Redhwan Qasem Shaddad
Taiz University, Communication and Computer, Faculty Member
- Wireless Mesh Networks, Wireless Communications, Optical Fiber Communications, Radio over fiber, optical access networks, wireless broadband access technologies, OFDM systems, wireless technologies for developing communities, telemedicine, MIMO Systems, Digital Image Processing, and 15 moreNeural Networks, Passive Optical Networks, FREE SPACE OPTICAL COMMUNICATION, Optical Access Networks, Fiber-Wireless Access Networks, Hybrid Wireless-Optical Broadband Access Networks, Communication Engineering, Data Communication and Computer Networks, Artificial Neural Networks, Optical Networks, Optics, Optic-Photonic Communication Networks, Free Space Optics, Optical wireless Communications, and WDM Optical Networksedit
Over the last few years, optical switching technology for data centers (DC) has gained much attention due to the potential and benefits of using optical components. The performance of the optical network is directly related to the type of... more
Over the last few years, optical switching technology for data centers (DC) has gained much attention due to the potential and benefits of using optical components. The performance of the optical network is directly related to the type of optical switching technique used. Optical burst switch (OBS) is currently being developed as a technology capable of supporting wide bandwidth, enabling high transmission of information and various types of traffic. Losses due to contention between bursts at the core nodes are one of the main problems that prevent the achievement of optical burst switching (OBS) technology on core networks. In this paper, wavelength conversion and deflection routing techniques used together to get the best solution for the problem of contention bursts that might be occurred at the core node. Performance evaluation was investigated by analysis of burst loss probability and steady-state throughput using steady-state occupancy probabilities and Poisson traffic model arrivals and the analyzed results are presented at different mean burst arrival rates and the different number of wavelengths.
Research Interests:
FiWi access network provides the end-users with a large amount of bandwidth and reliability in a flexible manner as it integrates the technical merit of the fiber and wireless network, FiWi access network is a promising access technology,... more
FiWi access network provides the end-users with a large amount of bandwidth and reliability in a flexible manner as it integrates the technical merit of the fiber and wireless network, FiWi access network is a promising access technology, because of the tremendous increase in traffic demands in the FiWi access network, achieving good survivability is facing major challenges as vast traffic could be disrupted due to the failure of any FiWi portion. In this study, all-optical network failures are addressed. Single and multiple segments addressing is allocated an ONU backup in each segment satisfying the shortest distance to backup ONUs in other segments and classified network segments as a cluster. So, backup fibers are deployed between the backup ONUs in each cluster in separate segments to create a protection scheme that satisfies maximum protection and minimum cost. The results accomplished minimizing the backup fiber cost by 20 % compared with the ring scheme and minimize the spare capacity that needs for maximum protection by sharing the spare capacity for segments in the same cluster
Research Interests:
The rapid development of smart devices and intelligent things led to exponentially increase the traffic of data in wireless networks in recent years. A heterogeneous network (Her-Net), and Millimeter Wave (mm-Wave) band are the suitable... more
The rapid development of smart devices and intelligent things led to exponentially increase the traffic of data in wireless networks in recent years. A heterogeneous network (Her-Net), and Millimeter Wave (mm-Wave) band are the suitable solutions for the new generation networks to enhance coverage, capacity, and users demand. The main aim of this paper is to plan a fifth-Generation Heterogonous Wireless Local Network (5G Het-WLN) using dense small cells at Taiz university, Taiz, Yemen. The coverage area of Taiz university divided into 4 regions, each region with one microcell operating at 38 GHz frequency band. A further 120 femtocells were distributed inside university buildings which operate at 60 GHz frequency band. The femtocells enhance the capacity and coverage requirement for indoor subscribers. The simulation of the network planning process is implemented using OMNET ++ simulation tool. The results indicated that, throughput in uplink and downlink reached to 5.5 Gbps and 8 Gbps respectively.
