First check to see if there is anything that may be blocking physical access to your wireless router, and also the distance from it to your TV.
Is your router fairly new or is it still running the old b or g protocols at 2.4 GHz? If so, you may want to upgrade to a newer 802.11n one. Performance and range of coverage has significantly improved.
If none of the above makes sense, here's a good explanation:
wireless networking - What are pros and cons of b, g and n WiFi standards on the same speeds? - Super User
Worse case...if the TV to router path is really ugly, you might want to look into products like these that use the home wiring for connections:
https://www.zyxel.com/us/en/products...ters.shtml?t=c
Tom @ VillagesAV is a great source of info and will get you connected if the above does not get you going.