The nature of a wireless communication channel is very unpredictable. To design a good communication link, it is required to know the statistical model of the channel accurately. The average symbol error probability(A...The nature of a wireless communication channel is very unpredictable. To design a good communication link, it is required to know the statistical model of the channel accurately. The average symbol error probability(ASER) was analyzed for different modulation schemes. A unified analytical framework was presented to obtain closed-form solutions for calculating the ASER of M-ary differential phase-shift keying(M-DPSK), coherent M-ary phase-shift keying(M-PSK), and quadrature amplitude modulation(QAM) over single or multiple Nakagami-m fading channels. Moreover, the ASER was estimated and evaluated by using the maximal ratio-combining(MRC) diversity technique. Simulation results show that an error rate of the fading channel typically depends on Nakagami parameters(m), space diversity(N), and symbol rate(M). A comparison between M-PSK, M-DPSK, and M-QAM modulation schemes was shown, and the results prove that M-ary QAM(M-QAM) demonstrates better performance compared to M-DPSK and M-PSK under all fading and non-fading conditions.展开更多
In this paper the impact of distinctive structure of antenna with branch correlation for an OFDM (orthogonal frequency division multiplexing)-based system, MC-CDMA (multi-carrier coded-division multiple-access) system...In this paper the impact of distinctive structure of antenna with branch correlation for an OFDM (orthogonal frequency division multiplexing)-based system, MC-CDMA (multi-carrier coded-division multiple-access) system, operating over the frequency selective fading environments is studied. For the reason of accordance with the working environments in the real world applications (urban areas) the correlated-Nakagami-m fading is adopted. Furthermore, the performance evaluation with average BER (bit error rate) formulas of MC-CDMA system with MRC (maximal ratio combining) diversity was derived with an alternative method of the complementary error function. The illustrated results are not only discussing the effect that comes from triangular, linear, and circular antenna array constructions, but the factors of branch correlation are also analyzed. Generally, it is known that the more the received branch number is, the more superior system performance of a multiple-access system will become. It is interesting to contrast to the geometric of the antenna array, that is, the little shape changing of the antenna is, the worse inferior system performance arrive at.展开更多
目的分析改良呼吸困难指数(m MRC)评估和慢性阻塞性肺疾病评估测试量表(CAT)评分评估慢性阻塞性肺疾病(COPD)患者病情严重程度的临床效果。方法选择2014年4月至2015年6月接受诊治的75例COPD稳定期患者作为研究对象,分析m MRC评估、CAT...目的分析改良呼吸困难指数(m MRC)评估和慢性阻塞性肺疾病评估测试量表(CAT)评分评估慢性阻塞性肺疾病(COPD)患者病情严重程度的临床效果。方法选择2014年4月至2015年6月接受诊治的75例COPD稳定期患者作为研究对象,分析m MRC评估、CAT评分与COPD病情严重程度的相关性。结果 m MRC评估级别、CAT评分分值均与COPD患者病情严重程度存在显著相关性。结论 m MRC评估、CAT评分均可反映COPD患者病情的严重程度,两者均与COPD患者病情严重分级存在密切联系。展开更多
基金Project supported by Research Fund Chosun University 2014,Korea
文摘The nature of a wireless communication channel is very unpredictable. To design a good communication link, it is required to know the statistical model of the channel accurately. The average symbol error probability(ASER) was analyzed for different modulation schemes. A unified analytical framework was presented to obtain closed-form solutions for calculating the ASER of M-ary differential phase-shift keying(M-DPSK), coherent M-ary phase-shift keying(M-PSK), and quadrature amplitude modulation(QAM) over single or multiple Nakagami-m fading channels. Moreover, the ASER was estimated and evaluated by using the maximal ratio-combining(MRC) diversity technique. Simulation results show that an error rate of the fading channel typically depends on Nakagami parameters(m), space diversity(N), and symbol rate(M). A comparison between M-PSK, M-DPSK, and M-QAM modulation schemes was shown, and the results prove that M-ary QAM(M-QAM) demonstrates better performance compared to M-DPSK and M-PSK under all fading and non-fading conditions.
文摘In this paper the impact of distinctive structure of antenna with branch correlation for an OFDM (orthogonal frequency division multiplexing)-based system, MC-CDMA (multi-carrier coded-division multiple-access) system, operating over the frequency selective fading environments is studied. For the reason of accordance with the working environments in the real world applications (urban areas) the correlated-Nakagami-m fading is adopted. Furthermore, the performance evaluation with average BER (bit error rate) formulas of MC-CDMA system with MRC (maximal ratio combining) diversity was derived with an alternative method of the complementary error function. The illustrated results are not only discussing the effect that comes from triangular, linear, and circular antenna array constructions, but the factors of branch correlation are also analyzed. Generally, it is known that the more the received branch number is, the more superior system performance of a multiple-access system will become. It is interesting to contrast to the geometric of the antenna array, that is, the little shape changing of the antenna is, the worse inferior system performance arrive at.
文摘目的分析改良呼吸困难指数(m MRC)评估和慢性阻塞性肺疾病评估测试量表(CAT)评分评估慢性阻塞性肺疾病(COPD)患者病情严重程度的临床效果。方法选择2014年4月至2015年6月接受诊治的75例COPD稳定期患者作为研究对象,分析m MRC评估、CAT评分与COPD病情严重程度的相关性。结果 m MRC评估级别、CAT评分分值均与COPD患者病情严重程度存在显著相关性。结论 m MRC评估、CAT评分均可反映COPD患者病情的严重程度,两者均与COPD患者病情严重分级存在密切联系。
