Digital Communications and Networks(DCN)

journal homepage: www.elsevier.com/locate/dcan

Blockchain-enabled ResourceManagement and Sharing for 6GCommunications

Hao Xu a, Paulo Valente Klaine a, Oluwakayode Onireti a, Bin Cao b,Muhammad Imran a, Lei Zhang ∗aaJames Watt School of Engineering, University of Glasgow, Scotland, United KingdombBeijing University of Posts and Telecommunications of China, Beijing, China

Abstract

The sixth generation (6G) network must provide performance superior to previous generations in order to meet the requirementsof emerging services and applications, such as multi-gigabit transmission rate, even higher reliability, sub 1 millisecond latencyand ubiquitous connection for Internet of Everything. However, with the scarcity of spectrum resources, efficient resourcemanagement and sharing is crucial to achieve all these ambitious requirements. One possible technology to enable all of this isblockchain, which has recently gained significance and will be of paramount importance to 6G networks and beyond due to itsinherent properties. In particular, the integration of blockchain in 6G will enable the network to monitor and manage resourceutilization and sharing efficiently. Hence, in this article, we discuss the potentials of blockchain for resource managementand sharing in 6G using multiple application scenarios namely, Internet of things, device-to-device communications, networkslicing, and inter-domain blockchain ecosystems.

KEYWORDS:6G, Blockchain, Resource Management, Network Slicing, Wireless Blockchain

1. Introduction

As of last year, the fifth generation of mobile net-works, 5G, is already being commercialized in someparts of the world, with the expectation of address-ing limitations of current cellular systems as well asproviding an underlying platform for new servicesto emerge and thrive [1]. 5G was envisioned to benot only a faster 4G, but also an enabler for severalother applications, such as the Internet of Everything(IoE), industry automation, intelligent transportation

∗Corresponding author: Lei Zhang1Hao Xu, Paulo Valente Klaine, Oluwakayode Onireti, Muham-

mad Imran and Lei Zhang are with James Watt School of Engi-neering, University of Glasgow (email: h.xu.2@research.gla.ac.uk;[Paulo.ValenteKlaine, Oluwakayode.Onireti, Muhammad.Imran,Lei.Zhang]@glasgow.ac.uk). This work was supported in partbythe U.K. EPSRC (EP/S02476X/1)

2Bin Cao is with Beijing University of Posts and Telecommuni-cations of China (email: caobin65@163.com ).

and remote healthcare, to name a few, by providingultra high reliability, latency as low as 1 millisecond,and increased network capacity and data rates [2].However, despite the emergence of new technologies,such as millimeter waves, massive Multiple-Input-Multiple-Output (MIMO) and the utilization of higherfrequency bands, it is clear that 5G will not be able toattend all of these requirements, albeit improving sig-nificantly from its predecessors. As such, research hasalready shifted towards the next generation of mobilenetworks, 6G [2, 3, 4, 5].

It is expected that by 2030 our society will shift to-wards a more digitized, data driven and intelligentlyinspired society, that needs a near-instant and ubiqui-tous wireless connectivity [4, 6]. Thus, several novelapplications that provide such interaction and integra-tion are bound to emerge in the next decade [4]. Assuch, some key trends that are foreseen to emerge inthe near future are: virtual and augmented reality, 8Kvideo streaming, holograms, remote surgery, the in-

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dustry 4.0, smart homes, fog computing, artificial in-telligence integrated services, unmanned aerial vehi-cles, and autonomous vehicles, to name a few [4, 5, 7].These, by their turn, will demand much more frommobile networks in terms of reliability, latency anddata rates than 5G and its improvements can sup-port [2, 4, 5]. As such, several research initiativesaround the globe are already working towards shapingthe direction of 6G, and some of its key requirementsare already being speculated, as [2, 3, 4]:

• Provide peak data rates of at least 1 Tb/s and la-tency of less than 1ms;

• Support user mobility up to 1000 km/h;

• Operate in GHz to THz frequency range;

• Increase the network spectral efficiency, energyefficiency and security;

• Harness the power of big data, enabling a self-sustaining wireless network;

• Support for a massive number of devices andthings, enabling the IoE.

To enable all of the above and increase the systemstotal capacity, two different approaches are possible,according to Shannon’s information theory: either in-crease the system bandwidth or improve the spectralefficiency [4, 8, 9]. It is well-known that spectrummanagement is a key to achieve efficient spectrum us-age and it still has issues. For example, it is knownthat current fixed paradigms for spectrum assignmentand resource management is a major challenge in mo-bile networks. This will become even more challeng-ing in 6G, due to the ever-growing number of sub-scribers and their need of intermittent connectivity, aswell as the development of more data-hungry appli-cations. Moreover, a number of studies have shownthat fixed spectrum allocation, despite being less com-plex, produces low spectrum efficiency, since licenseholders of that spectrum do not utilize it all the time(see [8] and references therein).

