248 CHAPTER 13 Networks on chips method to reduce power consumption. This technique, although successful in terms of transmission power, trades reliability for power, as it decreases a circuit's noise immunity and makes on-chip communication channels less reliable and lossier. Considering that unreliable communication leads to data retransmissions that may eventually require more power than the power saved, designers have come up with a technique that trades transmission speed for power rather than reliability [188]. In this case, the system uses a feedback scheme where voltage swing and operating frequency are determined online (in real time) by monitoring the error rate of transmitted data and the resulting data retransmissions. As the retransmis- sion rate decreases at a given operating frequency, the voltage swing decreases as well. In contrast, an increment in voltage swing occurs when the retransmission rate increases. An alternative innovative technology that leads to lower power consumption and improved performance in NoC design is that of silicon photonics. Silicon pho- tonics is the application of photonic systems with silicon as the optical medium. Conventional efforts suggest that integration of an optical network can be a viable solution that increases bandwidth, reduces latency, and reduces power consump- tion of the on-chip network [161].