NANONETWORKS: A NEW COMMUNICATION PARADIGM I. F. AKYILDIZ Georgia Institute of Technology BWN (Broadband Wireless Networking) Lab Atlanta, GA, USA & Universitat Politecnica de Catalunya N3CAT (Center for NaNoNetworking in Catalunya) Barcelona, Spain REFERENCES I.F. Akyildiz, F. Brunetti, and C. Blazquez, "NanoNetworking: A New Communication Paradigm", Computer Networks Journal, (Elsevier), June 2008. I.F. Akyildiz and J. M. Jornet, “Electromagnetic Wireless Nanosensor Networks”, Nano Communication Networks Journal (Elsevier), May 2010. IFA’2010 EURECOM 2 Nanotechnology Study of the control of matter on an atomic and molecular scale. – Enabling the miniaturization and fabrication of devices in a scale ranging from one to a few hundreds nanometers IFA’2010 EURECOM 3 3 Nanotechnology Diameter of human hair Typical cell diameter DNA double-helix diameter Carbon atoms bond length IFA’2010 EURECOM 20-200 µm 10 µm 2 nm 0.145 nm 4 4 NANOMATERIALS: GRAPHENE, NANOTUBES & NANORIBBONS Graphene: A one-atom-thick planar sheet of bonded carbon atoms in a honeycomb crystal lattice. * Carbon Nanotubes (CNT): A folded nano-ribbon (1991) * Graphene Nanoribbons (GNR): A thin strip of graphene (2004) IFA’2010 EURECOM 5 NANOMATERIALS: GRAPHENE, NANOTUBES & NANORIBBONS A graphene material sample used for testing its properties. IFA’2010 Ten graphene nanoribbons between a pair of electrodes Courtesy of the Exploratory Nanoelectronics and Technology (ENT) Group, School of ECE, GaTech. EURECOM 6 Nanomaterials: Graphene, Carbon Nanotubes & Nanoribbons Their electrical and optical properties, analyzed in light of Quantum Mechanics, offer: * High current capacity + High thermal conductivity Energy efficiency * Extremely high mechanical strength Robustness * Very high sensitivity (all atoms are exposed) Sensing capabilities New opportunities for device-technology: Nano-batteries, nano-memories, nano-processors, nano-antennas, nano-tx, nano-rx. IFA’2010 EURECOM 7 Design of Nano-Devices IFA’2010 EURECOM 8 Design of Nano-Machines Top-Down Bottom-Up Main Challenge: Main Challenge: Achieve molecular * Controlling the assembly process and atomic precision Examples: * Photolithography, * Micro-contact printing. IFA’2010 * Obtaining complex structures. Examples: * Molecular self-assembly * Molecular recognition. EURECOM Bio-Hybrid Main Challenge: * Isolation of biological nano-machines * Hybridization. Examples: Bacteria transport 9 DESIGN OF NANO-MACHINES Nano-Material based Nano-Machines IFA’2010 Biologically Inspired Nano-Machines EURECOM 10 POWER UNIT (NANO-BATTERIES) Zinc Oxide Nano Wires High density nano-wires used for nano-batteries. Improved power density, lifetime, and charge/discharge rates. IFA’2010 EURECOM 11 NANO-PROCESSOR * 45 nm transistor technology is already on the market * 32 nm technology is around the corner * World’s smallest transistor (2008) is based on a thin strip of graphene just 1 atom x 10 atoms (1 nm transistor) IFA’2010 EURECOM World smallest transistor Courtesy of Mesoscopic Physics group at the University of Manchester. 12 Graphene EM Nano-Transmitter Modulator Signal Generator Power Amplifier Antenna Information Can we develop an EM transmitter in the nano-scale in light of molecular electronics? – Yes, we can do that consistently with physics laws! – It may take us some time !! IFA’2010 EURECOM 13 Graphene EM Nano-Receiver Antenna LNA Demodulator Information IFA’2010 EURECOM 14 NANO-MEMORY Graphene-based micro-scale memories offer high density storage systems (e.g., 64 Gbits/cm2) IFA’2010 EURECOM 15 NANO-ANTENNAS Graphene can also be used to build antennas: – Using a single Carbon Nanotube (or a set of them): a nano-dipole – Using a single Graphene Nanoribbon: a nano-patch – Atom-precise antennas IFA’2010 EURECOM 16 A GRAPHENE-BASED NANO-ANTENNA J. M. Jornet and I.F. Akyildiz, “Graphene-based Nano-antennas for Electromagnetic Nanocommunications in the Terahertz Band”, in Proc. of 4th European Conference on Antennas and Propagation, (EUCAP), April 2010. – Propose, model and analyze a novel nano-antenna design