MIMO basics

08/11/15 Communication Theory 1Performance Analysis of MIMO Systems with IRMy!unwu "han#$uefen# "haoin $ue08/11/15 Communication Theory %Multi&le'In&ut Multi&le'Out&ut(MIMO)*+The use ofmulti&le antennas at ,oth en-s of a wireless lin. &romise si#nificant im&ro/ements in terms of s&ectral efficiency0 +1o all transmitter antennas use ortho#onal wa/es*2o0+1oes each recei/er antenna recei/e si#nals from all the transmitters* 3es0+4ow to -etect si#nals from -ifferent transmitters* +1ifferent transmission &aths ha/e -ifferent fa-in# (or in-e&en-ent fa-in#)008/11/15 Communication Theory 567am&le of a MIMO System (1'user)08/11/15 Communication Theory 8Performance AnalysisThe signal received at antenna j at time t is a noisy superposition of the n transmitted signals:+n transmit antennasm receiving antennasCti is transmitted by transmitter i at time t Rayleigh or Rician fading, quasistatic flat fading for l time slots, i,j is the fading coefficient from i to j, complex Gaussian variable ith mean E(i,j ) & variance !"# per dimension Constellation$independent jt sniit j ijtE c a d + %,&oise is 'ero$mean complex Gaussian random variable ith variance 20/%08/11/15 Communication Theory 5Performance AnalysisAssume the recei/er has com&lete channel information9 % % %% (( ( (% (% (lln n nlc c cc c cc c cc _ ,LLMM O ML% % %% (( ( (% (% (lln n nle e ee e ee e ee _ ,LLMM O ML:or co-e wor-s c an- e in l time slots9 assume c e0(!exp) ) , * + , *Sd c e E N ,) - %, (, , , %, (, *i jP c e n j m L L08/11/15 Communication Theory ;Performance Analysis+ The -istance ,etween these two co-e wor-s9 % % %% (( ( (% (% (lln n nlc c cc c cc c cc _ ,LLMM O ML% % %% (( ( (% (% (lln n nle e ee e ee e ee _ ,LLMM O ML:or co-e wor-s c an- e in l time slots9 assume c e0(% % %,(* ) * , ) mjltniitit j ie c e c d 08/11/15 Communication Theory