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The following topics are dealt with: MIMO and OFDM; UWB; 3G and 4G technology; signal processing and channel modelling; coding, detection and modulation; ad hoc and mesh networks; network protocol, traffic analysis; congestion control; RFID, Bluetooth and 802.1x technology; network security; sensor networks; multimedia technology; E-Commerce and E-Government; investment and financing; human resources...
On wireless communication systems, multiple-input multiple-output (MIMO) systems have dramatically the potential to improve the reliability and the performance. However, the MIMO wireless channel performance is generally affected by the antenna array configuration and environment characteristic. This paper highlights the impact of angle spread and depolarization effects on the MIMO channel capacity...
For this nonlinear compensation, we address the PAPR reduction method and linearization of HPA at the same time. High quality OFDM communication system is our goal, which can be possible to use the carrier interferometry in the OFDM system and to digitally linearize the nonlinear HPA. The first method is a CI/OFDM (carrier interferometry OFDM) for PAPR reduction of the OFDM signal and the second is...
The problem of allocating network resources to the users of a cellular network with multiple antennas in a fair way is investigated. We propose a packet scheduler called MIMO packet-by-packet generalized processor sharing (MPGPS). The scheduler can provide fair access to the channels for users and is work conserving. It also compensates lagging users and decreases the average delay of users. Comparisons...
Channel impulse response (CIR) can be estimated by time-domain processing (TDP) based on cyclic correlation in orthogonal frequency division multiplexing (OFDM) systems. We propose an improved generalized TDP method to reduce the estimation error by taking the average of different CIR values which are derived according to the different starting points of cyclic correlation. Moreover, an effective...
With spectrum spreaded by LAS multiple access codes and orthogonal subcarriers being utilized, LAS-OFDM system bring the merits of both technologies into play. By suitably designing the spread spectrum codes and keeping the guard period enough long, inter-symbol interference and multiple access interference are eliminated, which is due to the good correlation property of LAS codes. For the transmitted...
The existing uplink multi-user detection algorithm based on maximizing signal-to-noise-plus-interference-ratio (SINR) doesn't take full advantage of the system diversity benefit. A new order successive user cancellation (OSUC) detection algorithm is presented in this paper. However, OSUC suffers from error propagation especially with few receive antennas (RF chains). antenna selection (AS) technology...
This paper proposed a novel training pattern design algorithm for canceling multi-access interference (MAI) in the orthogonal frequency division multi-access (OFDM) system. This proposed algorithm firstly analyzed the MAI induce performance distortion in the carrier frequency offset (CFO) estimation using signal to interference ratio (SIR), then present a novel training sequence design algorithm to...
A method of channel estimation based on training sequences is proposed for MIMO-OFDM systems. Moreover, the criterion is derived by simplified means for optimum training sequences construction. Based on the criterion, two methods are proposed for construction of optimum training sequences. Computer simulations are conducted to evaluate the channel estimation and optimum training sequences construction...
The multiple transmit and receive antennas can be used in OFDM systems to improve communication quality and capacity.In this paper,a channel estimation method base on selection of channel time impulse response (CTIR) length for MIMO-OFDM system is investigated. Simulation results both in terms of mean square error(MSE) and symbol error rate(SER) via Monte Carlo show that Comparing with Conventional...
The recursive least squares (RLS) algorithm and the superimposed training sequences are applied to the orthogonal frequency division multiplexing (OFDM) systems to estimate channel state information (CSI). In order to reduce the interference caused by the unknown information data that is added with the superimposed training sequences, we present the following method: first, the information data are...
In this paper, a simple subspace based semi-blind channel estimator is developed for precoded OFDM systems. This channel estimator relies on redundant linear preceding. With this proposed channel estimator, the channel identifiability is guaranteed up to one scalar ambiguity, regardless of the channel zero locations and the underlying signal constellations. The ambiguity can be resolved with the known...
This paper presents the analysis of the performance of orthogonal space-time block coding (OSTBC) over fading channels with impulsive noise. We adopt an epsiv -mixture Gaussian noise model for the noise distribution. Based on an equivalent scalar additive mixture noise channel with a channel gain proportional to the Frobenius norm of the matrix channel for OSTBC, we derive the closed-form expressions...
In this paper, we present a scheduling algorithm to exploit multi-user diversity with one bit feedback information for multi-user MIMO system. Instead, the users in a cell only need feed back one-bit information about the comparison between the channel quality indicator and the defined threshold Cth, and then BS allocates the channel resource to one user experiencing favorable channel conditions....
Spatial correlation is one of the impairments in multiple- input multiple-output (MIMO) wireless communication systems. Capacity increases promised by MIMO systems mostly depend on the spatial correlation properties of the radio channels. This letter investigates the connection between these properties and the channel capacity. An analytical formula is derived for the fading correlation function of...
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