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In this paper, we propose a numerical formulation of decoupling matrix with rate one quasi-orthogonal space-time block code (QOSTBC) for eight transmit antennas. Tirkkonen et al. provided zero-forcing decoupling matrix for eliminating inter-symbol interference (ISI) in QOSTBC with 4 transmit antennas. We expand zero-forcing decoupling matrix with 8 transmit antennas, and also MMSE decoupling matrix...
In this paper, a joint power and subcarrier allocation scheme in single-cell uplink OFDMA systems is proposed based on game theory. Our goal is to maximize the power efficiency of each user under peak power constraint. For the purpose, a utility function is designed which can enhance the rate per joule of energy consumed greatly, and the existence and uniqueness of the Nash equilibrium of the function...
Error resilient coding is strongly demanded by voice communication over unreliable packet networks. In this paper, we propose a new multiple description scheme named distributed subframe interleaving, and employ this new scheme to create two novel multiple description codecs based on CELP. With introducing distributed subframe interleaving operated on two adjacent speech packets, parameters of LSP...
In cognitive radio systems, unlicensed users can use the frequency bands when the licensed users are not present. Hence reliable detection of available spectrum is the foundation of cognitive radio technology. In order to efficiently detect the licensed users under prior knowledge constraints in the fusion center, a novel cooperative spectrum sensing algorithm based on Dempster-Shafer theory is proposed...
In this paper, a novel double E-H shaped patch on a relatively thin substrate (about 0.01 ??0) is proposed. The design adopts contemporary techniques; L-probe feeding, inverted patch structure with air-filled dielectric, and slotted patch. The composite effect of integrating these techniques and by introducing the novel patch, offer a low profile, broadband, high gain, and compact antenna element...
For direct sequence spread spectrum communication systems suffering interference, code-aided interference suppression technique outperforms all of the previous linear or nonlinear methods. In this paper, we proposed an improved code-aided technique which can further improve the system performance greatly by using the eigenvector sign spreading sequence proposed in this paper, which depends on the...
In OFDMA cellular system, the inter-cell interference is the main interference of the system, which greatly degrades the system performance. In order to enhance cell average throughput and the cell-edge user's peak bit rate, a hybrid inter-cell interference mitigation scheme is proposed. The hybrid scheme combines the fractional frequency reuse scheme and the frequency hopping scheme, in which cell-edge...
To achieve full transmission rate, quasi-orthogonal space-time block coding is under research. But its performance still needs to be improved due to complex channel condition. Here we derive its expression for average signal to noise rate and provide a scheme with Quasi-Orthogonal STBC via Antenna Selection, which can improve its performance without extra RF chain.
A planar monopole UWB antenna with good time-domain performance is presented, calculation and analysis are made through time-domain pattern descriptors. The profile of antenna is simple and easy to be implemented. The proposed antenna is simulated by CST Microwave Studio, some factors which can affect the time-domain performance such as pulse fidelity are studied and taken into account in antenna...
A printed diversity antenna for ultra-wideband applications is proposed. The proposed antenna is composed of two square monopoles. In order to reduce the mutual coupling between the two elements, A cross shape stub is introduced. The antenna has been investigated numerically. As is reported, the operation bandwidth of the antenna is from 3.3 GHz to 10.5 GHz. Good isolations can be achieved. It may...
Transmit diversity (TD) is an efficient method to yield channel capacity in single-user multi-antenna system. In this paper, we first analyze scheduling based on TD in multi-user distributed antenna systems (DAS). We show that average throughput of the system grows with the total number of remote access units (RAUs) in DAS. However, when the total number of RAUs is constant, TD has little improvement...
We propose a wireless spectrum sharing framework based on waiting-line auction. Our framework includes both spectrum assignment and power allocation; it is designed to maximize the primary user??s profits as well as to optimize the overall rate under secondary users?? minimal rate requirements. On secondary users?? side, it is proved that bidders could achieve equilibrium bids according to Nash equilibrium...
It is commonly believed that there is a gap between the channel capacity and the highest achievable rate of equiprobable uniform constellation. To achieve shaping gain, non-uniform constellation following a Gaussian distribution has been designed for the AWGN channel and discussed widely along with Turbo codes. In this paper, we investigate the effect of non-uniform constellation and propose a scheme...
In the IEEE802.11a WLAN standard, orthogonal frequency division multiplexing (OFDM) modulation is employed. Diversity techniques are usually utilized to overcome fading channels in OFDM systems. Furthermore, a diversity technique with one antenna is desirable because the form factor of the terminal is important. Fractional sampling (FS) scheme is one of the diversity techniques with a single antenna...
This paper presents experimental results of an analog baseband circuit for China multimedia mobile broadcasting (CMMB) direct conversion receiver in 0.35 um SiGe BiCMOS process. It is the first baseband of CMMB RFIC reported so far. A 8th-order chebyshev low pass filter (LPF) with calibration system is used in the analog baseband circuit, the filter provides 0.5 dB passband ripple and -35 dB attenuation...
Cooperative diversity is an important technique in wireless communication and relay selection plays a significant role in this diversity technique. While some relay selection schemes only optimize the relay selection process under a simple power allocation, this paper analyzes the optimal power allocation, demonstrates the relationship between the position of the best relay node and the power allocation...
Cooperative diversity is an emerging technique that enables single-antenna terminals to share their resources (bandwidth and power) and achieve transmit diversity in a distributed fashion. In this work, an adaptive decode-and-forward(DF) cooperative diversity system based on quadrature signaling is proposed. Then a tight closed-form approximate bit error rate(BER) expression is derived in terms of...
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