Abdulaziz M. Al-hetar

A survey on access technologies for broadband optical and wireless networks

The bandwidth demand of telecommunication network is growing rapidly due to the increasing number of technology-intelligent end-users. The emerging optical and wireless access networks are continuously competing with each other to provide these requirements for the end-users. The optical access networks provide huge data rate and long-distance link, but it is less ubiquitous. The wireless access networks provide flexible and ubiquitous communication with a low deployment cost. However, its deployment scalability is limited by the spectrum and range limitations. The hybrid wireless optical broadband access network (WOBAN) is a powerful combination of optical backhaul and wireless front-end to contribute to a good scalability, cost effective and flexible communication system. This paper reviews the key enabling access technologies and progress advancements of these networks. The emerging optical and wireless access technologies are also presented and compared.

MMI-MZI Polymer Thermo-Optic Switch With a High Refractive Index Contrast

The 2 x 2 MMI-MZI polymer thermo-optic switch in a high refractive index contrast (0.102) with a new structure design is realized. The fabrication was done using standard fabrication techniques such as coating, photolithography, and dry etching. A crosstalk level of dB has been achieved. Meanwhile, the extinction ratio of 28.6 dB has been achieved in this device. The polarization-dependent loss of 0.3 dB was measured at 1550 nm wavelength. In terms of wavelength dependency, the device shows a good performance within C-band wavelength with vacillation of the insertion loss value around 0.88 dB. The power consumption of 1.85 mW was measured to change the state of the switch from the cross to bar state. The measured switching time was 0.7 ms.

SPECTRUM SHARING STUDIES OF IMT-ADVANCED AND FWA SERVICES UNDER DIFFERENT CLUTTER LOSS AND CHANNEL BANDWIDTHS EFFECTS

Spectrum sharing between wireless systems becomes a critical issue due to emerging new technologies and spectrum shortage. Recently, IMT-Advanced system has been allocated in the same frequency band (3500 MHz) along with fixed services on co-primary basis, which means that harmful interference probability may be transpired. Channel bandwidths (BW) and natural of deployment areas of wireless systems are of the main effective factors in spectrum sharing. Spectrum Emission Mask (SEM) model will be used to study these factors effects beside the interference to noise ratio (I/N )a s a fundamental criterion for coexistence and sharing between systems. The frequency and distance separation and antenna height effects are essential to be investigated to achieve spectrum sharing.

Point-point fixed wireless and broadcasting services coexistence with IMT-advanced system

Spectrum sharing analysis is remarkably important in investigating the possibility for coexistence between IMT-Advanced system and existing wireless services when operating in the same or adjacent frequency channel. The frequency band, 470{862MHz, is currently allocating to TV broadcasting services (TVBS) and sub- bands within it are also allocated to flxed wireless access (FWA) service. Recently, international telecommunication union-radio (ITU- R) sector has allocated sub-bands within 470{862MHz for IMT- Advanced systems. This concurrent operation causes destructive interference that in∞uences the coexisting feasibility between IMT- Advanced and these existing services, FWA and broadcasting. This paper addresses a timely and topical problem dealing with spectrum sharing and coexistence between IMT-Advanced systems and both FWA and TVBS within 790{862MHz. Co-channel and adjacent channel with an overlapping band and with or without guard band are intersystem interference scenarios investigated. The deterministic analysis is carried out by spectral emission mask (SEM) technique as well as interference to noise ratio graph. Various signiflcant factors such as channel width, propagation path lengths, environments losses, and additional losses due to antenna discrimination which in∞uence the feasibility of coexistence are evaluated. Feasible coexistence coordination procedures in terms of carrier frequency ofiset, separation

Simulation of apodization profiles performances for unchirped fiber Bragg gratings

The performances of various apodization profiles, namely Gaussian, raised sine and hamming function for unchirped fiber Bragg grating are presented. The performances investigated include reflectivity, full width half maximum bandwidth, and sidelobe level. Transfer matrix method was adopted to solve the coupled mode equation to simulate the spectral profile of the apodized fiber Bragg gratings. The apodization performances were investigated under various refractive index modulation values and various grating length values. The results show that Gaussian profile suppresses sidelobe level much more efficiently than raised sine and hamming function.

