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DS-CDMA通信系统中基于独立分量分析的盲多用户检测 总被引:3,自引:0,他引:3
本文研究了直接序列扩频码分多址(DS-CDMA)通信系统的多用户检测问题,提出了基于独立分量分析(ICA)方法的盲多用户检测算法,实现多用户信号的盲检测。该方法不需知道用户的扩频码就可完成多用户信号的盲检测。仿真结果验证了本文提出的方法的优良性能。 相似文献
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This paper introduces a new multiuser detection algorithm based on a gradient guided search that can achieve near-optimum performance while its implementation complexity is linear in the number of users. The new algorithm attempts to perform jointly optimum multiuser detection by updating one user's bit decision each iteration in the best possible way. When a decorrelating multiuser detector is employed to initialize the proposed algorithm, in all cases tested the gradient guided search converges to a solution with performance very close to optimum. Further, tests indicate that the proposed algorithm provides excellent performance for cases where other suboptimum algorithms perform poorly. Although we focus only on synchronous multiuser detection, the algorithm is equally applicable to asynchronous multiuser detection problems 相似文献
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研究多用户MIMO下行链路中最小和均方误差意义下线性预编码器/译码器的设计问题.针对该非线性、非凸性的优化问题,传统的联合优化算法性能有限且复杂度较高.提出一种新的设计方案.该方案首先利用信道正交化技术将MIMO下行信道分解成多个并行的等效单用户MIMO信道,然后通过解这些等效MIMO信道上的单用户均方误差最小化问题来获得和均方误差最小问题的近似解.仿真结果显示,该方案的性能要优于传统的联合优化算法. 相似文献
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一种多用户MIMO系统的公平调度算法 总被引:1,自引:0,他引:1
多用户多输入多输出(MIMO)系统中需要对用户进行合理调度,一般基于信道增益的调度算法忽略了用户之间的公平性。基于此,提出了一种公平的多用户调度算法,其思想是先根据信道条件数初选出用户,然后统计每个用户被选择的次数,如果次数之差的绝对值大于设定门限,则选择次数少的用户。这样既能获得多用户分集增益又兼顾了公平性。仿真结果表明,提出的调度算法在系统性能无明显损失的情况下保证了用户公平性。 相似文献
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Mobile Edge Computing (MEC) has been envisioned as an efficient solution to provide computation-intensive yet latency-sensitive services for wireless devices. In this paper, we investigate the optimal dynamic spectrum allocation-assisted multiuser computation offloading in MEC for overall latency minimization. Specifically, we first focus on a static multiuser computation offloading scenario and jointly optimize users' offloading decisions, transmission durations, and Edge Servers' (ESs) resource allocations. Owing to the nonconvexity of our joint optimization problem, we identify its layered structure and decompose it into two problems: a subproblem and a top problem. For the subproblem, we propose a bisection search-based algorithm to efficiently find the optimal users' offloading decisions and ESs’ resource allocations under a given transmission duration. Second, we use a linear search-based algorithm for solving the top problem to obtain the optimal transmission duration based on the result of the subproblem. Further, after solving the static scenario, we consider a dynamic scenario of multiuser computation offloading with time-varying channels and workload. To efficiently address this dynamic scenario, we propose a deep reinforcement learning-based online algorithm to determine the near-optimal transmission duration in a real-time manner. Numerical results are provided to validate our proposed algorithms for minimizing the overall latency in both static and dynamic offloading scenarios. We also demonstrate the advantages of our proposed algorithms compared to the conventional multiuser computation offloading schemes. 相似文献
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Multiuser bit loading for multicarrier systems 总被引:2,自引:0,他引:2
A multiuser bit-loading problem is investigated in multicarrier communication systems. Assuming knowledge of all the channel gains, we propose a multiuser bit-loading algorithm that attempts to minimize the total power to transmit a target rate-sum of all users. It is shown that this algorithm is optimal when the interference among users is nonexistent or strong. The simulation results show that the proposed algorithm finds a near-optimal solution for very-high-speed digital subscriber line systems. 相似文献
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S. Nayeb Nazar W.-P. Zhu M.O. Ahmad M.N.S. Swamy 《Circuits, Systems, and Signal Processing》2004,23(5):409-432
In this paper, the problem of multiuser detection for synchronous code division
multiple access systems in both additive white Gaussian noise and multipath channels is
addressed. A new multiuser detection receiver that uses an adaptive blind array along with
an adaptive parallel interference canceler is proposed. The replacement of a conventional
antenna array with a two-dimensional RAKE receiver is also considered for frequency
selective Rayleigh fading channels. By using a constrained optimization criterion along
with the gradient-projection algorithm, a blind algorithm for the adaptation of the array response
vector is proposed. The new algorithm is superior to a few typical blind algorithms
in the literature in terms of both performance and computational complexity. The proposed
receiver has the ability to cancel very strong multiple access interference coming from the
same direction as the desired signal. Simulation results are presented to show the excellent
performance of the proposed combination scheme in comparison to that of using either a
multiuser detection or adaptive antenna arrays in a severe near-far situation. 相似文献
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基于分布式天线的全双工中继系统结合了全双工中继两跳同时同频传输的能力和分布式天线高效覆盖的特性,为提升小区边缘和严重阴影衰落区域的频谱效率提供了一种有效途径。在自干扰抵消非理想的多用户场景下,利用分布式多天线波束成形可实现对系统中自干扰和多用户干扰的联合抑制。为此,该文首先建立了在各分布式天线节点独立发射功率约束下最大化多用户端到端和速率的最优化系统模型,进而提出一种双层迭代算法,解决原问题的非凸性求解难题。仿真结果验证了算法的有效性,表明在多用户分布式天线全双工中继系统中,所提波束成形设计能够有效抑制自干扰和多用户干扰,显著提高系统频谱效率。 相似文献
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An efficient resource-allocation scheme for spatial multiuser access in MIMO/OFDM systems 总被引:3,自引:0,他引:3