Research Interests:
Research Interests:
The global positioning system (GPS) is one of the most important and useful technologies that has been developed. The propagated wireless signals along GPS channel are affected by the ionospheric electron density irregularities, so the... more
The global positioning system (GPS) is one of the most important and useful technologies that has been developed. The propagated wireless signals along GPS channel are affected by the ionospheric electron density irregularities, so the GPS signals may experience amplitude and phase fluctuations. The global navigation satellite system (GNSS) ionospheric scintillation and total electron content (TEC) monitor (GISTM) receiver has been installed at UTeM, Malaysia (2.3139°N, 102.3183°E) for the purpose of monitoring ionospheric scintillation for many frequencies. In this paper, the GPS ionospheric scintillations are concerned for the dual frequency L1 (fL1 =3D 1.57542 GHz), and L2C (fL2=3D 1.2276 GHz). Data collection of ionospheric scintillation has been done during solar maximum cycle 2013/2014 for six months October 2013-March 2014. The solar activity effects on the GPS link performance especially when this activity increases, so the analysis of the GPS link ionospheric scintillation must be considered for this region. The ionospheric amplitude/phase scintillation, and the carrier-to-noise (C/No) ratio are reported in the proposed experimental GPS model. As a result for Malaysia, typical threshold received C/No ratio is 38 dB-Hz, that means C/No ratio should be greater than 38 dB-Hz to receive good signal at the GPS reciever.
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
For Long Term Evolution-Advance (LTE-A), this paper aims to minimize the cost of the radio link and the network infrastructure, taking into account the distribution of subscribers, the location of the area to cover and the quality of... more
For Long Term Evolution-Advance (LTE-A), this paper aims to minimize the cost of the radio link and the network infrastructure, taking into account the distribution of subscribers, the location of the area to cover and the quality of service constraints. The coverage and capacity planning, and its optimization are proposed for the urban area at Taiz city, Yemen. This paper involves hands-on simulation exercise on planning and optimization of LTE-A network using ATOLL planning software tool. After LTE optimization by using Automatic Cell Planning (ACP), Automatic Frequency Planning (AFP), Monte-Carlo algorithm and neighbor planning, the coverage, signal level and throughput have been improved. In addition, overlapping has been reduced. The optimization process improves the coverage rate from 90% up to 98.04%, Carrier-to-Interference-and-Noise Ratio (CINR) from 65.04% up to 77.6%, and total traffic supported by the network increases after the optimization by 30%.
Research Interests:
Research Interests:
The world is experiencing a massive advancement in the fifth generation (5G) of wireless networks communications., which will bring about a noticeable change in the communication system as well as the emergence of new technology to keep... more
The world is experiencing a massive advancement in the fifth generation (5G) of wireless networks communications., which will bring about a noticeable change in the communication system as well as the emergence of new technology to keep pace with this system including Software Design Network (SDN)., Network Function Virtualization (NFV) and Massive Multi inputs Multi outputs (M-MIMO), which will rapidly and effectively improve the quality of services for consumers. The high frequency of tens of GHz used in this type of network, leading to up to tens of gigabits per second in the data rate. This paper dealt with the planning of 5G networks in urban and suburban area in Taiz city. The main problem that faces in the 5G wireless network that in suburban area where the mobility is high, the network implemented using overlapped cells to provide mobility from one cell to another and. However, overlapping increases interference and, consequently, may reduce network capacity. Also, in urban area, the main problem is due to dense deployment of multi-tier heterogeneous networks (Het-Nets) causes the inter-tier and intra-tier interferences. Areas are divided into small cells of different sizes according to population density and other natural factors to achieve network density by millimeter wave (mm- Wave) technology that uses a frequency of 60 GHz., which is one of the most important characteristics of 5G networks resulting from an increase in the number of cells and (Het-Nets). So, it achieved a high data rate which reach to 8 Gbps at each cell. There are about 240 cells in urban area and 105 cells in the suburban area, so this made it able to provide services to more than 220,000 users in urban and more than 100,000 users in suburban in addition to the optimization of power, which has reached the value of power received less than -120 dBm.
