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Wireless Communications and Signal Processing (WCSP), 2011 International Conference on

Date 9-11 Nov. 2011

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Displaying Results 1 - 25 of 292
  • Abnormal ECG signal detection based on compressed sampling in Wearable ECG sensor

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (633 KB) |  | HTML iconHTML  

    Nowadays to diagnose cardiac arrhythmias Holter device is used to record 1 or 2 ECG leads during 24 or 48h. Power consumption limitations determine that the amount of data needs to be diminished without damaging the quality of information. To get a solution, we introduce a novel method based on Compressed Sensing (CS) technique to the Wearable ECG sensor (WES). The main principle underlying this framework is to sample analog signals at sub-Nyquist rate at the analog-digital converters (ADCs) and to classify directly compressed measurement into normal and abnormal state. Those compressed measurements which imply a risk of cardiac anomaly will be stored in a multimedia flash memory card or be transferred to the terminal of the network for a cardiologist to make an off-line diagnosis of cardiac arrhythmias using the reconstructed signals from the compressed measurements. In this paper we propose a scheme to directly classify compressed ECG samples into normal or abnormal states, thus avoiding reconstruction of the entire signal to perform this task. Our algorithm takes advantage of estimating parameters directly from the compressed measurements; thereby eliminating the reconstruct stage and reducing the computational complexity in WES. Direct cardiac arrhythmia detection based on CS reduces 34% energy consumption and 90% storage in WES for the reconstructed performance of 41dB. View full abstract»

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  • A method for cooperative relay selection in SC-FDMA uplink

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB) |  | HTML iconHTML  

    In this paper, an improved minimum total path loss (MTP) method combining with power allocation is proposed for the relay node selection. Single-relay assisted single-carrier frequency-division multiple-access (SC-FDMA) for uplink transmissions is characterized. For the sake of exploiting the benefits of the proposed method, we investigate both the direct transmission as well as the traditional MTP and the improved MTP cooperative transmission under the condition of amplify- and-forward (AF) cooperative strategy. Our simulation results show that both the bit-error-rate (BER) and the transmission reliability of the system of the improved MTP algorithm have been improved greatly. In addition, the transmission power is reduced. View full abstract»

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  • A 1 V folded common-gate CMOS low noise amplifier for Wireless Sensor Network applications

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (668 KB) |  | HTML iconHTML  

    This paper presents a 1 V folded common-gate CMOS low noise amplifier (LNA) for Wireless Sensor Network (WSN) applications. The LNA uses capacitive cross-coupling common- gate (CG) topology to achieve wonderful input matching and low noise figure (NF). A folded topology is employed to reduce the supply voltage and thus power consumption. A source follower acts as the buffer stage for measurement. The LNA is designed in 0.18 μm RF CMOS technology. For saving the chip area, a differential inductor has been designed, which has high inductance value with a small area. With a 1 V power supply, at 2.44 GHz, the post simulation exhibits a high voltage gain of 15.4 dB, and a low voltage gain of 0 dB, with the input impedance of mixer as the load impedance. At high-gain mode, power gain with S21 is 10.5 dB and NF is 3.8 dB. At low-gain mode, S21 is -6.4 dB and NF is 7.8 dB. Moreover, IPldB is -19 dBm and 1.4 dBm, at the two modes respectively. The LNA core consumes current about 2.35 mA. The total chip area is 1200 μm×580 μm. View full abstract»

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  • A soft IP Core for a Reflective Optical Sensor in a robot system on chip

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (542 KB) |  | HTML iconHTML  

    The development of a soft IP Core for a Reflective Optical Sensor of a credit card size robot is described. The broader goal of the project is the development of the robot into an autonomous line-following robot. The solution is achieved as an FPGA-based System-on-Chip design. The paper covers the development of the IP Core for the line sensor, its characteristics and the interfaces with the hardware on the robot. View full abstract»

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  • A time-difference-of-arrival location method based on residual sorting and weighted matrix amended

