It depends. What kind of coverage are you trying to get? How far? Is your wireless AP on the edge of your coverage area, or toward the middle? Are you able to connect from the client computer's location, but just want a stronger signal? Or are your devices too far apart to get any signal? Does it have to be wireless?
If the computer doesn't need to be mobile, a wired connection will be more reliable. If running CAT6 cable isn't practical, the next best choice would be something like a
powerline bridge, used like this:
router/switch computer
| |
| <- (ethernet cables) -> |
| |
bridge------------------------------bridge
^
^
(in-wall electrical wiring)
If the computer is a laptop or if you need wireless for other reasons, an antenna is less complicated, easier to setup, and probably less expensive than a repeater/range-extender, but it depends on what kind of coverage you need. Here's a few sample scenarios (not drawn to scale):
default:
( ( ( A ) ) )
hi-gain antenna:
( ( ( ( ( A ) ) ) ) )
directional antenna:
( A ) ) ) ) ) ) )
repeater:
( ( ( A ) ) )
( ( ( R ) ) )
combination:
( ( ( A ) ) )
B----------------------------B
( ( ( A ) ) )
(legend: A =access point, R =repeater, B =bridge)