Research Interests:
Next-generation access networks require simultaneous provision of wired and wireless services and high data rate to meet the huge demands for mobility and multiple services. In this paper, we propose a spectral efficient radio over fiber... more
Next-generation access networks require simultaneous provision of wired and wireless services and high data rate to meet the huge demands for mobility and multiple services. In this paper, we propose a spectral efficient radio over fiber scheme to simultaneously provide two spatial multiplexed multiple input multiple output (MIMO) wireless signals with baseband (BB) signal in one wavelength using a centralized light source. The proposed scheme can be applicable in wavelength division multiplexed passive optical network (WDM-PON). The BB signal is modulated at low extinction ratio. Using the same modulated light, the two MIMO signals that have the same career frequency are combined optically using polarization-division-multiplexing (PDM). The BER performance of 10-9 is achieved for the three signals after transmission of 20 km single mode fiber (SMF).
Research Interests:
Recent trends in research and scientific studies are represented in developing the wireless communication systems to achieve 5G networks with ultra-high reliability, ultra-low latency, high capacity, large amount of data transfer, massive... more
Recent trends in research and scientific studies are represented in developing the wireless communication systems to achieve 5G networks with ultra-high reliability, ultra-low latency, high capacity, large amount of data transfer, massive connection density, while improving the quality of service (QoS). Achieving ultra-low latency is one of the fundamental goals for 5G wireless networks to enable new services and applications such as, virtual reality, live content streaming, automated vehicle control, internet of things (IoT) where machines and tools can be controlled remotely with extreme response, and many delay sensitive applications over the mobile network. This paper investigates hybrid strategy of traffic dispersion and network densification, which aims to split and transmit an arrival traffic over multiple different paths within the ultra-dense network. This improved the capacity of, and reduced the communication delay in, planned 5G-wireless network for urban area in Taiz city, Yemen. For our proposed 5G-wireless network there are 376 microcells, which operates using millimeter-Wave (mm-Wave) with the 73 GHz band, and used as providers for 274702 subscribers within the covered urban area of Taiz city. The planned 5G-network is carried out using OMNET++ and MATLAB simulation tools, hence the performance of this network is evaluated by key performance indicators (KPIs) such as average throughput, and communication delay. Based on the obtained results the amount of network throughput has reached a high value, up to 9 Gbps at each cell, with 88% probability that average one hop delay less than 0.5 ms.
Research Interests:
To prevail against atmospheric attenuation considering unusual haze in tropical areas and to scale the growing demand for high capacity communication bandwidth and scalability, a prominent technique is used known as dense hybrid... more
To prevail against atmospheric attenuation considering unusual haze in tropical areas and to scale the growing demand for high capacity communication bandwidth and scalability, a prominent technique is used known as dense hybrid wavelength division multiplexing (DWDM)/multibeam free-space optics (FSO). In this study, attenuation arising due to haze scattering which is given as a function of link distance, wavelength and visibility is estimated from visibility data obtained from Malaysian meteorological department. Maximum attenuation of 20 dB/km has been observed due to unusual haze in Malaysia. This attenuation of 20 dB/km is applied on a proposed hybrid four channel of 1.5-Gb/s DWDM/multibeam FSO network with four wavelengths having standard downlink channel spacing of 100 GHz (~0.8 nm). The hybrid DWDM/multibeam FSO method has enhanced the performance of an FSO link in terms of the data rate, link distance, received power and scalability. The proposed approach facilitated access data to four end users at a data rate of 1.5 Gb/s each, over a link distance of 1,645 m at BER of 10−9 under 20 dB/km attenuation.
