Channel Characterization of Diffusion-based Molecular Communication with Multiple Fully-absorbing Receivers

In this paper an analytical model is introduced to describe the impulse response of the diffusive channel between a pointwise transmitter and a given fully-absorbing (FA) receiver in a molecular communication (MC) system. The presence of neighbouring FA nanomachines in the environment is taken into account by describing them as sources of negative molecules. The channel impulse responses of all the receivers are linked in a system of integral equations. The solution of the system with two receivers is obtained analytically. For a higher number of receivers the system of integral equations is solved numerically. It is also shown that the channel impulse response shape is distorted by the presence of the neighbouring FA interferers. For instance, there is a time shift of the peak in the number of absorbed molecules compared to the case without interference, as predicted by the proposed model. The analytical derivations are validated by means of particle based simulations

Channel Characterization of Diffusion-based Molecular Communication with Multiple Fully-absorbing Receivers

In this paper an analytical model is introduced to describe the impulse response of the diffusive channel between a pointwise transmitter and a given fully-absorbing (FA) receiver in a molecular communication (MC) system. The presence of neighbouring FA nanomachines in the environment is taken into account by describing them as sources of negative molecules. The channel impulse responses of all the receivers are linked in a system of integral equations. The solution of the system with two receivers is obtained analytically. For a higher number of receivers the system of integral equations is solved numerically. It is also shown that the channel impulse response shape is distorted by the presence of the neighbouring FA interferers. For instance, there is a time shift of the peak in the number of absorbed molecules compared to the case without interference, as predicted by the proposed model. The analytical derivations are validated by means of particle based simulations

Impact of SOA-Based Add-Drop Switch Nodes on High-Capacity Multicarrier Transmission for Metro-Access Networks

Internet-generated traffic growth is forcing the development of new low-cost solutions in metropolitan area networks (MANs), in particular in the transceiver and network node architectures. Semiconductor optical amplifier (SOA)-based wavelength blockers can be used as fundamental building blocks to add and drop optical channels in the node architecture of several network hierarchical levels. Even if its employment is advantageous in terms of costs and amplification bandwidth, the SOA can operate in a nonlinear regime. This work analyzes the impact of SOA-based node crossing on high-capacity discrete multitone (DMT) signals. In order to properly evaluate the interplay between optical channels and SOA self-gain modulation, both external and direct modulations are considered. Dual-sideband (DSB) and single-sideband (SSB) DMT variants are taken into account, showing no significant difference in the impact of SOA crossing for external modulation of a DFB laser. On the other hand, an important effect of subcarrier suppression arises on DSB DMT direct modulation of a vertical cavity surface emitting laser (VCSEL), less consistent for SSB DMT direct modulation. The analysis allowed to properly choose the bias current for the SOA employed in an experimental setup used to evaluate the transmission performance in a MAN scenario including add-drop lossless switch nodes. The experimental results demonstrate that a target capacity of more than 50 Gb/s per channel can be achieved in a 116-km MAN network composed of an SOA-based metro-access node and two metro-core aggregators, considering the transmission of three 25-GHzspaced DMT channels.</p

Impact of SOA-Based Add-Drop Switch Nodes on High-Capacity Multicarrier Transmission for Metro-Access Networks

Internet-generated traffic growth is forcing the development of new low-cost solutions in metropolitan area networks (MANs), in particular in the transceiver and network node architectures. Semiconductor optical amplifier (SOA)-based wavelength blockers can be used as fundamental building blocks to add and drop optical channels in the node architecture of several network hierarchical levels. Even if its employment is advantageous in terms of costs and amplification bandwidth, the SOA can operate in a nonlinear regime. This work analyzes the impact of SOA-based node crossing on high-capacity discrete multitone (DMT) signals. In order to properly evaluate the interplay between optical channels and SOA self-gain modulation, both external and direct modulations are considered. Dual-sideband (DSB) and single-sideband (SSB) DMT variants are taken into account, showing no significant difference in the impact of SOA crossing for external modulation of a DFB laser. On the other hand, an important effect of subcarrier suppression arises on DSB DMT direct modulation of a vertical cavity surface emitting laser (VCSEL), less consistent for SSB DMT direct modulation. The analysis allowed to properly choose the bias current for the SOA employed in an experimental setup used to evaluate the transmission performance in a MAN scenario including add-drop lossless switch nodes. The experimental results demonstrate that a target capacity of more than 50 Gb/s per channel can be achieved in a 116-km MAN network composed of an SOA-based metro-access node and two metro-core aggregators, considering the transmission of three 25-GHzspaced DMT channels.</p

Impact of Chirp in High-Capacity Optical Metro Networks Employing Directly-Modulated VCSELs

