An utterly smitten Petrarch is the speaker in this poem (and the other 365 in the collection). Of course, it's never a great idea to assume that the poet is the same person as the speaker. And sure, you could spend a lot of time trying to keep Petrarch the historical figure-poet separate from the speaker of the poem here, but you probably have better things to do.
In this poem, Petrarch plays the role of the unlucky, overwhelmed lover. He's met the perfect girl, but it turns out that she's also perfect for someone else. It can never be. His admiration of Laura's perfections are overcome by the despair he feels at never being able to see her again. Petrarch finds relief in two things: reliving the past, when he could actually see her in the 'hood, and envisioning an early death that will bring him relief and make Laura finally see how great he was.
To be honest, he's kind of a mess. The shifts in time and the movement from memory (the past) to imagination (future) are the result of his manic emotions. It's all very adolescent, especially for an older guy who's a cleric. But our speaker teaches us one very important lesson in this work: love-longing doesn't fade with time.