At the end of Parshas Vayechi, also the end of all of Bereishis, Yosef gives his brothers the key, the password that will enable their descendants to recognize the man who will come to bring G-d's word that their redemption is at hand. Pakod Yifkod. G-d will remember you.
Yet Yosef dies before his brothers. Why then is he the one given the signal to transmit when more logically it should have been one of the longer lived brothers.
The answer to that question lies in Yosef's unique role. Of all the family he was the only one who had descended to Egypt as a slave. Only he was qualified to pass on the word to those who would be slaves that despite their suffering and enslavement, redemption would yet come...because he had lived it. He had gone from being a lowly imprisoned slave to the ruler of Egypt. No matter how much the Egyptians oppressed and degraded their Jewish slaves, his example would remain to tell them that one day the slaves would be masters again.
The specific message too had a meaning that resonated with Yosef's salvation in Egypt. Yosef had at first tried to pin his hopes on the Wine Steward urging him to remember him. Yet the Wine Steward forgot. It was G-d who remembered, who had always remembered, setting each stage of the process until Pharaoh's dream to elevate Yosef from the pit. And that was the lesson Yosef had learned.
After his death a new Pharaoh came who forgot Yosef and again G-d remembered. Man forgets. G-d remembers. This was the message Yosef was uniquely qualified to pass on to the people of Israel.