I read in my analog communication book: "A relatively small increase in bandwidth buys a large advantage in terms of reduced transmission power. But a large increase in transmitted power buys a meager advantage in bandwidth reduction. Hence, in practice, the exchange between B and SNR is usually in the sense of increasing B to reduce transmitted power and rarely the other way round." So, if we increase a little bandwidth single power is reduced to a large extent. That's right. But is that an advantage?