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Wireless Communications and Signal Processing (WCSP), 2010 International Conference on

Date 21-23 Oct. 2010

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Displaying Results 1 - 25 of 241
  • Copyright

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    Freely Available from IEEE
  • [Title page]

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    Freely Available from IEEE
  • Neighbor selection and progress rate in multi-channel MIMO wireless networks: The two antenna case

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (355 KB)  

    With multiple antennas equipped at mobile nodes, we consider two types of antenna configurations: one MIMO radio or multiple SISO radios. In this work, we compare these two antenna configurations in terms of neighbor discovery and selection in multi-channel networks. For each antenna configuration, two neighbor selection schemes are studied. In the scheme of first forward neighbor selection (FFNS), the neighbor probing procedure stops as soon as a neighbor with forward progress is discovered on a certain channel. In the scheme of Optimal Stopping Neighbor Selection (OSNS), optimal stopping theory is employed to decide whether the neighbor probing should stop at each stage. As expected, OSNS always achieves better progress rate than FFNS with both antenna configurations. For the comparison between antenna configurations, we show that the configuration of one MIMO radio achieves better progress rate when the node density is low, while the configuration of multiple SISO radios gets better progress rate as node density increases. Our numerical examples corroborate the analysis. View full abstract»

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  • A time-sharing resource allocation method in heterogeneous cognitive OFDM network

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (299 KB) |  | HTML iconHTML  

    For a multiuser cognitive OFDM network, most existing adaptive resource allocation methods focus solely on fixed data-rate requirement (QoS guaranteed) or variable data-rate (no QoS guaranteed) conditions without any fairness consideration. In this paper, we investigate the resource allocation problem in a heterogeneous cognitive network with different QoS requirements. By decomposing the problem as a convex optimization, an optimal time-sharing resource allocation method is proposed to maximize the throughput of cognitive network under both subcarrier interference temperature limits and heterogeneous data-rate requirements. Finally, the performance of our proposed resource allocation algorithm is investigated by numerical results. View full abstract»

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  • A spectrum sharing method based on fuzzy logic in IEEE 802.22 WRAN

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB) |  | HTML iconHTML  

    This paper follows IEEE 802.22 proposed coexistence beacon protocol (CBP), the mechanism carry the information of dynamic resource renting and offering to solve the problem of spectrum sharing for inter-BS (Base Station) coexistence mechanism. Due to high flexibility and low complexity, fuzzy rules based on empirical laws can dynamically adjust parameters to control the radio resources. The fuzzy logic control (FLC) spectrum sharing for Inter-BS coexistence mechanism is chosen to make effective utilization of resources in IEEE 802.22 WRAN. The proposed scheme considers three kinds of traffic, voice, video and data respectively. The simulation results reveal that the proposed scheme can meet the goals of the dynamic spectrum sharing to improve resource utilization and fairness. View full abstract»

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  • Modified truthiness propagation algorithm for lossy source compression based on LDGM codes

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB) |  | HTML iconHTML  

    This letter considers the lossy source compression of a binary symmetric source using low-density generator matrix (LDGM) codes and truthiness propagation encoding algorithm. And a simple variant on the truthiness propagation is proposed by softening the a priori probability of the reconstructed source sequence. Comparisons with the truthiness propagation reveal that the proposed algorithm has better rate-distortion performance at low-to-medium code rates. View full abstract»

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  • Optimization of energy detection based cooperative spectrum sensing in cognitive radio networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (141 KB) |  | HTML iconHTML  

    Cooperation is necessitated for tackling the challenges caused by fading/shadowing effects, noise uncertainty and sensing time constraints in spectrum sensing of cognitive radio networks. This paper studies the optimization problem of energy detection based cooperative spectrum sensing (CSS), with the main focuses on the optimality of K out of N fusion strategy and cooperative-user number. The procedures for optimizing the fusion strategy under both the Neyman-Pearson (N-P) and Bayesian criteria are given, and the numerical results demonstrate that the optimal strategy outperforms others, with the maximum collective detection probability under N-P criterion, and the minimum detection risk under Bayesian criterion. Further, the optimal number of cooperative users is investigated, as a solution to the tradeoff between the cooperative spectrum sensing performance and the total sensing overhead. It is shown that the required sensing reliability and minimization of the sensing overhead can be guaranteed simultaneously, if only the local detection threshold and the fusion strategy are properly set. View full abstract»

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  • ISAR super-resolution imaging based on sparse representation