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (577 KB) |  | HTML iconHTML  

    In the cellular network, the NLOS(Non-Line-of-Sight) propagation of signals is the key factor of affecting positioning accuracy. Based on the COST259 model, this paper is aimed at selecting the best measurements from all of the measuring combinations by residual sorting and changing the weight coefficient with modifying the covariance matrix in Chan algorithm, the integration of the above two measures can mitigate the NLOS errors effectively. The simulation results show that the amended algorithm can improve the location accuracy and efficiency in the condition of NLOS propagation to some extent and meet the demands of E-911. View full abstract»

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  • Energy-efficient multi-user relay networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (723 KB) |  | HTML iconHTML  

    In this paper, multi-user relay networks are considered. We formulate a multi-user relay network model where all the relay nodes amplify and forward the signals from the source nodes to the destination nodes. Then we define the metric of energy efficiency and prove the quasi-concavity of the expression for energy efficiency. Moreover, a bisection method is raised to solve the problems. Three schemes including energy efficient(EE) scheme, spectrum efficient(SE) scheme and equal power allocation(EPA) scheme are compared, and the numeral results show that the EE scheme always achieve the highest energy efficiency, meanwhile, there has been a tradeoff between the energy efficiency and spectrum efficiency in practical designs. View full abstract»

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  • Accurate and computation-efficient localization for mobile sensor networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (777 KB) |  | HTML iconHTML  

    Localization is a fundamental problem in Wireless Sensor Networks (WSNs) and is more challenging than in the Static Sensor Networks in the result of location uncertainty caused by mobility of the sensor nodes. Existing range-free localization algorithms for WSNs are almost based on the sequential Monte Carlo Localization (MCL) algorithm. They either suffer from low sample efficiency or high communication- computation cost to achieve high localization accuracy. In this paper, we propose an accurate and computation efficient algorithm, called HCMCL, which could be categorized into MCL algorithms. In our algorithm, a series of distance constraint rules are created, which are based on the hop-count changes of sensor nodes. The constraints constructed from the rules can further reduce the size of sampling area and filter the samples more strictly. An existing technique called bounding-box is used in our algorithm to improve the sample efficiency by constructing a refined sampling area with the constraints constructed above. A method of weighting samples proposed in existing algorithm WMCL is also used in our algorithm to improve the localization accuracy. Simulation results show that the localization error in our proposed algorithm is much lower than the existing algorithms, especially when the sensor nodes move fast, and the computational cost is strongly reduced by a factor of up to 88 percent compared to WMCL. View full abstract»

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  • Time synchronization error and PRF in pulse jamming against ISAR

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2695 KB) |  | HTML iconHTML  

    Presently, study on jamming to inverse synthetic radar (ISAR) greatly advance, noise barrage jamming is relatively easy to perform due to its moderate transcendental requirement. In this paper, some key problems in synchronized noise pulse jamming to ISAR have been investigated. The impact of PRF of Noise FM jamming pulse and time synchronization on jamming effect has been studied. Characteristics of aiming mode jamming with diverse PRF and time synchronization error are simulated based on real data; jamming effect has been compared and analyzed, which can be referenced by implementation. View full abstract»

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  • Dual layered security protocol (DLSP)

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (398 KB) |  | HTML iconHTML  

    Sensor networks consist of tiny sensor nodes which are responsible for sensing, data processing, and sending the collected data to the appropriate destination. Sensor networks are plagued by many security problems but since they operate at very limited energy resources; consequently cryptographic techniques implemented by general wired networks are not feasible. As such, we need to approach the security related problems with a different perspective which dissents from regular network security algorithms. In our proposal we attempt to devise a technique which consumes lesser amount of energy to maintain security measures in sensor networks. The technique introduced in this paper utilizes two basic techniques and merges them to yield a low energy consuming process which renders more effective security services. View full abstract»

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  • Error resilient arithmetic coding for wireless robust image transmission

