Perhaps you should try some spelling variations:
optimization algorithms » optimisation algorithm, estimation algorithms, estimation algorithm
time approximation » _ approximation
one approximation » _ approximation, rough approximations
qoe optimization » game optimization, _ optimization, stage optimization

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((time approximation) OR (one approximation)) algorithm ) OR ( qoe optimization algorithms ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((time approximation) OR (one approximation)) algorithm ) or ( qoe optimization algorithms ))~".
• Adding a wildcard symbol may retrieve word variants: (( ((time approximation) OR (one approximation)) algorithm ) or ( qoe optimization algorithms ))*.