A new transfer mode and a switching architecture which can support loss free and no delay jitter service class with shorter switching delay compared with "stop and go queueing scheme" is proposed. This scheme combines ATM scheme with hierarchical STM framing concept.

This letter proposes a new routing strategy and a design of ATM switches. By partitioning internal links into subgroups based on the bandwidth of a connection request, an ATM switching network which is nonblocking in the wide sense at the connection level can be constructed without the need of internal-link speedup.

This letter describes the High-speed Statistical Retry switch (HSR switch) for high-speed ATM switching systems. The HSR switch uses a new matrix-shaped switching structure with buffers at input and ouptut ports, and a simple retry algorithm. The input buffers are very small, and no complicated arbitration function is employed. A cell is repeatedly transmitted from each input buffer at m times the input line speed until the input buffer receives an acknowledge signal from the intended output buffer. A maximum of one cell can be transmitted from each input buffer during the cell transmission time. The internal ratio (m) is decided according to the probability of cell conflict in the output line. Simulation results show that just a 10-cell buffer at each input port and a 50-cell buffer at each output port are required when m=4 to achieve a cell loss probability of better than 10^-8, irrespective of the switch size. At each crosspoint, cells on the horizontal input line take precedence over those on the vertical input line. Only a very simple retry algorithm is employed, no complex arbitration is needed, and the arbitration circuit at the crosspoint can be reduced by about 90% in size. The proposed ATM switch architecture is applicable to high-speed (Gbit/s) ATM switches for B-ISDN because of its simplicity.

A wavelength path (WP) network management scheme is proposed for a photonic network. Multimedia data streams are integrated into a single-mode fiber using wave-length division WP multiplexing; both analog/digital and STM/ATM communications are handled. The WP management scheme using WP blocks (WPBs) with guard bands is described. An initially assigned WP does not use the guard band and most bandwidth changes made to accommodate WP changes occur within the original WPB using the guard band. An effective WP assignment method based on a recursive packing scheme is also proposed. The proposed WP packing scheme with guard band realizes a maximum network efficiency of 98%, and the probability of WP reassignment is under 10%. The techniques introduced in this paper permit the realization of flexible and effective multimedia services with a multimedia photonic network.

This paper proposes a compact high-speed ATM switching architecture that employs a novel arbitration method. The NN matrix shaped crosspoint switch is realized with D small switch blocks (SSBs). The number of crosspoints and address comparators is reduced from N² to (N/D)². Each block contains N/D input lines and N/D output lines. The association between output lines and output ports is logically changed each cell period. This arrangement permits each input port to be connected to N/D output ports in each cell period. Output-line contention control is realized block-by-block so high-speed operation is realized. The traffic characteristics of the proposed switch architecture are analyzed using computer simulations. According to the simulation results, the cell loss rate of 10^-8 is achieved with only 100-cell input and output-buffers under the heavy random load of 0.9 for any size switch. The proposed ATM switching architecture can construct the Gbit/s high-speed ATM switch fabric needed for B-ISDN.

This paper deals with study results on the effect of nonlinear amplification in the CDMA system using offset-QPSK signals bandlimited with a square-root cosine roll-off filter. As a result of the study, it is shown that the nonlinear amplification does not affect bit error rate performance with reasonable out-of-band emission characteristics when the roll-off factor of the transmit filter is one.

This letter reports a high-sensitivity GaAs decision IC for ultra-high-speed optical transmission systems. The IC was designed using LSCFL (Low-power Source Coupled FET Logic) and fabricated with 0.2-µm-gate-length MESFETs with a cut-off frequency of 50GHz. The input voltage sensitivity was 35mV at 10Gbit/s. This is the highest sensitivity ever reported for a MESFET decision IC.

Recently, there has been increasing interest in Code Division Multiplex (CDM) systems. We reported the CDM system using the -chip shift multiplex operation. So far the performance of this system evaluated under the optimum . In this letter, we evaluate an influence of the phase difference between the groups on BER performance in 2M-plex system.

An automatic tap assignment method in sub-band adaptive filter is proposed in this letter. The number of taps of the adaptive filter in each band is controlled by the mean-squared error. The numbers of taps increase in the bands which have large errors, while they decrease in the bands having small errors, until residual errors in all the bands become the same. In this way, the number of taps in a band is roughly proportional to the length of the impulse response of the unknown system in this band. The convergence rate and the residual error are improved, in comparison with existing uniform tap assignment. Effectiveness of the proposed method has been confirmed through computer simulation.

In a two-layer self-diplexing antenna fed at two ports, theoretical analysis has already shown that the isolation characteristics can be improved by adjusting the angle between the feed locations of the transmitting and receiving antennas. In this letter, we experimentally investigate the isolation characteristics of the self-diplexing array antenna. First, calculated and experimental results for each feed location of the element antenna are compared and good agreement is found. Second, experimental results with a 19-element planar array indicate that a self-diplexing antenna with suitably chosen feed configuration is effective in improving the isolation in a phased array antenna.

Numerical solutions for the near-field of microstrip antennas are presented. The field distribution is calculated by taking the inverse Fourier transform involving the current distribution with the help of the spectral-domain moment method. A new technique to save the computation time is devised, and the field pattern of the circularly polarized antenna is illustrated.

We analyze the mutual coupling between two microstrip antennas (MSAs) with the finite-difference time-domain (FDTD) method. It is suitable for substrates which have a complex configuration or include feed line structures. The mutual coupling between two MSAs on discontinuous orthogonal substrates is successfully calculated.

Correlation between the surface-SAR and external magnetic near-field in a realistic head model for 1.5GHz microwave far-field exposure is described. The regression relation is shown between the one gram averaged SAR and squared external magnetic field on the cross sectional perimeter of the head model.

The main propagation effect on interference between a satellite system and an adjacent microwave terrestrial path is the differential rain attenuation. In the present paper, a prediction method for the differential rain attenuation statistics is proposed which is based on a model convective rain-cell structure of the rainfall medium. The assumption that the point rainfall statistics follows a lognormal form is also adopted. The results of the predictive procedure are compared with the only available set of experimental data taken from Yokosuka, Japan. The agreement has been found to be quite reasonable.

A radial line slot antenna (RLSA) is a high gain and high efficiency planar array. A single-layered RLSA is much simple in structure but the slot length must be varied to synthesize uniform aperture illumination. These are now commercialized for 12GHz band DBS reception. In RLSAs, considerable power is dissipated in the termination as is common to other traveling wave antennas; the uniform aperture illumination is not the optimum condition for high gain in RLSAs. Authors proposed a theoretical method reducing the termination loss for further efficiency enhancement. This paper presents the measured performances of the SL-RLSAs of this design with non-uniform aperture illumination. The efficiency enhancement of about 10% is observed; the measured gain of 36.7dBi (87%) and 32.9dBi (81%) for a 0.6mφ and 0.4mφ antennas respectively verify this technique.

Sea clutter was measured using an X-band radar at very high grazing angles between 8.2 and 17.5. The sea state was 7 with the wave height of 6 to 9m. The wind velocity was 25m/s. It is shown that sea clutter amplitudes obey the log-normal and K distributions using the Akaike Information Criterion (AIC) , which is more rigorous fit to the distribution to the data than the least squares method.

We observed a ship as a radar target embedded in sea clutter using a millimeter wave radar. The shape of the ship and sea clutter were discriminated by using texture analysis in image processing. As a discriminator, a nonlinear transformation of a local pattern was defined to deal with high order statistics.