There are about 15 daily one hour flights, operated by Norwegian and SAS, to Luleå from Stockholm, the main flight hub in Sweden that has connections to many European airports.
It takes approximately 10-15 minutes to get from the airport to xxxx hotel. Taxi to the city cost approximately 25 EUR. There is also a bus service taking you to the city (and further to campus LTU) for 4 EUR.
Overnight trains from Stockholm to Luleå are available every day.