In the 6G Internet of Things(IoT)paradigm,unprecedented challenges will be raised to provide massive connectivity,ultra-low latency,and energy efficiency for ultra-dense IoT devices.To address these challenges,we expl...In the 6G Internet of Things(IoT)paradigm,unprecedented challenges will be raised to provide massive connectivity,ultra-low latency,and energy efficiency for ultra-dense IoT devices.To address these challenges,we explore the non-orthogonal multiple access(NOMA)based grant-free random access(GFRA)schemes in the cellular uplink to support massive IoT devices with high spectrum efficiency and low access latency.In particular,we focus on optimizing the backoff strategy of each device when transmitting time-sensitive data samples to a multiple-input multiple-output(MIMO)-enabled base station subject to energy constraints.To cope with the dynamic varied channel and the severe uplink interference due to the uncoordinated grant-free access,we formulate the optimization problem as a multi-user non-cooperative dynamic stochastic game(MUN-DSG).To avoid dimensional disaster as the device number grows large,the optimization problem is transformed into a mean field game(MFG),and its Nash equilibrium can be achieved by solving the corresponding Hamilton-Jacobi-Bellman(HJB)and Fokker-Planck-Kolmogorov(FPK)equations.Thus,a Mean Field-based Dynamic Backoff(MFDB)scheme is proposed as the optimal GFRA solution for each device.Extensive simulation has been fulfilled to compare the proposed MFDB with contemporary random access approaches like access class barring(ACB),slotted-Additive LinksOn-lineHawaii Area(ALOHA),andminimum backoff(MB)under both static and dynamic channels,and the results proved thatMFDB can achieve the least access delay and cumulated cost during multiple transmission frames.展开更多
In this article we propose to facilitate local peer-to-peer communication by a Device-to-Device (D2D) radio that operates as an underlay network to an IMT-Advanced cellular network. It is expected that local services ...In this article we propose to facilitate local peer-to-peer communication by a Device-to-Device (D2D) radio that operates as an underlay network to an IMT-Advanced cellular network. It is expected that local services may utilize mobile peer-to-peer communication instead of central server based communication for rich mul-timedia services. The main challenge of the underlay radio in a multi-cell environment is to limit the inter-ference to the cellular network while achieving a reasonable link budget for the D2D radio. We propose a novel power control mechanism for D2D connections that share cellular uplink resources. The mechanism limits the maximum D2D transmit power utilizing cellular power control information of the devices in D2D communication. Thereby it enables underlaying D2D communication even in interference-limited networks with full load and without degrading the performance of the cellular network. Secondly, we study a single cell scenario consisting of a device communicating with the base station and two devices that communicate with each other. The results demonstrate that the D2D radio, sharing the same resources as the cellular net-work, can provide higher capacity (sum rate) compared to pure cellular communication where all the data is transmitted through the base station.展开更多
基金supported by the National Natural Science Foundation of China underGrant 62371036,supported authors Haibo Wang,Hongwei Gao and Pai Jiang.
文摘In the 6G Internet of Things(IoT)paradigm,unprecedented challenges will be raised to provide massive connectivity,ultra-low latency,and energy efficiency for ultra-dense IoT devices.To address these challenges,we explore the non-orthogonal multiple access(NOMA)based grant-free random access(GFRA)schemes in the cellular uplink to support massive IoT devices with high spectrum efficiency and low access latency.In particular,we focus on optimizing the backoff strategy of each device when transmitting time-sensitive data samples to a multiple-input multiple-output(MIMO)-enabled base station subject to energy constraints.To cope with the dynamic varied channel and the severe uplink interference due to the uncoordinated grant-free access,we formulate the optimization problem as a multi-user non-cooperative dynamic stochastic game(MUN-DSG).To avoid dimensional disaster as the device number grows large,the optimization problem is transformed into a mean field game(MFG),and its Nash equilibrium can be achieved by solving the corresponding Hamilton-Jacobi-Bellman(HJB)and Fokker-Planck-Kolmogorov(FPK)equations.Thus,a Mean Field-based Dynamic Backoff(MFDB)scheme is proposed as the optimal GFRA solution for each device.Extensive simulation has been fulfilled to compare the proposed MFDB with contemporary random access approaches like access class barring(ACB),slotted-Additive LinksOn-lineHawaii Area(ALOHA),andminimum backoff(MB)under both static and dynamic channels,and the results proved thatMFDB can achieve the least access delay and cumulated cost during multiple transmission frames.
文摘In this article we propose to facilitate local peer-to-peer communication by a Device-to-Device (D2D) radio that operates as an underlay network to an IMT-Advanced cellular network. It is expected that local services may utilize mobile peer-to-peer communication instead of central server based communication for rich mul-timedia services. The main challenge of the underlay radio in a multi-cell environment is to limit the inter-ference to the cellular network while achieving a reasonable link budget for the D2D radio. We propose a novel power control mechanism for D2D connections that share cellular uplink resources. The mechanism limits the maximum D2D transmit power utilizing cellular power control information of the devices in D2D communication. Thereby it enables underlaying D2D communication even in interference-limited networks with full load and without degrading the performance of the cellular network. Secondly, we study a single cell scenario consisting of a device communicating with the base station and two devices that communicate with each other. The results demonstrate that the D2D radio, sharing the same resources as the cellular net-work, can provide higher capacity (sum rate) compared to pure cellular communication where all the data is transmitted through the base station.