Research Interests:
ABSTRACT
Research Interests:
In this paper, a simple and bandwidth efficient hybrid wireless-optical broadband access network (WOBAN) based on orthogonal frequency division multiplexing (OFDM) is proposed and designed. It is an optimal combination of an optical... more
In this paper, a simple and bandwidth efficient hybrid wireless-optical broadband access network (WOBAN) based on orthogonal frequency division multiplexing (OFDM) is proposed and designed. It is an optimal combination of an optical backhaul and a wireless front-end for an efficient access network. The bandwidth efficient WOBAN based on OFDM provides an effective solution to eliminate intersymbol interference (ISI) caused by dispersive channels. There are two factors considered important here; multipath fading in wireless link and dispersion effects in fiber link. The physical layer performance is analyzed in terms of bit error rate (BER), error vector magnitude (EVM), and signal-to-noise ratio (SNR). An 8 Gb/s data rate has been achieved by the optical backhaul along optical fiber length of 20 km. The wireless front-end access point supports data rate up to 240 Mb/s along an outdoor wireless link.
Research Interests:
The propagated wireless signals along Global Positioning System (GPS) link suffer ionospheric scintillations due to the ionospheric electron density irregularities. The GPS ionospheric scintillation and Total Electron Content (TEC)... more
The propagated wireless signals along Global Positioning System (GPS) link suffer ionospheric scintillations due to the ionospheric electron density irregularities. The GPS ionospheric scintillation and Total Electron Content (TEC) Monitor (GISTM) receiver is established at UTeM, Malaysia (Latitude 2° 14′ N, Longitude 102° 16′ E) to monitor ionospheric scintillations during the 24th solar maximum from September 2013 to August 2014. The GPS ionospheric scintillations are measured for the dual frequency L1 (1.57542 GHz) and L2C (1.2276 GHz). The mathematical model of the ionospheric scintillation is statistically estimated based on the collected experimental data using the nonlinear regression (NLR) technique. The scintillation index S4(L2C) is estimated as mathematical function of S4(L1). The proposed mathematical model has been validated and achieved lowest root mean square error (RMSE) value of 0.0523 for the S4(L2C).
Research Interests:
Free Space Optics (FSO) or optical wireless systems provide high data rate solution for broadband communication applications. FSO links are highly weather-dependent because different weather conditions significantly affect the link... more
Free Space Optics (FSO) or optical wireless systems provide high data rate solution for broadband communication applications. FSO links are highly weather-dependent because different weather conditions significantly affect the link availability. In order to determine the best operational limit of an FSO link with respect to temperature and humidity, the effect of temperature and humidity on FSO network is studied in this work. Two new equations are proposed to model the effect of temperature and humidity on an FSO link operating at 850 nm in tropical climate. The first equation is developed to model the relationship between the humidity and temperature for tropical regions, while the second equation models the FSO link attenuation in terms of tropical temperature. In conclusion, it is suggested that FSO links can be operated with a normal variation of temperature and humidity in a tropical country to achieve near carrier class availability.
Research Interests:
Research Interests:
In the coming years, there will be a ground-breaking advancement in the field of wireless communications as the introduction of Fifth Generation (5G) network, which will be a turning point in communications systems and lead to the... more
In the coming years, there will be a ground-breaking advancement in the field of wireless communications as the introduction of Fifth Generation (5G) network, which will be a turning point in communications systems and lead to the creation of unparalleled new systems and innovations. Network planning suggested in this paper for Aden City's coastal area and contrasted it with our previous 5G wireless access network research planning that we had implemented in Taiz City's urban area. Such densification of the network could support different networks and multiple cells within the primary network, called heterogeneous networks (Het-Nets), and demonstrate how they vary between two cities according to a lot of points. The more challenges of the densification in 5G during planning of 5G are network densification, spectrum aggregation Millimeter Wave (mm-Wave) bands and spectral efficiency techniques, so more bandwidth is needed and Supporting mobility through such a highly Het-Net. In this paper, the planning process came up with solutions which gave us good results that show the planned network which use the frequency of 28 GHz reaching higher data rates that rise to 7.1 Gbps at each cell in Taiz City and 5.2 Gbps at each cell in Aden City. The number of cells up to 212 micro cells in Taiz city which considered as an urban area with 189624 users compared to 200 micro cells and 185543 users in Aden City.