As such, several approaches have been proposed toimprove spectrum management, such as Opportunis-tic Spectrum Access (OSA) or auction mechanisms.Despite the benefits of these approaches, issues interms of security, high computational power and con-vergence, are present. On top of that, even if suchprotocols provide some collaborations at the systemlevel, collaboration between users is still not consid-ered, hindering the overall performance of those solu-tions. Since 6G is expected to be much more coopera-tive than its preceding generations, with new technolo-gies such as wireless power transfer, mobile edge com-puting, the IoE and Device-to-Device (D2D) commu-nications, heavily relying on the cooperation betweendevices, novel approaches that do not rely on a central

authority controlling spectrum and resource manage-ment, such as blockchain, are needed [3, 2].

Due to its inherit characteristics, blockchain is be-ing regarded as the next revolution in wireless com-munications, with even the Federal CommunicationsCommission (FCC) emphasizing the crucial role that itcan play in 6G and beyond [10]. The main idea behindblockchain is that of an open and distributed database(ledger), where no single party has control and trans-actions3 are securely recorded in blocks. Each block ischained together to its predecessor in a sequential, ver-ified and secure manner, without the need of a trustedthird party. As such, blockchain is expected to revolu-tionize resource and spectrum sharing by eliminatingthe central authority and replacing it with a distributedone, enabling the trade of assets without them reach-ing the central server, improving network security andreducing its cost [11, 12].

This integration between wireless networks andblockchain will allow the network to monitor andmanage spectrum and resource utilization in a moreefficient manner, reducing its administration costs andimproving the speed of spectrum auction. In addition,due to its inherit transparency, blockchain can alsorecord real-time spectrum utilization and massivelyimprove spectrum efficiency by dynamically allocat-ing spectrum bands according to the dynamic demandsof devices [9]. Moreover, it can also provide the neces-sary but optional incentive for spectrum and resourcesharing between devices, fully enabling new technolo-gies and services that are bound to emerge [12]. Fur-thermore, with future wireless networks shifting to-wards decentralized solutions, with thousands of cellsdeployed by operators and billions of devices commu-nicating with each other, fixed spectrum allocation andoperator controlled resource sharing algorithms willnot be scalable nor effective in future networks. Assuch, by designing a communications network cou-pled with blockchain as its underlying infrastructurefrom the beginning, 6G and beyond networks can bemore scalable and provide better and more efficientsolutions in terms of spectrum sharing and resourcemanagement, for example. Moreover, with privacyin mobile networks becoming more and more criti-cal, due to the emergence of novel applications suchas automated vehicles, industry 4.0 and medical ap-plications, where even a minor failure can lead to dis-astrous consequences, blockchain can be of great ad-vantage in securing and storing sensitive information.Since all information in a blockchain is verified by allpeers and it is immutable, this can allow future mobilenetworks to have a permanent record of all events withits corresponding time-frame [8].

In contrast to other papers in the area, which an-

3These transactions can mean anything, such as holdings of adigital currency (i.e. Bitcoin), movement of goods across a sup-ply chain, spectrum and resource allocation in wireless networks,etc. [9].

Blockchain-enabled Resource Management and Sharing for 6G Communications 3

alyze the impact of applying blockchain in wirelessnetworks and spectrum management [8, 9, 10], in thisarticle, we dive deeper in the field of blockchain-enabled resource sharing and spectrum management.Based on that, in this paper a blockchain 6G-enabledresource management, spectrum sharing and comput-ing and energy trading is envisioned as an enabler forfuture use-cases. These resources are considered tobe in a resource pool, in which spectrum is dynami-cally allocated, network slices are managed and hard-ware is virtualized in order to enable the blockchainresource and spectrum management. Based on this en-visioned framework, a discussion on how blockchaincan enable resource sharing between devices, such asenergy, data, spectrum lease, and computing poweris presented. In addition, the motivations of utiliz-ing blockchain for different use-cases are highlighted,mainly in terms of the Internet of things (IoT) andD2D communications, network slicing, and networkvirtualization. Lastly, some future trends expected inthe realm of blockchain-enabled wireless networks arediscussed and conclusions are drawn.

The remainder of this paper is organized as fol-lows. Section 2 presents an overview of current spec-trum management and allocation techniques, as wellas a link between blockchain and spectrum manage-ment. Section 3 discusses the motivations behindblockchain, and overviews its fundamentals. Sec-tion 4 discusses some key applications of blockchainand how it can transform current wireless networks.Lastly, Section 5 concludes the article.

