IEEE Consumer Electronics Magazine - January/February 2023 - 97

the utility of SUs and promote SUs to purchase
their idle spectrums.
SUs involve unauthorized vehicles within the
coverage of the BS. They can sense the spectrum
hole, obtain the information of the idle frequency
band from the BS, purchase channel
resources, and sign insurance contracts with the
PU. In the case of failed transmission, SUs apply
for compensation from the PU.
In the proposed framework, spectrum transactions
between PUs and SUs are forwarded
based on the blockchain, in which all transactions
should be sent to edge authentication
nodes for authentication via broadcast. In this
way, a secure spectrum transaction environment
is established, thus guaranteeing the security
and privacy of the transactions.
As shown in Figure 1, PU1 uploads its spectrum
transaction information to BS3. The blockchain
system then broadcasts the information to
SUs within its range. After receiving the information,
SU3 sends the transaction request. Then,
the transaction server matches PU1 and SU3
through PSA. The resource coin is transferred
from the wallet address of SU3 to the wallet
address of PU1, and the blockchain system is
responsible for block creation. If the transmission
of SU3 fails, a compensation request can be
submitted to PU1 through the blockchain system.
After successful verification, the compensation
is transferred from the wallet address of PU1
to the wallet of SU3, and a new block is created.
The blockchain includes the spectrum allocation
results, the cost of SUs, the unique license,
and the contract of the transaction record so that
the PU can quickly verify the validity of the transaction
in case of compensation. As shown in
Figure 1, each block contains a block header and a
block body. The block header contains the hash
value of the previous block, the timestamp, the
hash value of the current block, and the root hash.
The block body contains details of the transaction,
including the insurance contract Cij selected by
SUj,the cost Costj of the spectrum transaction, the
matching result Matchij,the digitalsignature Signaturej
of the authorization node, the license Licensej
used by SUj, and the Merkle tree, which is a binary
tree used to store transaction information.
To improve the spectrum utilization and
ensure the utility of all SUs by promoting
January/February 2023
more SUs to purchase the channel resources
provided by PUs, the goal of the proposed
framework is to maximize the total utility U of N
SUs in the system:
U ¼ max
XN
i¼1
UðSUi;jÞ
(1)
where U(SUi,j) is the expected utility when
SUi purchases an insurance contract designed
by PUj.
Secure Spectrum Sharing Mechanism
The secure spectrum sharing mechanism is
made up of five parts: user registration, insurance-based
incentive mechanism, PSA, transfer
of assets, and block creation and verification.
First, each user registers with a legal authority
to obtain a private key, a public key, and a certificate.
Each user has a trading account to store
transactions. Users' digital assets are stored in
the corresponding digital wallets, and their real
addresses are hidden to protect privacy.
Then the insurance-based incentive mechanism
is performed. As shown in Figure 1, PU1
designs the corresponding insurance contracts
for a different type of SUs. Then, PU1 sends spectrum
resource selling information to the transaction
server, including its frequency band,
bandwidth, selling price, and insurance contract.
After receiving the broadcast information, SU3
sends a transaction request to the transaction
server. SU3 can purchase a single channel and
sign the insurance contract provided by PU1
simultaneously.
The matching between SUs and PUs is completed
by the PSA. In Figure 1, SU3 queries its
preference list and sends a transaction request
to PU1.PU1 also queries its preference list
and selects the highest ranking option to complete
transactions. This procedure repeats until
the whole system reaches a stable match, and
the preference-based spectrum allocation ends.
When the transaction requests of SUs are
completed, resource coins are transferred from
the wallet address of SUs to the corresponding
wallet address of PUs. PU1 can obtain the latest
uploaded block data from the storage server to
verify the correctness of the transaction. SU3
generates new transaction records that are
97
IEEE Consumer Electronics Magazine - January/February 2023

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