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (518 KB) |  | HTML iconHTML  

    Super-resolution imaging technique can improve resolution of ISAR image. Traditional methods based on spectrum estimation need to know the number of scattering centers in advance, and match two-dimensional poles in two-dimensional imaging. This paper researches sparsity of ISAR frequency signal and two-dimensional signal, and make super-resolution imaging equal to signal sparse representation. By Basic Pursuit algorithm, a clearer image is obtained without the number of scattering centers estimation and match processing. View full abstract»

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  • Lattice-reduction-aided robust detection for MIMO systems with channel estimation error

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (370 KB) |  | HTML iconHTML  

    In recently years, lattice-reduction (LR) has been proposed to improve the performance of linear and successive interference cancellation (SIC) detectors in MIMO systems. It is proved that LR-aided linear detectors collect the same diversity order as that exploited by the ML detector but with much lower complexity when perfect channel state information (CSI) is available at receiver side. However, in practice, CSI is always contaminated by channel estimation error. In this paper, we proposed MMSE based LR-aided robust linear and SIC detection schemes which are capable of improving the BER performance in the context of channel estimation error. Additionally, we derived the approximate value of error floor as a function of channel estimation error and proved the BER improvements of robust LR-aided MMSE(-SIC) detector on traditional LR-aided MMSE(-SIC) detector increase with the growing number of transmit and receive antennas. Simulation results validate the conclusion. View full abstract»

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  • Distributed precoding for multicell MIMO networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (498 KB) |  | HTML iconHTML  

    Distributed precoder for multicell multi-input multi-output (MIMO) networks is designed in this paper, which is implemented in a distributed manner instead of the central manner. Considering the interference can be transformed into the useful contribution, the criterion of maximizing the signal to leakage plus noise ratio (SLNR) is first introduced for the distributed precoder design. Moreover, in order to further reduce the channel state information feedback overhead, another precoder in terms of matching filter (MF) is then proposed for the distributed precoder design in multicell MIMO systems. Computer simulations have shown that the proposed precoding schemes outperform the existing method in terms of the achievable rate and the cumulative distribution function of the whole multicell MIMO system. View full abstract»

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  • Design of waveguide E-plane hybrid metal insert filters for millimeter-wave application

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB) |  | HTML iconHTML  

    Single and double E-plane metal insert irises are analyzed via Mode-Match-Method (MMM), and the position of the double irises is determined first, then single/double/hybrid metal insert filters are designed using the theory of network synthesis, the result demonstrates that hybrid metal insert filter is easier to fabricate because of its reasonable iris lengths. At last, the above three types of filters are analyzed by MMM, the result demonstrates that hybrid metal insert filter has better transmission characteristics than the single/double metal insert filter. The MMM results are also verified by the results of CST software. View full abstract»

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  • A simulated method of modeling wireless channel based on CDL

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    Rapid development of wireless communications gives prominence to simulation. Simulated methods of modeling wireless channel are of significance to wireless communications simulation on both link and system levels. There have been quite a lot of theoretical models which have accurately described the characteristics of wireless channel. However when it comes to the realization of wireless channel in simulation, there seem no accurate enough methods and conclusions. Current simulated methods are mostly built up based on TDL, which is a common framework to model micro fading and mainly focused on micro fading. As to macro fading, Doppler-effect and polarization of electromagnetic wave, this method behaves not well enough, and other statistical approximations is indispensable, such as shadow fading, Doppler power spectrum density and so on. To the question existed, this paper proposes a simulated method to accurately model wireless channel under given wireless environment, on the basis of cluster delay line. This method is highlighted with comprehensive consideration of macro and micro fading, Doppler, multi-path and polarization effect. Analysis and simulation results on characteristics of wireless channel such as signal envelope, coherent time and bandwidth, validate the proposed model. View full abstract»

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  • Sub-pixel image registration based on physical forces

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (167 KB) |  | HTML iconHTML  

    A new method for image registration has been previously proposed by the authors, which the registration is based on physical forces. The registration parameters are translation and rotation. This method assumes images like charged materials that attract each other. In this case, one of the images moves in the same direction as the applied force while the other one is still. The movement of the image continues until the resultant force becomes zero. This approach estimates the registration parameters simultaneously and leading to a better optimized set of registration parameters. The registration error for this method is 1 to 3 pixels. In this paper we aim to develop this method for the applications which need sub-pixel accuracy. First, by applying the Canny edge detector on the input images, the edge information is also used for the registration process to increase the robustness of this method in the presence of noise. After that, sub-pixel accuracy is provided for this method by using interpolation techniques. View full abstract»