Research Interests:
Network planning is an important step in the design of wireless networks, especially for 5 generation (5G). 5G networks must provide good service quality, high data rate and capacity. Therefore, 5G networks must be plan efficiently to... more
Network planning is an important step in the design of wireless networks, especially for 5 generation (5G). 5G networks must provide good service quality, high data rate and capacity. Therefore, 5G networks must be plan efficiently to deal with the increase of the data traffic. So, 5G wireless networks requires high grade of heterogeneity of small cell base stations, micro-cell base stations and macro cell base stations. In this paper, 5G wireless access network is planned for urban area in Ibb city, Yemen. The band 28 GHz of millimeter wave (mm-Wave) is used in this paper. Simulation results show that we need 223 micro cells to provide an acceptable services to 186532 subscribers in the covered urban area of Ibb city to satisfy densification network. The results also show that, the maximum achievable downlink and uplink throughput are 6.5 Gbps and 3.2 Gbps, respectively.
Research Interests:
A low cost fibre-wireless (FiWi) convergent network architecture including two multiple-input multiple-output (MIMO) wireless signals based on a 5G universal filter multicarrier (UFMC) waveform and wired signal over orthogonal frequency... more
A low cost fibre-wireless (FiWi) convergent network architecture including two multiple-input multiple-output (MIMO) wireless signals based on a 5G universal filter multicarrier (UFMC) waveform and wired signal over orthogonal frequency division multiplexed passive optical network (OFDM-PON) is presented. The proposed scheme utilizes a single side band frequency translation (SSB-FT) technique to provide a smooth and cost-efficient convergent system. A proof-of-concept downstream link over a 20 km standard-PON is conducted by simulation to confirm the successful transmission of 1 Gb/s data rate for each MIMO and 2.5 Gb/s for the wired signal using error vector magnitude (EVM) and bit error rate (BER) measurements.
Research Interests:
The 5G wireless networks will cause a huge revolution in wireless communications because of the evolution of smart devices and rising technologies and applications as well as its enormous ability to send and transfer millions of data very... more
The 5G wireless networks will cause a huge revolution in wireless communications because of the evolution of smart devices and rising technologies and applications as well as its enormous ability to send and transfer millions of data very quickly and in a short period of time. In this paper, the planning of 5G wireless access network is proposed in urban area of Taiz city, Yemen where the cells within the city divided into small cells and focused on the densest areas in city. This network densification can support various networks and multiple cells within the primary network, which are called Heterogeneous Networks (Het-Nets). The proposed wireless network uses the millimeter wave (mm-Wave) with the 28 GHz band which achieved data rate up to 7 Gbps at each cell. There are 212 micro cells to covered urban area and offer acceptable services to 189624 users in the city to satisfy densification network.
Research Interests:
The deployment of heterogeneous networks (HetNets) is one of the promising approaches to meet the 5G requirements. The traditional user association approach is inefficient for HetNets due to the high transmission power of macro base... more
The deployment of heterogeneous networks (HetNets) is one of the promising approaches to meet the 5G requirements. The traditional user association approach is inefficient for HetNets due to the high transmission power of macro base stations (BSs) and the low transmission power of small cell BSs, i.e., pico and femto BSs. This approach causes macro BSs to be overloaded whereas small cell BSs are lightly loaded. To address this load imbalance in 5G HetNets, 3GPP introduced the concept of cell range expansion (CRE) where the coverage area of small cell BSs is artificially increased by adding a bias value to the power received from small cells. Although the biasing approach can better balance the load among tiers, users at the expansion area suffer from severe interference coming from neighbouring macro BSs. This work utilizes coordinated multi-point transmission (CoMP) to reduce interference. User-centric clustering where a user can be served by a number of BSs is implemented. The results have sown that user-centric CoMP can significantly improve the SINR levels of all users and cell-edge users as well.
