arXiv subjects

Sanaa Hamid Mohamed

Publications and source records attributed to Sanaa Hamid Mohamed.

At least 19 recordsLinked to original sources

arXiv2026

Energy-Efficient Joint Optimization of VLC and Fog Computing Resources Allocation

In this paper, we consider an indoor networking architecture in which visible light communication (VLC) provides wireless connectivity between users and distributed fog computing resources and an energy-efficient passive optical network (PON)- based backhaul interconnects the VLC access points (APs). We investigate the joint optimization of the allocation of VLC and fog computing resources aiming to minimize processing and networking power consumption. We develop a mixed-integer linear programming (MILP) model that jointly optimizes access points (APs) selection, wavelength assignment and fog computing resources allocation to serve the requests of users. Compared to a statically preconfigured AP selection and wavelength assignment based on maximizing signal-to-interference-plus-noise ratio (SINR) independently of fog resource placement, the joint optimization achieves lower average total power consumption, driven by a reduction in processing power. These savings are attributed to the ability of the joint optimization to allow AP sharing across users and selecting more energy-efficient wavelengths that still satisfy quality of service (QoS) requirements.

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arXiv2026

Energy Efficient Point-to-Point PON-based Architecture for the Backhaul of a VLC System

This paper proposes a point-to-point passive optical network (P2P-PON) architecture as an energy-efficient and low-latency backhaul solution for visible light communication (VLC)-enabled indoor fog computing systems. The proposed architecture passively interconnects VLC access points and distributed in-building fog servers through dedicated optical links, enabling flexible peer-to-peer connectivity and efficient traffic aggregation. A mixed integer linear programming (MILP) framework is developed to jointly optimize processing resource allocation, traffic routing, power consumption, and end-to-end queuing delay across a multi-layer fog computing infrastructure. The model explicitly captures the power consumption of both networking and processing elements and incorporates a piecewise linear approximation of an M/M/1 queuing model to represent delay-sensitive applications. The performance of the proposed P2P-PON architecture is evaluated and compared against an arrayed waveguide grating router (AWGR)-based PON architecture under multiple indoor traffic scenarios. The results show that the proposed P2P-PON architecture reduces total power consumption by up to 64\% under power-aware optimization and by 15\% under delay-aware optimization, while reducing average end-to-end queuing delay by up to 76\% compared to the AWGR-PON architecture, due to the improved in-building connectivity and more effective utilization of distributed fog resources.

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arXiv2025

Energy-efficient PON-based Backhaul Connectivity for a VLC-enabled Indoor Fog Computing Environment

In this paper, we consider the use of visible light communication (VLC) to provide connectivity to indoor fog computing resources and propose an energy-efficient passive optical network (PON)-based backhaul architecture to support the VLC system. We develop a mixed-integer linear programming (MILP) model to optimize the allocation of computing resources over the proposed architecture, aiming to minimize processing and networking power consumption. We evaluate the performance of the proposed architecture under varying workload demands and user distributions. Comparative analysis against a backhaul architecture that is based on the state-of-the-art spine-and-leaf (S&L) network design demonstrates total power savings of up to 82%. Further comparison with centralized cloud processing shows improvements in energy efficiency of up to 93%. Additionally, we examine the improvements in energy efficiency obtained by splitting tasks among multiple processing nodes and propose enhancements to the architecture including dynamic bandwidth allocation, increased wavelength bandwidth and improved connectivity within rooms to alleviate networking bottlenecks. Furthermore, we introduce an inter-building architecture that leverages resources from neighboring buildings to support high-demand scenarios.

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arXiv2021

Resilient Architectures for Free Space Optical Wireless Interconnection Systems

In this paper, we propose the use of two Passive Optical Network (PON)-based network architectures to connect free-space Optical Wireless Communication (OWC) Access Points (APs) within a room with multiple users. We optimize through a Mixed Linear Integer Programming (MILP) model the assignment of mobile OWC users to more than one AP to improve the resilience of the fronthaul network, i.e the OWC system and the wired network linked to APs, and study the impact of users distribution and channel characteristics.

