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Distributed multiple-input multiple-output (DMIMO) system is a combination of distributed antenna systems (DAS) and co-located antenna systems (CAS). Power allocation between different antennas is a very important aspect in both DAS and CAS. In this paper, we investigate the downlink power allocation scheme in D-MIMO systems based on minimum symbol error rate (SER) criteria. We propose a power allocation...
Information theoretical results have shown that Distributed Antenna Systems (DAS) can obtain higher capacity than Co-located Antenna Systems (CAS). In this paper, we investigate a downlink port selection and power allocation scheme in Distributed Multiple-Input Multiple-Output (D-MIMO) systems, where Distributed Antenna (DA) ports randomly locate in the cell. The contribution of this paper can be...
In this paper, we propose a relay selection scheme based on cooperative MIMO (multi-input-multi-output) communication for network lifetime maximization in energy-constrained sensor networks. Compared with existing work, our distributions are: cooperative nodes choice is not based on minimizing energy consumption per communication but balancing remaining energy between participants including source...
Distributed localization algorithm continues to be an important and challenging topic in today's wireless sensor networks (WSNs). The accurate estimations of distances among nodes are premises for the accurate estimations of node positions. In this paper, we propose some schemes towards the DV-Hop algorithm to improve the distance estimations. These improvements are based on accurate analysis of hop...
In this paper, the pilot design aiming at mitigating the inter-cell interference in MIMO OFDM systems is addressed. We first compute the mean square error of the frequency domain LS joint channel estimation with the consideration of interfering cell. We then overview the optimal pilot sequences within a cell, which can cancel the intra-cell multiple access interference. Based on the mean square error...
In this paper, we consider the multiuser MIMO downlink channel with multiple antennas at both the base station and the users. We concentrate on the case where the transmitter has imperfect channel state information due to estimation error and feedback delay. A channel modification matrix and a scalar factor based on minimum mean square error criterion are derived to form an equivalent channel matrix...
In wireless sensor networks (WSN), the nodes have limited energy resource. So power conservation in individual node is of significant importance. In this paper we derive a cross-layer design method that combines adaptive modulation and coding (AMC) at the physical layer and two sleep modes according to monitoring type at the medium access layer (MAC) in healthcare monitoring WSN, judiciously to maximize...
Multiple input multiple output (MIMO) systems provide dramatic capacity gain through an increased spatial dimension. However, the capacity gain is reduced if the channel state information (CSI) is not perfect. The more exact the CSI is, the higher capacity gain we can obtain. In order to obtain higher capacity gain, this paper analyzes the two factors which mainly affect the reliability of CSI: the...
Orthogonal frequency division multiplexing (OFDM) systems encounter performance degradations due to the time varying (TV) channels in wireless environments. As delay spread increases, symbol duration should also increase, and then OFDM systems become more susceptible to time-variations. Time-variations introduce inter-carrier interference (ICI), which must be mitigated to improve the performance in...
Orthogonal frequency division multiplexing (OFDM) is robust against frequency selective fading due to the increase of the symbol duration. As the symbol duration increases, the OFDM systems become more susceptible to time-variations. Users moving at a quite high speed suffer the inter-carrier interference caused by the time varying (TV) channels. Meanwhile, users at the cell boundary are known to...
Orthogonal frequency division multiplexing (OFDM) systems encounter performance degradations due to the time varying (TV) channels in wireless environments. As delay spread increases, symbol duration should also increase, and then OFDM systems become more susceptible to time-variations. Time-variations introduce inter-carrier interference (ICI), which must be mitigated to improve the performance in...
In this paper, we address the problem of the design of pilots aiming at mitigating the inter-cell interference in OFDM systems. Based on the conventional pilot design used in the intra-cell, we design the pilots which can make the power of inter-cell interference distribute in all paths of the channel uniformly, and result in a variation coefficient of zero, then the better performance on system level...
We consider superimposing pilot signals onto data signals for channel estimation in multiple-input multiple-output (MIMO)-orthogonal frequency division multiplexing (OFDM) systems. This paper presents a channel estimation method, which is based on orthogonal pilot-constant amplitude zero autocorrelation code (CAZAC) for space-time block code (STBC) OFDM system. In this system, the proposed method...
A novel preamble sequence design for random access using complete complementary code sets in multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) scheme is proposed. By elaborate design, both the optimum cross-correlation function (CCF) property and sufficient available number of preamble sequences can be achieved. The generation method and the bound of extension code number...
In this paper, we first overview the least square (LS) space-time joint channel estimation in filtered multi-tone (FMT) system in multi-input multi-output (MIMO) system. Then the design of pilots aiming at mitigating the inter-cell interference in MIMO FMT systems is addressed. It is shown that if the pilots which result in a zero variation coefficient of the estimation error are used, the better...
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