The future of communication technology is moving from 5G to 6G with new innovations. Blockchain (BC) is a such immersive technology that significantly impacts the betterment of communication technology. BC-based spectrum-sharing solutions can be used in Dynamic Spectrum Access (DSA) systems to fulfill the need for secure and efficient communication. With the invention of cognitive radio networks, DSA became a popular topic for the scientific community. Spectrum misuse/violations can occur due to the rapid growth of spectrum sharing. As the system is open to malicious attacks, licensed spectrum owners must be identified and verified. However, the existing BC-based DSA solutions are more expensive, non-optimized, and lack spectrum misuse detection. This paper proposes a novel consensus algorithm called “Proof of Equation” for spectrum misuse detection. The core of the proposed algorithm is a consensus score calculation based on a numerical equation with three parameters rather than using cryptographic calculations. The performance of the proposed algorithm is studied using Python simulations, and simulation results show that the proposed algorithm outperforms the Proof of Work (PoW) and Proof of Stake (PoS) consensus algorithms in terms of block production time.
As blockchain technology and cryptocurrency become increasingly mainstream, ever-increasing energy costs required to maintain the computational power running these decentralized platforms create a market for more energy-efficient hardware. Photonic cryptographic hash functions, which use photonic integrated circuits to accelerate computation, promise energy efficiency for verifying transactions and mining in a cryptonetwork. Like many analog computing approaches, however, current proposals for photonic cryptographic hash functions that promise similar security guarantees as Bitcoin are susceptible to systematic error, so multiple devices may not reach a consensus on computation despite high numerical precision (associated with low photodetector noise). In this paper, we theoretically and experimentally demonstrate that a more general family of robust discrete analog cryptographic hash functions, which we introduce as LightHash, leverages integer matrix-vector operations on photonic mesh networks of interferometers. The difficulty of LightHash can be adjusted to be sufficiently tolerant to systematic error (calibration error, loss error, coupling error, and phase error) and preserve inherent security guarantees present in the Bitcoin protocol. Finally, going beyond our proof-of-concept, we define a ``photonic advantage'' criterion and justify how recent developments in CMOS optoelectronics (including analog-digital conversion) provably achieve such advantage for robust and digitally-verifiable photonic computing and ultimately generate a new market for decentralized photonic technology.
Pol Alemany, Ricard Vilalta, Raül Muñoz, Ramon Casellas · 5 authors
Data center (DC) interconnection allows us to have optical transmissions between DCs directly connected to optical networks, avoiding the use of a packet-based infrastructure. Thanks to the use of next-generation pluggable coherent optics, it is possible to create connectivity services (CSs) across multiple optical transport domains. In this multi-domain CS scenario, cloud operators and transport operators have to work together in the most dynamic way possible. To do so, they need a common place (i.e., a market) where the transport operators may expose their available optical resources and the cloud operators request (e.g., rent) them to be used in order to create end-to-end (E2E) CSs between DCs. Having multiple transport operators exposing their resource information in a common place requires a set of common rules (i.e., how much of the topology to show) to create E2E CSs requested between cloud operators. This paper makes use of the blockchain technology to present a blockchain-based extension for the software-defined network (SDN) architecture to allow each optical transport operator domain to become a peer in a blockchain network. In there, each peer follows the same rules and shares the same exact level of topology information by using a specific abstraction model to map the optical domain resources. This paper uses a set of three different abstraction models to validate their behavior on a blockchain system when managing multiple domain resources and the deployment of CSs across these domains. To do so, an experimental comparison on how the different abstraction models affect the performance of the blockchain system is presented.
Jingchi Li, Shaohua An, Honglin Ji, Xingfeng Li · 6 authors
For high-capacity and short-reach applications, carrier-assisted differential detection (CADD) has been proposed, in which the optical field of a complex-valued double sideband (DSB) signal is reconstructed without using a sharp-edge optical bandpass filter or local oscillator laser. The CADD receiver features a transfer function with periodical nulls in the frequency domain, while the signal-signal beat interference (SSBI) is severely amplified around the frequency nulls of the transfer function. Since the null magnitude at the zero frequency is inevitable, a guard band is required between the carrier and the signal, leading to a higher receiver bandwidth and implementation cost. To reduce the needed guard band, we propose a parallel dual delay-based CADD (PDD-CADD), in which an additional delay is placed parallel to the original delay in the conventional CADD. By this means, the modified transfer function has a sharper roll-off edge around the zero frequency. Consequently, the requirement on the guard band can be relaxed, which maximizes the bandwidth utilization of the system. The parallel delay is first optimized through numerical simulation. We then perform a proof-of-concept experiment to transmit a 100-Gb/s orthogonal frequency division multiplexing (OFDM) 16-ary quadrature amplitude modulation (16-QAM) signal over an 80-km single-mode fiber (SMF). After the fiber transmission, the proposed PDD-CADD can reduce the required guard band from 3 to about 1.2 GHz compared with the single delay-based conventional CADD. To our best knowledge, for the direct detection of a single polarization complex-valued DSB signal without using a sharp-roll-off optical filter, we achieve a record electrical spectral efficiency of 5.9 b/s/Hz.
