This paper proposes a novel high-temperature superconducting dual-band bandpass filter (HTS-DBPF), that employs a broadside coupling structure, in which quarter-wavelength resonators are formed on opposite sides of each substrate. This structure provides a dual-band operation of the BPF and flexibility, in the sense of having a wide range in selecting two center passband frequencies of the HTS-DBPF. This paper employs the ratio of the lower and higher center passband frequencies, α, as a criterion for evaluating the flexibility. The obtained α ranges are from 1 to 4.7, which are the widest for DBPFs for mobile communications applications, to the best knowledge of the authors. This paper presents a 2.4-/2.9-GHz band HTS-DBPF, as an experimental example, using a YBCO film deposited on an MgO substrate. The measured frequency responses of the HTS-DBPF agree with the electromagnetic simulated results. Measurement and simulation results confirm that the proposed filter architecture is effective in configuring a DBPF that can set each center passband frequency widely.

Estimating the packet loss ratio of TCP transfers is essential for passively measuring Quality of Service (QoS) on the Internet traffic. However, only a few studies have been conducted on this issue. The Benko-Veres algorithm is one technique for estimating the packet loss ratio of two networks separated by a measurement point. However, this study shows that it leads to an estimation error of a few hundred percent in the particular environment where the packet loss probabilities between the two networks are asymmetrical. We propose a passive method for packet loss estimation that offers improved estimation accuracy by introducing classification conditions for the TCP retransmission timeout. An experiment shows that our proposed algorithm suppressed the maximum estimation error to less than 15%.

The simple repetitive control system proposed by Yamada et al. is a type of servomechanism for periodic reference inputs. This system follows a periodic reference input with a small steady-state error, even if there is periodic disturbance or uncertainty in the plant. In addition, simple repetitive control systems ensure that transfer functions from the periodic reference input to the output and from the disturbance to the output have finite numbers of poles. Yamada et al. clarified the parameterization of all stabilizing simple repetitive controllers. Recently, Yamada et al. proposed the parameterization of all stabilizing two-degrees-of-freedom (TDOF) simple repetitive controllers that can specify the input-output characteristic and the disturbance attenuation characteristic separately. However, when using the method of Yamada et al., it is complex to specify the low-pass filter in the internal model for the periodic reference input that specifies the frequency characteristics. This paper extends the results of Yamada et al. and proposes the parameterization of all stabilizing TDOF simple repetitive controllers with specified frequency characteristics in which the low-pass filter can be specified beforehand.

This paper examines two-pass authenticated key exchange (AKE) protocols that are secure without the NAXOS technique under the gap Diffie-Hellman assumption in the random oracle model: FHMQV [18], KFU1 [21], SMEN- [13], and UP [17]. We introduce two protocol, biclique DH protocol and multiplied biclique DH protocol, to analyze the subject protocols, and show that the subject protocols use the multiplied biclique DH protocol as internal protocols. The biclique DH protocol is secure, however, the multiplied biclique DH protocol is insecure. We show the relations between the subject protocols from the viewpoint of how they overcome the insecurity of the multiplied biclique DH protocol: FHMQV virtually executes two multiplied biclique DH protocols in sequence with the same ephemeral key on two randomized static keys. KFU1 executes two multiplied biclique DH protocols in parallel with the same ephemeral key. UP is a version of KFU1 in which one of the static public keys is generated with a random oracle. SMEN- can be thought of as a combined execution of two multiplied biclique DH protocols. In addition, this paper provides ways to characterize the AKE protocols and defines two parameters: one consists of the number of static keys, the number of ephemeral keys, and the number of shared secrets, and the other is defined as the total sum of these numbers. When an AKE protocol is constructed based on some group, these two parameters indicate the number of elements in the group, i.e., they are related to the sizes of the storage and communication data.

We present a multi-channel sampling expansion for signals with selectively tiled band-region. From this we derive an oversampling expansion for any bandpass signal, and show that any finitely many missing samples from two-channel oversampling expansion can always be uniquely recovered. In addition, we find a sufficient condition under which some infinitely many missing samples can be recovered. Numerical stability of the recovery process is also discussed in terms of the oversampling rate and distribution of the missing samples.

The nondeterminism of message-passing communication brings challenges to program debugging, testing and fault-tolerance. This paper proposes a novel deterministic message-passing implementation (DMPI) for parallel programs in the distributed environment. DMPI is compatible with the standard MPI in user interface, and it guarantees the reproducibility of message with high performance. The basic idea of DMPI is to use logical time to solve message races and control asynchronous transmissions, and thus we could eliminate the nondeterministic behaviors of the existing message-passing mechanism. We apply a buffering strategy to alleviate the performance slowdown caused by mismatch of logical time and physical time. To avoid deadlocks introduced by deterministic mechanisms, we also integrate DMPI with a lightweight deadlock checker to dynamically detect and solve these deadlocks. We have implemented DMPI and evaluated it using NPB benchmarks. The results show that DMPI could guarantee determinism with incurring modest runtime overhead (14% on average).