A RIDGE WAVEGUIDE FOR THERMO-OPTIC APPLICATION

A thermal analysis and structure of a ridge single mode waveguide with a metal heater are presented. The steady-state temperature increases linearly and the thermal response becomes slower at the same power consumption, when the under-etched depth in the lower cladding increases. When the upper cladding thickness decreases, the thermal response becomes faster. This shows that a thinner upper cladding and a deeper etching are preferred to achieve a faster thermal response and lower power consumption, respectively. The numerical simulation also shows that the power consumption of the present ridge waveguide is almost a third of that for conventional one and the response time is half of that of the conventional one.

A novel optical single-sideband frequency translation technique for transmission of wireless MIMO signals over optical fiber

The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio over fiber (RoF) technique. However multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as MIMO signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical single-sideband frequency translation (OSSB-FT) technique is proposed to solve this problem. In this paper, three wireless MIMO signals are designed to transport over a 20 km standard single mode fiber (SMF) using the OSSB-FT technique by one optical source. Each wireless MIMO signal is with a 2.44 GHz carrier frequency, 1 Gb/s data rate, and 16 quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is excluded, since each wireless MIMO signal is carried on a specific optical wavelength.

Fixed wireless service coexistence with IMT-A system within UHF band

Coexistence analysis is exceedingly important in investigating the possibility for spectrum sharing between IMT-A system and existing wireless services. The 470–862 MHz frequency band is currently allocating to several services such fixed wireless access (FWA). International telecommunication union-radio (ITU-R) sector has allocated sub-bands within 470–862 MHz for IMT-A system. This concurrent operation causes a destructive interference that influences the coexisting feasibility between IMT-A and this existing service, FWA. This paper addresses a timely and topical problem dealing with spectrum sharing and coexistence between an IMT-A systems and FWA service within 790–862 MHz. Co-channel and adjacent channel with an overlapping band and with or without guard band are intersystem interference scenarios investigated. The deterministic analysis is carried out by spectral emission mask (SEM) technique. Different significant factors such as channel bandwidths, propagation path lengths, and clutter loss which influence the feasibility of coexistence are examined. Feasible coexistence coordination procedures in terms of separation distance, frequency offset, and guard band are suggested.

An Improved Mathematical Scheme for LTE-Advanced Coexistence with FM Broadcasting Service.

Power spectral density (PSD) overlapping analysis is considered the surest approach to evaluate feasibility of compatibility between wireless communication systems. In this paper, a new closed-form for the Interference Signal Power Attenuation (ISPA) is mathematically derived to evaluate interference caused from Orthogonal Frequency Division Multiplexing (OFDM)-based Long Term Evolution (LTE)-Advanced into Frequency Modulation (FM) broadcasting service. In this scheme, ISPA loss due to PSD overlapping of both OFDM-based LTE-Advanced and FM broadcasting service is computed. The proposed model can estimate power attenuation loss more precisely than the Advanced Minimum Coupling Loss (A-MCL) and approximate-ISPA methods. Numerical results demonstrate that the interference power is less than that obtained using the A-MCL and approximate ISPA methods by 2.8 and 1.5 dB at the co-channel and by 5.2 and 2.2 dB at the adjacent channel with null guard band, respectively. The outperformance of this scheme over the other methods leads to more diminishing in the required physical distance between the two systems which ultimately supports efficient use of the radio frequency spectrum.

Beam propagation modelling of the digital response in cosine S-bend waveguide branch

The crosstalk performance of cosine S-bend branch has been simulated using finite difference beam propagation method (FD-BPM) accomplished by BPMCAD. The simulation was done for TE mode at the operation wavelength of 1.55 mum. The overall crosstalk performance of the cosine S-bend is slightly higher compare to that of linear Y-branch. With the same opening branching angle, the waveguide separation of cosine S-bend branch is smaller than that of linear Y-branch. The waveguides gap can be reduced up to 33.2 %.