Cooperative feedback to improve capacity and error rate in multiuser diversity systems - an OFDM case study

The aim of the study was to create a hybrid forecasting method that could produce higher accuracy forecasts than previously used ‘pure’ time series methods. Mentioned methods were already tested with total automotive waste, hazardous automotive waste, and total medical waste generation, but demonstrated at least a 6% error rate in different cases and efforts were made to decrease it even more. Newly developed hybrid models used a random start generation method to incorporate different time-series advantages and it helped to increase the accuracy of forecasts by 3%–4% in hazardous automotive waste and total medical waste generation cases; the new model did not increase the accuracy of total automotive waste generation forecasts. Developed models’ abilities to forecast short- and mid-term forecasts were tested using prediction horizon.

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Reduced-Complexity Radio Architectures for Enhanced Receive Selection Combining in Multiuser Diversity Systems

International Journal of Antennas and Propagation ◽

10.1155/2012/454210 ◽

2012 ◽

Vol 2012 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Elpiniki P. Tsakalaki ◽

Osama N. Alrabadi ◽

Constantinos B. Papadias ◽

Ramjee Prasad

Keyword(s):

Antenna Selection ◽

Low Cost ◽

Spatial Diversity ◽

Antenna System ◽

Multiuser Diversity ◽

Selection Combining ◽

User Terminal ◽

Receive Diversity ◽

Diversity Systems ◽

System Properties

Although antenna selection is a simple and efficient technique for enhancing the downlink performance of multiuser diversity systems, the large antenna interelement spacing required for achieving spatial diversity is prohibitive for user terminals due to size restrictions. In order to allay this problem, we propose miniaturized switched beam receiver designs assisted by low-cost passive reflectors. Unlike conventional spatial receive diversity systems, the proposed angular diversity architectures occupy a small volume whereas the antenna system properties are optimized by controlling the strong reactive fields present at small dimensions. The systems are designed for maximum antenna efficiency and low interbeam correlation, thus yieldingNpractically uncorrelated receive diversity branches. The simulation results show that the proposed enhanced diversity combining systems improve the average throughput of a multiuser network outperforming classical antenna selection especially for small user populations and compact user terminal size.

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An Investigation of Microwave Link Degradation due to Atmospheric Conditions (A Case Study of Akure-Owo Digital Microwave Link)

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.62-64.159 ◽

2009 ◽

Vol 62-64 ◽

pp. 159-165 ◽

Cited By ~ 1

Author(s):

P.O. Otasowie ◽

F.O. Edeko

Keyword(s):

Bit Error Rate ◽

Error Rate ◽

Error Rates ◽

Atmospheric Conditions ◽

Bit Error Rates ◽

Data Acquisition Software ◽

Model Equations ◽

June July ◽

Microwave Link

This work investigates the microwave link degradation due to atmospheric conditions on the Akure-Owo Digital Microwave Link. Microwave line of sight measurements were carried out between January and December 2005 with a data acquisition software (PROCOMM PLUS SOFTWARE). The data collected were analyzed using MATLAB 7.0 SOFTWARE program to determine the months of the year that has the highest degradation due to atmospheric conditions and also the months of the year that has the highest bit error rates. The result showed that the months of January, June, July, August and September have the worst signal degradation of -0.97dbm, -2.0dbm, -3.97dbm, -3.97dbm, -1.97dbm. respectively. The result also showed that the bit error rates are good and acceptable throughout the months of the year. A model equation was developed to predict the signal strength received and the bit error rate in the microwave link investigated, when atmospheric conditions are taken into consideration. The results of the predicted model were validated by field data and the results obtained showed an error of -0.2% for the received signal level and zero error for the bit error rate which means that the developed model equations can be used to accurately predict the link degradation parameters.

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