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1777 KB) |  | HTML iconHTML  

    Compressed multimedia data is highly vulnerable to error propagation in noisy channel and even a single bit error can cause severe image distortion. To improve the reliability of image transmission, in this paper we propose a practical JPEG2000 based error resilient arithmetic coding (ERAC) scheme for wireless robust image transmission. Forbidden symbols are added at the encoder side and an efficient MAP sequence decoding method of ERAC is developed to estimate the original symbols. Furthermore, the error resilient performance of ERAC is intensively discussed. The entire scheme is designed and optimized on a fixed point DSP, which has already been successfully applicable to robust image transmission under complexity consideration. The experimental results demonstrate the effectiveness of our proposed scheme in improving the end-to-end reconstructed image quality 3 to 5 dB in PSNR at the expense of less than 5% redundancy. View full abstract»

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  • An improved interference mitigation scheme based on interference subspace alignment

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (553 KB) |  | HTML iconHTML  

    This paper proposes an improved interference subspace alignment scheme for the K-user interference channels, which combines the conventional interference subspace alignment algorithm and the power allocation algorithm between data streams. More specifically, in the proposed scheme a power allocation scheme is developed to mitigate the leftover interference from the conventional interference subspace alignment algorithm, achieving a performance improvement in terms of sum rate. The advantage of the proposed scheme is confirmed by computer simulation results. View full abstract»

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  • Stereoscopic visualization of monocular images in photo collections

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2858 KB) |  | HTML iconHTML  

    In this paper we propose a novel approach for 3D video/photo visualization using an ordinary digital camera. The idea is to turn any 2D camera into 3D based on the data derived from a collection of captured photos or a recorded video. For a given monocular input, the retrieved information from the overlapping photos can be used to provide required information for performing 3D output. Robust feature detection and matching between images is hired to find the transformation between overlapping frames. The transformation matrix will map images to the same horizontal baseline. Afterwards, the projected images will be adjusted to the stereoscopic model. Finally, stereo views will be coded into 3D channels for visualization. This approach enables us making 3D output using randomly taken photos of a scene or a recorded video. Our system receives 2D monocular input and provides double layer coded 3D output. Depending on the coding technology different low cost 3D glasses will be used for viewers. View full abstract»

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  • Robust correction of 3D geo-metadata in photo collections by forming a photo grid

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1380 KB) |  | HTML iconHTML  

    In this work, we present a technique for efficient and robust estimation of the exact location and orientation of a photo capture device in a large data set. The provided data set includes a set of photos and the associated information from GPS and orientation sensor. This attached metadata is noisy and lacks precision. Our strategy to correct this uncertain data is based on the data fusion between measurement model, derived from sensor data, and signal model given by the computer vision algorithms. Based on the retrieved information from multiple views of a scene we make a grid of images. Our robust feature detection and matching between images result in finding a reliable transformation. Consequently, relative location and orientation of the data set construct the signal model. On the other hand, information extracted from the single images combined with the measurement data make the measurement model. Finally, Kalman filter is used to fuse these two models iteratively and enhance the estimation of the ground truth(GT) location and orientation. Practically, this approach can help us to design a photo browsing system from a huge collection of photos, enabling 3D navigation and exploration of our huge data set. View full abstract»

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  • Cognitive radio spectrum sharing using improved Quantum Genetic Algorithm

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (591 KB) |  | HTML iconHTML  

    A key challenge in cognitive radios (CR) network is how to adaptively and efficiently allocate transmission powers and spectrum among CR users according to the surrounding environment. In this paper, we propose a novel spectrum sharing based on our improved Quantum Genetic Algorithm (QGA) in a non-cooperative game for CR network. We improved the original QGA by quantum crossover operator, in order to overcome the shortcoming of the original QGA easily falling into a local extremum when used to optimize the continuous functions with many extrema. We used our improved QGA as a competitive strategy and conducted several simulations in two-user system and multi-user system. From simulation results, it is evident that the proposed improved QGA based spectrum sharing scheme has better convergence rate and higher sum capacity than GA based scheme even in multi-user CR system, namely up to 2bit/s/Hz increase in capacity. The simulation results also show that the population size of QGA affect sum capacity of cognitive radio system. The results demonstrated the effectiveness and the applicability of QGA in spectrum sharing in multi-user cognitive radio system. View full abstract»

