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In this paper, we study applying dual branch transmit switch-and-stay combining (SSC) technique for underlay cognitive radio (UCR) networks. In UCR, the secondary user is allowed to share the spectrum with the primary (licensed) user under the condition that interference at the primary receiver is below a predetermined threshold. Assuming binary phase-shift keying (BPSK) modulation and Rayleigh fading...
Long Term Evolution (LTE) is an emerging 4G wireless access technology. Multiple-Input Multiple-Output (MIMO) systems are a primary enabler of the high data rate sought to be achieved by LTE. Closed-Loop-Spatial-Multiplexing and Open-Loop-Spatial-Multiplexing are the two primary MIMO transmission modes used in the LTE downlink. An LTE Base Station (eNodeB) is expected to select and switch transmission...
In the IEEE802.11n WLAN standard, orthogonal frequency division multiplexing (OFDM) modulation is employed. Diversity techniques are implemented to overcome multipath fading in the OFDM systems. A fractional sampling (FS) scheme is one of the diversity techniques with a single antenna. This scheme also can be applied in a MIMO-OFDM system to increase its capacity. In this paper, the effect of FS in...
Based on the requirements of LTE-Advanced standardization, this paper provides an 8-Tx diversity scheme for LTE-Advanced downlink. The proposed scheme considers the complexity, compatibility, performance and etc. together. What's more, this paper gives the simulation results of the proposed scheme and shows the feasibility of the scheme.
The performance of ground to satellite Free Space Optical (FSO) communication link is degraded due to the presence of atmospheric turbulence that causes fluctuations in both intensity and phase of the received optical signal. In this paper, bit error rate (BER) performance of FSO link using transmit diversity is investigated for coherent (sub-carrier BPSK and sub-carrier QPSK) and non-coherent (OOK...
Based on modifying and combining traditional multi-input multi-output (MIMO) channel models of space-diversity and polarization-diversity, a space-polarization diversity statistical MIMO channel model, which comprises a covariance matrix and a cross-polar discriminations (XPD) matrix, is proposed in this paper. Angle projection is also applied in order to extend this model to any polarization diversity...
In a receive diversity system the use of multiple antennas at one end of the link produces multiple channels. A useful, although ill-defined, metric for such a link is the number of independent channels provided. In this letter we discuss several candidate metrics and compare their utility. We show that most of the metrics available in the literature have limitations and can exhibit non-physical behaviour...
This paper proposes a new approach for designing diversity antenna directivities based on spherical mode expansion. The antenna directivity is expanded by spherical wave functions and spherical mode coefficients. Spherical mode coefficients, which specify the antenna directivity, can be estimated from a given antenna volume and an angular profile of incident waves. In this paper, we derive the optimal...
In this paper, we will introduce Alamouti SFBC multi-antenna capabilities of Long Term Evolution's downlink channel. Alamouti's simple algorithm will be generalized by using four transmit antennas based on a combination of SFBC and Frequency Shift Transmit Diversity FSTD, and by using MIMO 2×2 transmission scheme. To prove the efficiency of these techniques, we will consider spatial correlation between...
The paper investigates the average pair-wise error probability (PWEP) performance of orthogonal space-time coded MCPM (OST-MCPM) systems for two transmit antennas over independent and correlated channels. Simple upper boundary expression at high SNR is derived to evaluate the PWEP in correlated channel. The achievable diversity gain of this system decreases due to the signal correlation between the...
Antenna selection has long been a pragmatic method for exploiting spatial diversity in wireless systems with lower complexity than space-time or MIMO coding, and potentially having reduced hardware cost due to the reduction in the number of RF chains required. Whilst receive antenna selection is perhaps more common, transmit antenna selection also has several advantages, particularly for hardware-costly...
We propose an adaptive space-time block code (A-STBC) for the wireless communication system. A group of minimum-decoding-complexity quasi-orthogonal STBC (MDC-QO-STBC) matrices which are the same size and code rate but different in the performance of combating inter-symbol-interference are obtained, and a specific matrix is selected from the group for a certain channel according to its channel state...
This paper proposes an improved detection for space time transmit diversity (STTD) using the decision-feedback (DF) detection over time-selective fading channels.
This paper presents the performance of a Fractional Sampling OFDM receiver with delay diversity. Delay diversity achieves transmit diversity by intentionally ingenerating paths which have different delays at a transmitter side. However, the correlations between subcarriers are not always low. The proposed scheme which combines the delay diversity and the FS offers diversity gain by reducing the correlation...
Transmit antenna selection (TAS) in multiple-input-multiple output (MIMO) has several advantages, particularly in hardware-costly transmit schemes such as those requiring linearisation. However TAS requires either channel knowledge, or receiver knowledge at the transmitter, typically achieved using data transmission in the reverse direction. This process involves a reverse channel bandwidth cost,...
This paper proposes a frequency synchronization algorithm for time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) system with multiple antenna transmit diversity. The training sequences used in the transmit diversity TDS-OFDM system are orthogonal and have near-optimal autocorrelation property, and the carrier frequency offset (CFO) estimation algorithm is based on these...
In this paper, we investigate MIMO systems with transmit antenna selection over an intra-class correlated Rayleigh fading channel. In our study, one single transmit antenna with an aim to maximizing the total received signal-to-noise ratio (SNR) is selected for transmission, while it is assumed that the receive side use all the available antennas. Using binary-phase-shift-keying (BPSK) modulation...
Although uncorrelated channels are commonly assumed in cyclic delay diversity (CDD) based multiple input and multiple output (MIMO) orthogonal frequency division mutiplexing (OFDM) systems, correlated channels can evolve due to closeness of antennas or lack of scatterers in the environment. To mitigate the correlation effect, a random continuous phase offset is induced into the transmitting symbols...
A new scheme consisting of a combination of transmit diversity, spatial multiplexing and beamformer is presented for the spatial correlated channels. The proposed scheme exploits the benefits of combining transmit diversity and spatial multiplexing to provide diversity and multiplexing gain. Based on channel's correlation matrix, a robust beamformer is designed. Simulation results show that the robust...
In MIMO (multiple input multiple output) system, a wireless channel can be divided into several individual subchannels in order to expand the processing capacity comparing to SISO (single input single output) system. The correlation between these subchannels is critical to the system performance, and can be reduced by various diversity schemes. The space diversity has better performance for NLOS(non-line-of-sight)...
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