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arXiv2020

Optimizing Co-flows Scheduling and Routing in Data Centre Networks for Big Data Applications

This paper optimizes the scheduling and routing of the co-flows of MapReduce shuffling phase in state-of-the-art and proposed Passive Optical Networking (PON)-based Data Centre Network (DCN) architectures. A time-slotted Mixed Integer Linear Programming (MILP) model is developed and used for the optimization with the objective of minimizing either the total energy consumption or the completion time. The DCN architectures include four state-of-the-art electronic switching architectures which are spine-leaf, Fat-tree, BCube, and DCell data centres. The proposed PON-based DCN architectures include two designs that utilize ports in Optical Line Terminal (OLT) line cards for inter and possibly intra data centre networking in addition to passive interconnects for the intra data centre networking between different PON groups (i.e. racks) within a PON cell (i.e. number of PON groups connected to a single OLT port). The first design is a switch-centric design that uses two Arrayed Waveguide Grating Routers (AWGRs) and the second is a server-centric design. The study also considers different traffic patterns defined according to the distribution of map and reduce tasks in the servers and data skewness.

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arXiv2020

VM placement over WDM-TDM AWGR PON Based Data Centre Architecture

Passive optical networks (PON) can play a vital role in data centres and access fog solutions by providing scalable, cost and energy efficient architectures. This paper proposes a Mixed Integer Linear Programming (MILP) model to optimize the placement of virtual machines (VMs) over an energy efficient WDM-TDM AWGR PON based data centre architecture. In this optimization, the use of VMs and their requirements affect the optimum number of servers utilized in the data centre when minimizing the power consumption and enabling more efficient utilization of servers is considered. Two power consumption minimization objectives were examined for up to 20 VMs with different computing and networking requirements. The results indicate that considering the minimization of the processing and networking power consumption in the allocation of VMs in the WDM-TDM AWGR PON can reduce the networking power consumption by up to 70% compared to the minimization of the processing power consumption.

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arXiv2020

Caching Video-on-Demand in Metro and Access Fog Data Centres

This paper examines the utilization of metro fog data centres and access fog datacentres with integrated solar cells and Energy Storage Devices (ESDs) to assist cloud data centres in caching Video-on-Demand content and hence, reduce the networking power consumption. A Mixed Integer Linear Programming (MILP) model is used to optimize the delivery of the content from cloud, metro fog, or access fog datacentres. The results for a range of data centre parameters show that savings by up to 38% in the transport network power consumption can be achieved when VoD is optimally served from fully renewable-powered cloud or metro fog data centres or from access fog data centres with 250 m2 solar cells. Additional 8% savings can be achieved when using ESDs of 100 kWh capacity in the access fog data centres.

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arXiv2020

Standards for Energy Efficient Virtualization, Content Distribution and Big Data in Beyond 5G Networks

Power consumption in communication networks and the supporting computing systems continues to increase due to the increase in traffic and processing requirements, and due to the relatively slower improvements in energy efficiency. Future networks are expected to continue to move computing algorithms and capabilities into the network including increased use of analytics, machine learning and intelligence applied to big data in the network, with content caching and virtualization. This article summarizes the key features of five new IEEE standards currently being developed to improve the energy efficiency of networks beyond 5G.

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arXiv2020

Impact of user distribution on optical wireless systems

In this paper, we investigate the impact of user distribution on resource allocation in visible light communication (VLC) systems, using a wavelength division multiple access (WDMA) scheme. Two different room layouts are examined in this study. Three 10-user scenarios are considered, while an optical angle diversity receiver (ADR) with four faces is used. A mixed-integer linear programming (MILP) model is utilized to identify the optimum wavelengths and access point (AP) allocation in each scenario. The results show that a change in user distribution can affect the level of channel bandwidth and SINR. However, a uniform distribution of users in the room can provide a higher channel bandwidth as well as high SINR above the threshold (15.6 dB) for all users compared to clustered users, which is a scenario that has the lowest SINR with supported data rate above 3.2 Gbps.

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arXiv2020

Resilience in Optical Wireless Systems

High reliability and availability of communication services is a key requirement that needs to be ensured by service providers. Since the direct line-of-sight (LOS) beam is prone to blockage in indoor optical wireless communication systems, a backup link needs to be at hand in case of blockage, and hence channel allocation algorithms should be blockage-aware. In this paper, the impact of beam blockage due to a disc with varying size and distance from the receiver is studied where blockage is quantitatively evaluated using percentage blockage for 512 room locations at 25 cm separation. It was found that assigning two links with maximum separation between the serving access points can reduce or eliminate blockage compared to the case when resilience is not implemented. Increasing the number of allocated access points per user further increases resilience.

