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Site Selection Diversity Transmit Power Control (SSDT). MS1. BS2. Tx BTS1 = Tx BTS2. MS2. BS1. SHO Downlink Transmissions with MRC. Tx BTS2. MS1. BS2. Tx BTS1 = 0. MS2. BS1. SHO Downlink Transmissions with SSDT. MRC SSDT. 1. 0.9. 0.8. 0.7. 0.6. 0.5. 0.4. 0.3. 0.2. 0.1.
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MS1 BS2 TxBTS1 = TxBTS2 MS2 BS1 SHO Downlink Transmissions with MRC.
TxBTS2 MS1 BS2 TxBTS1 = 0 MS2 BS1 SHO Downlink Transmissions with SSDT.
MRC SSDT 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -80 -60 -40 -20 0 20 40 60 Tx Power with MRC and SD (for each BTS) P(x>) Two-way SHO 1 cell Three-way SHO Tx Power (dBm)
0.04 MRC SSDT 0.035 0.03 0.025 0.02 0.015 0.01 0.005 -220 -200 -180 -160 -140 -120 -100 -80 -60 Interference Contributions of MRC and SSDT (3-Way soft-handoff) P(x) MRC Mean = -123.4 SSDT Mean < -129.0 0 Int. Power (dBm) (downlink case)
Downlink data1 MS broadcasts selected BS with Cell ID code which consists of several feedback bits BS2 (ID:10) 01 10 Downlink data2 MS More sophisticated Cell ID code can be considered BS1 (ID:01) Candidate Cell Broadcast by MS (Cell ID code-word)
Technical Refinements • Feed Back Information(FBI) bit. • Relation with Tx Diversity in SHO. • - Dual-operation of SSDT and Tx Div in 3GPP • Signalling • - Cell ID code. • - Up-date rate.
SSDT Status in 3GPP • SSDT was first proposed at ETSI SMG2 in ‘98 • Intensive discussions are made mainly in 3GPP TSG-RAN1 • SSDT related text was included in 7 Release ‘99 documents • - SSDT procedure : TS25.214 • - Layer 1 signaling : TS25.211 • - Functionality requirements of BS: TS25.133 • - Performance requirements and testing: • TS25.101, TS34.121, TS25.104, TS25.141