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  • Localized address autoconfiguration in wireless ad hoc networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB) |  | HTML iconHTML  

    We propose a localized address autoconfiguration (LaConf) scheme for wireless ad hoc networks. Address allocation information is maintained on the network border nodes, called addressing agents (AAs), which are locally identified by geographic routing protocol GFG. When a node joins the network, it acquires an address from a neighboring AA (if any exists) by local communication or from the head AA (a geographic extreme AA) by GFG-based multi-hop communication. Geographic Hash Table (GHT) is adopted for duplicate address detection. Each address is hashed to a unique location in the network field, and the associated assignment information is stored along the face perimeter enclosing that location (in the planar graph used). When a node receives an address assignment, it consults with the perimeter nodes around the hash location of the assigned address about any conflict. AAs detect network partition and merger locally according to neighborhood change and trigger AA re-selection and network re-configuration (if necessary). We evaluate LaConf through simulation using different planar graphs. We also propose to apply connected dominating set (CDS) concept to improve the performance. View full abstract»

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  • A UHF wide bandwidth Omni-directional wire antenna based on Genetic-Algorithms

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (94 KB) |  | HTML iconHTML  

    In this paper, a small ultra-wide antenna is proposed based on the Genetic Algorithms and MOM. The antenna is fed at the middle and lumped elements are loaded at appropriate location. The simulated and measured results indicate that the antenna has many advantages such as ultra-wide band from 30 MHz to 512 MHz, the VSWR of the antenna is below 2.5. The Horizontal radiation pattern of the antenna is almost Omni-direction, and the gain of the antenna is greater than -3.5dB in 90% working band. View full abstract»

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  • Performance analysis of self-calibration algorithm for concentric-UCA

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (129 KB) |  | HTML iconHTML  

    A new decoupling algorithm is proposed to estimate DOA of concentric uniform circular arrays (C-UCA). The new algorithm can calibrates mutual coupling of the inner sub-arrays, compensate for mutual coupling between sub-arrays, and then estimate DOA of signal sources. This algorithm transforms joint problem into cascade problem and gets the parameters by one dimension spectrum peak value searching, which avoids multidimensional nonlinear searching of multi-parameters joint estimation. The simulation and theoretic analysis validate the good performance of the proposed algorithm. View full abstract»

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  • A unified framework for SNR mismatch in turbo algorithms

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (378 KB) |  | HTML iconHTML  

    In this paper, we propose a unified framework to examine the effect of SNR mismatch on the performance of turbo algorithms, such as turbo equalization and turbo decoding. The proposed framework is based on a general model for a biased estimate of the signal-to-noise ratio (SNR) of the channel. It is shown how the estimation model can unify previously SNR mismatch models, which become special cases. Finally, simulation results show the effect of SNR mismatch on the bit error rate (BER) performance of a turbo equalizer based on the biased estimate of the channel SNR. View full abstract»

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  • A Markovian game-theoretical power control approach in cognitive radio networks: A multi-agent learning perspective

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    Due to the lack of learning and adaptation abilities in traditional game models, e.g., the strategic Nash game, they can't describe the dynamic behaviors and strategy interactive selections well in the cognitive context. The Markov game theoretical modeling approach is investigated to deal with the power control in the cognitive radio (CR) context, which well captures the learning and adaptation abilities of CRs. With the complex interaction relationship of multiple secondary users (SUs), multiple primary users (PUs) with wireless coexistent environment into consideration, both the secondary overall utility maximization and fairness among the SUs are considered from the mathematical model formulation and the algorithm design perspective. A power control approach to searching for the fair and optimal Nash equilibrium solution (NES) based on the improved multi-agent Q-learning is proposed. Meanwhile, the parameters of the presented algorithm are analyzed through simulations. The numerical results confirm that the proposed algorithm can improve the system utility and also guarantee the fairness among the SUs well. View full abstract»

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  • Design and implementation of microwave amplifiers with matching transformers

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (114 KB) |  | HTML iconHTML  

    A synthesizing method is proposed to design and implement wideband amplifiers in the microwave frequency range. The wideband amplifier is implemented by using Chebyshev matching transformers (CMT). In particular, the effective bandwidth of the CMT wideband amplifier increases 2.3GHz over the balance amplifier. The size of the CMT amplifier reduces to 30% of the balance amplifier. Two types of amplifier are built and tested. A methodology of designing the CMT amplifier is presented and implemented to validate this new method correct by measuring. View full abstract»