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arXiv2020

Delay Adaptation Method for Relay Assisted Optical Wireless Systems

In this paper, we investigate optical wireless repeaters as relay terminals between a transmitter and a user in an Infrared Optical Wireless Communication (IROWC) system. A delay adaptation method is introduced to solve the problem of irregular signal arrival time from different relay terminals. Three different relay terminal deployment scenarios were investigated in a typical two-phase relay IROWC system with the proposed delay adaptation method. The simulation results indicate that the proposed system has better impulse response compared to the conventional system and that the root-mean-square delay spread of the relay system with the delay adaptation method is on average 30% less than the conventional system.

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arXiv2020

Beam Blockage in Optical Wireless Systems

In this paper, we use the percentage blockage as a metric when an opaque disc obstructs the Line-of-Sight link from the access point to the receiver in an optical wireless indoor communication system. The effect of the different parameters of the obstructing object are studied, these are the radius, the height, and the horizontal distance from the receiver in the positive y direction. The percentage of blocked room locations to the total number of room locations when varying the disc parameters is studied assuming a single serving link. It was found that depending on the dimensions of the obstructing object and the distance from the receiver in addition to which access point is serving the user, that blockage can vary between 0% up to 100%. Furthermore, the service received by a user, in terms of beam blockage depends on the access point they are connected to. The resulting fairness challenges will be addressed in resource allocation optimization in future work.

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arXiv2020

Resource Allocation in Co-existing Optical Wireless HetNets

In multi-user optical wireless communication (OWC) systems interference between users and cells can significantly affect the quality of OWC links. Thus, in this paper, a mixed-integer linear programming (MILP) model is developed to establish the optimum resource allocation in wavelength division multiple access (WDMA) optical wireless systems. Consideration is given to the optimum allocation of wavelengths and access points (APs) to each user to support multiple users in an environment where Micro, Pico and Atto Cells co-exist for downlink communication. The high directionality of light rays in small cells, such as Pico and Atto cells, can offer a very high signal to noise and interference ratio (SINR) at high data rates. Consideration is given in this work to visible light communication links which utilise four wavelengths per access point (red, green, yellow and blue) for Pico and Atto cells systems, while the Micro cell system uses an infrared (IR) transmitter. Two 10-user scenarios are considered in this work. All users in both scenarios achieve a high optical channel bandwidth beyond 7.8 GHz. In addition, all users in the two scenarios achieve high SINR beyond the threshold (15.6 dB) needed for 10-9 on off keying (OOK) bit error rate at a data rate of 7.1 Gbps.

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arXiv2020

Effect of receiver orientation on resource allocation in optical wireless systems

Optical wireless communication (OWC) systems have been the subject of a significant amount of interest as they can be used in sixth generation (6G) wireless communication to provide high data rates and support multiple users simultaneously. This paper investigates the impact of receiver orientation on resource allocation in optical wireless systems, using a wavelength division multiple access (WDMA) scheme. Three different systems that have different receiver orientations are examined in this work. Each of these systems considers 8 simultaneous users in two scenarios. WDMA is utilised to support multiple users and is based on four wavelengths offered by Red, Yellow, Green and Blue (RYGB) LDs for each AP. An angle diversity receiver (ADR) is used in each system with different orientations. The optimised resource allocations in terms of wavelengths and access point (AP) is obtained by using a mixed-integer linear programming (MILP) model. The channel bandwidth and SINR are determined in the two scenarios in all systems. The results show that a change in the orientation of the receiver can affect the level of channel bandwidth and SINR. However, SINRs in both scenarios for all users are above the threshold (15.6 dB). The SINR obtained can support t data rate of 5.7 Gbps in both scenarios in all systems.