Research Interests:
Research Interests:
For communication and computing sciences researchers, the Internet of Everything (IoE) is one of the most attractive topics. It is the field that represents the interconnection between the internet of things (IoT) and people's need... more
For communication and computing sciences researchers, the Internet of Everything (IoE) is one of the most attractive topics. It is the field that represents the interconnection between the internet of things (IoT) and people's need for several kinds of technological services. Thus, some literature considers the modern ages as the IoE era. Smart city, 5G, and 6G become part of IoE vocabularies list, besides many techniques and applications that have been utilized by researchers for conducting IoE business and academic projects. In this study, IoE directions have been explored, so papers that have IoE in IEEE Xplore’s indexed terms have been investigated. Retrieved papers have been categorized and systematically reviewed. Diverse perspectives have been studied statistically, presented visually, and papers’ directions are reviewed carefully. The relations between categories have been counted and available information about the IoE world is introduced, the main goal was discovering IoE methods and applications, that have been presented from 2020 to 2021.
Research Interests:
Recently, demand for fifth generation (5G) wireless communication is very high due to its bandwidth-efficient and high data rate. Thus, a high-performance microstrip patch antenna (MPA) is required to be designed. In this paper, we... more
Recently, demand for fifth generation (5G) wireless communication is very high due to its bandwidth-efficient and high data rate. Thus, a high-performance microstrip patch antenna (MPA) is required to be designed. In this paper, we propose a compact E-shaped MPA for the V and E band and backhaul applications. The proposed antenna has small size dimensions of 3 × 2.9 × 0.508 mm3 and a low-cost Rogers/RT Duroid is used as a substrate material with a loss tangent of 0.0012. E-shaped slots and Defected ground structure (DGS) are implemented on patch and ground, respectively. Both techniques are used to improve the performance of the proposed antenna in terms of bandwidth and return loss. This achieves 14.56 GHz bandwidth from 63.05-77.61 GHz with a gain of 7.11 dB and return loss of −45.71 dB at centered frequency equals 66.33 GHz. For further enhancement, the insert feed technique is used. As a result, the proposed design has a good performance in terms of antenna return loss, gain, bandwidth, characteristics impedance, and high efficiency at the resonant frequency. Therefore, it can be a candidate for V and E band and backhaul outdoor environments applications. Higher Frequency Structural Simulator (HFSS) tool is used for simulation.
Research Interests:
To meet demands of the future realization, new progresses in communication systems require a low-cost, lightweight, low-profile, and high-performance antenna. In this paper triple-band microstrip patch antennas (MPAs) is proposed and... more
To meet demands of the future realization, new progresses in communication systems require a low-cost, lightweight, low-profile, and high-performance antenna. In this paper triple-band microstrip patch antennas (MPAs) is proposed and designed for THz applications. The proposed antenna has the dimensions of 56.8× 66.8× 5µm3, uses Quartz-glass as a substrate material with a loss tangent =0 and thickness of 5 µm. Partial ground technique is implemented to improve the return loss and bandwidth of proposed antenna. This obtains bandwidth of 140, 700 and 410 GHz with return loss of −19.3, −29.2 and −22.5 dB at resonant frequencies 2.5 THz, 4 THz, and 5.4 THz respectively. The proposed antenna has been fed by means of microstrip feed line having impedance of 50 Ω. The results of antenna designed are suitable for THz applications. Higher Frequency Structural Simulator (HFSS v13) tool is used to simulate the proposed antenna.