2. Spectrum Management

To meet the increasing high data rate demand of 5Gand beyond applications, the capacity of the networkshas to increase, hence, there is also an increase in thedemand for spectrum. A dynamic policy for the man-agement of the spectrum license has recently been pro-posed to manage the spectrum efficiently [13]. It al-lows unlicensed secondary users to opportunisticallyaccess the licensed spectrum without interfering withthe licensed primary user. One of the options for us-ing the new spectrum license is to distribute opera-tion parameters to policy-based radio via a database.Such model has been established for sharing the Tele-vision White Space (TVWS) and the Citizen Broad-band Radio Service [14]. Recently, the applicationof blockchain as trusted database has emerged [15]where information such as spectrum sensing and datamining outcomes, spectrum auction results, spectrumleasing mappings and the idle spectrum informationare securely recorded on the blockchain. Blockhainthus brings new opportunities to Dynamic SpectrumManagement (DSM) [9, 10, 15] and it has recentlybeen identified as a tool to reduce the administrativeexpenses associated with DSM [16]. In particular, thefeatures of blockchain can improve conventional spec-

trum management approaches such as spectrum auc-tion [8]. Further, blockchain can aid in overcoming thesecurity challenges and the lack of incentive associ-ated with DSM [15]. Since blockchain is a distributeddatabase, it lends this property such that records in theDSM system are recorded in a decentralized manner.

One of the key areas where blockchain finds appli-cation in spectrum management is in recording its in-formation. Note that blockchain can record informa-tion as transactions, while spectrum management re-lies on databases such as the location-based databasefor protecting the primary users in the TVWS [17].With blockchain, information about spectrum man-agement such as 1) the TVWSs; 2) spectrum auc-tion results; 3) the spectrum access history; and 4)the spectrum sensing outcomes, can be made avail-able to the secondary user. As such, the benefits ofrecording the spectrum management information withblockchain are discussed here

• Contrary to conventional third party databases,blockchain enables users to have direct controlof the data in the blockchain, thus guaranteeingthe accuracy of the data. In particular, informa-tion on TVWS and other underutilized spectrumcan be recorded in a blockchain. Such data couldinclude the usage of the spectrum in frequency,time and the geo-location of TVWS, and the pri-mary users’ interference protection requirement.

• Improved efficiency of spectrum utilization withefficient management of the secondary users’mobility, and the primary users’ varying traf-fic demands. This is supported by the decen-tralized nature of the blockchain with primaryusers recording information on idle spectrum,which can be readily accessed by unlicensed sec-ondary users. Moreover, secondary users canmake their arrival into the network or departurefrom it known to other users by initiating a trans-action.

• Access fairness can be achieved with blockchainbased approaches where access history isrecorded. This is not the case with the tradi-tional Carrier Sensing Multiple Access (CSMA)schemes where access is not coordinated. Ac-cess can be managed in blockchain via smart con-tracts, where a threshold is defined and users canbe denied access to a specific band for a specifiedperiod of time when they reach the pre-definedaccess threshold.

• Blockchain provides a secure and verifiable ap-proach to record information related to spec-trum auction. Spectrum auction has been estab-lished as an efficient approach for dynamic al-location of spectrum resources [18]. The ben-efits of the blockchain based approach include1) it prevents frauds from the primary users

4

by providing transparency; 2) it guarantees thatthe auction payments are not rejected, since alltransactions are verified before they are recordedon the blockchain; and 3) it prevents unautho-rized secondary users from accessing the spec-trum since all secondary users can coopera-tively/collaboratively supervise and prevent suchunauthorized access.

In [9], the authors explored the applications ofblockchain in spectrum management including pri-mary cooperative sharing, secondary cooperative shar-ing, secondary non-cooperative sharing and primarynon-cooperative sharing. Moreover, in [19], the au-thors utilized a blockchain verification protocol forenabling and securing spectrum sharing in cogni-tive radio networks. Spectrum usage based on theblockchain verification protocol was shown to achievesignificant gain over the traditional Aloha medium ac-cess protocol. The authors in [20] proposed a pri-vacy preserving secure spectrum trading and shar-ing scheme, which was based on blockchain technol-ogy, for unmanned aerial vehicle (UAV) assisted cel-lular networks. Furthermore, in [21], the authors pro-posed a consortium blockchain-based resource sharingframework for V2X which couples resource sharingand consensus process together by utilizing the repu-tation value of each vehicle. In [10], the authors pro-posed the integration of blockchain technology andartificial intelligence (AI) into wireless networks forflexible and secure resource sharing.

3. Benefit of Using Blockchain

3.1. Blockchain Basis

Blockchain has a huge boost in the cryptocurrencyand ledger keeping industry, and thanks to the vi-tality of the community, the technology has gainedmuch attention from policymakers, mobile operators,and infrastructure commissioners [22]. Blockchainsare distributed databases organized using a hash tree4,which is naturally tamper-proof and irreversible [24].It has the attribute of adding distributed trust, and itis also built for enabling transaction consistency in adatabase. Furthermore, blockchain allows for atom-icity, durability, auditability, and data integrity [25].Besides its chain-link data structure nature, the Con-sensus Mechanism (CM), which ensures a unambigu-ous ordering of transactions and guarantees the in-tegrity and consistency of the blockchain across geo-graphically distributed nodes, is of great importance toblockchains. The CM largely determines blockchainsystem performance, such as transaction throughput,

4A hash tree or Merkle tree is a tree in which every leaf nodeis labeled with the hash of a data block, and every non-leaf nodeis labeled with the cryptographic hash of the labels of its childnodes [23]

delay, node scalability, and security level, etc. Assuch, depending on application scenarios and perfor-mance requirements, different CMs can be consid-ered. Commonly used CMs include Practical Byzan-tine Fault Tolerance (PBFT), Proof of Work (PoW),or Proof of Stake (PoS), a detailed analysis of perfor-mance and security of consensuses and how they canbe used in different resource management and sharingscenarios are stated in Section 3.2.

