16 Low-Power Operation
Many Bluetooth devices will be battery powered. Because a Bluetooth radio can use up to 30 mA when receiving, it is important that it be used as little as possible to save battery power. Bluetooth provides low-power modes of operation to minimise nonessential operation and conserve power.
It can take several seconds to set up an ACL link, so once one has been established, devices which are likely to have more data to transfer don’t want to lose it and have to go through the delay of setting it up again. For instance, if a headset is connected to a cellular phone, it is vital that the headset can pick up a call quickly before the caller decides that nobody’s listening and hangs up. But in between calls there are long periods ...
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