tailieunhanh - CDMA 120 – cdmaOne and CDMA2000 Concepts and Terminology phần 3

Hầu hết các thông tin tương tự sẽ bị xóa và các tiêu chuẩn sẽ tham khảo các tiêu chuẩn hiện hành tương tự IS-553A khi áp dụng. Cuối cùng, TIA/EIA-95 sẽ thêm các hiệu chỉnh kỹ thuật và khả năng mới. TIA/EIA-95 là Nghị định thư sửa đổi 4. | 80-13321-1 X11 CDMA 120 - cdmaOne and CDMA2000 Concepts and Terminology Section 2 Background Coherent Non-Coherent Detection Qualcomm cdma university CDMA 120 Section 2-29 Coherent Detection of the Forward Link Coherent detection requires that the carrier signal used in the transmitter and the receiver are perfectly matched in both frequency and phase. In cdmaOne systems the Forward link detection in the mobile is coherent. Forward link is BTS mobile. Non-coherent Detection of the Reverse Link of IS-95 Non-coherent detection refers to the case where the phase information is not available to the receiver. In cdmaOne systems the Reverse link is a non-coherent link since the phase information is not available. As a result the detection process at the Base Station becomes non-coherent. Reverse link is mobile BTS. Note For CDMA2000 Radio Configuration RC-3 to RC-6 a Pilot is provided on the Reverse link and therefore coherent demodulation can be employed. 2002 QUALCOMM Incorporated 2-29 CDMA 120 - cdmaOne and CDMA2000 Concepts and Terminology 80-13321-1 X11 Section 2 Background Qualcomm cdma university Signal-to-Noise Ratio CDMA 120 Section 2-30 Pn Signal-to-Noise ratio SNR Signal-to-Noise ratio is used to evaluate the performance of a radio communication system. It is defined as the decibel of the ratio of signal power to noise power . P SNR 10log- - Pn 2002 QUALCOMM Incorporated 2-30 CDMA 120 - cdmaOne and CDMA2000 Concepts and Terminology 80-13321-1 X11 Section 2 Background QUALCOWW Correlation cdma university CDMA 120 Section 2-31 1 V -1 V a Complete Correlation 1 V -1 V 0 V -1 a 3 1 V -1 V íht Mn X b No 1 V 1 Correlation 1 V -1 V b Correlation Correlation is a measure of similarity between any two arbitrary signals. It is computed by multiplying the two signals and then summing integration the result over a defined time window. For example Figure a the two signals are identical and therefore their correlation is 1 or 100 . .