If u r starting off then ther is only one book worth refering and thats Bernd Sklar.Digital communications.Later u can slowly switch over to Simon Haykin
In my opinion, if u can read some equation, maybe you can read digital communication by projas, you can understand the theory if you study it from maths
as all saying for proakis but if u really also wanted a good book ten u can also seen for sanjay sharma. its an indian autor but ieee students also sees this book . its a very good book. fora ptustudent i also ear a autor katre wosebooks also good.