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  • Improved joint compensation scheme of transmitter and receiver IQ imbalances in OFDM systems

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (414 KB) |  | HTML iconHTML  

    The in-phase and quadrature-phase (IQ) imbalances can be present at both the transmitter and receiver in OFDM systems and lead to system performance degradation. An improved LS based joint channel and IQ imbalance estimation scheme is proposed. Simulations show that the improved scheme with only two training symbols per frame could achieve better BER performance than the original LS compensation scheme using up to 32 training symbols per frame. View full abstract»

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  • Wideband dynamic base station selection for downlink coordinated multipoint system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (559 KB) |  | HTML iconHTML  

    One of the major goals we try to achieve in Long Term Evolution Advanced (LTE-A) is to support higher downlink peak and average cell throughput than LTE Release 8. As one of the promising technologies targeting to the goal, coordinated multipoint transmission/reception (CoMP) is a major topic being discussed recently. CoMP technique significantly mitigates the co-channel interference and thus increases the cell-edge user throughput. In this paper, we propose a novel transmission scheme named wideband dynamic base station selection to further improve the performance of CoMP system. We compare the proposed scheme with the existing joint transmission (CoMP-JT) and coordinated beam-forming (CoMP-CBF) transmission schemes. The simulation results present that the proposed scheme has a good trade-off between the backhaul overhead and system performance. View full abstract»

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  • Dynamic updating based key management algorithm for wireless sensor networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (519 KB) |  | HTML iconHTML  

    In wireless sensor networks, sensor nodes are inherently restricted by insufficient hardware resources, such as computing capacity and battery lifetime. As a result, current key management schemes are difficult to be deployed in wireless sensor networks. This paper proposes a new key management method that the shared keys are dynamic updated for wireless sensor networks. The proposed scheme loads two hash functions and an initial key into the base station, cluster heads, and sensor nodes. Every node including the cluster heads and sensor node authenticates its neighbor nodes with the initial key. Then every node establishes pair wise key with each of its neighbor node to ensure transmission secrecy. The pair wise keys are updated between node and its neighbors within a random interval time, which is triggered by the base station. The security of this scheme is analyzed and it shows that it is robust to the guessing attacks, replay attacks, man-in-the-middle attacks and node capture attacks. The results show this scheme can also save communication resources. View full abstract»

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  • A low-voltage CMOS Programmable Gain Amplifier for WSN application

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1054 KB) |  | HTML iconHTML  

    This paper presents a low-voltage and low-power Programmable Gain Amplifier (PGA) designed in a 0.18μm CMOS process, which is applied in Wireless Sensor Network (WSN). To achieve high gain range and linearity performance, multi-stage cascade based on gm-boosted differential pair with degenerated resistor and fully-differential resistive feedback topology is used. AC coupling is utilized to eliminate the DC offset due to its stability, low power and easy to implement. The voltage gain of this PGA can be changed from 0dB to 70dB with 2dB step. The -3dB bandwidth is larger than 11MHz at the highest gain. The current consumption is only 1.9mA with a supply voltage of IV. View full abstract»

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  • A limited feedback strategy for cooperative multicell MISO systems

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (562 KB) |  | HTML iconHTML  

    Coordinated beamforming is a promising technique to mitigate inter-cell interference arisen from universal frequency reuse in cellular systems. Sharing channel information in neigh- boring cells increases the overall system capacity at the cost of a large feedback requirement. In this paper, an optimized feedback strategy is proposed for multicell beamforming where cooperation is restricted to share only the channel information of active users among coordinated base stations. In order to optimize the feedback link efficiency and improve the overall system performance, we optimize the limited feedback bandwidth based on different average receive power from the serving and neighboring cells. Simulation results demonstrate that the proposed strategy utilizes the limited feedback bandwidth more efficiently, thereby achieving higher sum-rate of the entire multicell system. View full abstract»

