Hi Gopinadh, 2nd year is perfect one for starting preparation of Gate exam, for basic understanding and strengthening of the foundations, Electronic devices and circuits by Milliman is the best book you can read, for communications, principles of communications by herbert taub is the best, for signals and systems, book by oppenheim is the best. For LICA, book by Ramakant A.Gayakwad is the best, for AWP, John.D krauss book is the best and other subjects can have any books as reference.

Hope this helps.

All the best.