Zaid A. Shamsan

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.

Co-channel and adjacent channel interference evaluation for IMT-Advanced coexistence with existing fixed systems

Due to spectrum scarcity and emerging various wireless applications, coexistence and sharing between IMT-advanced and fixed wireless access (FWA) systems becomes a recently critical issue. At WRC-07, ITU-R allocated 3400-3600 MHz band for the coming fourth generation (4G) or IMT-Advanced on a co-primary basis along with existing FWA systems. Therefore, coexistence and sharing requirements like separation distance and frequency separation coordination must be achieved in terms of both co-channel and adjacent channel frequencies. Co-sited the two base stations antennas and non co-sited coexistence of the two systems are analyzed (depending on interference to noise ratio of -6 dB as a standard coexistence criteria). The interference analysis models, adjacent channel interference ratio ACIR and spectral emission mask (SEM) are applied in the mentioned band to extract the additional isolation needed to protect adjacent channel interference. Finally, possible intersystem interference mitigation techniques are suggested.

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 MODEL FOR COMPATIBILITY OF CO- SITED IMT-ADVANCED AND POINT TO MULTIPOINT SERVICES

GHz fixed wireless access system is a point-to- multipoint wireless technology providing broadband services. In this paper, point-to-multipoint fixed cellular service network structure such as Local Multipoint Distribution (LMDS) service is proposed to share same network area and frequency band (3400-3600 MHz) with the fourth generation of mobile (IMT-Advanced) represented by mobile Worldwide Interoperability for Microwave Access (WiMAX) service on base of co-sited systems. As a result of space and frequency domain sharing, harmful interference probability may be transpired between the two services. Different network cell sizes and different channel bandwidths were considered in dense urban area to investigate the intersystem interference effects based on the average interference to noise ratio INR as a fundamental criterion for coexistence and sharing coordination between different systems. Adjusting of antenna discrimination loss is also proposed to facilitate the frequency efficiency and accomplish frequency sharing.

LTE-advanced compatibility with digital broadcasting receiver at 800 MHz

Coexistence between IMT-Advanced system and existing digital broadcasting is a matter of considerable when operating in a same or adjacent frequency channel within the band 790-862 MHz, which is recently allocated for mobile IMTAdvanced Systems represented by LTE-Advanced system. This can cause intersystem interference that affects on the coexisting feasibility between LTE-Advanced and digital broadcasting Receiver. In this paper, an efficient, simplified and graphical scheme for spectral emission mask and interference power level is proposed to investigate different channel overlapping scenarios between the two systems. A range of significant factors such as bandwidth, propagation distance, losses due to clutter, and antenna discrimination losses that can affect on the compatibility feasibility of the two systems are employed. The results demonstrate that using co-channel may unworkable unless some intersystem interference mitigation techniques are applied.

Intersystem Interference Scenarios between Fixed and IMT-Advanced Services in Different Terrestrial Regions

The Coexistence and intersystem interference coordination between systems is difficult to be achieved and relies on many technical factors. In this paper, intersystem interference scenarios such as co-channel, zero-guard band, and adjacent channel will be analyzed to determine the coexistence coordination requirements between IMT-Advanced and fixed services. These coordination requirements in terms of frequency separation and separation distance will be considered in dense urban, urban, suburban, and rural areas using spectral emission mask as an effective intersystem interference analysis model. Antenna height and different channel bandwidths effect as main effectual factors for systems coexistence will be taken into account.

Rain fading mitigation in BWA using Site Diversity

Local Multipoint Distribution Services (LMDS) is a terrestrial fixed radio technology for broadband communication applicable as point to multipoint wireless system operating at frequencies above 20 GHz. The most serious impairment at these frequencies is rain fading specially in the tropical areas. Many techniques could be used to overcome rain fading and applying Site Diversity as a possible solution to reduce the effect of rain. The rain attenuation in Malaysia was calculated and the effects of a moving rain cell over an LMDS system were analyzed. Different situations of interference according to the position of the rain over LMDS were elaborated. The site diversity was implemented and simulated based on the ITU-R to enhance LMDS using C/I ratio under rainy conditions with and without site diversity technique. Different cell sizes of LMDS with and without site diversity were considered.

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.

IMT-advanced coexistence method with fixed services in different geographical areas at 3500 MHZ

At WRC-07, the frequency band 3500 MHz has been allotted for the next generation of mobile International Mobile Telecommunication-Advanced (IMT-Advanced). Meanwhile this band is already in used by fixed services which means that harmful interference probability may be transpired. In this paper, a new coexistence method between the aforementioned services in various geographical deployment areas (dense urban, urban, suburban, and rural areas) will be applied. Spectrum emission mask is an effective interference model will be invested and interference to noise ratio of −6 dB is the used coexistence criterion. Co-channel, zero-guard band, and adjacent channel are three intersystem interference scenarios will be investigated. The analysis will focus to determine required minimum separation distance and frequency separation under different attenuation situations due to local clutter and height of antennas.