Power saving with passive standby mode using bitmap-based activity logs for energy-efficient set-top box

A set-top box (STB) increases its energy efficiency with active standby and passive standby modes. Compared to the active standby mode, the passive standby mode saves more power by turning off more STB functions, but it results in longer activation latency. For an energyefficient STB, in this paper, power saving with the passive standby is studied. The STB operates the passive standby mode when it is not in use, and the passive standby mode is switched to the active standby mode before a user turns on the STB in order to reduce the activation latency. To do that, the passive standby uses activity logs, which are represented in a bitmap form, to find a user pattern and to predict the next user activity. In the presented power saving method with the passive standby, recent activities is reflected with more weights to quickly find a new user pattern, instead of waiting until activity logs for a new user pattern are accumulated. The method is evaluated via simulations and discussed1. © 1975-2011 IEEE.