based on a metallic multi-conducting band Graphene Nanoribbon (GNR) and resembling a nanopatch antenna. IFA’2010 EURECOM 17 OUR CONTRIBUTIONS Developed a quantum mechanical framework to model the transmission line properties of GrapheneNanoRibbons: Contact resistance Quantum capacitance Kinetic inductance as a function of different design variables Ribbon dimensions System temperature System energy IFA’2010 EURECOM 18 WHAT DID WE LEARN? Graphene can be used to manufacture nano-antennas with atomic precision. Using nano-antennas, EM waves will be radiated in the Terahertz Band (0.1-10 THz): New opportunities for electromagnetic nano-scale communications New opportunities for Terahertz technology. IFA’2010 EURECOM 19 DESIGN OF NANO-MACHINES Nano-Material based Nano- Machines IFA’2010 Biologically Inspired Nano-Machines EURECOM 20 BIOLOGICAL NANO-MACHINES I.F. Akyildiz, F. Brunetti, and C. Blazquez, "NanoNetworking: A New Communication Paradigm", Computer Networks Journal, (Elsevier), June 2008. A CELL The most sophisticated existing nano-machine: - Efficient energy consumption + Harvesting Mechanisms - Multi-task computing + DNA processing - Multi-sensing + Actuation IFA’2010 EURECOM 21 BIOLOGICAL NANO-MACHINES: POWER CELLULAR RESPIRATION Cell gains useful energy. By combining –Glucose –Amino Acids –Fatty Acids –Oxygen IFA’2010 The cell obtains energy which is used to synthesize Adenosine TriPhosphate or ATP EURECOM 22 HOW ABOUT AN ATP BATTERY? Mitochondria: a membrane enclosed organelle found in most eukaryotic cells. ** They generate most of the ATP per cell. ** Only present in eukaryotic cells. IFA’2010 EURECOM 23 BIOLOGICAL NANO-MACHINE: PROCESSOR/MEMORY Cells pose a good example of multi-tasking processors. In each cell, the “instructions” are contained in the genes, which are portions of DNA. Enzymes are bio-molecules that catalyze (trigger) the expression of a gene -> DNA processors. IFA’2010 EURECOM 24 BIOLOGICAL NANO-MACHINE PROCESSOR/MEMORY DNA: A nucleic acid that contains the instructions used in the development and functioning of all known living organisms. The manipulation of DNA or Hybridization will allow us to obtain user-defined biological Nano-machines IFA’2010 EURECOM 25 BIOLOGICAL NANO-MACHINE: TRANSCEIVER: EMISSION PROCESS A cell (the transmitter) synthesizes and releases in the medium molecules (proteins), as a result of the expression of a DNA sequence. IFA’2010 EURECOM BIOLOGICAL NANO-MACHINE: RECEIVER: RECEPTION PROCESS Another cell (the receiver) captures those molecules and creates an internal chemical pathway that triggers the expression of other DNA sequences. IFA’2010 EURECOM BIOLOGICAL NANO-MACHINE: RECEIVER: RECEPTION PROCESS IFA’2010 EURECOM BIOLOGICAL NANO-MACHINE: RECEIVER: RECEPTION PROCESS Receptor-ligand binding: A ligand is a substance that is able to bind to and form a complex with a bio-molecule to serve a biological purpose A receptor is a protein molecule, embedded in either the plasma membrane or the cytoplasm of a cell. IFA’2010 EURECOM 29 BIOLOGICAL NANO-MACHINE: PHEROMONE ANTENNA Ll. Parcerisa and I.F. Akyildiz, "Molecular Communication Options for Long Range Nanonetworks“ , Computer Networks (Elsevier) Journal, Fall 2009. Pheromones are bigger molecules externally released by plants, insects and other animals that trigger specific behaviors among the receptor members of the same species. IFA’2010 EURECOM 30 NANO-COMMUNICATION PARADIGMS EM Based Communication Molecular Communication for Nano-Material Based for Biological Nano-Networks Nano-Networks IFA’2010 EURECOM 31 TERAHERTZ BAND FOR EM BASED NANO-NETWORKS J.M. Jornet and I.F. Akyildiz, “Channel Capacity of Electromagnetic Nanonetworks in the Terahertz Band”, in Proc. of IEEE ICC, Cape Town, South Africa, 2010. – Developed an Attenuation and Noise model for EM communications in the Terahertz Band (0.1-10 THz) – Uniqueness of the Terahertz band: * Terahertz channel is seriously affected by the presence of different molecules present in the medium * High molecular absorption attenuates the travelling wave