This paper explores a system that integrates non-orthogonal multiple access (NOMA) with mobile edge computing (MEC), supported by a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-R...
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wireless networks contain an inherent distributed spatial diversity that can be exploited by relays. Relay networks can take advantage of the broadcast-oriented nature of wireless transmission, but require more radio ...
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wireless networks contain an inherent distributed spatial diversity that can be exploited by relays. Relay networks can take advantage of the broadcast-oriented nature of wireless transmission, but require more radio resource to transmit data for their multi-hop traits. Fortunately, incremental relaying technique, which can choose direct or multi-hop transmission adaptively, can efficiently utilize resource. In this article, the incremental transmission with amplify-and-forward (AF) relays is focused on. A practical hybrid-automatic retransmission request (HARQ) protocol is designed, and the related optimal relay selection strategy is proposed. To analyze the cooperative diversity of system with the proposed protocol, the capacity lower bound is deduced. Simulation and analytical results indicate that by adopting the optimal relay selection strategy, the system with the proposed HARQ protocol can achieve an order of cooperative diversity that equals the aggregated number of the relay and source nodes.
A hybrid system of cellular mode and device-to-device (D2D) mode is considered in this paper, where the cellular resource is reused by the D2D transmission. With the objective of capacity maximization, the power opt...
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A hybrid system of cellular mode and device-to-device (D2D) mode is considered in this paper, where the cellular resource is reused by the D2D transmission. With the objective of capacity maximization, the power optimization of D2D sub-system is considered, taking into account quality of service (QoS) requirement. The power optimization problem is divided into two stages: The first stage is the admission control scheme design based on the QoS requirement of D2D users, and the second is power allocation to maximize aggregate throughput of admissible D2D users. For the D2D admission control problem, a heuristic sorting-based algorithm is proposed to index the admissible D2D links, where gain to Interference ratio (GIR) sorting criterion is used. Applying an approximate form of Shannon capacity, the power allocation problem can be solved by convex optimization and geometric programming tools efficiently. Based on the theoretical analysis, a practical algorithm is proposed. The precision can reach a trade-off between complexity and performance. Numerical simulation results confirm that combining with GIR sorting method, the proposed scheme can significantly improve the D2D system's capacity and fairness.
Self-configuration of physical cell identity (PCI) is a key feature for the long term evolution advanced (LTE-A) network. The PCI is used to identify the different cells in the system, becoming an essential cell c...
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Self-configuration of physical cell identity (PCI) is a key feature for the long term evolution advanced (LTE-A) network. The PCI is used to identify the different cells in the system, becoming an essential cell configuration parameter. Considering the uncoordinated deployments of the evolved Node B (eNodeB) and the limited number of PCI, the PCI assignment for cells would be quite complex. This paper presents and puts forward a graph theory based centralized PCI self-configuration scheme (GT-PCIS). The PCI self-configuration problem is mapped to the well-known minimum spanning tree (MST) problem in order to optimize the PCI reuse distance and decrease the multiplexing interference throughout the entire network. The proposal provides a greedy search to make the locally optimal selection of PCI at each stage, and to achieve a global optimum. To demonstrate the algorithm validity, performances of GT-PCIS and manual configuration are evaluated. Simulation results show that the proposed GT-PCIS outperforms other configuration algorithms even under the condition of severe PCI deficiency.
As a viable component of 6G wirelesscommunication architecture,satellite-terrestrial networks support efficient file delivery by leveraging the innate broadcast ability of satellite and the enhanced powerful file tra...
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As a viable component of 6G wirelesscommunication architecture,satellite-terrestrial networks support efficient file delivery by leveraging the innate broadcast ability of satellite and the enhanced powerful file transmission approaches of multi-tier terrestrial *** the paper,we introduce edge computing technology into the satellite-terrestrial network and propose a partition-based cache and delivery strategy to make full use of the integrated resources and reducing the backhaul *** on the interference effect from varied nodes in different geographical distances,we derive the file successful transmission probability of the typical user and by utilizing the tool of stochastic *** the constraint of nodes cache space and file sets parameters,we propose a near-optimal partition-based cache and delivery strategy by optimizing the asymptotic successful transmission probability of the typical *** complex nonlinear programming problem is settled by jointly utilizing standard particle-based swarm optimization(PSO)method and greedy based multiple knapsack choice problem(MKCP)optimization *** results show that compared with the terrestrial only cache strategy,Ground Popular Strategy,Satellite Popular Strategy,and Independent and identically distributed popularity strategy,the performance of the proposed scheme improve by 30.5%,9.3%,12.5%and 13.7%.
