W-CDMA technology and FOMA installation plan 3 rd September, 2002 Network planning Dept. NTT DoCoMo 2 Today’s Items Principle of CDMA - Frequency allocation - Principle of DS-CDMA - Transmit power control Basic W-CDMA Transmission Technologies - Two-layer spreading code assignment - Inter-BS asynchronous mode Characteristics of W-CDMA - Statistical Multiplexing effect - MS stand-by time - Coherent RAKE reception (RAKE time diversity) 3G Roll Out Plan - FOMA service content - 3G Roll out plan 3 In case of 3 cell repetition Frequency Allocation f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 1 f 2 f 2 f 3 f 1 f 1 f 3 f 2 f 1 f 3 f 1 f 3 f 2 f 2 f 1 f 3 f 3 f 2 f 3 f 2 FDMA / TDMA CDMA Same frequency in all area. Take care of frequency allocation. 4 Principal Diagram Frequency Synthesizer Channel Coding Data Modulation Spreading Code ~ Spreading ~ Filter Data Demodulation Channel Decoding Spreading Code Frequency Synthesizer Despreading W B(5MHz) B(5MHz) W W SF (spreading factor)= Symbol rate of transmitted data Chip rate of spread data 5 Principal Diagram (Waveform of spreading codes in DS-CDMA) 1 -1 1 1 1 1 -1 1 -1 1 -1 1 -1 1 -1 -1 1 -1 1 1 -1-1-1-1 1 1 0 -2 0 0 0 2 2 -2 1 -1 1 -1 1 -1 1 -1 1 -1 1 1 1 Integrate & dump User 1 User 2 Transmitted data sequence Spreading code Spreading code Composite signal Spreading code Recovered transmitted data sequence for user 1 receiver User 1 Integration over the symbol length to recover 6 despreading despreading Power control Transmit Power Control MS MS MS MS Near – far problem Node B Node B TPC is essential Minimize the Tx power Increase the system capacity 7 SIR measurement TPC bit Target SIR SIR Up Link Transmit power control Closed loop transmit power control in the Uplink Tslot Transmit Power Control Down Link 1dB step 8 Today’s Items Principle of CDMA - Frequency allocation - Principle of DS-CDMA - Transmit power control Basic W-CDMA Transmission Technologies - Two-layer spreading code assignment - Inter-BS asynchronous mode Characteristics of W-CDMA - Statistical Multiplexing effect - MS stand-by time - Coherent RAKE reception (RAKE time diversity) 3G Roll Out Plan - FOMA service content - 3G Roll out plan 9 Two-layer Spreading Code Assignment Scrambling Code 10m sec length (38,400 chip) Channelization Code 4 chip 　 　 | 512 chip X transmission data is spread by scrambling codes and channelization codes. Extremely large number of scrambling code can be used. Elimination of interference components arising form multiple CH Increase the system capacity 10 How to use (1/2) Down Link Scrambling Code Channelization Code Up Link MS (A) Scrambling Code MS (B) Node-B Node-B Channelization Code