This paper proposes a new algorithm for evaluating the number of chaining variable conditions (CVCs) in the selecting step of a disturbance vector (DV) for the analysis of SHA-1 collision search. The algorithm is constructed by combining four strategies, that can evaluate the number of CVCs more strictly compared with the previous approach. By using our method, we found some DVs that have 57 (or 59) essential CVCs for 1st (or 2nd) block in the case if we assume that we can modify messages up to step 25, which we have not confirmed the practicability of the assumption.

We propose frequency shifted optical single sideband (OSSB), a novel OSSB modulation scheme. It uses a continuous wave to up-convert the source signal, and the signal and the continuous wave then undergo suppressed carrier OSSB modulation simultaneously. This scheme inherently has no unwanted sidebands, even if the suppressed carrier OSSB modulator is defective. Experiments of 12 GHz RF signal transmission confirm that it achieves 2.4 dB relaxation in chromatic dispersion power fading under the condition of 15 dB SSR.

In this letter, we propose a cache organization that substantially reduces the memory bandwidth of motion compensation (MC) in the H.264/AVC decoders. To reduce duplicated memory accesses to P and B pictures, we employ a four-way set-associative cache in which its index bits are composed of horizontal and vertical address bits of the frame buffer and each line stores an 8 2 pixel data in the reference frames. Moreover, we alleviate the data fragmentation problem by selecting its line size that equals the minimum access size of the DDR SDRAM. The bandwidth of the optimized cache averaged over five QCIF IBBP image sequences requires only 129% of the essential bandwidth of an H.264/AVC MC.

A transducer with a wide step from a post-wall waveguide to a hollow waveguide width is proposed which is tolerant against the aperture offset. The modes in the step width of about 1.50 wavelengths are stable for the aperture offset and the fields are not so perturbed while in the conventional stepped structure with step width of about 1.00 wavelength, the higher evanescent mode of TE30 is excessively enhanced by the aperture offset. The operation of the transducer with the wider step is robust for the fabrication errors in the millimeter wave band. It is also suggested that the anti-symmetrical TE20 mode which is excited only by non-zero offset or the misalignment of the aperture exists in both structures and can not be the dominant factor for the improvement. The transducers are designed and fabricated at 61.25 GHz using PTFE substrate with glass fiber of εr=2.17. The bandwidth for the reflection lower than -15 dB is almost unchanged (6.30-6.60 GHz) for the offset from -0.2 mm to 0.2 mm, while it is degraded in the conventional stepped structure, from 7.65 GHz for no offset to 3.30-5.70 GHz for the same range of the offset.

One-dimensional photonic crystal (PC) with alternating layers of TiO2 and SiO2 was fabricated with spin coating and low temperature baking, resulting in a successful tuning of the PC stop band so as to block the amplified spontaneous emission (ASE) of a π-conjugate polymer film. Single PC as a substrate, not a cavity with two PC's, of the polymer film was sufficient to shift the tangential ASE to the energy at PC stop band edge, indicating that the tangential ASE propagating along the interface was modulated by its evanescent-field tail in the PC, which opens the new pathway for low-threshold coherent luminescence from an ultrathin π-conjugate polymer film with ultimate mode volume.

This paper presents a memory-efficient motion estimation (ME) technique for high-resolution video compression. The main objective is to reduce the external memory access, especially for limited local memory resource. The reduction of memory access can successfully save the notorious power consumption. The key to reduce the memory accesses is based on center-biased algorithm in that the center-biased algorithm performs the motion vector (MV) searching with the minimum search data. While considering the data reusability, the proposed dual-search-windowing (DSW) approaches use the secondary windowing as an option per searching necessity. By doing so, the loading of search windows can be alleviated and hence reduce the required external memory bandwidth. The proposed techniques can save up to 81% of external memory bandwidth and require only 135 MBytes/sec, while the quality degradation is less than 0.2 dB for 720 p HDTV clips coded at 8 Mbits/sec.

A new formulation of equal-length asymmetric parallel coupled line (APCLs) having zero at z=-1 (θ = π) is employed to study band-stop filters. Such representations offer additional flexibility in the design of filter circuits through two extra variables. An optimization algorithm is used to tune the characteristic impedances of APCLs so that the transfer function of the signal line is close to the system function of an ideal prototype filter. Two band-stop filters are realized in the form of microstrip lines and their frequency responses are measured to validate this new formulation.

This letter proposes a fast carrier search method, the Carrier Search Step method (CSSM), to quickly detect the carrier frequency even when mobile stations have no knowledge of the carrier frequencies used [1]. CSSM consists of two operations: 1) mobile stations use the coarse-to-fine search to detect the synchronization channel (SCH), and 2) the center frequency of SCH is shifted within the channel bandwidth so that mobile stations can detect the SCH in an early step of the coarse-to-fine search. Compared with conventional methods, CSSM can reduce carrier search time by 90% when SCH bandwidth is 1.08 MHz and the channel bandwidth is 5 MHz. The reduction in carrier search time strengthens as the channel bandwidth increases.

