The fully-decoupled radio access network (FD-RAN) is an innovative architecture designed for next-generation mobile communication networks, featuring decoupled control and data planes as well as separated uplink and downlink transmissions. To further enhance energy efficiency, this paper explores a green approach to FD-RAN by incorporating adaptive base station (BS) sleeping and resource allocation. First, we introduce a holistic power consumption model and formulate a energy efficiency maximization problem for FD-RAN, involving joint optimization of user equipment (UE) association, BS sleeping, and power control. Subsequently, the optimization problem is decomposed into two subproblems. The first subproblem, involving UE power control, is solved using a successive lower-bound maximization approach based on Dinkelbach’s algorithm. The second subproblem, addressing UE association and BS sleeping, is tackled via a modified, low-complexity many-to-many swap matching algorithm. Extensive simulation results demonstrate the superior effectiveness of FD-RAN with our proposed algorithms, revealing the sources of energy efficiency gains.

This paper first develops an analytical framework to investigate the performance of uplink (UL)/downlink (DL) decoupled access in cellular vehicle-to-everything (C-V2X) networks, in which a vehicle's UL/DL can be connected to different macro/small base stations (MBSs/SBSs), separately. Using the stochastic geometry analytical tool, the UL/DL decoupled access C-V2X is modeled as a Cox process, and we obtain the following theoretical results, i.e., 1) the probability of different UL/DL joint association cases i.e., both the UL and DL are associated with the different MBSs or SBSs, or they are associated with different types of BSs; 2) the distance distribution of a vehicle to its serving BSs in each case; 3) the spectral efficiency of UL/DL in each case; and 4) the UL/DL coverage probability of MBS/SBS. The analyses reveal the insights and performance gain of UL/DL decoupled access. Through extensive simulations, the accuracy of the proposed analytical framework is validated. Both the analytical and simulation results show that UL/DL decoupled access can improve spectral efficiency. The theoretical results can be directly used for estimating the statistical performance of a UL/DL decoupled access C-V2X network.

Ultra reliable low latency communication (URLLC) in vehicular networks is crucial for safety-related vehicular applications. Mini-slot with a short packet that carries only a few symbols is used to reduce the transmission time interval and enable quick scheduling for URLLC that requires extremely low latency. However, a single air interface transmission of URLLC packets may fail due to the high mobility of vehicles. Leveraging multi-connectivity technologies, the real-time reliability of URLLC can be greatly enhanced without relying on packet retransmission. In this paper, we propose a multi-connectivity URLLC downlink transmission scheme for vehicular networks, where the URLLC packet is duplicated and transmitted over multiple independent wireless links to improve packet reliability. Specifically, we design a multi-agent cooperative deep reinforcement learning algorithm, called transformer associated proximal policy optimization (TAPPO), to achieve real-time robust power allocation for multi-connectivity URLLC with imperfect channel state information (CSI). The transformer neural network architecture is employed to share the information among multiple links serving the same URLLC user and choose appropriate transmit powers, enabling cooperation to ensure reliability while minimizing inter-cell interference and energy consumption. Extensive simulation results validate the effectiveness of multi-connectivity packet duplication for URLLC and proposed TAPPO for power allocation.

The increasingly severe energy consumption caused by exploding wireless demands attracts considerable research. Remarkably, base station (BS) sleeping is a promising technique to enable the green network. A disruptive and original fully-decoupled radio access network (FD-RAN) architecture aiming at the next-generation mobile communication networks is developed, which removes the obstacles to achieving BS sleeping, i.e. deficient cooperation between BSs, coupled data-control transmission and coupled uplink-downlink transmission. In this paper, we investigate the joint user association and uplink BS sleeping considering power control in the FD-RAN with the superiority of fully decoupled architectures. Specifically, we propose an energy consumption model for the uplink FD-RAN and tackle the mixed-integer second-order cone problem to minimize the whole network energy consumption by leveraging the many-to-many swap matching theory. Extensive simulation results validate a higher energy efficiency of the uplink FD-RAN compared to the traditional cellular network and cell-free networks and demonstrate the effectiveness of our proposed algorithm.