This letter proposes an analog active noise control (ANC) circuit with an all-pass filter (APF). To improve performance of the previously reported analog ANC circuit, we inserted an APF to the circuit in order to fit phases of a noise and an electrical signal in the circuit. As a result, we confirmed improvement of the noise canceling effect of the analog ANC circuit.

This paper presents a low-power LDPC decoder that can be used in Multimedia Wireless Sensor Networks. Three low power design techniques are proposed in the decoder design: a layered decoding algorithm, a modified Benes network and a modified memory bypassing scheme. The proposed decoder is implemented in TSMC 0.13 µm, 1.2 V CMOS process. Experiments show that when the clock frequency is 32 MHz, the power consumption of the proposed decoder is 38.4 mW, the energy efficiency is 53.3 pJ/bit/ite and the core area is 1.8 mm2.

This paper describes mobile backhaul optical access network designs for future cellular systems, in particular, for those systems that exploit coordinated multipoints (CoMP) transmission/reception techniques. Wavelength-division-multiplexing passive optical networks (WDM-PON) are primarily considered and two proposals to enhance mobile backhaul capability of WDM-PONs for CoMP are presented. One is physical X2 links that support dedicated low latency and high capacity data exchange between base stations (BSs). The other is multicasting in WDM-PONs. It effectively reduces data/control transmission time from central node to multiple BSs joining CoMP. Evaluation results verify that the proposed X2 links and the multicasting enable more BSs to join CoMP by enhancing the mobile backhaul capability, which results in improved service quality for users.

This paper presents the design of a second-order and a fourth-order bandpass filter (BPF) for 60 GHz millimeter-wave applications in 0.18 µm CMOS technology. The proposed on-chip BPFs employ the folded open loop structure designed on pattern ground shields. The adoption of a folded structure and utilization of multiple transmission zeros in the stopband permit the compact size and high selectivity for the BPF. Moreover, the pattern ground shields obviously slow down the guided waves which enable further reduction in the physical length of the resonator, and this, in turn, results in improvement of the insertion losses. A very good agreement between the electromagnetic (EM) simulations and measurement results has been achieved. As a result, the second-order BPF has the center frequency of 57.5 GHz, insertion loss of 2.77 dB, bandwidth of 14 GHz, return loss less than 27.5 dB and chip size of 650 µm810 µm (including bonding pads) while the fourth-order BPF has the center frequency of 57 GHz, insertion loss of 3.06 dB, bandwidth of 12 GHz, return loss less than 30 dB with chip size of 905 µm810 µm (including bonding pads).

In this paper, we present a transmission scheme for a multiple-input multiple-output (MIMO) quasi-static fading channel with imperfect channel state information at the transmitter (CSIT). In this scheme, we develop a precoder structure to exploit the available CSIT and apply spatial coupling for further performance enhancement. We derive an analytical evaluation method based on extrinsic information transfer (EXIT) functions, which provides convenience for our precoder design. Furthermore, we observe an area property indicating that, for a spatially coupled system, the iterative receiver can perform error-free decoding even the original uncoupled system has multiple fixed points in its EXIT chart. This observation implies that spatial coupling is useful to alleviate the uncertainty in CSIT which causes difficulty in designing LDPC code based on the EXIT curve matching technique. Numerical results are presented, showing an excellent performance of the proposed scheme in MIMO fading channels with imperfect CSIT.

Finding DC operating points of nonlinear circuits is an important and difficult task. The Newton-Raphson method adopted in the SPICE-like simulators often fails to converge to a solution. To overcome this convergence problem, homotopy methods have been studied from various viewpoints. However, most previous studies are mainly focused on the bipolar transistor circuits and no paper presents the global convergence theorems of homotopy methods for MOS transistor circuits. Moreover, due to the improvements and advantages of MOS transistor technologies, extending the homotopy methods to MOS transistor circuits becomes more and more necessary and important. This paper proposes two nonlinear homotopy methods for MOS transistor circuits and proves the global convergence theorems for the proposed MOS nonlinear homotopy method II. Numerical examples show that both of the two proposed homotopy methods for MOS transistor circuits are more effective for finding DC operating points than the conventional MOS homotopy method and they are also capable of finding DC operating points for large-scale circuits.