Research Interests:
Due to appear new applications such as information showering and the vehicular applications that demand a high data rate, better bandwidth utilization, and good quality of service (QoS) in wireless communication systems, that can only be... more
Due to appear new applications such as information showering and the vehicular applications that demand a high data rate, better bandwidth utilization, and good quality of service (QoS) in wireless communication systems, that can only be achievable in Fifth Generation (5G). This paper proposes compact triple-band Y-shaped microstrip patch antennas (MPAs) for 5G applications. The proposed antenna has a dimension of $5 \times 5 \times 0.381$ mm3, uses Rogers/ RT Duroid 5870 as a substrate material, and a loss tangent of 0.0012. The Defected ground structure (DGS) in the middle and groove at the top of the ground plane was implemented. This achieves -10 dB bandwidth from 29.55-30.72 GHz with a maximum gain of 6.834 dB, from 57.36-63.34 GHz with a maximum gain of 10.196 dB, and from 68.56-94.281 GHz with a maximum gain of 8.628 dB at resonant frequencies 30.1 GHz, 60 GHz, and 81.3 GHz respectively. The proposed antenna has a high gain and a broad bandwidth making it a candidate for 5G millimeter-wave (mmwave) applications. Higher Frequency Structural Simulator (HFSS v13) tool is used to simulate the proposed antenna.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT Current passive optical networks (PONs) (Gigabit PON (GPON) and Ethernet PON (EPON)) will run out of bandwidth sooner or later due to the ever increasing bandwidth demand. The aforementioned and the new next generation PON stage... more
ABSTRACT Current passive optical networks (PONs) (Gigabit PON (GPON) and Ethernet PON (EPON)) will run out of bandwidth sooner or later due to the ever increasing bandwidth demand. The aforementioned and the new next generation PON stage 1 (NG-PON1) standards (10 Gigabit-PON (XG-PON) and 10 Gigabit Ethernet-PON (10G-EPON)) are based on time division multiplexing (TDM-PON), which has its limitations such as limited bandwidth. In this paper, hybrid TDM-WDM PON and stacked TDM-PON architectures are evaluated and compared as solutions for NG-PON stage 2 (NG-PON2). Both architectures are fully capable of satisfying the requirements of NG-PON2. Stacked TDM-PON has the advantage of being compatible with the currently deployed optical distribution network (ODN). Considering four wavelengths and 10 Gb/s/wavelength, the hybrid TDM-WDM PON does not seem to offer noticeable advantages over stacked TDM-PON.
Research Interests:
ABSTRACT Free space optics (FSO) is an optical communication technology that uses light propagating in free space to transmit data for telecommunications or computer networking, and is exposed to atmospheric attenuation, like absorption... more
ABSTRACT Free space optics (FSO) is an optical communication technology that uses light propagating in free space to transmit data for telecommunications or computer networking, and is exposed to atmospheric attenuation, like absorption and scattering. These types of attenuations seriously degrade the strength of transmitted signal, especially when single beam FSO system is used. So to overcome this problem, a multiple beam FSO transceiver system has become dominance and is usually used. In this paper simulation models are obtained by using average rain attenuation which is evaluated from the five months collected rain intensity data. These models are obtained to demonstrate the results concerning link distance and received optical power of using multiple beam FSO system and comparing it with single beam FSO system. Comparison is carried out in terms of signal to noise ratio (SNR), geometrical losses, atmospheric losses, and bit error rate (BER). From the results it is clear that, by using up to four beams has improved geometrical loss, sensitivity of the receiver, SNR, and link distance.
Research Interests:
Research Interests:
ABSTRACT
Research Interests:
ABSTRACT In this paper, a spectral efficient hybrid wireless optical broadband access network (WOBAN) is proposed and demonstrated based on the transmission of wireless multi-input multi-output orthogonal frequency division multiplexing... more
ABSTRACT In this paper, a spectral efficient hybrid wireless optical broadband access network (WOBAN) is proposed and demonstrated based on the transmission of wireless multi-input multi-output orthogonal frequency division multiplexing (MIMO OFDM) signals over wavelength division multiplexing passive optical network (WDM PON). By using radio over fiber (ROF) techniques, the optical fiber is well adapted to propagate multiple wireless services having different carrier frequencies. It is a known fact that multiple wireless signals having the same carrier frequency cannot propagate over a single optical fiber at the same time, such as MIMO signals feeding multiple antennas in fiber wireless (FiWi) system. A novel optical single-sideband frequency translation technique is designed and simulated to solve this problem. This technique allows four pairs of wireless MIMO OFDM signals with the same carrier frequency for each pair to be transmitted over a single optical fiber by using one optical source per wavelength. The crosstalk between the different MIMO channels with the same frequency is eliminated, since each channel is upconverted on specified wavelength with enough channel spacing between them. Also the maximum crosstalk level between the different MIMO channels with different frequencies is very low around −76 dB. The physical layer performance of the proposed WOBAN is analyzed in terms of the bit error rate (BER), error vector magnitude (EVM), and signal-to-noise ratio (SNR). The proposed WOBAN achieves 7.68 Gb/s data rate for 20 km for the optical back-end and 240 Mb/s for the outdoor wireless front-end.
