I have spoken in The Near-Far Effect about the Near-Far Effect, and I myself didn't know much about it, so I had to go and find some info on it.
Well, the concept is quite easy, but the implications can be seen in many applications, and more often at these times in which wireless communication has become a casual matter. Imagine yourself in a corner of a room with a friend of yours, who is sitting on the other side of the same room. You can still talk to each other, a bit loud, of course, but there's no problem.
Now, someone carrying his loud mp3 sits close to you. It's much easier for you to listen to the mp3 than to your friend, and, if you still want to talk to her, you start to scream, or speak a lot louder. That brings us to the situation where things get rough: the unpolite guy sets his sound even louder, so that he can enjoy his music, and everyone starts getting louder and louder, until nothing else can be heard correctly (or people start punching each other...).
Some wireless communication systems work in the same manner: transmitters and receivers work in a certain power level, but when something with equal or higher power comes between them, they try to set higher powers, till their possible limits.
CDMA is a cell phone channel division standard that allows transmition towers to select which phones they will serve, and they pick them using their power as choice parameter. When a phone (P1) moves closer to another tower, and may eventually have greater power than another phone (P2) that's already registered in that tower, the tower may, and probably will, disconnect P2 in preference of P1, which is not fair (at least for the user). Regulating organizations are developing ways to mitigate this problem, through power control inside the CDMA cells.
Part 2
Well, the concept is quite easy, but the implications can be seen in many applications, and more often at these times in which wireless communication has become a casual matter. Imagine yourself in a corner of a room with a friend of yours, who is sitting on the other side of the same room. You can still talk to each other, a bit loud, of course, but there's no problem.
Now, someone carrying his loud mp3 sits close to you. It's much easier for you to listen to the mp3 than to your friend, and, if you still want to talk to her, you start to scream, or speak a lot louder. That brings us to the situation where things get rough: the unpolite guy sets his sound even louder, so that he can enjoy his music, and everyone starts getting louder and louder, until nothing else can be heard correctly (or people start punching each other...).
Some wireless communication systems work in the same manner: transmitters and receivers work in a certain power level, but when something with equal or higher power comes between them, they try to set higher powers, till their possible limits.
CDMA is a cell phone channel division standard that allows transmition towers to select which phones they will serve, and they pick them using their power as choice parameter. When a phone (P1) moves closer to another tower, and may eventually have greater power than another phone (P2) that's already registered in that tower, the tower may, and probably will, disconnect P2 in preference of P1, which is not fair (at least for the user). Regulating organizations are developing ways to mitigate this problem, through power control inside the CDMA cells.
Part 2
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