and introduces noise into the channel IFA’2010 EURECOM 32 PATH-LOSS Determined by: – Spreading Loss: accounts for the attenuation due to the expansion of the wave as it propagates through the medium. – Absorption Loss: accounts for the attenuation due to molecular absorption. A f , d d B A f , d d B A f , d d B s p r e a d a b s IFA’2010 EURECOM 33 SPREADING LOSS Depends on the frequency of the wave f and the total path length d: 4 f d A f , d 2 0 l o g s p r e a d c A dominant term in the total path loss computation !! IFA’2010 EURECOM 34 ABSORPTION LOSS Molecular composition of the channel: 1 A fd , a b s fd , where τ is the transmittance of the medium and accounts for the molecular absorption of the channel; i.e., measures the amount of radiation that is able to pass through the medium. IFA’2010 EURECOM 35 MOLECULAR ABSORPTION Using Beer-Lambert law we obtain the transmittance of the medium τ as: P k fd fd , 0 e P i where IFA’2010 f is the wave frequency d is the path length P0 is the output power Pi isthe input power, and k is the medium absorption coefficient. EURECOM 36 MOLECULAR ABSORPTION Medium absorption coefficient k depends on the particular mixture of particles found along the channel: i , g k f k f i , g where f is frequency ki,g is absorption coefficient of each isotopologue i of a gas g. e.g., Air in an office is mainly composed of * Nitrogen (78.1%) * Oxygen (20.9%) and * Water vapor (0.1-10%). IFA’2010 EURECOM 37 MOLECULAR ABSORPTION Absorption coefficient of a specific isotopologue i of a gas g T p , gi , g S T Pi k f Q f p 0T i , g where p s y s te m p r e s s u r e p r e f e r e n c ep r e s s u r e( 1a tm ) 0 T te m p e r a tu r e T S ta n d a r d P r e s s u r eT e m p e r a tu r e( 2 7 3 .1 5K ) S T P ig , Q m o le c u la rv o lu m e tr icd e n s ity ig , a b s o r p tio nc r o s ss e c tio n IFA’2010 EURECOM 38 MOLECULAR ABSORPTION For a given gas mixture, the volumetric water density can be obtained from the ideal gas laws equation as: n p i , g i , g Q q N q N A A V R T i , g where nn u m b e ro fm o le so fag iv e ng a s Vv o lu m e i,g q m ix in gra tioo fais o to p o lo g u eio fg a sg N A A v o g a d roC o n s ta n t Tte m p e ra tu re R g a sc o n s ta n t IFA’2010 EURECOM For example, with a 10% of water vapor, one molecule of H2O is found every 1 µm3 39 MOLECULAR ABSORPTION Absorption cross section can be further decomposed in * the absorption line intensity Si,g and * the absorption line shape Gi,g: f S G f i , g i , g i , g Si,g depends on the type of molecules. We obtain this value from the HITRAN database. IFA’2010 EURECOM 40 MOLECULAR ABSORPTION The continuum absorption is obtained from Van Vleck-Weisskopf assymetric line shape h c f t a n h 2 i , g 2 k T f 1 1 i , g L B G f 2 2 2 2 i , g i , g i , g i , g i , g i , g f h c f c ff ff c c L c L t a n h 2 k T B where h is the Planck Constant c is the speed of light in vacuum kb ithe Boltzmann constant and αLi,g is the broadening coefficient. IFA’2010 EURECOM 41 NOISE The total noise at the receiver will be mainly contributed by: – Electronic noise: predictably low due to large Mean Free Path of electrons in graphene, more accurate models are needed. – Molecular noise: which also appears due to molecular absorption. IFA’2010 EURECOM 42 WHAT DID WE LEARN? – Terahertz communication channel has a strong dependence on * the transmission distance * medium molecular composition. – Main factor affecting the performance of the Terahertz band the presence of water vapor molecules. – Terahertz frequency band offers incredibly huge bandwidths for short range (less than 1m) deployed nano-networks IFA’2010 EURECOM 43 Total Path Loss 1km 100 1m 50 1mm IFA’2010 150 We can certainly not go further Distance For the middle range, there are several windows TENTHS OF GIGAHERTZ S WIDE. Can we exploit this? Maybe not nano… but micro? Standard Atmosphere (1% H2O) 2 4 6 Frequency [THz] 8 EURECOM 10 0 The almost absence of molecules in short distance does simplify everything in the short range. 