Fast adaptive transmission has been recently identified as a key technology for exploiting potential system diversity and improving power-spectral efficiency in wireless communication systems. An adaptive resource-allocation approach, which jointly adapts subcarrier allocation, power distribution, and bit distribution according to instantaneous channel conditions, is proposed for multiuser multiple-input multiple-output (MIMO)/orthogonal frequency-division multiplexing systems. The resultant scheme is able to: 1) optimize the power efficiency; 2) guarantee each user's quality of service requirements, including bit-error rate and data rate; 3) ensure fairness to all the active users; and 4) be applied to systems with various types of multiuser-detection schemes at the receiver. For practical implementation, a reduced-complexity allocation algorithm is developed. This algorithm decouples the complex multiuser joint resource-allocation problem into simple single-user optimization problems by controlling the subcarrier sharing according to the users' spatial separability. Numerical results show that significant power and diversity gains are achievable, compared with nonadaptive systems. It is also demonstrated that the MIMO system is able to multiplex several users without sacrificing antenna diversity by using the proposed algorithm. 相似文献
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In a multiuser direct sequence code division multiple access system, retrieval of the transmitted signals with a conventional receiver is difficult when there is chip asynchronism, multipath propagation and the associated near-far problem. It is shown that despite these problems, an adaptive linear receiver based on a mixed cross-correlation and constant modulus algorithm has the potential to retrieve all users simultaneously. Moreover, for the assumed transmission model, a necessary condition for global convergence of the proposed algorithm is also provided 相似文献
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In [1], an evolution strategy (ES) multiuser detector was proposed and exhibits good performance. This letter analyzes the search behavior of the ES detector and points out it can be greatly enhanced via a simple technique. A heuristic multiuser detection algorithm is presented, which employs the neighborhood structure characteristics of the optimum multiuser detection (OMD) problem and produces local optima efficiently. A well-chosen perturbation strategy is applied to improve the solution quality in the following step. Simulations results show the meta-heuristic algorithm proposed can find the (near) optimum solution rapidly with lower computational complexity and has better bit error rate (BER) performance. 相似文献
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针对STBC-MIMO MC-CDMA多用户检测方法存在计算复杂度高、工程实现困难的问题,提出利用一种混合量子进化算法(HQEA)解决STBC-MIMO MC-CDMA多用户检测问题,该算法不仅具有较低的计算复杂度,而且解决了量子进化算法容易陷入局部最优解、参数个数较多和通过查表来更新量子门的问题。仿真表明,该算法在STBC-MIMO MC-CDMA系统多用户检测问题上,具有比其他智能算法更强的跳出局部最优和寻找全局最优的能力。 相似文献
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提出了一种新颖的基于粒子群优化和多级检测的混合算法的多用户检测器。介绍了最佳多用户检测模型以及粒子群优化算法的基本思想。进行了理论依据和仿真性能分析。仿真结果表明:该检测器在误码率性能上明显优于传统检测器和解相关检测器,在抗“远一近效应”上也优于传统检测器与多级检测器,计算复杂度较低。 相似文献
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L. K.K. Y.M. L. R.S. 《AEUE-International Journal of Electronics and Communications》2006,60(7):513-520
In a code-division multiple-access (CDMA) system, multiuser detection (MUD) can exploit the information of signals from other interfering users to increase the system capacity. However, the optimum MUD for CDMA systems requires the solution of an NP-hard combinatorial optimization problem. It is well known that the computational complexity of the optimum multiuser detector is exponential with the number of active users in the system. In this paper, we apply a hybrid algorithm to develop a suboptimal MUD strategy. The result of symmetric successive overrelaxation (SSOR) preconditioned conjugate-gradient method is first used to initialize the reduced-complexity recursive (RCR) multiuser detector. Then, RCR algorithm is applied to detect the received data bit by optimizing an objective function in relation with the linear system of decorrelating detector. Simulation results for the synchronous case show that the performance of our proposed SSOR-RCR multiuser detector is promising and outperform the decorrelator and linear minimum mean squared error multiuser detector with lower computational complexity. 相似文献
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We present herein a decoupled multiuser acquisition (DEMA) algorithm for code-timing estimation in asynchronous code-division multiple-access (CDMA) communication systems. The DEMA estimator is an asymptotic (for large data samples) maximum-likelihood method that models the channel parameters as deterministic unknowns. By evoking the mild assumption that the transmitted data bits for all users are independently and identically distributed, we show that the multiuser timing estimation problem that usually requires a search over a multidimensional parameter space decouples into a set of noniterative one-dimensional problems. Hence, the proposed algorithm is computationally efficient. DEMA has the desired property that, in the absence of noise, it obtains the exact parameter estimates even with a finite number of data samples which can be heavily correlated. Another important feature of DEMA is that it exploits the structure of the receiver vectors and, therefore, is near-far resistant. Numerical examples are included to demonstrate and compare the performances of DEMA and a few other standard code-timing estimators 相似文献