In downlink multi-user multi-input multi-output (MU-MIMO) system, not every user (user equipment (UE)) can calculate accurately signal to interference and noise ratio (SINR) without prior knowledge of the othe...
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In downlink multi-user multi-input multi-output (MU-MIMO) system, not every user (user equipment (UE)) can calculate accurately signal to interference and noise ratio (SINR) without prior knowledge of the other users' precoding vector. To solve this problem, this article proposes a channel inversion precoding scheme by using the lower bound of S1NR and zero-forcing (ZF) algorithm. However, the SINR mismatch between lower bound SINR and actual SINR causes the inaccurateness of adaptive modulation and coding (AMC). As a result, it causes degradation in performance. Simulation results show that channel inversion precoding provides lower throughput than that of single user multi-input multi-output (SU-MIMO) at high signal-to-noise ratio (SNR) (〉14 dB), due to the SINR mismatch, although the sum-rate of channel inversion precoding is higher than that of SU-MIMO at full SNR regime.
In cognitive radio networks, the unlicensed users can utilize the unoccupied licensed spectrum opportunistically. In this paper, we propose a joint power and end-to-end rate control algorithm considering restricting t...
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Inter-carrier interference (ICI) due to Doppler spread is analyzed for OFDM system in highly mobile applications, and then an iterative ICI mitigation method is developed. With the Jakes' model for the Doppler pow...
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Inter-carrier interference (ICI) due to Doppler spread is analyzed for OFDM system in highly mobile applications, and then an iterative ICI mitigation method is developed. With the Jakes' model for the Doppler power spectrum and linear model in one OFDM symbol interval for time-varying channel, the analytical closed-form expression of signal-to-interference ratio (SIR) and signal-to-interference-plus-noise ratio (SINR) are developed with neither assumption on the statistical characteristic of ICI nor constraint on the statistical model for the fading channels. Then, a joint detection algorithm is proposed to iteratively mitigate ICI and estimate channel and detect symbols, where the ICI from a few neighboring interfering subcarriers which contribute the majority of ICI power is regenerates and partially subtracted from the received signal in order to mitigate decision error accumulation. The number of concerned interfering subcarriers and the optimal partial ICI cancellation factor are investigated for the tradeoff of complexity reduction and Mean square error (MSE) minimization. Simulation results verify the proposed method can mitigate ICI effectively.
In the relay enhanced cellular network (REC), user terminals can flexibly select transmission routes to get service. This paper investigated the effect of route selection schemes on the system performance of REC. Besi...
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As is known, distributed Turbo coding (DTC) performs close to the theoretic outage probability bound of a relay channel when correct decoding is assumed at the relay. However, decoding error is inevitable in practic...
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As is known, distributed Turbo coding (DTC) performs close to the theoretic outage probability bound of a relay channel when correct decoding is assumed at the relay. However, decoding error is inevitable in practical fading channels due to the error-prone feature of radio channels, and the decoding error propagation in DTC scheme will severely degrade the error performance of the relay system. As a result, it is necessary to evaluate the error performance of the DTC scheme in multi-hop relaying wireless systems in practical fading channels. Moreover, the theoretical method of analysis provides an effective tool for obtaining the error performance besides lengthy simulations. In this article, the concept of equivalent signal-to-noise ratio (SNR) of the two-hop relay channel and the method of computing equivalent SNR are developed, and then the upper bound on the bit error probability (BEP) of DTC relay systems is analyzed by use of Turbo code's distance spectrum, the concept of uniform interleaver, the limit-before-averaging technique, and the union bound method. Both theoretical analysis and numerical simulation are implemented for relay systems with DTC scheme over quasi-static Rayleigh fading channels. The results show that the upper bound approaches the simulation results in the medium to high SNR region.
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