Perhaps you could try giving him some more sleep cues?
For example, firstly following a very consistent bedtime routine: Bath, bottle in nursery,dim lights read a book, cuddle/song, put in cot etc. If you follow the same thing every night, then he should start to learn that it is time to sleep.
I would also recommend removing anything from the room and cot (especially) that may distract him e.g. lots of toys/mobiles. He is becoming more aware of his surroundings and frm this age, anything that may catch his eye is enough to make him stir and waken fully.
Make his room really dark - light can waken them in a light sleep too.
Both my DS have white noise playing in their rooms to block the noise of aircraft and noisy neighbours!
Finally, I have always played our BT monitor music (which thankfully you can also control remotely!!) EVERY time my DS2 has gone to bed (both nap and bedtime) - it is his key cue that it is time to sleep. From the moment he hears it, he rolls over and goes to sleep. I have done this since the day he was born (now 7 mo).
Make sure when you try new things that you give them a week to work - NOTHING with a baby happens overnight!
Good Luck