Cellular vehicle-to-everything (C-V2X) network is a promising solution to support on road diverse quality of services (QoS) such as ultra reliable low latency communication (URLLC) and enhanced mobile broadband (eMBB). However, satisfying the stringent QoS requirements in high-dynamic C-V2X environment is very challenge. In this paper, we leverage the multi-connectivity technology to enhance the reliability of downlink URLLC in C-V2X. Specifically, with the aid of the cloud radio access network (C-RAN), the network controller duplicates each URLLC packet and transmits its replicas over multiple independent wireless links. To ensure the reliability of URLLC links while maximizing the average rate of eMBB links, we design a coordinated multi-agent deep reinforcement learning algorithm for real-time power allocation of multi-connectivity URLLC links. Each URLLC link is treated as an agent here, and its transmit power is its action. The multiple links serving the same URLLC user are coordinated with a three-layer neural network for information sharing, allowing them to cooperatively choose transmit powers in terms of ensuring reliability while minimizing inter-cell interference and energy consumption. Extensive simulation results validate the effectiveness of the proposed power allocation algorithm for multi-connectivity downlink URLLC.

With the emergence of numerous new applications and the explosive growth of Internet of Things (IoT) devices in beyond 5G (B5G) networks, the massive yet delay-sensitive personalized content delivery has imposed a crucial challenge to mobile network operators (MNOs). Cooperation among MNOs for sharing the communication, caching, and computing (3C) 3-D resources in an economic yet real-time manner has provided a promising solution to address this challenge. In this article, we investigate the 3C resource sharing among multiple MNOs to realize efficiently and economically personalized content delivery, where a third-party 3C resource provider (CRP) is introduced to manage the sharing 3C resource pool. By leveraging the multidimensional contract theory, we propose an optimal 3C resource contract scheme for the CRP in a realistic asymmetric information scenario, and the appointed 3C resources in one contract will be allocated to the MNO who signs it. For each MNO, we establish a partial transcoding model to achieve the optimal orchestration on the 3C resources, where the closed-form solution of caching placement and transcoding strategy is obtained. Then, MNOs can choose the most suitable contracts to sign based on the service requirements from end users. In particular, we analyze the global incentive compatibility and feasibility of the proposed multidimensional contract approach, which is theoretically proven to achieve the optimal solution. Extensive simulation results demonstrate the efficiency of the proposed 3C resource sharing mechanism compared with other benchmark schemes. Specifically, the proposed 3C resource sharing scheme can reduce 35% delivery delay compared with the nonsharing scheme.

Two-tier computing paradigm that takes full advantage of both the end-user and the cloud computation capabilities has emerged as a promising way to deal with computationally-intensive tasks in the next generation wireless networks. For promoting the integration of the two-tier computing, federated learning (FL) provides an effective framework to enable the collaboration between the end-user and the cloud. However, the key performance metric, i.e., FL training latency, will be severely affected by the worst wireless link quality in both uplink and downlink. In this paper, aiming at accelerating the FL enabled end-cloud two-tier computing over the wireless networks, we introduce the uplink and downlink fully-decoupled radio access network (FD-RAN) architecture to enhance the minimum wireless link rate via multiple base stations (BSs) access collaboration and power management solution. First, the Lagrange dual decomposition and the binary variable relaxation methods are leveraged to obtain an optimal multiple BS access scheme for the enhancement of minimum uplink and downlink SINR. Subsequently, we exploit the successive convex approximation (SCA) algorithm to deal with the uplink power control and downlink power allocation with a proved data rate lower bound. Furthermore, considering the dynamic channel realizations, a stochastic optimization technique with a convex surrogate function is utilized to find the best end-cloud two-tier computing scheme for FL applications. Simulation results have demonstrated the effectiveness of our proposed joint multiple access collaboration and power management solution over FD-RAN for achieving a faster FL enabled two-tier computing task.

To enable flexible base stations (BS) association and dynamic resource management for personalized user equipment (UE) download service provision in the next-generation mobile communication network (6G), in this paper, we investigate the downlink (DL) transmission scenario in an origin fully-decoupled radio access network (FD-RAN) architecture. Considering the unique fully-decoupled UL/DL access feature, we propose an efficient two-stage DL channel estimation method in the FD-RAN. We formulate a novel multi-connectivity and dynamic resource cooperation problem with joint multiple-BS and multiple-UE association and coordinated beamforming, aiming at maximizing the weighted sum achievable rate in DL FD-RAN. By leveraging the many-to-many swap-matching theory and fractional relaxation approach, we solve the dynamic UE scheduling problem with multiple-BS and multiple-UE association and the coordinated beamforming problem, respectively. Extensive simulation results based on standard 3GPP 36.873 urban micro channel demonstrate that the proposed framework can improve the average spectral efficiency by 34.9% as compared to the traditional maximum ratio transmission beamforming method.