44 NUMERICAL RESULTS 2 1m 3 Distance Distance 4 1m 1 1mm 1mm MOLECULAR NOISE TEMPERATURE 2 4 6 8 IN THE TERAHERTZ BAND 2 4 Frequency [THz] Frequenc Noise Temperature [k] Noise Temp 1km 1km 200 150 1m 100 Distance Distance 250 1m 50 1mm 2 4 6 8 Frequency [THz] IFA’2010 EURECOM 1mm 2 4 Frequenc 45 TERAHERTZ COMMUNICATIONS Some novel properties: – Extreme large bandwidths – The noise in the terahertz band is neither additive nor white. IFA’2010 EURECOM 46 RESEARCH CHALLENGES IN TERAHERTZ COMMUNICATIONS – Accurate channel models accounting for molecular absorption, molecular noise, multi-path, etc. – New communication techniques (e.g., sub-picosecond or femtosecond long pulses, multicarrier modulations, MIMO boosted with large integration of nano-antennas?). – This band is still not regulated, we can contribute to the development of future communication standards in THz band. IFA’2010 EURECOM 47 RESEARCH CHALLENGES IN TERAHERTZ COMMUNICATIONS – New information encoding techniques, definition of new codes tailored to the channel characteristics (time varying channel, non white noise). – Frame and packet size, synchronization issues, transceivers architectures, etc. need to be defined. – Network topology issues, network connectivity, network capacity, how are they affected by the channel? IFA’2010 EURECOM 48 RESEARCH CHALLENGES IN TERAHERTZ COMMUNICATIONS – New MACs exploiting the properties of the THz band (e.g., collisions among femtosecond pulses may be negligible, OFDMA may be useful in such big bandwidths). – New routing protocols and transport layer solutions for reliable transport in terahertz networks. Cross-layer solutions? – What are the applications enabled by this huge bandwidth? IFA’2010 EURECOM 49 COMMUNICATION PARADIGMS FOR NANO-NETWORKS EM Based Molecular Communication for Communication for Nano-Machines Nano-Machines IFA’2010 EURECOM 50 A Possible Solution: Molecular Communication Defined as the transmission and reception of information encoded in molecules IFA’2010 A new and interdisciplinary field that spans nano, ece, cs, bio, physics, chemistry, medicine, and information technologies EURECOM 51 Nanonetworks vs Traditional Communication Networks Traditional Communication Molecular Communication IFA’2010 EURECOM 52 Molecular Communication Molecular Communication Short Range (nm to µm) Wired Molecular Motors IFA’2010 Long Range (mm to m) Medium Range (µm to mm) Wireless Ion Signaling (e.g., calcium, sodium, potassium, chlorine) Wireless Wired Wireless Pheromones Flagellated Bacteria Catalytic Nanomotors EURECOM Axons Capillaries Light transduction Pollen/Spores 53 Short-Range Communication Calcium Ions (Wireless) Molecular Motors (Wired) IFA’2010 EURECOM 54 Short-Range Communication using Molecular Motors What is a Molecular Motor? – Is a protein or a protein complex that transforms chemical energy into mechanical work at a molecular scale – Has the ability to move molecules IFA’2010 EURECOM 55 Short-Range Communication using Molecular Motors Molecular Motors: * Found in eukaryotic cells in living organisms * Molecular motors travel or move along molecular rails called microtubules * Movement created by molecular motors can be used to transport information molecules IFA’2010 EURECOM 56 Short-Range Communication using Molecular Motors IFA’2010 EURECOM 57 Short-Range Communication using Molecular Motors Encapsulation of information: Information can be encapsulated in vesicles. A vesicle is a fluid or an air-filled cavity that can store or digest cell products. IFA’2010 EURECOM 58 Short-Range Communication using Molecular Motors Encoding Select the right molecules that represent information IFA’2010 Transmission Propagation Attach the information packet to the molecular motor Microtubules (molecular rails) restrict the movement to themselves EURECOM Reception Decoding Information molecules are detached from molecular motors Receiver nanomachine invokes the desired reaction according to the received information 59 Short-Range Communication using Calcium Signaling Two Different Deployment Scenarios Direct Access Exchange of information among