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IMT-2000 을 위한 스마트 안테나 기술. 이 종 헌. 중앙연구원. IMT-2000 개발그룹. 주 요 내 용. Background Space-Time Propagation Channel General Structure & Operation Considerations for Application Processing Algorithms Testbed & Implementation Issues. CDMA 시스템의 용량.
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IMT-2000을 위한 스마트 안테나 기술 이 종 헌 중앙연구원 IMT-2000개발그룹
주 요 내 용 Background Space-Time Propagation Channel General Structure & Operation Considerations for Application Processing Algorithms Testbed & Implementation Issues
CDMA 시스템의 용량 Sectorization Smart Antenna Channel Coding Antenna Tilting Multiple User Detection Past Power Control Variable Rate Codes Coherent Detection Antenna Diversity Smart Antenna Rake Combining GP : Processing Gain GC : Coding Gain GS : Sectorization Gain a : Signal to MAI Power Ratio s : Power Control Error (Eb/No)req : Required Bit Energy to Noise Density Ratio f : Frequency Reuse Factor L : Average to Peak Transmission Rate
Analytical BER Performance of CDMA D=1 BER, Pb D=2 G(j ) = Azimuth Pattern N = Spreading Factor K = Number of Mobiles with in a Cell b = Reuse Factor D=3 D=4 D=5 D=6 D=7 Number of mobiles with in a cell
Cell Coverage Analysis Example (Voice Traffic Only) 849MHz 1.98GHz
Diversity & Combining Techniques Diversity • Space Diversity • Polarization Diversity • Angle Diversity • Time Diversity • Frequency Diversity Combining • Selection • Equal Gain Combining • Maximum Ratio Combining
Wide Band Delay Profile Measurement System Rx Module Tx Module • Carrier Frequency : 1950MHz • Receive Level : < -110dBm • PN Code Length : 1023.5 Sequence • PN Code Rate : 50Mcps • Demodulation : BPSK(DS-SS) • Resolution : 6m(20ns) • Dynamic Range : < 30dB • Carrier Frequency : 1950MHz • Bandwidth : < 100MHz • Transmit Power : >+37dBm(5W) • PN Code Rate : 50 Mcps • PN Code Length : 1023 Sequence • Modulation : BPSK(DS-SS)
Measurement Point WP1 and WP2 Rx WP1 WP2
Adaptive Tracking Beam Optimal Space-Time Combining Types of Smart Antenna Systems Switched Multiple Beam Interference Interference Interference Nulling
Phased Array Concept I0 I-1 I-2 IM I1 I2 I-M +2a 0 +a -a +Ma -2a -Ma d
d' = d sin(q) d = l/2 t' = d sin(q)/(f l) s(t) q s(t) s(t) = b ej(2pft+f) s(t-t') s(t- t') = b ej[2pf(t-t’) +f] = b ej(2pft +f) e-j2pft’ = b ej(2pft +f) e-j2pf[dsin(q)/fl] = s(t) e-jpsin(q) d d' s(t-2t') Array Response Vector
Array Response Vector (cont.) Array Response Vector
B/F # 1 # 1 Rake Combiner B/F # 2 # 2 Rake Output # 3 B/F # 3 2-Dimensional RAKE for Space-Time Processing
Operation Mobile A Gain=M Moblie B Gain=1 Range=1 Range=M1/r+a
Mobile A or B with Sector Antenna Mobile A Mobile B Impulse Response
Receiver Receiver Receiver Channelizer Channelizer Channelizer Space-Time Processing User Signal General Structure of Smart Antennas
z0,1 T c0 w0,1 u0(l) b0(l) x1(t) zN-1,1 T cN-1 wN-1,1 z0,M T uN-1(l) c0 w0,M bN-1(l) xM(t) zN-1,M T cN-1 wN-1,M x(t) Despreading {z i(l)} Beamformer {ui(l)} Detection bi(l) Beamforming for CDMA (Symbol Rate Beamforming Example)
Beamforming Algorithms Spatial Reference Beamforming - DOA based array response vector estimation Temporal Reference Beamforming - Wiener solution (Minimizing Mean Squared Error) Signal Structure Based Beamformnig - Blind beamforming (ex: CMA)
u: S의 eigenvalue의 최대값에 해당하는 eigenvector Beamforming Algorithm (cont.) Stanford Method - Code Filtering
Beamforming Algorithm (cont.) Pilot Assisted Method Wiener Solution Array 출력과 기준 신호 사이의 오차를 최소화 r = E[z.d] R = E[z.z*] Wiener Solution w = R-1.r Eigen Filter w: Rpost의 eigenvalue의 최대값에 해당하는 eigenvector
Test-Bed - TSUNAMI Project Technology in Smart Antennas for Universal Advanced Mobile Infrastrucure
배열 안테나 데이터 획득 시스템 멀티채널 수신기 Testbed - SK Telecom
Forward Link Processing - Feedback Method Base Mobile x1 x1 x2 x2 xN xN Feedback Processing
Forward Link Processing - Direct Use 2025MHZ 2200MHz
Considerations for CDMA IMT-2000 Up to 20MHz Bandwidth at 2GHz Multirate Services using Variable Spreading or Multicode Reverse Link Pilot Symbol or Channel Forward Link Auxiliary Pilot or Pilot Symbol Dedicated Control Channel
Switched or Adaptive Beam? Generic Properties Switched : Discrete Tracking with Fixed Beam Easy to Implement Adaptive : Flexible Beam Pattern Potential Capability of Adaptive Tracking SIR Improvement (in dB) 6 Ant. Elements Processing Gain=20dB SNR=10dB Space Processing Only (Single Beam)
Analog or Digital Beamforming? Digital Analog High dependency on RTT standards Difficult to apply to multi bandwidth systems Dependent on the A/D converter resolution Difficult to measure the resulting beam patterns Critical array calibration effects No additional loss and IMD Relatively easy to control the sidelobe Easy mass production Low dependency on RTT standards Easy to apply to multi bandwidth systems Independent on the A/D converter resolution Easy to measure the resulting beam patterns Being mitigate the array calibration problems Additional loss and IMD Relatively difficult to control the sidelobe Difficult mass production
2 2 3 3 4 4 1 1 Analog Beamformer 45o 45o -90o 0o 1 2 3 4 90o Hybrid 2 4 1 3 Lens Type Matrix Type