To cope with the even more urgent spectrum and energy efficiency challenge for trillion-level terminal access and data uploading in the next generation mobile communication network (6G), in this paper, we investigate the uplink transmission in an original fully-decoupled radio access networks (FD-RAN) architecture. Specifically, we propose a resilient uplink base station cooperative reception framework in FD-RAN, which is a large-scale fading based two-tier signal combination approach for the uplink transmission, including the localized signal combination at the base station and centralized signal combination at the edge cloud, respectively. Then, we formulate a weighted sum-rate maximization problem for the uplink transmission optimization, and decompose it into two subproblems. A spectrum-efficiency maximized virtual service cluster selection (SEMVS) algorithm is designed by leveraging the channel statistical information for solving subproblem one, and a fractional programming based power control (FPPC) algorithm is introduced for the power optimization of subproblem two. Compared to the typical RAN architectures with corresponding access and power control methods, simulation results demonstrate the significant performance improvements of uplink FD-RAN with the proposed solution.

The uplink (UL)/downlink (DL) decoupled access has been emerging as a novel access architecture to improve the performance gains in cellular networks. In this paper, we investigate the UL/DL decoupled access performance in cellular vehicle-to-everything (C-V2X). We propose a unified analytical framework for the UL/DL decoupled access in C-V2X from the perspective of spectral efficiency (SE). By modeling the UL/DL decoupled access C-V2X as a Cox process and leveraging the stochastic geometry, we obtain the joint association probability, the UL/DL distance distributions to serving base stations and the SE for the UL/DL decoupled access in C-V2X networks with different association cases. We conduct extensive Monte Carlo simulations to verify the accuracy of the proposed unified analytical framework, and the results show a better system average SE of UL/DL decoupled access in C-V2X.

With the rapid development of Internet of Vehicles (IoV), an increasing number of vehicular users (VUEs) will connect to the Internet via 5G and beyond 5G(B5G) networks, which makes the spectrum resource becoming extremely scarce. However, the traditional spectrum allocation method cannot well adapt to the explosive growth of IoV traffic, and an efficient spectrum management for the IoV in B5G networks is an urgent challenge. In this paper, we propose a Stackelberg game and federated learning assisted spectrum sharing framework for the IoV. First, we develop a power control strategy for the region nodes considering its revenue and energy consumption, while VUEs can dynamically change their spectrum resource request strategy to maximize their revenue. We find the Stackelberg equilibrium using the alternating direction method of multiplier (ADMM) algorithm. To maximize the global revenue of region nodes, we leverage federated learning to realize the interaction between the region nodes and the central node. In specific, each region node utilizes deep learning to fit the relationship between the allocated power and its revenue. Then, they upload the network parameters to the central node. After collecting the network parameters from all region nodes, the central node can make the global decision about the spectrum allocation to the region nodes. Numerous simulation results verify the effectiveness of the proposed framework compared with the benchmark methods.

The emerging uplink (UL) and downlink (DL) decoupled radio access networks (RAN) has attracted a lot of attention due to the significant gains in network throughput, load balancing and energy consumption, etc. However, due to the diverse vehicular service requirements in different vehicle-to-everything (V2X) applications, how to provide customized cellular V2X services with diversified requirements in the UL/DL decoupled 5G and beyond cellular V2X networks is challenging. To this end, we investigate the feasibility of UL/DL decoupled RAN framework for cellular V2X communications, including the vehicle-to-infrastructure (V2I) communications and relay-assisted cellular vehicle-to-vehicle (RAC-V2V) communications. We propose a two-tier UL/DL decoupled RAN slicing approach. On the first tier, the deep reinforcement learning (DRL) soft actor-critic (SAC) algorithm is leveraged to allocate bandwidth to different base stations. On the second tier, we model the QoS metric of RAC-V2V communications as an absolute-value optimization problem and solve it by the alternative slicing ratio search (ASRS) algorithm with global convergence. The extensive numerical simulations demonstrate that the UL/DL decoupled access can significantly promote load balancing and reduce C-V2X transmit power. Meanwhile, the simulation results show that the proposed solution can significantly improve the network throughput while ensuring the different QoS requirements of cellular V2X.

