Performance of Subcarrier and Power Allocation Orthogonal Frequency-Division Multiplexing on Millimeter Wave

Local multipoint distribution system (LMDS) that operated in millimeter waves can be used to fulfill the need of bit rate higher than 40 Mbps. However it has problem when applied in tropic country such as Indonesia because of the high rainfall. Therefore LMDS system was developed by cross-layer mechanism.  In this research we used joint subcarrier and power allocation (JSPA) technique in multi-user cross-layer OFDM. This technique is proposed to increase the performance of telecommunication system even there were disturbance of rain attenuation. The research is discussing the performance of transmission capacity, data rate, utility and fairness of JSPA algorithm that applied in rain attenuation measurement in Surabaya. The result shows the increment of performance system using JSPA technique. For 40 dB rain attenuation, JSPA can achieves respectively average capacity of transmission up to 173,3%, 189,9 % for data rate and 9,6% for fairness system. The application of JSPA technique improve the performance of utility 13,61-15,48 bps/H

An Adaptive Modulation in Millimeter-Wave Communication System for Tropical Region

 The dominant propagation factor affecting the outage and the spectral efficiency of millimeter-wave communication systems operating at frequencies 30 GHz is rain attenuation. An adaptive modulation is proposed to improve the outage and spectral efficiency performance of the system. This paper presents an analytical procedure for the evaluation of the outage and spectral efficiency of the system in Indonesia with heavy rain rate. By comparing analytic and simulation a validation was conducted. The results show that adaptive modulation can significantly improve the outage and the spectral efficiency performance of the system, for links with long distance

Heterogenous Traffic Performances on Local Multipoint Distribution Service System in Rainy Environment

Local multipoint distribution service (LMDS) system provides high bitrates services up to 40 Mbps operating in millimeter bands. The radio system can be employed to serve heterogenous traffics in any applications such as video surveillance, public internet hotspots and other services. However, the implementation in tropical area faces transmission problems which degrade signal reception, such as heavy rain. This paper examines the performance of heterogenous traffics in LMDS in a rainy environment. Some techniques to tackle rain ploblems were implemented and the effects were assesed. It was proven that PHY and MAC layers contribute to performances enhancement on rainy environment as long as the system uses the suitable scheduler. A packet-based scheduler was proposed by considering packet impact on quality. The results showed that the proposed technique is able to improve video performance about 0.02% over the maximum signal to noise (mSNR) scheduler, maintain voice decoding rate as well as the priority fair (PF) scheduler and increase data decodibility 0.2%

Analysis of different OCDMA techniques A reviewÂ

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Proceedings of the Twentieth NASA Propagation Experimenters Meeting (NAPEX 20) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop

The NASA Propagation Experimenters (NAPEX) Meeting is convened each year to discuss studies supported by the NASA Propagation Program. Representatives from the satellite communications (satcom) industry, academia, and government who have an interest in space-ground radio wave propagation are invited to NAPEX meetings for discussions and exchange of information. The reports delivered at these meetings by program managers and investigators present recent activities and future plans. This forum provides an opportunity for peer discussion of work in progress, timely dissemination of propagation results, and close interaction with the satcom industry

Proceedings of the Twentieth NASA Propagation Experimenters Meeting (NAPEX XX) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop

The NASA Propagation Experimenters (NAPEX) Meeting and associated Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop convene yearly to discuss studies supported by the NASA Propagation Program. Representatives from the satellite communications (satcom)industry, academia, and government with an interest in space-ground radio wave propagation have peer discussion of work in progress, disseminate propagation results, and interact with the satcom industry. NAPEX XX, in Fairbanks, Alaska, June 4-5, 1996, had three sessions: (1) "ACTS Propagation Study: Background, Objectives, and Outcomes," covered results from thirteen station-years of Ka-band experiments; (2) "Propagation Studies for Mobile and Personal Satellite Applications," provided the latest developments in measurement, modeling, and dissemination of propagation phenomena of interest to the mobile, personal, and aeronautical satcom industry; and (3)"Propagation Research Topics," covered a range of topics including space/ground optical propagation experiments, propagation databases, the NASA Propagation Web Site, and revision plans for the NASA propagation effects handbooks. The ACTS Miniworkshop, June 6, 1996, covered ACTS status, engineering support for ACTS propagation terminals, and the ACTS Propagation Data Center. A plenary session made specific recommendations for the future direction of the program

Queueing theory approach to rain fade analysis at microwave and millimeter bands in tropical Africa.

Ph. D. University of KwaZulu-Natal, Durban 2014.With an overwhelming demand of larger bandwidth required for high capacity data with content-rich services ranging from high-speed video streaming to multimedia content, there is a continuous need to migrate to higher microwave bands, particularly beyond the regular Ku and Ka bands (between 11 - 40 GHz). The presence of precipitation at these microwave and millimeter bands (3-300 GHz) generally induce rain fade, which is a constraint to network providers intending to achieve optimal service delivery, at acceptable signal to noise ratios (SNRs). In practice, fade countermeasures – static or dynamic – are necessary to combat the consequences of chronic fluctuations of rainfall resulting in signal deterioration and impairment over communication links. However, the implementation of dynamic fade countermeasures is systematically tied upon the available Channel State Information (CSI), which is often timevariant relative to the occurrence of precipitation events. Time-variation of rainfall events are perceptible in measurable rainfall microstructural parameters which vary intensely in space and time. These spatio-temporal variations yield the generation of observable random patterns of signal attenuation during rain events, often in a stochastic manner. To this end, researchers have emphasized on understanding the underlying behaviour of generic rainfall microstructural parameters such as rainfall rate, rainfall Drop Size Distribution (DSD) and radar reflectivity. Therefore, the investigation of these stochastic properties of rainfall processes is primary in the determination of recognisable patterns of rainfall rate and other microstructures. This thesis introduces the queueing theory approach via the Markov Chain technique to investigate the time-varying characteristics of the rainfall process from distrometer data in subtropical and equatorial Africa. Rainfall data obtained from these two climatic locations, at one minute integration time, were processed from sites in Durban, South Africa and Butare, Rwanda, over a specified measurement period. Initial investigation and comparison of rainfall microstructures undertaken at both sites clearly show key differences in their probability distribution profiles at Stratiform-Convective (SC) bounds. The underlying queue discipline of rainfall spikes and their queue metrics are determined and appraised for system performance using rainfall time series database. The results show rain spike generation processes vividly exhibit a First-Come, First- Served (FCFS) semi-Markovian distributed traffic of M/Ek/s discipline, with a varying degree of servers, for different rainfall regimes. Comparison of queue statistics results over different rainfall regimes at the two locations reveal significant differences in their queue metrics and performances. The knowledge obtained from the queue statistics and SC probability analysis are further employed in the determination and classification of rainfall cells, rainfall growth models and path attenuation prediction. The results are compared and validated with data collected from a 6.73km, 19.5 GHz terrestrial link in Durban