Interference Resistant Blind Acquisition and Channel Estimation for CDMA Communication Systems

The time sca#M over whicha cha#4][ is observed determines whethera deterministic orsta#212MH23 cha#[[5MH23][NMa is a#M propria#MH We showtha# the cha#][4 estima#H22 a#stima#H of Tsa#]UxMH a#a Xu a#M thea#MU4x3]MH2 a#4Ma#x3] ofSa yeed a#e Aa#dM[N sha#[ a common MMSE formula#M[[N They di#er only in the a#MUU52]MH of the cha#x24 cha#N52MH2U34 tion. From this observa#ser we developa new blind MMSE interferenceresista# t a#U1123MH for both timinga#ingM[2xx4 a#N cha#UU[ estima#1N2 tha# isa#U]xx5MH1 to both deterministica #t sta#M44UxMH cha#122 models. Simula#[U32 illustra#H the e#ectiveness of the new method. 1.I#lF ODUCTI#4 Accura## timinga#i cha#2xN estima#H1U a#s critica# to demodula #54M in wireless communica#]x1 systems. In codedivision multiple a#iple (CDMA) systems this a#isM ts to the estima#MH[ ofa globa# dela y o#seta#s corresponding cha#1]N coe#cients for RAKE combining. The presence of multia#H[42 interference (MAI)ma# es cha#U14 estima#H[4 pa#tima#H[42 cha#]xMH[31] Conventiona# CDMA receiverstrea# MAIa# ba# kground noisea#i rely oncorrela#H[211UMa timing a#M4U54MH[1[ However, the performa#[1 of conventiona# receiverssignifica# tlydegra#4N in the presence of strong MAI tha# ma y be encountered in highly mobilescena#[22[ A va#422 y of MAI-resista# ta#342UMH[xU a#] cha#[]] estima# tion techniquesha ve been proposed recently tha# exploit the structure of interference, including nonlinea# MUSIC-ba#UN methods a#M linea# MMSE filteringa#terin hes [1, 2, 3, 4]. Thispa# er focusses onlinea# filtering methods due to their simplicitya#N potentia#MU better performa#U2 under low SNRscena#25M [5]. Deta#MU[ cha#253MHU[NU]Ma of the cha#5]U depends on the rela#[N e timesca#Ux over which the modula#UN3 a#l cha#355 used for communica#5]U va#U33U Very slowly va#[14[ cha#4 nelsma y..