ARJ  Volume 105 No 1

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Table of Contents & Guest editorial (~440 kB)

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1. Low-Complexity Detection and Transmit Antenna Selection For Spatial Modulation

2. Reed-Solomon Code Synbol Avoidance

3. Determination of Specific Rain Attenuation Using diferent Total Cross Section Models for Southern Africa

4. The Influence of Disdrometer Channels on Specific Attenuation due to rain Over Microwave Links in Southern Africa

LOW-COMPLEXITY DETECTION AND TRANSMIT ANTENNA SELECTION FOR SPATIAL MODULATION
by N. Pillay and H. Xu

Abstract: In this paper, we propose a novel low-complexity detection technique for conventional Spatial Modulation (SM). The proposed scheme is compared to SM with optimal detection (SMOD),SM with signal vector based detection (SM-SVD) and another reduced complexity detectiontechnique, presented in the literature. The numerical results show that the proposed scheme canmatch the error performance of SM-OD very closely, even at low bit-error rate (BER). The computational complexity at the receiver, is shown to be independent of the symbol constellation size,and hence, offers a much lower complexity compared to existing schemes.To further improve the error performance, we then propose two closed-loop transmit antennaselection (TAS) schemes for conventional SM. We assume the receiver has knowledge of the channeland a perfect low-bandwidth feedback path to the transmitter exists. From evaluation of the BERversus normalized signal-to-noise ratio (SNR) and the complexity analysis, the proposed schemesexhibit a significant improvement over SM-OD and other improved SM schemes in terms of error performance and/or complexity.
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REED-SOLOMON CODE SYMBOL AVOIDANCE
by T. Shongwe and A. J. Han Vinck

Abstract: A Reed-Solomon code construction that avoids or excludes particular symbols in a linearReed-Solomon code is presented. The resulting code, from our symbol avoidance construction, hasthe same or better error-correcting capabilities compared to the original Reed-Solomon code, butwith reduced efficiency in terms of rate. The codebook of the new code is a subset of the originalReed-Solomon code and the code may no longer be linear. We also present computer search results forthe bound on the number of symbols that can be avoided, and we make an attempt to find an expressionfor the bound. Such a code, by symbol avoidance, can be well suited to a number of applications,some of which include markers for synchronization, frequency hopping signatures, and pulse position modulation.
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DETERMINATION OF SPECIFIC RAIN ATTENUATION USING DIFFERENT TOTAL CROSS SECTION MODELS FOR SOUTHERN AFRICA
by S.J. Malinga, P.A. Owolawi and T.J.O. Afullo

Abstract: In terrestrial and satellite line-of-sight links, radio waves propagating at Super HighFrequency and Extremely High Frequency bands through rain undergo attenuation (absorption andscattering). In this paper, the specific attenuation due to rain is computed using different total crosssection models, while the raindrop size distribution is characterised for different rain regimes in thefrequency range between 1 and 100 GHz. The Method of Moments is used to model raindrop sizedistributions, while different extinction coefficients are used to compute the specific rain attenuation.Comparison of theoretical results of the existing models and the proposed models against experimental outcomes for horizontal and vertical polarizations at different rain rates are presented.
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THE INFLUENCE OF DISDROMETER CHANNELS ON SPECIFIC ATTENUATION DUE TO RAIN OVER MICROWAVE LINKS INSOUTHERN AFRICA
by O. Adetan and T. Afullo

Abstract: The influence of raindrop channels on the measured rain rate and specific rainfall attenuation in Durban (29o52'S, 30o 58'E), South Africa for six rain rate values: 1.71, 4.46, 22.97,64.66, 77.70 and 84.76 mm/hr selected from the rain events that occurred on the 27th December 2008 is analyzed in this work. Consecutive and alternate drop channels are removed to study the influence of raindrop diameters on the overall measured rain rate. The three-parameter gamma and lognormal models are used for the purpose of analysis. In general and for the two models considered, the lower channels (channels 1 to 5) do not alter significantly the overall rain rate and equally produce minimal attenuation. The critical raindrop channels contributing the larger percentage to the overall rain rate are created by D ≥ 0.771mm. The deviations of the measured and estimated rain rates are very small for all the rainfall rates selected. The estimation of the specific rain attenuation at frequency of 19.5 GHz is also discussed. The error estimation using the two models are also analysed.
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