. Moreover, effects of the decoding cost functions, non-linear EH model and channel quality between the users are studied, and performance characteristics of the system are discussed.
Visible Light Communications: A Novel Indoor Network Planning Approach
(2021) Abedi, Mohsen; Dowhuszko, Alexis A.; Wichman, Risto
A4 Artikkeli konferenssijulkaisussa
We propose a Partition-based Visibility (PV) graph modeling to find the minimum number of Visible Light Communications (VLC) nodes and their locations for reliable indoor coverage. VLC network offers a low-cost technology on a license-free spectrum to complement the contemporary mobile network services offered on Radio Frequency (RF) bands. However, VLC suffers from propagation limits: Firstly, in presence of opaque obstacles such as walls, doors, and even curtains, strong link blockage is experienced as the power of reflections is much weaker than the power of the Line-of-Sight (LoS) link. Secondly, the received optical power at users drops as the angle of irradiance between a LED lamp and the user increases, imposing a range constraint on the VLC nodes. So, inspired by the Art Gallery Problem, we optimize the number and the locations of VLC nodes by characterizing the PV graph as a dual presentation of the floor plan and a Maximal Clique Clustering algorithm, which is able to solve not only the art gallery problem but also to extend the approach for the range constrained case.