cells located next to each other IFA’2010 Indirect Access Cells deployed separately without any physical contact EURECOM 60 Short-Range Communication using Calcium Signaling Direct Access: Ca2+signal travel through gates IFA’2010 EURECOM 61 Short-Range Communication using Calcium Signaling – Gap Junctions: Biological gates that allow different molecules and ions to pass freely between cells (membranes). IFA’2010 EURECOM 62 Short-Range Communication using Calcium Signaling – Indirect Access: Transmitter nano-machine release information molecules to the the medium. Generate a Ca2+ at the receiver nano-machine. IFA’2010 EURECOM 63 Short-Range Communication using Calcium Signaling Encoding Information is encoded in Ca2+ IFA’2010 Transmission Involves the signaling initiation Signal Propagatio n Propagation of the Ca2+ waves EURECOM Reception Receiver perceives the Ca2+ concentration Decoding Receiver nano-machine reacts to the Ca2+ concentration 64 Problems of Short Range Molecular Communication – Molecular Motors: Molecular motors velocity is 500 nm/s They detach of the microtubule and diffuse away when they have moved distances in the order of 1 µm Development of a proper network infrastructure of microtubules is required Molecular motors move in a unidirectional way through the microtubules very long communication delays ! IFA’2010 EURECOM 65 Problems of Short Range Molecular Communication – Calcium Signaling Very high delays for longer (more than few µm) distances IFA’2010 EURECOM 66 Medium Range Molecular Communication M. Gregori and I. F. Akyildiz, "A New NanoNetwork Architecture using Flagellated Bacteria and Catalytic Nanomotors," IEEE JSAC (Journal of Selected Areas in Communications), May 2010 • Flagellated bacteria • Catalytic nanomotors • Pheromones • Pollen & Spores • Ion Signaling • Molecular Motors IFA’2010 EURECOM 67 Medium Range Molecular Communication: Flagellated Bacteria – Bacteria are microorganisms composed only by one prokaryotic cell. – Flagellum allows them to convert chemical energy into motion. – Escherichia coli (E. coli) has between 4 and 10 flagella, which are moved by rotary motors, fuelled by chemical compounds. – E. coli bacteria is approximately 2 µm long and 1 µm in diameter. IFA’2010 EURECOM 68 Medium-Range Communication using Flagellated Bacteria – Information is expressed as a set of DNA base pairs, the DNA packet, which is inserted in a plasmid. Encoding Transmission Propagation DNA packet is introduced inside the bacteria’s cytoplasm, using: • Bacteria sense gradients of attractant particles. – Plasmids – Bacteriophages – Bacterial Artificial Chromosomes (BACs) IFA’2010 Reception • They move towards the direction and finds more attractants (chemotaxis). • The receiver releases attractants so the bacteria can reach it. EURECOM Decoding DNA packet is extracted from the plasmid using: Restriction endonucleases enzymes 69 Why Bacterial Communication? Spans medium range to long range (μm to tens of cm) No need of infrastructure – Better than molecular motors Reliable transfer of huge amount of information – Up to 100Kbyte per bacteria (400K base pairs) using a plasmid. IFA’2010 EURECOM Objective Analyze the communications aspects of flagellated bacteria-based information transport – Delay and range And relation with other parameters (receiver size, bacteria speed, bacteria run period) How? Simulation!! – Others: routing, coding IFA’2010 EURECOM Why Simulation? Bacteria perform BIASED RANDOM WALK – Moves more or less randomly, but tends to climb concentration gradients of attractants We simulate a bacteria that – Starts swimming in a random direction – Starts at given distance from spherical receptor of certain size Delay time to reach the receptor Range maximum distance IFA’2010 EURECOM Simulation Model acterium RUNS or TUMBLES IFA’2010 EURECOM Medium Range Molecular Communication: Catalytic Nanomotors (Nanorods) – Au/Ni/Au/Ni/Pt striped nanorods are catalytic nanomotors, – 1.3 µm long and 400 nm on diameter, – can be externally directed by applying magnetic fields. We propose