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  • An improved distributed iterative beamforming algorithm with cooperative base stations

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB) |  | HTML iconHTML  

    In this paper, an improved distributed iterative beamforming algorithm is proposed for cooperative base stations, and the detailed characterizations with instantaneous and statistical CSI are presented. Firstly, virtual signal-to-interference- plus-noise ratio (SINR) instead of user rate is chosen as decision criterion to avoid feeding back message by users to tell the base stations which strategy should be initialized with and whether to terminate the iteration. Then, the number of iterations is decreased through solving a constrained optimization problem of maximizing the virtual SINR for a given level of generated interference to the other users which can be converted into a standard convex optimization problem and solved by tools of mathematical programming. Finally, the performance of the proposed algorithm is evaluated. View full abstract»

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  • Analysis of other spot-beam interference in TD-SCDMA compatible satellite system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (597 KB) |  | HTML iconHTML  

    In this paper, other spot-beam interference value is studied based on a mobile satellite system (MSS) compatible with TD-SCDMA by theoretical analysis and numerical simulation. A system model to calculate the interference value is presented by making assumptions such as perfect power control and uniformly distributed users. Numerical results of other spot-beam interference value with different frequency reuse factors and different spot-beam overlap values are obtained. Additionally, the influence of other spot-beam interference value is shown by an example of network design, which shows the mobile satellite system compatible with TD-SCDMA should use frequency reuse factor 1. View full abstract»

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  • An energy optimization scheme based on rate guarantee in emergency mesh network

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (525 KB) |  | HTML iconHTML  

    The wireless mesh network (WMN) is effective emergency networks in disaster area which has a flexible network topology. The efficiency of the energy is particularly important in the emergency communication network. In paper, we proposed an energy optimization scheme based on framework of wireless mesh networks. This scheme ensures rate achieved under the condition of the original transmission power in the wireless mesh network, by reducing mutual interference between nodes to make the transmission power of the nodes down, thus extends the lifespan of emergency network effectively. A number of simulation results show that the proposed scheme can reduce the transmission power of nodes while ensuring the end-to-end data rates. View full abstract»

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  • Implementation of MVDR detector using cascaded modular structure

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB) |  | HTML iconHTML  

    In the paper, blind MVDR detector is implemented using a simplified cascaded modular structure. A vector filter is introduced for adaptive interference cancellation in each module of the structure and the weight vector is determined based on a maximum magnitude cross correlation criterion which maximizes the magnitude of the cross correlation between the output of the nonadaptive filter and that of the weight vector filter. The performance of the proposed structure has been evaluated via computer simulation and shown to be comparable to that of the optimum method under asymptotic condition. When the number of received vectors is non-ideal, the proposed method outperforms the optimum method. View full abstract»

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  • Analysis of channel correlation characteristics in GEO mobile satellite communications

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (466 KB) |  | HTML iconHTML  

    Channel prediction is the premise for the application of adaptive transmission in mobile satellite communications with long propagation delay. Particularly, in GEO mobile satellite communication systems, the satellite channel correlation characteristics are analyzed for the mobile terminals at different positions and along different directions, and the predictability of the satellite channel is discussed associated with the channel correlation results. The foundation for the application of adaptive transmission in GEO mobile satellite communications is established accordingly. View full abstract»

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  • Dynamic channel allocation algorithm based on parameter estimation in cognitive radio

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (571 KB) |  | HTML iconHTML  

    Dynamic channel allocation is studied for cognitive radio. Based on the characteristic of primary users' service in cognitive radio, this article proposed that apply mixed Poisson distribution to build model for primary users' service then estimate the probability density function of channel unoccupied duration by using EM algorithm to evaluate the parameter of mixed Poisson distribution model and addressed a multiple channel allocation algorithm based on the result of channel estimation. Numerical simulations have demonstrated the anticipated performance of the algorithm which proposed in the article at conflict rate and throughput. Meanwhile, the proposed algorithm have lower implementation complexity for practical reality. View full abstract»

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