Mobile edge computing (MEC) has been widely considered as an effective technology to handle computationally intensive tasks generated by mobile devices. However, the computation resources at an edge node is usually several orders of magnitude smaller than that of a cloud. Thus, it is rather vital to take an investigation into the collaboration between the cloud and the edge. In this paper, to fully exploit the computation power of the cloud server and achieve energy efficient task offloading, we propose an LEO-assisted terrestrial-satellite network (TSN) architecture for cloud-edge collaborative computation offloading. We formulate the collaborative cloud-edge computing problem that minimizes the energy consumption of the whole TSN under the quality-of-service (QoS) constraints. The optimization problem is further decomposed into two subproblems which are solved by deep neural networks (DNN) and successive convex approximation (SCA) algorithm, respectively. Simulation results show the effectiveness of our proposed cloud-edge collaborative computation offloading architecture on achieving a lower energy cost.

Considering the high-density and high-dynamic feature of cooperative unmanned aerial vehicles (UAVs) swarm, also referred to as flocking of flying ad hoc networks (FANETs), reliable medium access control (MAC) protocol design for network connectivity maintaining and network information sharing is a challenging issue. In this article, we propose a self-adaptive carrier sense multiple access with collision avoidance (CSMA/CA)-based MAC protocol for flocking of FANET, namely, FMAC, to provide reliable broadcast information service under density-varying flocking scenarios. To represent the varying trend of UAV density during flocking, we define the collective neighboring potential (CNP) in the FMAC protocol. Specifically, at the beginning of each period, each UAV computes the current CNP based on available neighbors' motion states. Then, the value of CNP at the start of the next period regarding the same neighbors is predicted using UAV's kinetic equation. After that, each UAV can update the contention window (CW) size by comparing the current CNP and the predicted CNP, and CW will be decreased (increased) if the current CNP is larger (smaller) than the predicted one for enough period. The simulation results show that the proposed FMAC protocol can ensure high successful transmission probability under density-varying flocking scenarios and outperforms the typical MAC solutions.

With a massive number of Internet-of-Things (IoT) devices connecting with the Internet via 5G or beyond 5G (B5G) wireless networks, how to support massive access for coexisting cellular users and IoT devices with quality-of-service (QoS) guarantees over limited radio spectrum is one of the main challenges. In this paper, we investigate the multi-operator dynamic spectrum sharing problem to support the coexistence of rate guaranteed cellular users and massive IoT devices. For the spectrum sharing among mobile network operators (MNOs), we introduce a wireless spectrum provider (WSP) to make spectrum trading with MNOs through the Stackelberg pricing game. This framework is inspired by the active radio access network (RAN) sharing architecture of 3GPP, which is regarded as a promising solution for MNOs to improve the resource utilization and reduce deployment and operation cost. For the coexistence of cellular users and IoT devices under each MNO, we propose the coexisting access rules to ensure their QoS and the priority of cellular users. In particular, we prove the uniqueness of the Stackelberg equilibrium (SE) solution, which can maximize the payoffs of MNOs and WSP simultaneously. Moreover, we propose an iterative algorithm for the Stackelberg pricing game, which is proved to achieve the unique SE solution. Extensive numerical simulations demonstrate that, the payoffs of WSP and MNOs are maximized and the SE solution can be reached. Meanwhile, the proposed multi-operator dynamic spectrum sharing algorithm can support more than almost 40% IoT devices compared with the existing no-sharing method, and the gap is less than about 10% compared with the exhaustive method.

The Uplink (UL) and Downlink (DL) decoupled cellular access through flexible cell association has attracted a lot of attention due to numerous benefits such as higher network throughput, better load balancing, and lower energy consumption, etc. In this paper, we introduce a novel reinforcement learning aided decoupled RAN access framework for Cellular Vehicle-to-Everything (V2X) communications, and propose a two-step RAN slicing approach to dynamically allocate the radio resource to V2X services in different time granularity. We derive an innovative QoS metric of V2V cellular mode by taking consideration of the bidirectional nature of V2V cellular communications. Moreover, we maximize the sum utility considering the proposed QoS metric by leveraging the Deep Deterministic Policy Gradient (DDPG) enabled RAN slicing method. Simulation results are provided to demonstrate the advance of the proposed reinforcement learning aided decoupled RAN slicing framework in achieving load balancing, maximizing total network utility and satisfying the QoS metric of Cellular V2X communications.