The blockchain opens up transparent and distributedinformation reformation, which can benefit all aspectsof industries, accommodating all range of centraliza-tion using different CMs. In perspective of usingblockchain technology in 6G, the massive deploymentof blockchain may lead to a major step forward for thecommunications industry and all other departments ofthe economy.

The transparent information flows on theblockchain are not only valuable assets for bothusers, and operators, but also to service providers andsocieties. In social practice, the authority has alwaysattempted to grip every detail for every operationand transaction. However, it would never track downevery happened transaction if they are not born tobe recorded. Blockchain occurs to be the ideal toolfor tracking of transactions if the blockchain nativetransactions are de facto in panoptic scenarios. Theblockchain native resources and assets will stimulatea new era of information revolution. Such reformationwill significantly improve the system efficiencyand security thanks to the better public order [32].It enables the Infrastructure as a Service (IaaS),Blockchain as a Service (BaaS) [33] to spread out interms of feasibility, and now the infrastructure canbe organized in a distributed way by allowing theinfrastructure to trade without further efforts to becentrally managed.

Later, such an ecosystem incubates the Blockchainas an Infrastructure (BaaI), which provides a solidtool-chain for settlements between the producer, thetrader, and the consumer, as shown in Fig. 1. As seenin Fig. 1, blockchains can be the information backboneof a local distributed resource management system inthe way of organizing the customers and producers inan open, transparent market, breaking up the informa-tion barriers to publicize the resources, and acceleratethe flow of transactions.

Blockchain has incubated the new horizon of re-source trading for fixed assets, such as licensed spec-trum and computing hardware. In our proposedblockchain 6G resource management scheme, trade-able spectrum, and computing resources are inte-grated parts of resource pools, where spectrum isdynamically allocated, network slices are managed,and the hardware is virtualized in order to facilityblockchain-enabled resource management. The auto-mated blockchain-enabled resource management re-lies on the programmable blockchain feature, which

Blockchain-enabled Resource Management and Sharing for 6G Communications 5

Energy & Infrastructure Communication Computing

URLLCeMMBmMTC

Distributed Storage

Blockchain Broker A

Distributed Power Users

Smart Grid

Spectrum Sharing

DG Unit

IOTINTERNET OF THINGS

IoT

Network Slicer

MVNO

Transactions

Computing Resource SharingEnergy Sharing

ComputingBlockchain TransactionEnergy

Blockchain Broker B

Blockchain Broker C

Roaming

D2D Communication

Relaying

On BlockchainTransactions

On Blockchain

Operator A Operator B

Edge Computing

Cloud Computing

Communication Flow

Spectrum Sharing

Fig. 1: Blockchain-enabled resource management framework

Table 1: Comparison of blockchain consensus

ConsensusSuitable Typeof Blockchain Latency/TPS BFT∗

CommunicationComplexity†

SecurityThreshold‡

EnergyUsage Scalability

PBFTConsortium /

Private Low/ High[26] Yes [26] O(n2)[26] 33%[26] Low Low [26]

RAFTConsortium /

PrivateVery Low /

Very High[27] No[27] O(n)[28] 50%[27] Low Medium[28]

PoW /

PoS Public High/ Low [29] Yes[30] O(n) [29] 50% [29] High High[29]

Proof ofStorage Public High /Low [31] Yes[30] O(n) [31] 50% [31] Low High [31]

∗The ability to tackle byzantine fault.† n indicates the number of participants.‡The given percentages stands for the maximum acceptable faulty nodes or attack.

in most cases are described as smart contracts5. Thecontract’s content is transparent for both public andagreement making parties, which makes it publiclytraceable. The virtual machine concept is used in thesmart contract executions, where the code will be ex-ecuted by a node on the virtual stack, and its resultswill be stored on the chain as a transaction record. Thetemper-proof ability and fully automated process givethe contract high immutability against breaches of thecontract and misrepresentations.

5The smart contract is essentially an executable program codestored on the chain, representing terms of agreements triggered au-tomatically when certain conditions are met [34].

3.2. Impact of Consensus and Security Performance

If the impressive and resistive data structure ofblockchain is the facade of a building, the consensusis the pillars. Blockchain has various options on theCM. Choosing a suitable consensus for 6G resourcemanagement is the most critical step of making a se-cured and efficient future-proof blockchain system.As the CM, which ensures an unambiguous orderingof transactions and guarantees the integrity and con-sistency of the blockchain across geographically dis-tributed nodes, is of importance to blockchains sinceit determines its performance in terms of TPS, delay,node scalability, security, etc.

