几个容易记错的概念ACIR、ACLR与ACS

qcg125

ACLR是发射功率与其在邻道经过接收滤波之后的功率之比，3GPP TS 25.104：Adjacent Channel Leakage power Ratio (ACLR) is the ratio of the transmitted power to the power measured in an adjacent channel. Both the transmitted power and the adjacent channel power are measured through a matched filter (Root Raised Cosine and roll-off 0.22) with a noise power bandwidth equal to the chip rate，即经过RRC滤波后的平均发射功率与在邻道经RRC滤波后的平均接收功率之比。例如频率间隔为5MHz时，3GPP TS 25.104规定基站ACLR不小于45dB，TS 25.101规定UE ACLR不小于33dB。
    ACS是接收机滤波器对相邻信道信号的抑制能力，3GPP TS 25.104：ACS is the ratio of the receiver filter attenuation on the assigned channel frequency to the receive filter attenuation on the adjacent channel(s).例如3GPP TS 25.101规定频率间隔为5MHz时UE的ACS为33dB。
    ACIR是邻道发射机到达接收机的功率与实际对接收机造成的干扰的功率之比。ACIR、ACLR与ACS的关系可用以下公式表达：1/ACIR=1/ACLR+1/ACS。假设邻道发射机到达接收机的功率为Ri，接收的邻道泄露功率为Ril，那么1/ACLR=Ril/Ri；Ri经过接收滤波器之后的功率为Rif，那么1/ACS=Rif/Ri。那么1/ACIR=(Ril+Rif)/Ri。对于UMTS系统而言，下行链路的ACIR以UE的ACS为主，上行链路的ACIR以UE的ACLR为主。