Studies on User Grouping for MMSE equalizer in Downlink MC-CDMA Systems

[[abstract]]本論文提出在下行多載波分碼多重存取(Multi Carrier-Code Division Multiple Access，簡稱MC-CDMA)系統中以強制歸零檢測法(Zero forcing equalizer)和以最小均方錯誤組合(Minimum Mean Square Error Combining，簡稱MMSE)為解調器的用戶分組與適應性調變機制。在頻率選擇性衰減通道下，根據通道狀態資訊(channel state information)將用戶分配至衰減較小的群組後，可適性調變可以增加系統頻譜效率與降低系統位元錯誤率。在用戶分組後，每位用戶依據通道狀態調整所使用的調變與功率，讓基地台在有限的傳送功率下能最大化系統的傳輸量，同時也能根據每位用戶的位元錯誤率門檻，讓所有用戶達到預期的位元錯誤率。[[abstract]]We propose a user grouping and adaptive modulation algorithm for Zero forcing equalizer and Minimum Mean Square Error Combining equalizer (MMSE) in downlink Multi Carrier-Code Division Multiple Access (MC-CDMA) systems. Under a frequency-selective fading channel, we assign the users into groups by their channel state information and the adaptive modulation is used to improve the spectrum efficiency and reduce the BER. After grouping, we allocate transmission power for each user based on their channel state information. Our scheme aims at maximizing the total systems data rate under the total power and user’s BER constraints.[[note]]碩