Real option effect of uncertainty - irreversiblity vs fixed cost There is a growing literature (e.g. Bloom, 2009) studying negative macroeconomic impacts of heightened uncertainty. One channel through which uncertainty can discourage economic activity, and investment in particular, is via real option effect, where if firms face irreversibility or fixed cost in investment, higher uncertainty will encourage them to postpone investment, or exercise their "option to wait".

My question is: which of the two forms of nonconvex adjustment costs (fixed cost vs. irreversibility) is more important for this mechanism, and how do they differ in their effects? Is there any good reference explaining the issue, preferably in discrete-time setting? (I'm aware there's large literature on real options in continuous time, but so far I'm more familiar with discrete-time macroeconomic models).
There exists a post on capital adjustment costs, which gives a good overview of the different types of capital adjustment costs. 

http://economictheoryblog.com/2015/08/20/capital-adjustment-costs

However, ultimately the post summarizes Cooper, R. W., &amp; Haltiwanger, J. C. (2006). On the nature of capital adjustment costs. The Review of Economic Studies, 73(3), 611-633.

Regarding your question, I guess as long as there are any sunk costs associated to investment you destroy future option, regardless the nature of these costs. Consequently the nature of capital adjustment cost should not really change the way uncertainty affect investment through real option effects.