6

Depending on the access criteria, the chain can bedivided into public and private. The public chain ispermission-less, which uses proof-based consensus toprovide a secured, reliable network for every partici-pant without requiring their identities at entry points.In the 6G resource pool, there are potential anonymousclients and providers on ad-hoc basis [4]. The benefitof adopting a public chain is significant for ad-hoc net-works, where the barriers of identification and securityare broken down for panoptic information exchanges.As such, public chains can potentially promotes theefficiency of the community and regulate the order ofparticipants [32]. However, if participants are con-cealed, violations and malicious activity are emergingthreats to the system. The consortium/private chain, incontrast, is permissioned, meaning that entry is con-trolled. It has a rather stable community composition,where the identity of participant is not kept secret. Thenetwork faces fewer threats from unknown attacks buthas challenges within the network, for instance, themalicious byzantine node6.

Before adapting to any new technologies, secu-rity and reliability are always the principle concerns.Blockchain technology is born to outperform existingsolutions regarding security performance and robust-ness. Table 1 shows the comparison between widelyused CMs of blockchain regarding 6 aspects: latency,TPS, complexity, security, energy consumption, andscalability. As it can be seen, private/consortium con-sensuses show better latency, TPS and energy con-sumption performance alongside lower ability to scaleup, however, the applied application prioritize latencyand TPS over scalability. On the other hand, proof-based mechanisms have decent performance on scal-ability, but sacrifice latency and TPS. In some caseslike proof of work, it also consumes a huge amountof power. However, their good scalability gives themcapability to grow fast in the public network and doesnot suffer from a surge of users, which makes them ex-cellent at mass market trading and distributed file stor-age system. Regarding the security performance, it isworth noting that the non-byzantine consensuses as-sume non-malicious activities, but byzantine consen-sus has tolerance not only against inactivity, but alsoagainst false and erroneous messages. PBFT func-tions with less than (n − 1)/3 byzantine nodes, andsome variants of PBFT provides higher tolerance withtrades-off of latency, such as multi-layer PBFT.

Besides the consensus which secures the blockchainfrom top-level threats, the communication link shouldbe hardened to prevent external security breaches. Thewireless communication is in peril of jamming andspoofing because of open channels. In the practiceof wireless blockchain network, the communicationfailure will result the node failure and thus lower

6A byzantine node is a malicious node that conceals its exis-tence and tempers the consensus, which tampers with the securityof network.

the security level. To mitigate the transmission suc-cess rate, collision avoidance mechanism like Car-rier Sense Multiple Access with Collision Avoidance(CSMA/CA) and physical layer security can be con-sidered.

4. Application Scenarios

4.1. IoT and D2D Communications

The IoT is a paradigm which envisions that allour daily objects and appliances will be connected toeach other, collecting and sharing information. Thiswill allow the automation of certain tasks and enableseveral other applications to emerge, such as smarthomes, smart transportation and wearable devices,smart farming, healthcare, machine-to-machine com-munications, etc. [35]. In order to reach such automa-tion and growth, it is necessary to have proper stan-dards and protocols for IoT devices. However, cur-rent solutions still rely on a centralized model, whichincurs in a high maintenance cost for manufacturers,while consumers also lack trust in these devices. That,combined with the resource constraints of IoT devices,privacy and security concerns, as well as poor interop-erability among different vendors, makes IoT a chal-lenging domain [36, 37]. Similarly, D2D communica-tions, a paradigm that envisions the communicationsand share of data between devices, also shares simi-lar challenges to the IoT [38]. For example, mobiledevices are constrained by battery, while security isan ever-present concern in mobile communications.Moreover, in order to fully enable D2D communica-tions, a proper incentive for trading and sharing re-sources, such as power or data is needed, as currentD2D paradigms lack motivation to do so [38].

In this context, blockchain is an excellent com-pliment to both IoT and D2D communications, asit can provide the underlying infrastructure with im-proved interoperability, privacy, reliability and scala-bility [37]. In the context of resource management,for example, blockchains can be used to perform spec-trum sharing and record all the spectrum utilizationand lease requests [9]. Moreover, it can provide theincentive needed for devices to share and trade re-sources, as current protocols lack the incentive to doso. By integrating blockchain into IoT and D2D, itcan provide rewards every time devices share theirpower or data, allowing for a more cooperative andtrusted network environment [37, 22]. Moreover, thisreward mechanism can also be applied in the contextof spectrum sharing, in which whenever a user leasesspectrum to another, a reward can be assigned, creat-ing a more collaborative environment and improvingspectrum efficiency [8, 9]. Furthermore, blockchainscan be utilized in the realm of Vehicular-to-Anything(V2X) communications, by encouraging vehicles totrade energy or information with each other [10]. Inaddition, another key aspect of V2X communications

Blockchain-enabled Resource Management and Sharing for 6G Communications 7

is how to guarantee a secure communication betweenvehicles and public key infrastructures (PKI). In thiscontext, blockchain can be utilized as the infrastruc-ture to provide secure and private communications tothe PKI, or also the communication between PKIsfrom different vendors [22].