Research Interests:
Research Interests: Computer Science, Communication System, Performance Evaluation, Computer Network, Bit Error Rate, and 13 morePhysical Layer, Optical network, Optical physics, Wireless access, Optical fiber, Next Generation, wireless ATM links, Front end, Signal to Noise Ratio, Electrical And Electronic Engineering, Optical Wireless, Access Network, and Time division multiplex
In this paper, a simple and bandwidth efficient hybrid wireless-optical broadband access network (WOBAN) based on orthogonal frequency division multiplexing (OFDM) is proposed and designed. It is an optimal combination of an optical... more
In this paper, a simple and bandwidth efficient hybrid wireless-optical broadband access network (WOBAN) based on orthogonal frequency division multiplexing (OFDM) is proposed and designed. It is an optimal combination of an optical backhaul and a wireless front-end for an efficient access network. The bandwidth efficient WOBAN based on OFDM provides an effective solution to eliminate intersymbol interference (ISI) caused by dispersive channels. There are two factors considered important here; multipath fading in wireless link and dispersion effects in fiber link. The physical layer performance is analyzed in terms of bit error rate (BER), error vector magnitude (EVM), and signal-to-noise ratio (SNR). An 8 Gb/s data rate has been achieved by the optical backhaul along optical fiber length of 20 km. The wireless front-end access point supports data rate up to 240 Mb/s along an outdoor wireless link.
Research Interests:
ABSTRACT Next generation (NG) technologies are proposed to provide high data rate, broadband multiple services, scalable bandwidth, and flexible communication for manifold wireless end-users (WEDs). The fiber-wireless (FiWi) network is a... more
ABSTRACT Next generation (NG) technologies are proposed to provide high data rate, broadband multiple services, scalable bandwidth, and flexible communication for manifold wireless end-users (WEDs). The fiber-wireless (FiWi) network is a promising network for the NG technologies, since it is a powerful combination of optical backhaul and wireless front-end. The optical backhaul of the FiWi network is a tree network connecting the central office (CO) and wireless front-end. The wireless front-end consists of access points (APs) which are widespread to penetrate multiple WEDs. There are two main schemes to transmit the wireless signals in the FiWi system: (1) baseband-over-fiber (BBOF) transmission scheme, (2) radio over fiber (ROF) transmission scheme. This paper will review and discuss the concept and architecture of the FiWi system. This review is important to report the architectures, advantages, disadvantages, and the main parameters of these transmission schemes.
Research Interests:
Research Interests:
Long Term Evolution (LTE) networks are designed with overlap between cells to support mobility along the network cells and to avoid out of coverage area; especially in suburban and rural area because high mobility. The overlapping results... more
Long Term Evolution (LTE) networks are designed with overlap between cells to support mobility along the network cells and to avoid out of coverage area; especially in suburban and rural area because high mobility. The overlapping results in interferences which reduce network capacity so this paper aims to bring customer demands for high-quality networks. This paper involves a good understanding of radio network planning and optimization of LTE and perform a case study in Taiz governorate with a selected suburban and rural area of 86.846 km2. Self-organizing networks (SONs) are widely considered to improve the end users’ quality of experience. The simulation was performed using ATOLL software. The radio frequency (RF) optimization involves Inter-Cell Interference Coordination (ICIC). The downlink (DL) LTE coverage area is enhanced and increased to 84 km2 with probability of 97%. In addition, the overlapping zone is reduced to 0.4% and the block error rate (BLER ≥ 0.2) is reduced to ...