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arXiv2020

Impact of room size on WDM optical wireless links with multiple access points and angle diversity receivers

Optical wireless communication (OWC) systems have been the subject of attention as a promising wireless communication technology that can offer high data rates and support multiple users simultaneously. In this paper, the impact of room size is investigated when using wavelength division multiple access (WDMA) in conjunction with an angle diversity receiver (ADR). Four wavelengths (red, yellow, green and blue) can be provided in this work based on the RYGB LDs transmitter used. Three room sizes are considered with two 8-user scenarios. A mixed-integer linear programming (MILP) model is proposed for the purpose of optimising the resource allocation. The optical channel bandwidth, SINR and data rate have been calculated for each user in both scenarios in all rooms. Room A, which is the largest room, can provide a higher channel bandwidth and SINR compared to the other rooms. However, all rooms can provide a data rate above 5 Gbps in both scenarios.

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arXiv2020

Shared optical wireless cells for in-cabin aircraft links

The design of a wireless communication system that can support multiple users at high data rates inside an aircraft is a key requirement of aircraft manufacturers. This paper examines the design of an on-board visible light communication (VLC) system for transmitting data on board Boeing 747-400 aircraft. The reading light unit of each seat is utilised as an optical transmitter. A red, yellow, green, and blue (RYGB) laser diode (LD) is used in each reading light unit for transmitting data. An angle diversity receiver (ADR), which is an optical receiver that is composed of four branches (in this work), is evaluated. The signal-to-interference-plus-noise ratio (SINR) and data rate are determined. Three scenarios have been examined where, in the first scenario, one device is used, in the second scenario two devices are used and in the third scenario three devices are used by each passenger. The proposed system can offer high SINRs that support high data rates for each passenger by using simple on-off-keying (OOK).

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arXiv2019

A Survey of Big Data Machine Learning Applications Optimization in Cloud Data Centers and Networks

This survey article reviews the challenges associated with deploying and optimizing big data applications and machine learning algorithms in cloud data centers and networks. The MapReduce programming model and its widely-used open-source platform; Hadoop, are enabling the development of a large number of cloud-based services and big data applications. MapReduce and Hadoop thus introduce innovative, efficient, and accelerated intensive computations and analytics. These services usually utilize commodity clusters within geographically-distributed data centers and provide cost-effective and elastic solutions. However, the increasing traffic between and within the data centers that migrate, store, and process big data, is becoming a bottleneck that calls for enhanced infrastructures capable of reducing the congestion and power consumption. Moreover, enterprises with multiple tenants requesting various big data services are challenged by the need to optimize leasing their resources at reduced running costs and power consumption while avoiding under or over utilization. In this survey, we present a summary of the characteristics of various big data programming models and applications and provide a review of cloud computing infrastructures, and related technologies such as virtualization, and software-defined networking that increasingly support big data systems. Moreover, we provide a brief review of data centers topologies, routing protocols, and traffic characteristics, and emphasize the implications of big data on such cloud data centers and their supporting networks. Wide ranging efforts were devoted to optimize systems that handle big data in terms of various applications performance metrics and/or infrastructure energy efficiency. Finally, some insights and future research directions are provided.

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arXiv2019

Networking and processing in optical wireless

Optical wireless communication (OWC) is a promising technology that can provide high data rates while supporting multiple users. The Optical Wireless (OW) physical layer has been researched extensively, however less work was devoted to multiple access and how the OW front end is connected to the network. In this paper, an OWC system which employs a wavelength division multiple access (WDMA) scheme is studied, for the purpose of supporting multiple users. In addition, a cloud/fog architecture is proposed for the first time for OWC to provide processing capabilities. The cloud/fog-integrated architecture uses visible indoor light to create high data rate connections with potential mobile nodes. These optical wireless nodes are further clustered and used as fog mini servers to provide processing services through the optical wireless channel for other users. Additional fog processing units are located in the room, the building, the campus and at the metro level. Further processing capabilities are provided by remote cloud sites. A mixed-integer linear programming (MILP) model was developed and utilised to optimise resource allocation in the indoor OWC system. A second MILP model was developed to optimise the placement of processing tasks in the different fog and cloud nodes available. The optimisation of tasks placement in the cloud-/fog-integrated architecture was analysed using the MILP models. Multiple scenarios were considered where the mobile node locations were varied in the room and the amount of processing and data rate requested by each optical wireless node is varied. The results help identify the optimum colour and access point to use for communication for a given mobile node location and OWC system configuration, the optimum location to place processing and the impact of the network architecture. Areas for future work are identified.

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