to use them as a carrier to transport the DNA information among nano-sensors IFA’2010 EURECOM 74 Medium-Range Communication using Catalytic Nanomotors – Information is expressed as a set of DNA base pairs, the DNA packet, which is inserted in a plasmid. Encoding Transmission Propagation • Nanorods are introduced in a solution of AEDP • Magnetic Fields guide the nanorod to the receiver • AEDP binds with the Nickel segments Decoding DNA packet is extracted from the plasmid using: Restriction endonucleases enzymes • DNA packets (plasmids) are attached to nanorods • CaCl2 solution is used in order to compress and immobilize the plasmid IFA’2010 Reception EURECOM 75 Long-Range Communication using Pheromones L. Parcerisa and I.F. Akyildiz, "Molecular Communication Options for Long Range Nanonetworks“ Computer Networks (Elsevier) Journal, Fall 2009 , Features: Communication Range Medium Carrier IFA’2010 mm - m Wet and dry • • Pheromones Pollen & Spores EURECOM 76 Long-Range Communication using Pheromones Communication Features: IFA’2010 EURECOM 77 Long-Range Communication using Pheromones Encoding Selection of the specific pheromones to transmit the information and produce the reaction at the intended receiver IFA’2010 Transmission Releasing the pheromones through liquids or gases Signal Propagation Pheremones are diffused into the medium EURECOM Reception Pheremones bind to the Receptor Decoding Interpretation of the information (Different pheremones trigger different reactions) 78 Research Challenges in Nano-Networks Development of nano-machines, testbeds and simulation tools IFA’2010 Information Theoretical Approach EURECOM Architectures and Communication Protocols 79 MOLECULE DIFFUSION CHANNEL MODEL M. Pierobon, and I. F. Akyildiz, ``A Physical Channel Model for Molecular Communication in Nanonetworks,’’ IEEE JSAC (Journal of Selected Areas in Communications), May 2010. Molecule Diffusion Communication: Exchange of information encoded in the concentration variations of molecules. RN TN Emission process IFA’2010 Diffusion process EURECOM Reception process 80 END-TO-END IFA’2010 EURECOM OBJECTIVE OF THE PHYSICAL CHANNEL MODEL Derivation of DELAY and ATTENUATION as functions of the frequency and the transmission range Non-linear attenuation with respect to the frequency Distortion due to delay dispersion IFA’2010 EURECOM 82 MODELING CHALLENGES FOR THE PHYSICAL CHANNEL Transmitter Propagation How chemical reactions allow the modulation of molecule concentrations as transmission signals ? How the “particle diffusion” controls the propagation of modulated concentrations ? Receiver How chemical reactions allow to sense the modulated molecule concentrations from the environment and translate them into received signals ? IFA’2010 EURECOM 83 MOLECULE DIFFUSION CHANNEL MODEL Transmitter Model Design of a chemical actuator scheme (chemical transmitting antenna) Analytical modeling of the chemical reactions involved in an actuator Signal to be transmitted Modulated concentration IFA’2010 EURECOM 84 MOLECULE DIFFUSION CHANNEL MODEL Propagation Model Solution of the diffusion physical laws (FICK’s First and Second Laws (1855)) in the presence of an external concentration modulation Modulated concentration Space-time concentration evolution IFA’2010 EURECOM 85 MOLECULE DIFFUSION CHANNEL MODEL Receiver Model Design of a chemical receptor scheme (chemical receiving antenna) Analytical modeling of the chemical reactions involved in a receptor Propagated modulated concentration Received signal IFA’2010 EURECOM 86 FURTHER RESEARCH CHALLENGES FOR CHANNEL MODEL Noise Capacity Throughput IFA’2010 EURECOM 87 FINAL GOAL OF MOLECULAR COMMUNICATION RESEARCH Physical Channel Model Noise Representation How information is transmitted, propagated and received when a molecular carrier is used How can be physically and mathematically expressed the noise affected information transmitted through molecular communication Molecular Channel Capacity Information Encoding/Decoding Concentration Chemical structure Encapsulation IFA’2010 EURECOM 88