By plane:

There are train connections to the airports Frankfort (3.5 hours), Munich (4,5-5 h) and Leipzig (2 h) with one exchange each. Train connections are found here: (for Frankfort use the stations "Frankfurt(M)Flughafen", for Munich "München Flughafen Terminal" and for Leipzig "Leipzig/Halle Flughafen".
By train:

From the train station Jena-Paradies, the downtown hotels are in walking distance (<15 min).
From the train station Jena-West, you can use a bus, which is either waiting in front of the station or running from a stop about 100 m to the left. You can use every bus, and pay (coins only) inside the bus. It is one station to downtown ("Stadtzentrum"), which is also the final destination. This bus stop is less than 50 m from the hotel IBIS. The distance from the station to the IBIS hotel is about 400 m. Western.
By car:

Coming from the North (Berlin) or South (Munich) on the Autobahn A9, take the A4 on "Hermsdorfer Kreuz" towards Erfurt / Frankfurt M.. To reach the IBIS or Maxx hotel, leave at exit "Jena-Zentrum". And go towards city center ("Zentrum"). When you cross the Saale river and go below the railway tracks, you have to take the 2. left turn in the Löbdergraben (speeding camera!) for the hotel IBIS.
To go to the Best Western or directly to the conference site, the IPHT at the "Beutenberg Campus", you have to leave at the exit Jena-Göschwitz and go towards city center. The Best Western is on the left hand site when the road climbs up a steep hill. Follow the signs "Beutenberg Campus" to the left. When you reach the campus, take the entrance at the left and follow the signs to the IPHT. to the IPHT.