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Network-on-Chip
12.2 Future Trends
One of the upcoming NoC architectures discussed in the book is threedimensional (3D) NoC. The NoC layers grow vertically with reduced communication overhead. The other directions, which are in progress, include
the following:
• Photonic NoC
• Wireless NoC
12.2.1 Photonic NoC
Photonic communication can provide large data transfers with minimal power
consumption. Photonic NoC provides the following two major advantages:
• Multiple terabits per second (Tbps) communication on a single waveguide (link) with limited power dissipation
• Power consumption that is independent of the link length and scales
only with link transmission interface circuitry, such as modulators,
drivers, and receivers
A major problem with the implementation of photonic NoC is the lack of optical memory and impracticality of optical processing. Shacham et al. (2007)
proposed a hybrid approach for this situation. An optical plane is used for
high-bandwidth multiwavelength transmission links, whereas an electronic
plane performs network management and control functions (Figure  12.1).
The communication takes place as follows:
1. A photonic circuit is reserved by a source core by sending a path
setup packet over the electronic network to the destination core.
The destination replies with a short acknowledgment pulse over the
photonic network.
2. The source sends data over the photonic circuit, combining the timedivision multiplexing (TDW) and wavelength-division multiplexing
(WDM).
3. The communication is terminated by the source transmitting a teardown packet, commonly known as path teardown process.
12.2.2 Wireless NoC
Deb et al. (2012) has shown that silicon-integrated antennas can operate in a
millimeter-wave range of few tens to 100 GHz. Carbon nanotubes (CNTs) show
excellent emission and absorption characteristics leading to an antenna-like