However, despite all of these benefits, the integra-tion of blockchains in the IoT and D2D domain is stillchallenging [11, 10, 9]. In the case of public chains,for example, the decentralized CMs often require ex-tensive computing power from network nodes (suchas PoW based blockchains). This can be a problem, asmost IoT devices are power constrained. This is spe-cially true for devices powered by cellular IoT, whichcan be deployed in very remote or difficult to accessareas and are expected to have over ten years of batterylife [39]. Thus, the utilization of blockchain in cellularIoT, especially when considering the computation ofthe consensus algorithm, can significantly reduce thelife-time of cellular IoT devices, limiting their com-munication capabilities and effectiveness. As such, itis still not clear how the generation of the PoW couldbe done when integrating public blockchains with IoTor D2D communications [37]. Hence, other CMs suchas PBFT are being proposed in the context of IoT ap-plications [37, 40]. Another challenge in integratingblockchain to small devices comes due to their limitmemory capabilities. Since in blockchain every nodeneeds to have a record of all the current and previousblocks in the chain, it can be infeasible to store such ahuge amount of data in IoT devices. Thus, it is still notclear how blockchain can be fully integrated in IoT.Moreover, blockchain still has privacy issues, as it hasbeen shown by other studies that by analyzing transac-tion patterns, identities of users could be inferred [11].

On top of that, it is also known that blockchain in-troduces delay, due to its decentralized approach andits CMs. As such, this additional delay might alsoimpact the performance of certain wireless commu-nication use-cases, such as in V2X, industrial appli-cations, or D2D and it is still an area to be investi-gated. Moreover, in V2X scenarios, information secu-rity and resilience are critical, since any small failurecan lead to catastrophic and even fatal consequences.As such, in those cases, blockchain can provide an ad-ditional secure layer in order for vehicles to performkey management exchange, as in [41], or even to pro-tect a vehicle’s identity and location, in what is knownas pseudonym management [42]. Lastly, another im-portant challenge in this realm, which has not beenlargely explored is how the performance of the wire-less link affects the performance of blockchain [12].Despite recent works investigating the suitability ofthe CSMA/CA protocol in wireless blockchain net-works [43], or the security performance and opti-mal node deployment of blockchain-enabled IoT sys-tems [44], more research needs to be done in this area.

MNO MVNO HardwareOwner

OTT Provider

Verticle Industry

Network Manager

NetworkSlice

Broker

Smart Contracts Layer

Distributed Ledgers

Fig. 2: Spectrum management using blockchain and smart contract.

4.2. Network Slicing

Network slicing is a very promising technology infuture cellular architecture, and it is aimed at meet-ing the diversified requirements of different verticalindustry services. Network slicing is a specific formof virtualization that allows multiple logical networksto run on top of a shared physical network infrastruc-ture [45]. A network slice is realized when a numberof Virtualized Network Functions (VNF) are chainedbased on well defined service requirements, such asthe massive Machine Type Communication (mMTC),enhanced Mobile Broadband (eMBB) and the ultra-Reliable Low Latency Communication (uRLLC). Themanagement and orchestration of network slices mustbe trusted and well secured, in particular for accom-modating applications that require high security, suchas in the case of remote robotic surgery and V2X com-munications [46].

Network slicing also enables Mobile Network Op-erators (MNO) to slice a single physical networkinto multiple virtual networks which are optimizedbased on specified business and service goals [47].Hence the term Mobile Virtual Network Operators(MVNOs). The implementation of MVNOs necessi-tate the integration of a network slice broker into thearchitecture, as seen in Fig. 2.

4.2.1. Network Slicing BrokerThe aim of a network slice broker is to enable

MVNOs, industry vertical market players, and Over-The-Top (OTT) providers to dynamically request andrelease the network resources from the infrastructureprovider entity based on their needs [48]. The net-work slicing brokering relies on the ability of theMNO/Communication Service Providers (CSP) to au-tomatically and easily negotiate with the requests ofthe external tenants of the network slice based on thecurrently available resources with the infrastructureprovider. In [48], the authors proposed the conceptof 5G network slice broker that could lease networkresources on-demand basis.

8

Operator 1 Operator 2

Inter-Carrier Network Slices

Smart Contract

Monitor MonitorInter-Carrier Settlements App 1 Inter-Carrier Settlements App 2

BSS/OSS BSS/OSS

APP Data/Voice, Video, Control

Inter-Carrier Network Slicing with Blockchain for Settlements

Blockchain Platform

Remote Drone Terminal

Remote Surgery OperatorRobotic Surgeon

Drones

Fig. 3: Network slicing applied with use of blockchain.

