文档介绍：Prakshep Mehta (03307909) Guided By: Prof. . Shevgaonkar MIMO Antenna Systems for MIMO Antenna Systems for munication munication Outline ?Introduction...Why MIMO?? ?What is MIMO ?? ?From SISO to MIMO ?The ”pipe ” interpretation ?To exploit the MIMO channel ?BLAST ?Space Time Coding ?Special Cases ?Still to Conquer Foschini, Bell Labs 1996 Tarokh, Seshadri & Calderbank 1998 What is MIMO ?? Initial Assumptions Initial Assumptions ?Flat fading channel ( B coh>> 1/ T symb ) ?Slowly fading channel ( T coh>> T symb ) ?n r receive and n t transmit antennas ?Noise limited system (I) ?Receiver estimates the channel perfectly ?We consider space diversity only H 11H 21””Classical Classical ”” receive diversity receive diversity = log 2[1+(P T ?? 2)·|H| 2] [bit/(Hz ·s)] H = [ H 11 H 21] Capacity increases logarithmically with number of receive antennas... ????????*2 2 det log HH I t Tnσ P C H 11H 22 Multiple Input Multiple Output systems Multiple Input Multiple Output systems H 12H 21??????? 22 21 12 11HH HHH C = log 2det[ I +(P T ??? 2 )·HH ?]= ???????????????? 22 212 22 1 log 2 1 log???? T TP P Where the ? i are the eigenvalues to HH ?????m=min(n r, n t) parallel channels, equal power allocated to each ”pipe ” Interpretation: Receiver Transmitter MIMO capacity in general MIMO capacity in general ??????????????????? mi it T t Tn P HH n PIC 1 2 2 *2 21 log det log??? H unknown at TX H known at TX ?????????? mi iipC 1 2 21 log ?? Where the power distribution over ”pipes ” are given by a water filling solution ???????????????? mi mii iTpP 111??????????p 1p 2p 3p 4 ), min( trnnm? The Channel Eigenvalues The Channel Eigenvalues Orthogonal channels HH ?=I, ? 1=? 2=…= ? m=1)/1( log ), min( 1 log 22 1 2 2 tT rt mi it TnPnnn P C???????????????? diversity ? Capacity increases linearly with min( n r , n t ) ? An equal amount of power P T/n t is allocated to each ”pipe ” Transmitter Receiver To Exploit the MIMO Channel To Exploit the MIMO Channel Time s0s0 s0