Energy reduction through crosstalk avoidance coding in networks on chip

Commercial designs are currently integrating from 10 to 100 embedded processors in a single system on chip (SoC) and the number is likely to increase significantly in the near future. With this ever increasing degree of integration, design of communication architectures for large, multi-core SoCs is a challenge. Traditional bus-based systems will no longer be able to meet the clock cycle requirements of these big SoCs. Instead, the communication requirements of these large multi processor SoCs (MP-SoCs) are convened by the emerging network-on-chip (NoC) paradigm. Crosstalk between adjacent wires is an important signal integrity issue in NoC communication fabrics and it can cause timing violations and extra energy dissipation. Crosstalk avoidance codes (CACs) can be used to improve the signal integrity by reducing the effective coupling capacitance, lowering the energy dissipation of wire segments. As NoCs are built on packet-switching, it is advantageous to modify data packets by including coded bits to protect against the negative effects of crosstalk. By incorporating crosstalk avoidance coding in NoC data streams and organizing the CAC-encoded data packets in an efficient manner, so that total number of encoding/decoding operations can be reduced over the communication channel, we are able to achieve lower communication energy, which in turn will help to decrease the overall energy dissipation.