The 3GPP’s study on orchestration and manage-ment of network slicing for 5G & beyond networks in-dicated the establishment of mutual trust between theactors (MVNOs, MNOs, OTT providers) as a prereq-uisite for an effective and efficient multi-operator slicecreation [49]. Hence, trust and security are importantfactors to be considered in the implementation, designand integration of a network work slice broker.

4.2.2. Integration of Blockchain to Network Slicingand Resource Brokerage

A major challenge associated with network slicingand resource brokerage is the need to keep a transpar-ent, fair and open system within the available numberof resources and several suspicious players.

Blockchain and Distributed Ledger Technology(DLT) functionalities can be utilized to address theaforementioned trust and security issues associatedwith the implementation of network slicing either forthe coexistence of various application and services, orfor both the service and operational use-cases of CSPs.The trading of network slice can be blockchain-basedwhere the blockchain smart contract orders the sliceorchestration based on the agreed SLA from the 5Gnetwork slice broker. Blockchain can be integrated fortaking the record of how each resource has been usedand how each service provider has performed againstthe SLA. Blockchain combines a distributed networkstructure, CM and advanced cryptography to presentpromising features which are not available in the exist-ing structures. The key gain that is achieved throughblockchain is the integration of the trust layer whichlowers the collaboration/cooperation barrier and en-ables an effective and efficient ecosystem. Furtherthe distributed nature of blockchain prevent the singlepoint of failure problem and thus enhance security.

Fig. 3 illustrates the provision of remotesurgery/consultation and remote control of dronesover a long distance (with network operators in differ-ent geographies), while leveraging on network slicingand blockchain technologies. Here, a blockchainbased approach is used to automate the reconcilia-tion and the payment between provider in different

geographies. Without this approach a more costlymanual intervention or the integration of a third partyfor settlement would be required. Blockchain can alsoenable seamless access of devices to a diverse numberof networks. However, this might require the networkprovider to manage rules, agreement and transactionsacross a rising number of access points. Blockchaincan play a reinforcing role such as in the case ofauditing agreement. Once information is stored ona blockchain, it can be acted upon through “smartcontracts” [24].

In [50], the authors proposed a model where bro-kering is managed by the 5G network slice broker [48]while the payout, billing and leasing are managed bythe blockchain-based slice leasing ledger which is in-corporated in the service layer. Blockchain can en-able secure and automated brokerage of network slic-ing while proving the following gains:

• Significant savings in the operational (transactionand coordination) cost;

• Speed up the slice negotiation process leading toa fall in the cost of slicing agreement;

• Increased efficiency of operation for each net-work slice [51];

• Increased security of the network slice transac-tions;

• The creation a blockchain-enabled contract forMVNOs and MNO that cannot afford the re-quired network capital investment which couldbe on the high side. In particular, the frequencyspectrum could be leased by large operators orplayers on a pay-as-you-go basis or in real time.

Blockchain can also enhance the enforcement of quitestraightforward agreement which are related to manybrokering operations. Furthermore, the negotiation onSLAs can be more efficient when pricing and Qualityof Service (QoS) levels are identified as smart contractparameters.

Other opportunities associated with blockchain inthe next generation networks include

• The settlement of transaction between multiplecarriers including voice transactions and Call De-tail Records (CDRs) of all involved call partici-pants;

• Managing the Service Level Agreement (SLA);

• Simplification of roaming terms and agreementbetween multiple operators;

• Managing money transfer across boarders andcross-carrier payment platform;

• Managing user/nodes identity and authenticationprocess;

• Managing Licensed Spectrum Access (LSA) viathe blockchain-based carrier marketplace.

Blockchain-enabled Resource Management and Sharing for 6G Communications 9

4.3. Inter-domain Blockchain Ecosystem

Shareable resources are the new assets defined bythe distributed resources operators, which are not lim-ited to communication but energy and computing sec-tions. While communication infrastructure also relieson the energy and computing resource provision, asshown in Fig. 1. Thus, a trusted blockchain-enabledtrading ecosystem including energy, computing andcommunication can be built to enable an efficient andsustainable 6G.

In the ecosystem, we can find various streams ofblockchain transaction, energy and computing flowsusing shared communication assets in the resourcemanagement scheme, as seen in Fig. 1. Arrows inFig. 1 represents the flow directions and they arestarted with the provider, through the inter-domainsharing scheme to reach the final consumers on bothlocal level with consortium blockchain and nationalor global level via public blockchain. The ecosystemis not limited to the scope of energy, communicationand computing as it can expand itself to wider rangethrough cross-field integration to reach, for instance,automotive, finance, manufacturing, logistic chain andso on.