A solution-processed photosensitive passivation layer with a low dielectric constant (PPLD) has been developed for an a-Si thin film transistor. The PPLD has three highly important properties: a low leakage current, low water absorption, and high-transparency. In addition to providing passivation, the PPLD doubles as a planarization layer. The photoactive property of the PPLD is convenient for its adaption to LCD manufacturing process. A photoactive compound contained in the PPLD enables the formation of contact holes and patterns via a photolithography process. Meanwhile, the PPLD requires ITO workability and strong adhesion property on metal and glass substrates. Apart from the above features, an a-Si TFT must perform with extremely high reliability if it is to replace the conventional inorganic passivation layer (SiNx:H). This reliability has been achieved by an a-Si TFT and LCD panel coated with the PPLD. A reliability test was conducted under a high-temperature, high-humidity (HH) condition to examine how resistant the electronic characteristics were to change. The PPLD-coated LCD panel display view showed no defects for a test duration of HH200 hours. This high reliability was presumed to be at least partly attributable to the low water absorption rate of the passivation layer and the suppression of the increase of the TFT off-leakage current by the PPLD, a passivation layer designed to be non-polar as possible. Judging from the results of these experiments, this solution-processed passivation layer seems to be a viable substitute for the conventional inorganic passivation layer. For a larger screen LCD and higher drive frequency, the problem of RC delay has been emerged. The low dielectric constant of the PPLD will suppress the RC delay of the signal and realize both a higher pixel and a higher drive frequency.

In the framework of the modernization plan of COMPASS system, the existing COMPASS signals should be transmitted along with the modernized signals to maintain backward compatibility. In this paper, an efficient multiplexing scheme based on the optimal aligning method for combining COMPASS Phase II B3 and Phase III B3 signals is proposed, which offers significantly higher efficiency than Interplex and Generalized Majority Voting (GMV) multiplexing methods. The proposed scheme can provide potential opportunities for COMPASS system and other global navigation satellite systems (GNSS) modernization and construction plans.

We demonstrate how Hsiang and Shih's authentication scheme can be compromised and then propose an improved scheme based on the Rabin cryptosystem to overcome its weaknesses. Furthermore, we discuss the reason why we should use an asymmetric encryption algorithm to secure a password-based remote user authentication scheme using smart cards. We formally prove the security of our proposed scheme using the BAN logic.

In order to improve the detection performance in passive millimeter-wave (PMMW) imaging, a new method forwarding a null in the direction of human body and objects is proposed. The forward-nulling PMMW imaging using a dielectric tube occupied by cooling water placed near the focus line of a parabolic cylinder are performed. It is shown experimentally that the contrast between human body and conducting objects such as a conducting plate and a conducting sphere is improved by the presence of the cooling dielectric tube and parabolic cylinder.

In this paper, a contactless measurement technique of passive intermodulation (PIM) using a coaxial tube excited with standing waves is proposed. The principle of the proposed method is described using a two-port network model with the lumped resistances representing the losses of a specimen and test equipment. To show its validity, a test using nickel wires producing high PIM is carried out, and its PIM-dependency on DUT-position in the coaxial tube is simulated using the FDTD method. The simulated result shows a good agreement to the experiment. Through the examination, it is found that the power consumption by the PIM source in a specimen is essential in PIM production, and sensitive PIM detection does not require good matching condition. Finally, the relation between PIM-source size and generated PIM level is also examined. The result shows that at least 18 dB-PIM reduction is obtained by PIM source size in a half-wavelength conductive wire.

In this paper, a novel charge coupled device matched filter (CCD-MF) for Electrical code division multiplexing (ECDM) decoder is proposed and experimentally demonstrated. Simulation results clarify the influence of low charge transfer efficiency (CTE) and the validity of a parallel CCD-MF we proposed. A 15-channel ECDM system using a 2 Gchip/s, 2-parallel CCD-MF is experimentally demonstrated.

The power of laser radar received echoes varies over a large range due to many factors such as target distance, size, reflection ratio, etc, which leads to the difficulty of decoding codes from the received noise buried signals for spectrum code modulated laser radar. Firstly, a pseudo-random noise (PN) code modulated laser radar model is given, and the problem to be addressed is discussed. Then, a novel method based on Inter Symbol Interference (ISI) is proposed for resolving the problem, providing that only Additive White Gaussian Noise (AWGN) exists. The ISI effect is introduced by using a high pass filter (HPF). The results show that ISI improves laser radar receiver decoding ratio, thus the peak of the correlation function of decoded codes and modulation codes. Finally, the effect of proposed method is verified by a simple experiment.

As anonymity increasingly becomes a necessary and legitimate aim in many applications, a number of anonymous authentication schemes have been suggested over the years. Among the many schemes is Lee and Kwon's password-based authentication scheme for wireless environments. Compared with previous schemes, Lee and Kwon's scheme not only improves anonymity by employing random temporary IDs but also provides user-friendliness by allowing human-memorable passwords. In this letter, we point out that Lee and Kwon's scheme, despite its many merits, is vulnerable to off-line password guessing attacks and a forgery attack. In addition, we show how to eliminate these vulnerabilities.