system directly inspired by the nerve
fibers that transport muscle movements, external sensorial stimuli,
and neural communication signals
to and from the brain. The latter are
inspired by the capillaries, which are
the smallest blood vessels inside the
human body. Capillaries connect arterioles and venules and their main
function is to interchange chemicals
and nutrients between the blood and
the surrounding tissues. The feasibility and practicality of these systems
still needs to be investigated, but they
can serve as a starting point for future
bio-inspired nanocommunication
systems.
Last but not least, we proposed
and studied in Gregori and Akyildiz4
a molecule transport technique using
two different types of carrier entities,
namely, flagellated bacteria and catalytic nanomotors. On the one hand,
the flagellated bacteria are able to carry DNA messages introduced inside
their cytoplasm. When set free in the
environment, the carrier bacteria are
headed to the receiver, which is continuously releasing bacteria attractant particles. Upon contact with the
receiver, the bacteria release the DNA
message to the destination. On the
other hand, the catalytic nanomotors
are defined as particles that are able to
propel themselves and small objects.
Nanomotors can be loaded with DNA
molecules and their propagation can
be guided using preestablished magnetic paths from the emitter to the receiver. Nanomotors can also compose
a raft and transport the DNA message
through a chemotactic process. The
propagation of information by means
of guided bacteria or catalytic nanomotors is relatively very slow (in the
order of a few millimeters per hour),
but the amount of information that
can be transmitted in a single DNA
strand makes the achievable information rate relatively high (up to several
kilobits per second). All these results
require us to rethink well-established
concepts in communication and network theory.
Developing Nanonetworking
Protocols
Nanonetworks are systems composed
by interconnected nanomachines
that communicate by following spe-
While there is
still a long way
to go before a
fully functional
nanomachine is
realized, we believe
hardware-oriented
research and
communication-
focused
investigations
will benefit from
being conducted
in parallel from
an early stage.
cific protocols. These protocols must
address various issues not only common to conventional networks, but
also arising from the peculiarities of
the different nanocommunication
options. For this, several features required in any communication network, such as Medium Access Control (MAC) mechanisms, addressing
schemes, or information routing techniques, must be designed in light of
the properties of the aforementioned
nanocommunication paradigms
Terahertz nanonetworks. The Terahertz Band provides a very large transmission bandwidth. On the one hand,
this can be used to support very high-speed communication among nano-devices. On the other hand, a very
large bandwidth enables new channel access techniques, which can ease
the tasks of the MAC protocol. For example, when using femtosecond-long
pulses for communication among
nano-devices,
2 the chances of having
a collision between different nanomachines‘ transmissions are almost nonexistent. As a result, very simple MAC
protocols can be used. For instance,
nanomachines can just transmit
whenever they have some information
ready and then they just wait for an acknowledgment. New ways to verify the
integrity of the message that has been
transmitted and to accordingly inform
the transmitter will be necessary. In
addition, in light of the capabilities of
nanomachines, new coding schemes
and error correction mechanisms will
have to be developed. When it comes
to addressing and routing, it will also
be the capabilities of nanomachines
what will determine what is possible
and what is not. For example, it seems
unfeasible to assign a unique ID to every component of a nanonetwork. Alternatively, by exploiting again the nature of pulse-based communications,
we think that nanomachines will have
a notion of the distances among them,
which can be used for addressing and
routing purposes. At the same time,
in our vision, we believe that in some
applications it will not be necessary to
uniquely identify every nanomachine,
but it will be enough by just classifying the nanomachines according to
their internal status, for example, the
sensing readings.