Transceivers are selectively activated to reduce power in a network of data processing devices linked by a data transmission loop. Each of the devices is linked by a transceiver, and passes data from a previous device in the loop to a next device in the loop when not transmitting data onto the loop....http://www.google.com.hk/patents/US5898828?utm_source=gb-gplus-share專利 US5898828 - Reduction of power used by transceivers in a data transmission loop
