This paper analyzed the connection points of Main Distribution Frames (MDF), which are installed between outside plants and inside plants (service nodes). This paper also proposes a connecting system for forthcoming FITL (Fiber In The Loop) networks. NTT has developed the Subscriber Line Cross-Connecting Module (LXM) for the FITL network and will continue to introduce LXMs and deploy optic subscriber networks in big cities throughout Japan.

One of the functions that should be provided in ATM LANs is multicast communication. For multicast communication on ATM LANs, the architecture of switch fabric and protocols for signaling have been studied. However, when data communication using a multicast connection such as LAN emulation service is provided, ABR service on a multicast connection (Multicast ABR) is also required. ABR service has been actively discussed in the ATM forum. Unfortunately, the study on flow control mechanism for Multicast ABR is not enough. This paper discusses the suitable flow control mechanism for Multicast ABR and shows its performance.

This paper presents a method for simply estimating characteristics of signals received by a millimeter wave car radar. In this method, the substitution of a radar target with a set of scattering points is introduced to take account of the phenomenon that only a part of the target is irradiated with the radio wave from the radar antenna with a sharp beam; the phenomenon is peculiar to the car radar which operates in a compact range. The positions of these scattering points and the RCS values for the scattering points are appropriately determined on the basis of a measured RCS image for the target. The RCS image means a spatial distribution of RCS values on the surface of the target. In addition, influence of the ground, which is a dominant clutter in car radar environments, and characteristics of the car radar hardware can be included in the estimation method. The estimated characteristics of the signal received by the car radar are compared with the measured ones under typical cases in the car radar environments. The comparison verifies not only that the received signal characteristics are well estimated even when the range is rather short but also that the substitution of the target with scattering points is valid. The proposed method can realize the estimation of the received signal characteristics. Furthermore, the method can be developed into a computer simulation for evaluating the target detection performance of the car radar.

In this letter, we propose a blind adaptive receiver with nonlinear structure for DS/CDMA communication systems. The proposed receiver requires the signature waveform and timing for only the desired user. It is shown that the blind adaptation is equivalent to the adaptation with the training signal and the function to be minimized has no local minima.

We propose a method for accomplishing accurate RCS (Radar Cross Section ) images of a car in a compact range. It is an improved method based on an ISAR (Inverse Synthetic Aperture Radar) technique. To obtain accurate RCS values, an idea of an image correction function for the Fourier transform used in the ISAR processing is introduced. The role of the image correction function is to compensate the difference of the propagation loss as to the different scattering points on a target. As a result, `sensitivity' of imaging in the compact range is kept uniform. Hamming window is suitable for the Fourier transform to accomplish RCS images because of its low sidelobe level and the sharpness of a mainlobe. When hamming window is adopted, the spatial resolution is approximately twice the size of granularity which is determined by the ISAR parameters. To verify the improvement of the RCS images obtained by means of our method, several numerical target models are employed. The results of the investigation show that uniformity of `sensitivity' for obtained RCS images is achieved in the compact range and accurate images with the resolution of twice the size of granularity are accomplished without blurs or distortions in the unambiguous area. RCS images for rear aspects of a passenger car are investigated with the spatial resolution of 50 mm in the 60 GHz band. The RCS image varies with the aspect angle of the car and the specular reflection occurs for the millimeter wave. When the curvature on the car edge is small, a blurred RCS image is observed. The reason is that a scattering center of the specular reflection moves so widely that it can't be regarded as a fixed point. This causes elongation of the RCS image. A peak value in the dominant area for each aspect angle is less the 0 dBsm and no remarkable areas where the RCS value exceeds-20 dBsm is found any more on the car except such the dominant area.

In this contribution an algorithm for joint detection in fast frequency hopping/multiple frequency shift keying (FFH/MFSK) multiple access (MA) systems is presented. The new algorithm - referred to as REC algorithm - evaluates ambiguities which occur during the decision process and iteratively reduces the number of candidate symbols. The REC algorithm is of low complexity, suitable for every addressing scheme, and effective for both an interference-only channel and a fading channel. For the interference-only channel the REC algorithm enables maximum likelihood (ML) joint detection with low computational effort.

