This work proposes a novel synergetic decoding algorithm that efficiently resolves the assignment and message sharing routing for each user while accounting for practical network constraints and develops a merge-and-split algorithm with lexicographic preference to solve the problem of minimizing the RRHs utilized without compromising the performance.
Abstract
In this work, we investigate the performance of the distributed cooperative massive access (DCMA) framework in large-scale network setups by incorporating stochastic geometry modeling. A partially centralized cell-free cloud-radio access (C-RAN) architecture is considered where remote radio heads (RRHs) decode transmitted messages and cooperate with each other to enhance system performance. Specifically, they can share decoded messages via feedback links, allowing receivers to cancel inter-user interference through successive interference cancellation (SIC), thus improving the decoding capabilities of the system. For such a network, we propose a novel synergetic decoding algorithm that efficiently resolves the assignment and message sharing routing for each user while accounting for practical network constraints. Furthermore, using game theory, we develop a merge-and-split algorithm with lexicographic preference to solve the problem of minimizing the RRHs utilized without compromising the performance. Simulation results show that the proposed framework significantly outperforms systems that do not implement SIC or take advantage of the cooperation between RRHs in terms of outage probability. Finally, we evaluate the performance of the proposed algorithms and validate their efficiency.
In this paper, we consider a coexisting network of cellular transmission and device-to-device (D2D) communication, in which BS wants to communicate with far user, meanwhile, a D2D source desires to transmit information to a D2D destination. However, due to heavy shadowing or severe path loss, their direct links are not available. To cope with this problem, a relay is employed to assist the involved transmission. For such a relay-assisted spectrum sharing network, two transmission schemes are designed, i.e., multiple access broadcast NOMA (M-NOMA) scheme and time division broadcast NOMA (T-NOMA) scheme. For each scheme, we first perform power optimization to minimize the outage probability (OP) of D2D communication under the quality of service (QoS) constraint of cellular transmission. Based on the optimization results, we derive the OPs for both cellular and D2D signals. To gain more insights, the asymptotic OPs and the average throughput for both schemes are provided as well. On this basis, we further propose a more superior hybrid M/T-NOMA cognitive communication scheme, in which the system will adaptively select the one with higher system throughput between M-NOMA and T-NOMA as the final transmission scheme. Simulation results validate the accuracy of our analyses, and reveal the performance gain of our schemes over the benchmark schemes.
Yafang Zhang, Ye Tian, Haixia Li et al.· Scientific Reports· 0 citations
This article addresses the planning and allocation of spectral resource blocks for unicast (UC) and Multicast-Broadcast Single Frequency Network (MB-SFN) transmissions in dense Sixth-Generation (6G) cellular networks, where the choice of transmission mode directly influences spectral efficiency and Quality of Service (QoS). The objective is to identify the conditions under which the intercellular cooperation inherent to MB-SFN becomes more efficient than the UC mode for spectral resource block utilization under QoS constraints. To this end, we conduct a comparative performance analysis based on: i) Monte Carlo (MC) simulations, used as a numerical benchmark to accurately capture complex radio interactions, and ii) a fluid analytical framework, based on a continuous approximation of the network in which the discrete structure of base stations is replaced by a homogeneous surface density. Within this framework, we derive analytical expressions for the Signal-to-Interference-plus-Noise Ratio (SINR), enabling a tractable characterization of aggregate interference. Resource block allocation expressions are then proposed for both modes, incorporating SINR and outage probability as QoS constraints. The main contribution of this paper lies in deriving, using the fluid framework, an explicit analytical expression for the critical user threshold that characterizes the switch from UC mode to MB-SFN mode, beyond which the latter becomes more spectrum-efficient. The switching decision highlights the duality between the two modes: MB-SFN is constrained by the minimum SINR with resource consumption independent of the number of users, whereas UC mode depends on the average SINR and consumption proportional to the number of users. An in-depth analysis of the combined effect of network parameters is also conducted, highlighting their interactions and their influence on the switching threshold. Finally, the strong agreement with MC simulations validates the accuracy of the fluid framework, providing an effective analytical tool for optimizing adaptive transmission strategies.
