Page 181 - Proceedings of the 2017 ITU Kaleidoscope

Challenges for a data-driven society

the nanoscale object under study. Therefore, the Table 1. OSI to nanoscale communication network
nanodevices proposed in these papers would support the mapping
standard whenever they include a communication element at OSI protocol Framework nanoscale
the nanoscale. These communication elements (transmitter, layer component
receiver, medium, message, and message carrier) are also Application -
named in the definition, even though they are not described
in detail. Presentation -
Session -
2.2. Framework Transport -
Network
Field
The second block defined by the standard provides a Data Link Specificity
conceptual, general and small-scale framework consisting of
an appropriate number of components comprising well- Message Motion
defined functions and with interoperability among them. Physical Carrier Perturbation
The framework offers the organization and structure
required to implement procedures and models. To this end, using these metrics, researchers can measure and
a set of interconnecting components is introduced, namely: objectively compare the grade of improvement or
(i) message carrier, (ii) motion, (iii) field, (iv) perturbation, deterioration that different nanoscale network designs
and (v) specificity. experience.
The message carrier is described as the physical entity The standard classifies the metrics in function of each
which transports the message across the medium. In component. So, metrics related to the message carrier
particular, in EM nanocommunications, message carrier measure how the transmitted information is influenced by
would indicate the EM wave. The motion component the radio channel. Typical network metrics, such as
represents the physical phenomenon that enables the message lifetime (a message carrier is discarded when
message carrier to move (in EM, the wave propagation and exceeding a given time-to-live [TTL]) or information and
phase velocity). This component may be randomly communication energy (the energy required to move and
propagated through the medium, which would hamper the steer a message carrier) are proposed for this component.
propagation of the wave. To avoid this concern, the field On the other hand, metrics referring to the motion
component organizes and guides the movement of the component differ from usual network metrics and focus on
motion component. Concerning the EM the physics behind the message carrier transmission
nanocommunication system, this would correspond to the through the medium. Note that these metrics mainly
omni/directional antenna. The perturbation component evaluate molecular communications. Something similar
refers to the mechanism required to accommodate the occurs with the metrics related to the field component,
message carrier to the medium in order to transmit the which copes with the extent to which the message carrier
signal that contains the message (equivalent to a motion can be controlled, evaluating whether it follows an
modulation). Finally, specificity makes reference to the intended gradient. Specificity metrics point to the capacity
reception of the message carrier by a specific receiver of the message carrier to deliver a message to a specific
(receptor sensitivity/antenna aperture). destination. These metrics, in fact, are quite similar to those
This framework is compared to the Open System used in conventional EM links. Specificity (percentage of
Interconnection (OSI) model in order to place the five message carriers not addressed to an intended nanodevice
aforementioned components in the traditional which are not accepted by the intended nanodevice),
communication protocol stack, as specified in Table 1 sensitivity (percentage of message carriers addressed to an
(extracted from [10]). Due to their tiny size and their close intended nanodevice which are checked and processed by
relation to physical aspects, the nanoscale framework the correct intended nanodevice), or angular spectrum
components are situated in the lower layers of the OSI (quantifying the distribution of the intensity of nanoscale
stack, even breaching the separation between them. In communication signals received at each nanodevice as a
section 3, we will discuss this issue, analyzing the functions function of angle-of-arrival), are some of the metrics
and requirements of each component. suggested for this component.
Finally, the standard offers some other general metrics to
2.3. Metrics assess the performance of the entire nanoscale network. For
instance, the metric bandwidth-volume ratio, included in
The third section of the standard addresses the definition of this segment, is employed to evaluate the total amount of
common metrics to give information about the information exchanged by nanodevices belonging to the
interoperability among system components, together with nanoscale network, divided by the total system volume.
the computation and comparison of performance in a
nanoscale communication network. Evaluating networks by

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