Analysis and Design of Energy-Efficient Bus Encoding Schemes

In computer system buses, most of the energy is spent to change the voltage of each line from high to low or vice versa. Bus encoding schemes aim to improve energy efficiency by reducing the average number of transitions between successive uses of the bus. We derive in closed form the performance of optimal and suboptimal low-weight line codes designed for this purpose, and propose new algorithms for their implementation. We then show that some low-complexity suboptimal schemes have a small performance loss with respect to the optimal ones. For example, by adding 8 lines to a 128 lines bus, we save 20.7% of energy with the optimal scheme and 19.4% with suitable suboptimal schemes.