M. Younes, Clency Perrine· IEEE Open Journal of the Com...· 0 citations
Due to their resilience and global coverage, satellite networks are poised to become a key component for non-terrestrial networks in the future. However, given the scarcity of spectrum resources, the dense deployment of low Earth orbit (LEO) satellites introduces significant interference challenges. Meanwhile, the limited computing power and backhaul capacity of satellites have become bottlenecks hindering the development of advanced interference mitigation techniques. This paper studies beamforming in GEO-LEO heterogeneous multi-satellite systems. For the GEO system, we develop a multicast beamforming approach based on a nonlinear eigenvalue problem (NEPv) for beam direction design and Lagrange dual decomposition (LDD) for power allocation. For the LEO system, we propose a general distributed beamforming framework and two distributed beamforming methods. Specifically, we first leverage equivalent multi-dimensional fractional programming (FP) to decompose the objective function. The resulting subproblems are then optimized in a distributed manner across multiple satellites via the parallel block coordinate descent (PBCD) method. For the distributed optimization subproblems, we derive semi-closed-form solutions using Lagrangian dual ascent (LDA) and alternating direction method of multipliers (ADMM) for scenarios without and with GEO-LEO interference avoidance, respectively. Simulation results show that the proposed NEPv-LDD method strictly satisfies the QoS constraints of users and achieves near-optimal performance with low complexity. For the LEO beamforming, the developed distributed FP (DiFP) framework exhibits strong scalability in large-scale constellations. Built upon the DiFP framework, the proposed DiFP-NoSIA incurs almost no performance loss, while DiFP-ADMM shows only an 8.58% performance degradation compared to the centralized benchmark.
Xin Chen, Zhiyong Luo· IEEE Transactions on Wireles...· 0 citations
Recently, wireless local area networks (WLAN) with dense access points (APs) and multi-AP coordination (MAPC) have emerged as promising solutions for enabling coordinated transmission and reducing interference. Several coordination schemes have been proposed for MAPC. Among them, coordinated spatial reuse (C-SR) and coordinated beamforming (C-BF) enable simultaneous transmissions within overlapping basic service sets. However, these schemes involve trade-offs: C-SR offers lower overhead but provides limited signal-to-interference-plus-noise ratio (SINR) gain, whereas C-BF offers significant SINR improvement at the cost of increased overhead. Consequently, the optimal scheme depends on network conditions, such as AP density and user distribution. However, conventional MAPC employs only a single coordination scheme regardless of the situation. Therefore, we propose an adaptive coordination scheme selection method that estimates the expected performance of each scheme by evaluating trade-offs based on environmental information, without relying on channel state information. Simulation results confirm that our scheme selection method outperforms conventional approaches and improves system throughput. The adaptive coordination scheme selection overcomes the performance limitations of conventional MAPC, thereby accelerating the advancement of future WLANs.
Kouki Iizuka, Hiroaki Hashida, Y. Kawamoto et al.· IEEE Transactions on Cogniti...· 0 citations
Simulation results demonstrate that the APS NOMA scheme outperforms both the FPS NOMA and Orthogonal Multiple Access schemes, reducing OP significantly across a range of SNRs, making it highly effective for reliable and energy-efficient communication in future wireless networks.
S. Ajibowu, O. Adeleke, M. Asafa et al.· Nigerian Journal of Technolo...· 0 citations
This letter investigates resource allocation for a generalized coordinated direct and relay transmission (CDRT) framework assisted by an amplify-and-forward unmanned aerial vehicle (UAV), where the considered UAV simultaneously forwards the base station’s signals and delivers its own local information, yielding a unified transmission architecture well aligned with practical sensing and control applications. To manage the highly coupled interference topology among direct, forwarded, and relay-originated streams, we adopt the rate-splitting multiple access (RSMA) strategy. We formulate a joint optimization of precoding vectors, the UAV amplification matrix, and rate-splitting parameters to maximize the system sum rate. A penalty-based alternating optimization algorithm that combines semidefinite relaxation and successive convex approximation is customized to tackle the intertwined non-convex fractional terms. Simulation results demonstrate substantial sum-rate gains over the pure-forwarding, NOMA, and SDMA schemes in most considered cases, with the advantage becoming more pronounced under full-load and moderately overloaded conditions.
Dan Jiang, Yuanyuan Gao, Qiao Su et al.· IEEE Wireless Communications...· 0 citations