With the significant advance of Internet of Vehicles (IoV), a massive number of vehicular users will connect with the Internet via 5G and the beyond 5G (B5G) networks, which will further worse the spectrum scarcity problem in 5G/B5G networks. Therefore, how to enable dynamical and efficient spectrum resource sharing for IoV users is imperative. To this end, we investigate an evolutionary game enabled spectrum sharing blockchain framework for IoV. Specifically, We use alliance nodes and blockchain framework to assist in the completion of multi-WSP spectrum resource allocation, sharing, and the allocation results storage. We first propose an evolutionary game scheme to allocate the spectrum resource among different WSPs. To reflect the vehicle users' communication demand more appropriately, the vehicle mobility is taken into consideration when defining the payoff of the vehicle users. After completing the spectrum allocation, we illustrate the process of allocation results recording and block generation in our established blockchain verification system, where the transactions ledger of spectrum allocation will be stored in each alliance node in a distributed way. Numerical results exhibit the fast convergence speed of the spectrum allocation approach. Moreover, simulations results from our established hyperledger platform validate the effectiveness and implementability of the investigated spectrum sharing blockchain framework.

For the massive access of Internet-of-Things (IoT) devices in 5G or beyond 5G (B5G) wireless networks, how to support the coexisting of cellular users and massive IoT devices with quality-of-service (QoS) guarantees over limited spectrum is challenging. In this paper, inspired by the active radio access network (RAN) sharing standard of 3GPP, we present a heterogeneous multi-operator spectrum sharing architecture by leveraging the spectrum trading to support the coexistence of QoS-guaranteed cellular users and massive IoT devices with non-orthogonal multiple access (NOMA). In the architecture, we formulate the spectrum trading between the wireless spectrum provider (WSP) and mobile network operators (MNOs) as a Stackelberg pricing game. Meanwhile, for each MNO, the cellular users and massive IoT devices can be both serviced in the uplink NOMA networks with QoS guarantees. For the pricing game, we prove the uniqueness of the equilibrium solution, which can maximize the payoffs of MNOs and WSP simultaneously. Moreover, we propose an iterative pricing algorithm to achieve the equilibrium solution with theoretical optimality guarantees. Simulation results demonstrate that our framework can support more IoT devices and reach the optimal spectral bandwidth price.

With the emergence of automated driving technology, wireless demand for secure information exchange among automated vehicles has increased dramatically. To this end, we design a security-aware dynamic device-to-device (D2D) spectrum resource sharing mechanism to enhance the security of vehicular D2D communications with the improved spectrum efficiency. Considering both resource block (RB) sharing and power control, we model this joint D2D spectrum resource sharing process as a weighted bipartite graph matching problem whose weights are obtained through deriving the closed-form solutions of power control in an algebraic method. Then, the global optimal solutions of the matching problem are obtained by using the Hungarian algorithm. Furthermore, a security-aware RB and power allocation (SA-RBPA) mechanism compatible with existing cellular networks is proposed for the small cell base station applications. Extensive simulation results have shown that, compared with existing approaches that consider RB reusing strategy or power control scheme optimization alone, the SA-RBPA scheme is able to realize a better spectrum efficiency and security performance.

Vehicular platooning communication has been widely recognized as a promising traffic management technique for connected vehicles to improve the traffic capacity, on-road safety, and energy efficiency, etc. However, due to the high mobility and dense vehicular communication scenario, how to improve the radio resource efficiency of vehicular platooning communications is a challenge issue. In addition, considering the broadcast nature of vehicular communications, vulnerable vehicular platooning communications could be exposed to potential eavesdroppers, which would be a hidden danger for connected vehicle applications. In this paper, we investigate the secure radio resource sharing problem in device-to-device (D2D) enabled multiplatooning vehicular communications. Based on the physical layer security theory, we propose a security aware joint channel and power allocation (SA-JCPA) scheme, in which the closed-form expression for power control is derived through an algebraic method and the channel sharing strategy is obtained by leveraging a maximum weight bipartite graph matching approach. Through extensive simulations, it is demonstrated that our proposed SA- JCPA scheme can achieve efficient and secure radio resource utilization.