Organizations who intend to fuse such resourcescan be recognized as Virtual Infrastructure Operators(VIO), since they do not own all of the resources buta vendor of combined sets of resources. An exam-ple of VIO can be found in remote regions, where lo-cal infrastructure investors tend to have off-grid Dis-tributed Generation (DG) units [52], for instance, solarand wind farms and micro Combined Heat and Power(microCHP) to offer energy and heat to remote users inthe form of Distributed Energy Resources (DER) [53].A local based integration of such resources, aka, Vir-tual Power Plant (VPP), plays the role of the vendorsfor electricity and heat and also buys from or sells toother grids, with unfilled demands and excess elec-tricity. Since these establishments are far away fromthe central network and lack of a cost-effective wayof trading regarding the communication and deliverycost, it is ideal to broke with other local providers andexchange the electricity for other goods. For example,the communication relay service and computing ser-vice for DG sensors in exchange of powering up thehardware, hence, the ecosystem is fostered while theinternal demands grows. Besides the operator ownedresources, there are many common resource contain-ers among all participants.

However, blockchain ecosystem has to accommo-date the performance and security requirement of theintended application. In terms of the performance andsecurity, the consensus is the major concern in thephase of planning. Different consensuses can be ap-plied to the sharing scheme. For example, a publicchain is more suitable to inter-domain transactions ontop level operators like the national grid and first tierMNO. However, if the resources are local-oriented,

the private chain can be hosted for IoT and local/off-grid nodes, where the information from a private chainis kept within the network with confidence for externalauditing. An ecosystem may introduce multiple con-sensuses on different chains to achieve its best results.

Beyond the deployment of blockchain, the actualhardware plays important roles in the ecosystem, ascurrent blockchain applications are designed for up-per layer applications, it lacks of understanding ofthe portable solutions for mobile device, such asdrones, cars and IoT. It is worth noting that the wire-less capability for blockchain is essential in 6G de-ployment. Wireless blockchain-enabled nodes em-power the Machine-to-Machine (M2M) trade amongdistributed and shared resources, therefore it becomesessential that the remote nodes are wireless enabled.In the near future, the VANET-enabled car equippedwith blockchain nodes can recharge the battery frommultiple wireless charging points while moving andtrade the information it carries, for instance, the LightDetection and Ranging (LiDAR) mapping data, relay-ing the internet access, edge computing resource andanything that can be used by the remote DG unit us-ing wireless communication, D2D, and edge comput-ing. The transactions are kept in the blockchain andcarried by the vehicular network then mined by thelocal infrastructure or base station blockchain nodes.Later, the mined blocks will be relayed by satellite-linked base stations for a fee [54]. The auction of spec-trum and network slices can be found on data relay andshort-range Vehicle to Ground (V2G) communication,which requires huge local bandwidth to achieve lowerlatency. This example intends to give an insight ofinter-domain blockchain ecosystem, and further addi-tional features are all made possible based on the inter-domain transactions.

4.4. Challenges of Applying Blockchain Technologyin Resource Sharing and Spectrum Management

Though blockchain has many advantages, some fea-tures need to be eliminated when applied to the re-source sharing and spectrum management scenarios.Here we highlight some of the challenges of applyingblockchain technology in resource sharing and spec-trum management.

Storage: Each replica node in the conventionalblockchain network must process and store a copy ofthe completed transaction data. This can give rise toboth storage and computation burden on IoT devices,which are generally resource constrained, thus limit-ing their participation in the blockchain network.

Underlying Networking: Implementing a consen-sus mechanism within the blockchain is computation-ally expensive and it also requires significant band-width resources. Meanwhile, resources are very lim-ited in future network thus meeting the resource re-quirement for large transaction throughput might behard to achieve with the current system.

10

Scalability of the Blockchain Network: The scal-ability of the blockchain network is a serious issuein current systems. The number of replicas in theblockchain network relates directly to the throughput(i.e., number transactions per second) and latency (i.e.,time required to add a transaction to the blockchain).Hence, sustaining the huge volume of transactionsexpected in blockchain-enabled future networks de-mands solutions on improving the throughput of theblockchain system.

5. Conclusion

In this article, a blockchain-enabled 6G resourcemanagement, spectrum sharing, and computing andenergy trading was envisioned as an enabler for fu-ture use-cases. We first briefly introduced the cur-rent spectrum management and allocation techniquesand discussed the link between blockchain and spec-trum management. We have then given the motiva-tion behind blockchain as well as an overview of itsfundamentals. Moreover, we have discussed some ofthe key application of blockchain and the transforma-tion that it brings to the current wireless networks.The discussed applications include IoT and D2D com-munications, network slicing, and the inter-domainblockchain ecosystem.

To enable the full ecosystem and manage theresource for 6G, we have identified the follow-ing open problems: 1) development of lightweightblockchain solutions for low-cost IoT devices; 2)high-performance blockchain and decentralization forthe vertical industries and future networks; 3) Devel-oping blockchain solutions ecosystem by consideringthe security and privacy issues; 4) implementation ofblockchain protocols over the wireless channel andevaluating fundamental limits relating to the perfor-mance and security.

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