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  • Wideband band-pass filters with spurious band suppression

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (135 KB) |  | HTML iconHTML  

    In this paper, we investigate the cause of the second harmonic of the parasitic pass-band of coupled-serial-shunted lines band-pass filters. Filters are employed substrate suspension, wavy-edge coupling, ring resonators, and a combination of the wavy-edge coupling and ring resonators to suppress the harmonic pass-band. Using a continuous perturbation of the wavy-edge and ring resonators of the harmonic pass-band of the parallel-coupled line filter is rejected. A synthesizing method is presented to design Chebyshev type II band-pass filters in the microwave frequency range. Chebyshev type II band-pass filters are implemented to validate this method correct by measuring. View full abstract»

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  • PDA+LDPC iterative detector for cooperative CDMA networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (77 KB) |  | HTML iconHTML  

    The cooperative CDMA system proposed in this paper performs two phases of transmission. In phase I, each user node transmits its own information which is received by the base station (BS) as well as the other user nodes; in phase II, each partner node relays a processed version of the information received in the previous phase. Two iterative detectors are developed at the B S to combat multiple access interference (MAI). The first one named as PDA+LDPC-I performs detection just in the latter phase. The second one named as PDA+LDPC-II operates in both phases. During the latter phase, it firstly eliminates the signals corresponding to the users which were correctly decoded in the former phase, then performs detection on the resultant signals. Simulation results demonstrate that PDA+LDPC-II outperforms PDA+LDPC-I. View full abstract»

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  • Joint network coding and channel coding for cooperative relay communication system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (407 KB) |  | HTML iconHTML  

    This paper we propose a scheme of joint network coding and channel coding for cooperative relay communication system. With the proposed joint network coding and channel coding, the soft probability information can be combined with the redundancy contained in the relay transmission by the operation relationship in network coding and diversity gain can be obtained. Simulation results show that the scheme of joint network coding and channel coding significantly outperforms that of separate network-channel coding. View full abstract»

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  • On the tradeoff performance of severely fading channels

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (390 KB) |  | HTML iconHTML  

    The diversity-multiplexing tradeoff function is of extreme importance for a given multiple antenna channel. Since severely fading scenarios arise in a variety of applications, this paper makes efforts to derive the diversity-multiplexing tradeoff function for severely fading channels. It is found that the tradeoff performance is specially related to the maximum eigenvalue of the channel matrix and the channel model's degrees of freedom (CMDF), which represents the extent of the fading. For the infinite CMDF, the diversity-multiplexing tradeoff function coincides with the existing result for the richly scattered Rayleigh fading channel. View full abstract»

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  • The study of routing strategies in vehicular ad-hoc networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (469 KB) |  | HTML iconHTML  

    Vehicular ad hoc networks (VANETs) are a particular category of mobile ad hoc networks (MANETs) characterized by a high mobility and a reduced connectivity. As a prerequisite to communication, an efficient route between network nodes must be established, and it must be adapt to the rapidly changing topology of vehicles in motion. This is aim of VANET routing protocols. The simulation scene was set up by means of the NS2 simulation platform in this paper. The performances of ad hoc on-demand distance vector (AODV) and dynamic source routing (DSR), two classical routing protocols of MANET and VANET, are simulated and analyzed, and the conclusion that the AODV protocol is more suitable for VANET than the DSR protocol is derived. View full abstract»

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  • NLOS error mitigation based on modified Kaiman filter for mobile location in cellular networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (134 KB) |  | HTML iconHTML  

    Non-line-of-sight (NLOS) propagation biases Time of Arrival (TOA) and Time Difference of Arrival (TDOA). It causes the principal error for the mobile location in cellular networks. To mitigate the positioning error, a mobile positioning approach based on modified Kalman filter is proposed in this paper. With this approach, the true range is estimated based on the measurements, and the estimated range is utilized to location solution, which can reduce the impact of NLOS effectively. In our approach, the modified Kalman filter adapt its parameters with the estimate of NLOS's standard deviation, which make the approach remain effective in different environments. Simulation results show that this approach presents a good positioning accuracy even under NLOS propagation environments. The approach can be well applicable to mobile location in cellular networks. View full abstract»

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