In this paper, an alternative approach is presented, to design equalizers (or matching networks) with commensurate (or equal length) transmission lines. The new method automatically yields the matching network topology with characteristic impedances of the commensurate lines. In the implementation process of the new technique first, the driving point impedance data of the matching network is generated by tracing a pre-selected transducer power gain shape, without optimization. Then, it is modelled as a realizable bounded-real input reflection coefficient in Richard domain, which in turn yields the desired equalizer topology with line characteristic impedances. This process results in an excellent initial design for the commercially available computer aided design (CAD) packages to generate final circuit layout for fabrication. An example is given to illustrate the utilization of the new method. It is expected that the proposed design technique is employed as a front-end, to commercially available computer aided design (CAD) packages which generate the actual equalizer circuit layout with physical dimensions for mass production.

This paper proposes an efficient design algorithm for power/ground (P/G) network synthesis with dynamic signal consideration, which is mainly caused by Ldi/dt noise and Cdv/dt decoupling capacitance (DECAP) current in the distribution network. To deal with the nonlinear global optimization under synthesis constraints directly, the genetic algorithm (GA) is introduced. The proposed GA-based synthesis method can avoid the linear transformation loss and the restraint condition complexity in current SLP, SQP, ICG, and random-walk methods. In the proposed Hybrid Grid Synthesis algorithm, the dynamic signal is simulated in the gene disturbance process, and Trapezoidal Modified Euler (TME) method is introduced to realize the precise dynamic time step process. We also use a hybrid-SLP method to reduce the genetic execute time and increase the network synthesis efficiency. Experimental results on given power distribution network show the reduction on layout area and execution time compared with current P/G network synthesis methods.

In this letter, a two channel frequency domain speech enhancement algorithm is proposed. The algorithm is designed to achieve better overall performance with relatively small array size. An improved version of adaptive null-forming is used, in which noise cancelation is implemented in auditory subbands. And an OM-LSA based postfiltering stage further purifies the output. The algorithm also features interaction between the array processing and the postfilter to make the filter adaptation more robust. This approach achieves considerable improvement on signal-to-noise ratio (SNR) and subjective quality of the desired speech. Experiments confirm the effectiveness of the proposed system.

To realize the compact ultra-wideband (UWB) bandpass filters, a novel filter prototype with two short-circuited stubs loaded at both sides of a stepped-impedance resonator (SIR) via the parallel coupled lines is proposed based on a distributed filter synthesis theory. The equivalent circuit of this filter is established, while the corresponding 7-pole Chebyshev-type transfer function is derived for filter synthesis. Then, a distributed-circuit-based technique was presented to synthesize the elements' values of this filter. As an example, a FCC UWB filter with the fractional bandwidth (FWB) @ -10 dB up to 110% was designed using the proposed prototype and then re-modeled by commercial microwave circuit simulator to verify the correctness and accuracy of the synthesis theory. Furthermore, in terms of EM simulator, the filter was further-optimized and experimentally-realized by using microstrip line. Good agreements between the measurement results and theoretical ones validate the effectiveness of our technique. In addition, compared with the conventional SIR-type UWB filter without short-circuited stubs, the new one significantly improves the selectivity and out-of-band characteristics (especially in lower one -45 dB@1-2 GHz) to satisfy the FCC's spectrum mask. The designed filter also exhibits very compact size, quite low insertion loss, steep skirts, flat group delay and the easily-fabricatable structure (the coupling gap dimension in this filter is 0.15 mm) as well. Moreover, it should be noted that, in terms of the presented design technique, the proposed filter prototype can be also used to easily realize the UWB filters with other FBW even greater than 110%.

Ultra wideband (UWB) radar cross sections (RCSs) of several targets have been measured using various combinations of transmitting and receiving linear polarizations (V-V, H-H, and +45- -45) with a view to obtaining information on the design of vehicular short-range radars. This paper reports the UWB RCSs (σLR and σLL) of a typical passenger automobile using two circular polarization combinations (L and R denote left and right circular polarizations). The wideband measurements were carried out with use of a vector network analyzer by sweeping the frequency from 24.5 to 28.8 GHz in a radio anechoic chamber. The UWB RCSs were derived by integrating the received power in the frequency domain. Similar to the linear polarization results, fluctuations of the RCSs were smaller in the UWB than in narrowband for both L-R and L-L, because the ultra-wide bandwidth cancels out RCS plunges caused by narrowband interference among reflected waves from various facets of the target. The median of (σLR- σLL) was 2 dB, while the median of (σHH - σ+45 - -45) or (σVV-σ+45- -45) was 6 dB. This is because the body of the automobile comprises a number of smaller scattering objects yielding σ LL, either similar to the corner reflectors or asymmetrical to the radar boresight. Frequency-domain responses showed a number of notches caused by the interference between numerous reflecting waves having power levels of a similar order and different round-trip path lengths. Some representative reflective parts of the automobile were identified through analyses of time-domain responses.

