Page 183 - Proceedings of the 2017 ITU Kaleidoscope

Challenges for a data-driven society

scheme. The most accepted solution for powering Table 2. Example of the equivalence between EM
nanodevices involves the use of piezoelectric nanoscale network components and the IEEE P1906.1
nanogenerators [6], [8], [13], which are able to convert framework
mechanical strains (e.g. bloodstream movement) into IEEE P1906.1
electric energy. The energy harvested is stored in a component Implemented component
nanocapacitor to feed the nanodevice components when the Transmitter CNT-based nanoantenna
energy level exceeds a given threshold. Nevertheless, the
main drawback to these nanogenerators is the scarce amount Receiver CNT-based nanoantenna
of energy harvested per unit of area, which strictly limits the Message Sodium concentration
communication capabilities of nanodevices. In addition, the
available energy depends on the physical medium in which Medium Air
nanodevices are deployed (if nanodevices take advantage of Message carrier Electromagnetic (EM) wave
environmental movement, the energy harvested will be Sensor, message carrier
greater than in a static medium) and the area of the Component < 100 nm (THz frequency wave)
nanogenerator. On the other hand, parameters related to the
transmission and reception of EM waves, such as power Non-standard physics Impact of scale on resonance
transmission or signal to noise ratio (SNR), are not treated Motion Radiation and waveguide
by the IEEE P1906.1 standard. This recommendation Field Intensity/directional antenna
should attract even more attention when human bodies are Perturbation RF modulation
involved, since the high transmission power envisaged for Receptor sensitivity/antenna
nanodevices [9] could affect health. The SNR at reception Specificity
is also an important parameter to consider in order to ensure aperture
robust and reliable nanoscale communications. Although
the standard deals with the channel capacity (computed by nanoscale communication network with the macro world is
using the Shannon theorem), and therefore, calculating the an issue not considered by the standard.
upper limit for the physical data rate, in the case of a low Higher OSI layers could be implemented, including
SNR value, the receiver would not be able to demodulate traditional functions (e.g. security techniques to improve the
the radio signal. privacy of data); however, due to extremely restricted
Aside from the shortcomings concerning the physical layer, nanodevice capabilities regarding processing, energy
we have also noticed a remarkable insufficiency of the harvesting or memory, serious doubts have been posed
IEEE P1906.1 standard to give some recommendations about their feasibility.
about the data link layer. As can be observed in Table 1, the
standard places the framework components specificity and 4. IEEE P1906.1 STANDARD OPEN ISSUES ON EM
motion at the data link layer. In EM communications, these COMMUNICATIONS
components are identified with signal radiation (motion)
and antenna aperture in reception (specificity) -see Table 2-. Analyzing the shortcomings identified in the IEEE P1906.1
However, as EM nanoscale communication networks must standard, we suggest some tips that should be considered in
contain a huge number of nanodevices due to their future EM nanoscale communications studies in order to
extremely limited transmission range (derived from the high offer the scientific community ways of confronting open
path loss suffered in the THz band [12], [14]), some research challenges not treated by the standard.
techniques are required to enhance the data transmission
robustness between adjacent nanodevices. Specifically, As previously mentioned, one of the main goals of the IEEE
medium control access to arbitrate transmissions and avoid P1906.1 standard is to join efforts towards the development
message collisions, flow control to encompass the bitrate of of nanoscale communications, so the lack of a strict
the communication link, or error detection mechanisms definition leaves the door open to different considerations.
would be required. In addition, the number of fields and The ambiguity of the definition may be a practical reason
control/payload/footer length of the reference message is why the IEEE P1906.1 standard has not been taken into
not defined by the standard, which could lead to the design account in recent nanoscale communication works [15]–
of different and even non-interoperable data link layers. [18]. Therefore, we believe that a more detailed standard
definition should be elaborated to better define the
Concerning the network layer, nanodevices may have to appropriate setting for developing future interoperable
reply to a request from an external macroscale device or nanoscale communication networks, subject to common
may need to immediately report new events to external end conditions. In particular, the definition should include,
personnel (e.g. a doctor). Due to the very limited firstly, the concept of a nanodevice as a device at the
transmission range of nanodevices, this information flow nanoscale, and, secondly, the division of the standard into
could require the creation of multi-hop routes. The IEEE two clearly separated parts, one focused on EM
P1906.1 standard establishes the field component as a communications and the other specifically for molecular
piece/part of the network layer, but it does not cover the nanoscale communications. The result would be a suitable
functionalities related to multi-hop end-to-end definition in order to provide a more complete
communications. In addition, the interconnection of the

– 167 –