In this paper, we study the effect of noisy links on the steady-state performance of incremental recursive least-squares (RLS) adaptive networks. In our analysis, using weighted spatial-temporal energy conservation approach, we arrive a variance relation which contains moments that represent the effects of noisy links. We evaluate these moments and derive closed-form expressions for the mean-square deviation (MSD) and excess mean-square error (EMSE) to explain the steady-state performance at each individual node. The derived expressions have good match with simulations.
In this paper, it is demonstrated that the first and second spurious passbands suppression in microstrip hairpin filters can be achieved by simply patterning appropriate geometries of several Defected Microstrip Structure (DMS) in parallel coupled sections. By properly tuning DMS resonator dimensions, multiple transmission zeros can be generated in the vicinity of spurious harmonics and a wide stopband can be obtained. Experimental results verify that 25dB and 40dB suppression for the first and the second harmonics, respectively, without affecting the main passband response.
Compatibility is a great matter of concern in field of Global Navigation Satellite Systems. This paper analyzes the traditional methodology of compatibility assessment based on effective carrier-power-to-noise density ratio. Meanwhile, a more accurate compatibility assessment model that includes two new factors, Pseudo-Random-Noise codes and Doppler offset, is suggested. Then, the simplified calculation for this improved model with good balance of computational efficiency and accuracy is presented. Finally, using this accuracry model with simplified calculation, the simulation results of compaitibility between Galileo and Compass on E1/B1 band are given.
The complexity of the exhaustive search decoding technique such as Maximum Likelihood Block Detection (MLBD) grows exponentially with the size of transmitted data. In this paper, a Lattice Sphere Decoding (LSD) technique is proposed for detection in block data transmission systems (BDTS). Simulation results at 10dB channel SNR of BDTS with LSD using block size of 20 performs are near Hybrid Micro Genetic Algorithm (HMGA) and slightly inferior than the exhaustive search technique using the channels with spectral nulls. In term of complexity, the proposed LSD technique requires only 460 and 126 objective functions evaluation using radius selection based on Babai Estimation (BE) and off-line observation respectively, while the HMGA and exhaustive search requires 3750 and 220 objective functions evaluation respectively.
Combining inertial navigation principles with signal processing, this paper first proposes a simplified but efficient mathematical model of INS-assisted second-order tracking loops so as to analyze the tracking capability. Secondly, the optimal bandwidth of INS-assisted Phase Lock Loop (PLL) is proposed to remove the period-amplitude outcome caused by Schuler frequency, and thus to ensure the absolutely satisfactory tracking capability. By theoretical simulation, the INS-assisted tracking ability superior to the receiver without aiding is quantized according to different grades of INS, and the optimal bandwidth is evaluated. The results verify the availability.
The TE21 tracking mode coupler is usually used in satellite auto tracking feed antennas. A mode coupler comprises a power dividing section and a mode converting section. The power divider splits the input signal into two parts, which are coupled to an overmoded circular waveguide through longitudinally slots. This paper presents the effects of shape and size of slots on sidewall coupling. A prototype x band mode converter with rounded-end shaped slots is built and tested. A back-to-back transmission measurement shows good agreement with simulation results. The optimum size and shape of side wall slots has 20%, 3dB transmission bandwidth.
High frequency EM backscatter modeling of large waveguide type geometries is a difficult task. In analysis of radar range profile, wider bandwidths make modeling even more challenging. Here, a new dispersive scattering center model is used based on Model Based Parameter Estimation (MBPE) approach. The model is capable of representing the radar range extension according the nonlinear variations of the scattering phase. A population-based Maximum Likelihood (ML) algorithm is used to calculate the parameters. The PRONY method is used for initialization. Wideband sparse measured frequency domain samples are the inputs of the model. The results are compared with IFFT outcomes.
A novel microstrip lowpass filter is proposed to achieve a very wide stopband and high selectivity as well as compact size. This filter utilizes a resonator with symmetric structure that consists of a transmission line, loaded with open stubs. Each stub ends with a defected taper and these tapers are coupled two by two to generate enhanced capacitances and increase the selectivity. Two units of these resonators are then used in combination with open stubs and triangular shaped resonators to widen the stopband and form the final filter. This filter is then fabricated and measured. The measured and simulated results are in good agreement.
In this paper, we design and analyze an asynchronous pipelined FIFO called a micropipeline with the awareness of “place & route” (P&R) on an FPGA device. We use a commercially available 65nm Virtex-5 devices and design a high-speed implementation of the asynchronous four-phase micropipeline with considering its layout on the device. The layout of our design is modified manually to meet timing constraints and to accelerate the speed of circuits. The asynchronous FIFO implemented on the Virtex-5 device shows 452MHz throughput and 648ps per-stage latency at the simulation under the worst case operating condition and around 472MHz throughput is observed at the actual measurement on a real working chip at room temperature.
A spatial-mode multiplexer/demultiplexer using a Bragg reflector tapered hollow waveguide is proposed. Depending on each spatial mode, vertical radiation takes place at a cut-off condition while the radiation position is dependent on the order of each spatial mode. Modeling of our structure is carried out by using a mode-matching method. The result shows low wavelength dependence and no noticeable polarization dependence while a low insertion loss is expected. Also a tapered hollow waveguide consisting of highly reflective multilayer mirrors with a wafer bonding process is fabricated. Clear vertical radiation could be observed, depending on the order of spatial modes. Our proposed device enables us to integrate surface-normal optical devices such as photo-detectors and VCSELs. The device will be useful for ultra-high capacity optical interconnects using spatial mode multiplexing.
This letter presents a new Wavelet Packet (WP) OFDM system using a Sliding Window (SW) technique. The SW is used to increase signal orthogonality and thus reduces the Doppler frequency effect in the received data. This is done by reducing the round-off error and long correlation time of the received data. Simulation results show that the proposed system offers significant BER gains over the standard WP-OFDM system without SW under flat fading and the Additive White Gaussian noise (AWGN) channel.
In this paper, a new FDFD algorithm for calculating a band gap diagram of 2-Dimensional (2D) lossy photonic crystals (PC) is developed. It is also shown that the FDTD method can not be successfully applied to the lossy PCs.