Exact bit error probabilities (BEP) are derived in closed-form for binary pulsed direct sequence (DS-) and hybrid direct sequence time hopping code division multiple access (DS/TH-CDMA) systems that have potential applications in ultra-wideband (UWB) communications. Flat Nakagami fading channel is considered and the characteristic function (CF) method is adopted. An exact expression of the CF is obtained through a straightforward method, which is simple and good for any arbitrary pulse shape. The CF is then used to obtain the exact BEP that requires less computational complexity than the method based on improved Gaussian approximation (IGA). It is shown under identical operating conditions that the shape of the CF, as well as, the BEP differs considerably for the two systems. While both the systems perform comparably in heavily faded channel, the hybrid system shows better BEP performance in lightly-faded channel. The CF and BEP also strongly depend on chip length and chip-duty that constitute the processing gain (PG). Different combinations of the parameters may result into the same PG and the BEP of a particular system for a constant PG, though remains nearly constant in a highly faded channel, may vary substantially in lightly-faded channel. A comparison of the results from the exact method with those from the standard Gaussian approximation (SGA) reveals that the SGA, though accurate for both the systems in highly-faded channel, becomes extremely optimistic for low-duty systems in lightly-faded channel. The SGA also fails to track several other system trade-offs.

This paper presents the analysis of in-band interference caused by pulse-based ultra-wideband (UWB) systems. The analysis contains both plain Impulse Radio UWB (IR-UWB) and Transmitted Reference UWB (TR-UWB) systems as a source of interference. The supposed victim is a narrowband BPSK system with a band-pass filter. The effect of pulse-based UWB systems is analyzed in terms of bit error rate. The analysis is given in terms of the specific combinations of pulse repetition frequency and center frequency of the narrowband bandpass filter. In those situations, the UWB interference cannot be modeled as a Gaussian noise. It also manifests situations in which the victim is under the severest or the slightest interference from TR-UWB. According to its result, the analysis is validated via simulation.

This Letter employs transmission-line theory for the impedance-matching circuits for a single-chip power amplifier (PA) and verifies for 5 GHz-band wireless LAN (IEEE 802.11a) applications. The presented matching circuits are composed of conductor-backed coplanar waveguide (CPW) meander-line resonators and impedance (K) inverters. One of the advantages of the presented circuits is that it can save on-chip space occupied by the matching circuits compared to that using the spiral inductors, thus reducing the cost. The prototype chip, which consists of PA and matching circuits, is designed employing the presented theory and fabricated. A few of the measured results to verify the design theory are presented.

A highly integrated frequency quadrupler MMIC that uses three-dimensional MMIC (3D-MMIC) technology is presented. It consists of four driver amplifiers, two doublers, and a 2-band elimination filter. These seven circuits are integrated in only a 2.36 mm2 area. The filter sufficiently suppresses spurious output components. The third and fifth harmonic components, which are the spurious components nearest to the desired component, are well suppressed. The desired/undesired ratio is about 40 dB. The driver amplifiers make the quadrupler output a constant power of the desired multiplied signal under low input power. The MMIC supplies +5 dBm of the fourth harmonic component in the input power range from -10 dBm to +5 dBm. The power dissipation of the MMIC is only 160 mW.

Ultra wideband (UWB) technologies are expected to be used in ultra-high-speed wireless personal area networks (WPAN) and wireless body area networks (WBAN). UWB human electromagnetic phantoms are useful for performance evaluation of antennas mounted in the vicinity of a human body and channel assessment when a human body blocks a propagation path. Publications on UWB phantoms, however, have been limited so far. This paper describes the development of liquid UWB phantom material (aqueous solution of sucrose) and UWB arm and torso phantoms. The UWB phantoms are not intended to evaluate a specific absorption rate (SAR) in a human body, because UWB devices are supposed to transmit at very low power and thus should pose no human hazard.

A new elliptic-function bandpass filter (BPF) is proposed, which utilizes an inter-digital coupled line (IDCPL) as a left-handed transmission line. The IDCPL is employed in order to realize a negative coupling between non-adjacent resonators in a wideband BPF. As the authors' knowledge, the left-handed operations of the IDCPL has rarely utilized before, although the IDCPL itself has been widely used in many microwave circuits without being paid attention to the left-handed operations. Measured characteristics of two BPFs are presented in this paper, one is targeted for 3-4 GHz WiMAX systems, and the other is for 3-5 GHz ultra wideband communication systems (UWB).

This paper describes a novel Wilkinson power divider operating at two arbitrary different frequencies. The proposed divider consists of two-section transmission lines and a series RLC circuit connected between two output ports. The circuit parameters for a dual-band operation are derived by the even/odd mode analysis. Equal power split, complete matching, and good isolation between two output ports are numerically demonstrated. Dual-band and broadband Wilkinson power dividers can be successfully designed. Finally, verification of this design method is also shown by electromagnetic simulations and experiments.