Step 1: Convert all fractions into decimals.
\[
a=\frac12=0.5
\]
\[
b=\frac29\approx0.222
\]
\[
c=\frac7{12}\approx0.583
\]
\[
d=\frac8{15}\approx0.533
\]
\[
e=\frac{11}{16}=0.6875
\]
Step 2: Arrange from largest to smallest.
\[
0.6875>0.583>0.533>0.5>0.222
\]
Therefore,
\[
e>c>d>a>b
\]
Hence the descending order is
\[
\boxed{e,c,d,a,b}
\]