Shifeng Ding, Gangxiang Shen, Kevin X. Pan, Sanjay K. Bose · 6 authors
In communication networks, network virtualization can usually provide better capacity utilization and quality of service (QoS) than what can be achieved otherwise. Under this operation, once the capacity of a virtual optical network (VON) is allocated, it will be static for a certain period, for example, a service contract period. However, in reality, the actual traffic demand of a VON always fluctuates, which would lead to a mismatch between the capacity assigned and the actual traffic demand carried. This mismatch would further cause degradation of provisioned network services and inefficiency in assigned network capacity. To overcome this issue, we propose a new scheme, called spectrum trading (ST), to trade spectrum resources between VONs in the context of an elastic optical network (EON). The key idea is to allow different VONs to trade their spectrum resources according to their actual capacity requirement at different time instants. A VON with unused spectra can trade away its unused spectra to other VONs that are short of spectrum resources at that time. in exchange, it is rewarded with some credit for its contribution to the ST community, which it can then use later to obtain extra capacity, if needed. The trust-worthiness of the trading records between the VONs is ensured in a distributed fashion through a blockchain- assisted ledger that is updated whenever a new trade occurs. A software-defined control plane is also developed to enable spectrum trading with the support of the blockchain-assisted ledger. The performance of the ST scheme is evaluated and compared with the scenario without such trading. Results show that the proposed ST scheme is efficient in improving the QoS of each VON and significantly improves overall network capacity utilization.
Yoshitomi Eduardo Maehara Aliaga, Diego Fernandes Gonçalves Martins, Marco Aurélio Amaral Henriques
Neste trabalho apresentamos uma proposta mecanismo de consenso para blockchain baseado em PoS, que viabiliza a participação de usuários de uma maneira mais justa. Através da utilização de tempo discreto o protocolo utiliza rodadas, onde apenas participantes que passaram no desafio da rodada possam gerar o bloco. O protocolo garante uma participação mais igualitária pois não é possível gerar o bloco antes da próxima rodada esperada.
Vincent Messié, Gaël Fromentoux, Xavier Marjou, Nathalie Labidurie Omnes
In this article, we highlight a novel solution for densifying 5G access networks. Taking benefits from local actors and prosumers, our proposal allows offering a better connectivity to end-users in a model involving network operators and a crowd of local actors. We show that building a multi-actors and densified access network infrastructure has become possible in a distributed way. Incumbent actors with a large footprint act as trusted partners securing the infrastructure and providing guarantees, while the crowd of local actors deploys multiple access points and are rewarded for their contribution. Rewarding is possible thanks to a distributed Bandwidth & Identity ledger along with a Proof of Bandwidth (PoB) mechanism. This article presents the main principles of this new connectivity platform, BALAdIN (Bandwidth Ledger AccountIng Networks), which relies on a consortium blockchain with access control mechanisms removing communitarian Wifi and ad hoc networks drawbacks. Indeed, combining distributed ledgers and edge networks allows local actors to cooperate with trusted parties, which leverages the full potential of multi-actors access networks.
In this chapter we discuss pseudorandom generators. Loosely speaking, these are efficient deterministic programs that expand short, randomly selected seeds into much longer “pseudorandom” bit sequences (see illustration in Figure 3.1). Pseudorandom sequences are defined as computationally indistinguishable from truly random sequences by efficient algorithms. Hence the notion of computational indistinguishability (i.e., indistinguishability by efficient procedures) plays a pivotal role in our discussion. Furthermore, the notion of computational indistinguishability plays a key role also in subsequent chapters, in particular in the discussions of secure encryption, zero-knowledge proofs, and cryptographic protocols. The theory of pseudorandomness is also applied to functions, resulting in the notion of pseudorandom functions, which is a useful tool for many cryptographic applications. In addition to definitions of pseudorandom distributions, pseudorandom generators, and pseudorandom functions, this chapter contains constructions of pseudorandom generators (and pseudorandom functions) based on various types of one-way functions. In particular, very simple and efficient pseudorandom generators are constructed based on the existence of one-way permutations. We highlight the hybrid technique , which plays a central role in many of the proofs. (For the first use and further discussion of this technique, see Section 3.2.3.) Organization . Basic discussions, definitions, and constructions of pseudorandom generators appear in Sections 3.1–3.4: We start with a motivating discussion (Section 3.1), proceed with a general definition of computational indistinguishability (Section 3.2) next present and discuss definitions of pseudorandom generators (Section 3.3), and finally present some simple constructions (Section 3.4). More general constructions are discussed in Section 3.5.