| The researth into the prob1em of signa1's parameter estimate has neverstopped. Up to now, this prob1em is a1ways studied with assumptiofl ofcondi tional invertibi l ity of design matrix.In this thesis, we first consider the performance comparison betweenoptima11y weighted LS estimate and 1inear unbiased minimum varianceestimate in the condition of design matrix invertibi 1 ity. Under acondition on noise variance matrix invertibi l ity, the difference betweentwo estimates error variances can be ca1cu1ated, and the two estimatescan converge to the same one under a certain condition.Second, we obtain general ized answers of weighted LS and optima1ly -weighted LS under a condition on singu1ar matrix, and discuss theperformance comparison between generalized optima11y weighted LSestimate and linear unbiased minimum variance estimate.Final1y, we present genera1ized Matrix Schwarz inequa1 ity. |