Directly modulated long-wavelength vertical cavity surface emitting lasers (VCSELs) are considered for the implementation of sliceable bandwidth/bitrate variable transceivers for very high capacity transmission (higher than 50 Gb/s per wavelength) in metropolitan area systems characterized by reduced cost, power consumption, and footprint. The impact of the frequency chirp measured for InP VCSELs with different kinds of design (high-bandwidth very short cavity and widely-tunable with micro electro-mechanical systems (MEMS) top mirror) is analyzed in case of discrete multitone (DMT) direct modulation in combination with 25-GHz wavelength selective switch (WSS) filtering. The maximum transmitted capacity for both dual side- and single side-band DMT modulation is evaluated as a function of the number of crossed nodes in a mesh metro network, comparing VCSEL based transmitters performance also with the case of external electro-absorption modulator use. Finally, the maximum reach achieved based on the received optical signal to noise ratio (OSNR) and the fiber span length is discussed. The results confirm the possibility to use directly-modulated long-wavelength VCSELs for the realization of sliceable bandwidth/bitrate variable transmitters targeting 50-Gb/s capacity per polarization, also in the presence of 5 crossed WSSs for reaches of hundreds of kilometers in multi-span Erbium-doped fiber amplified (EDFA) metro links supported by coherent detection

All-optical aggregation and distribution of traffic in large metropolitan area networks using multi-Tb/s S-BVTs

Current metropolitan area network architectures are based on a number of hierarchical levels that aggregate traffic toward the core at the IP layer. In this setting, routers are interconnected by means of fixed transceivers operating on a point-to-point basis where the rates of transceivers need to match. This implies a great deal of intermediate transceivers to collect traffic and groom and send it to the core. This paper proposes an alternative scheme based on sliceable bandwidth/bitrate variable transceivers (S-BVTs) where the slice-ability property is exploited to perform the aggregation of traffic from multiple edges �� -to-1 rather than 1-to-1. This approach can feature relevant cost reductions through IP offloading at intermediate transit nodes but requires viable optical signal-to-noise ratio (OSNR) margins for all-optical transmission through the network. In this work, we prove through simulation the viability and applicability of this technique in large metro networks with a vertical-cavity-surface-emitting laser-based S-BVT design to target net capacities per channel of 25, 40, and 50 Gb/s. The study reveals that this technology can support most of the paths required for IP offloading after simulation in a semi-synthetic topology modeling a 20-million-inhabitant metropolitan area. Moreover, OSNR margins enable the use of protection paths (secondary disjoint paths) between the target node and the core much longer than primary paths in terms of both the number of intermediate hops and kilometers.European Union H2020 project PASSION, grant no. 780326 (http://www.passion-project.eu/)

SOA Impact on High-Capacity DMT Signals in Switching/Aggregation Node for Future MAN

The impact of the crossing of SOA-based MAN nodes on DMT high-capacity transmission is experimentally evaluated. We provide an optimization of the saturation levels of the SOAs enabling add/drop functionalities to preserve the transmitted throughput.</p

Impact of Crosstalk in SDM Short-Reach Systems in Presence of Multicarrier Transmission

The effect of the coherent crosstalk in space-division multiplexed (SDM) optical systems is investigated both with simulations and experimentally. Short-reach links based on direct detection are taken into account with multi-subcarrier modulated signals propagating in few-mode fibers or in multi-core fibers. The limitations induced by the signal beating among the different mode/core channels is evaluated. Countermeasures are proposed, also with suitable experimentation

Transmitter and receiver solutions for VCSEL exploitation in access and metro networks

The high capacity demand, to support broadband services and everything-to-internet connectivity is pushing the limits of both access and metro networks, requiring the adoption of novel strategies for the optical transceiver modules. This represents an opportunity for the adoption in these network scenarios of novel photonic technologies based on single-mode vertical cavity surface emitting lasers (VCSELs) at long wavelengths. On one hand, the access network evolution requires a line rate increase beyond 10 Gb/s, targeting 50 Gb/s propagation in passive optical networks (PONs) over a few tens of kms in standard single mode fiber (SSMF) with simple, cost effective and energy efficient transceivers. On the other hand, the future metropolitan area network (MAN) will need to handle multi-Tb/s traffic in a very dynamic scenario, over variable distances up to hundreds of kms while promoting sustainability, reducing the CapEx and OpEx costs and power consumption. Both needs can be fulfilled by adopting VCSEL direct modulation with multicarrier modulation formats such as discrete multitone (DMT), in combination with distinct transmitter architectures and receiver solutions to support different aggregate capacity requirements and transmission reaches. In any case DMT with bit/power loading enables flexible rate and adaptive distance for metro network applications and link adaptation and PON resource usage optimization for future access networks. In this work, we report our recent results on the adoption of VCSEL technology in both scenarios, with special focus on the receiver and transmitter adopted architectures.NO ACKNOWLEDGEMENT