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The dynamic adjustment of TDD UL-DL configuration based on the instantaneous traffic conditions can be an effective way to optimize the system performance. Small cells in LTE heterogeneous network are considered to be one of the candidates for the dynamic adjustment. In this paper, we focus on UL-DL reconfiguration algorithms to conduct the dynamic adjustment, where the QoS requirement differences...
Device-to-Device (D2D) communication is considered to be a promising resource reuse technology for local users. Unlike the previous studies on centralized scheduling methods, we develop several distributed resource management schemes for D2D communication underlay cellular networks. In the distributed resource management framework, each D2D user independently decides the transmit resources and power...
Conventional channel estimation algorithms devised for OFDM systems suffer from significant performance degradation in the presence of interference. This paper develops a robust least square (LS) channel estimation scheme with low complexity. The received pilot symbols are first separated into several groups, then each group is divided into two parts. After that, we apply the conventional LS algorithm...
Cognitive radio technology is considered to be an effective solution to improve the spectrum utilization efficiency. The dynamic spectrum allocation algorithm assigns the available spectrum to the secondary users. In this paper, we propose a spectrum allocation algorithm based on the graph-coloring theory. Unlike some already existed allocation algorithm, our algorithm considers the bandwidth matching...
This paper studies the resource allocation problem in orthogonal frequency division multiple access (OFDMA) cooperative relaying cellular systems. Most existing work on resource allocation does not fully consider all the influential factors for such systems. In the paper, we formulate the optimization problem for resource allocation, including relay selection, subcarrier assignment, and power allocation...
Coordinated scheduling is a hot topic recently. Inter-cell interference is crucial to the improvement of system throughput, especially in OFDMA system. In this work, the optimization of beamforming in multiple-input single-output (MISO) downlink system is considered. The uplink-downlink duality has been widely used in this sort of research. By the conclusion of a previous work, we provide some practical...
Maximum-likelihood detection (MLD) is the optimal scheme for multiple-input multiple-output (MIMO) channels. However, due to its exponentially high complexity, many alternative algorithms, including some parallel detection (PD) ones with low complexity and high stability, have been proposed for practical applications. Nevertheless, the existing PD algorithms are unable to exploit sufficiently the...
A novel channel estimation algorithm for sounding reference signal in DFT-spread OFDM (DFT-S OFDM) system is proposed, which can estimate the channel response with high efficiency. According to the MSE metric between the estimated channel response and the real one, the simulation result shows that the intra-cell interference is neglectable while the effect of the inter-cell interference is so serious...
Many applications of mobile ad hoc networks (MANETs) adopt hierarchical structure for the scalability and simplify of management. Clustering is the most popular method to impose a hierarchical structure in MANETs. As a newly proposed weighing based clustering algorithm, the weighted clustering algorithm (WCA) has improved performance compared with other previous clustering algorithms. However, the...
It is well-known that, the cyclic prefix (CP) protects orthogonal frequency-division multiplexing (OFDM) system from inter-block interference (IBI), but it also reduces the spectral efficiency. In this paper, a low-complexity turbo equalization algorithm is proposed for multiple input multiple output (MIMO) OFDM system without CP. In our algorithm, tail cancellation is performed firstly by using the...
The maximum likelihood detection with QR decomposition and M-algorithm (QRM-MLD) has been proposed as a near-optimal multiple-input multiple-output (MIMO) detection scheme which can achieve near maximum likelihood (ML) performance with complexity greatly reduced. However, the performance of the QRM-MLD algorithm will deteriorate with the increasing of the number of transmit antennas, as well as the...
For orthogonal frequency-division multiplexing (OFDM) system, the length of cyclic prefix (CP) is selected on the basis of the expected maximum delay spread. When the CP length is shorter than the maximum delay spread, inter-symbol interference (ISI) and inter-carrier interference (ICI) will occur. By means of conventional one-tap frequency domain equalization (FDE), the desired symbols can not be...
Maximum-likelihood detection (MLD) can achieve optimum performance for the vertical Bell laboratories layered space-time (V-BLAST) architecture. However, due to its exponentially high computational complexity, several near-optimal detection algorithms, including some parallel detection (PD) ones with low complexity and high stability, have been proposed instead for practical systems. Nevertheless,...
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