When the performance of the marketing department is to improve, should managers and employees receive a (higher) fixed salary or a variable salary?

Higher Fixed Salary with Bonus

the success of the Marketing Dep. is the main reason for any company to improve.

I do agree that they should receive a higher fixed salary.  

Marketing department is like back bone of company and the marketing staff should be facilite with neccessaries tools to get attractions for customer and as motivational factory they should be paid higher salaries but subject to targeted results.