In this paper, we consider the protein structure alignment problem, which is a very important problem in molecular biology. Since an outline of protein structure is represented by a sequence of points in three-dimensional space, this problem is defined as the following geometric pattern matching problem: given two point sequences P and Q in three-dimensions and a real number δ > 0, find a maximum-cardinality set of point pairs such that the distance between each pair is at most δ under the condition that any translation and rotation can be applied to P. Since it is very difficult to solve this problem exactly, we consider algorithms that solve it approximately. We propose three algorithms: BASICALIGN, RANDALIGN and FRAGALIGN whose worst case time complexities are O(n8), O((n7/k3) polylog(n)) and O(n4) respectively, where n denotes the size of larger input structure and k denotes the minimum size of the alignment to be obtained. All of these have the following common framework: a series of initial superpositions are computed; for each of such superpositions, a rough alignment is first computed using a dynamic programming technique, and then it is refined through an iterative improvement procedure which also uses dynamic programming; the best alignment among them is selected as an output. The difference among three algorithms lies in the methods of finding initial superpositions. BASICALIGN, RANDALIGN and FRAGALIGN use exhaustive search, random sampling technique and fragment-based search, respectively. We prove guaranteed approximation ratios (in the sense of distances between point pairs) for theoretical versions of BASICALIGN and RANDALIGN. Practical versions of RANDALIGN and FRAGALIGN were implemented and compared with a previous algorithm using real protein structure data. The experimental results show that FRAGALIGN is best among them and it outputs good alignments quickly.

A direct-mapped cache takes less time for accessing data than a set-associative cache because the time needed for selecting a cache line among the set is not necessary. The hit ratio of a direct-mapped cache, however, is lower due to the conflict misses caused by mapping multiple addresses to the same cache line. Addressing cache memory by virtual addresses reduces the cache access time by eliminating the time needed for address translation. The synonym problem in virtual cache necessitates an additional field in the cache tag to denote the process to which cache line belongs. In this paper, we propose a new virtual cache architecture whose average access time is almost the same as the direct-mapped caches while the hit ratio is the same as the set-associative cashes. A victim for cache replacement is selected from those that belong to a process which is most remote from being scheduled. The entire cache memory is divided into n banks, and each process is assigned to a bank. Then, each process runs on the assigned bank, and the cache behaves like a direct-mapped cache. Trace-driven simulations confirm that the new scheme removes almost as many conflict misses as does the set-associative cache, while cache access time is similar to a direct-mapped cache.

The quality of a modular software system depends on the reliabilities of the software modules and the software operational profile. When the software is designed for multiple customers having different operational profiles, different customers may experience different software quality. It is important to ensure that no customer will suffer from a poor software quality. In this paper, we formulate and solve three reliability allocation problems for modular software system designed for multiple customers. In these reliability allocation problems, we consider the software operational profile of every customer while fulfilling such practical constraints as cost budget and software quality requirement. The numerical results show that when the operational profiles of the customers are more skewed, it is more beneficial to take their operational profiles into account.

Research and standardization activities on FPLMTS are under way throughout the world. This paper shows recent study results on radio transmission technologies in ARIB (Association of Radio Industries and Businesses), which in the standardization organization in Japan. On-going study shows two TDMA based and four CDMA based radio transmission technologies under study. These technologies need to be further studied in detail. The proposal from ARIB is expected to be summarized around the end of the year 1996.

A current controlled CMOS output driver was designed by using a temperature-insensitive reference current generator. It eliminates the need for overdesign of the driver transistor size to meet the delay specification at high temperature. Comparison with the conventional CMOS output driver with the same transistor size showed that the ground bounce noise was reduced by 2.5 times and the delay time was increased by 1.4 times, at 25 for 50pF load. The temperature variations of the DC pull-up and pull-down currents of the new output driver were 4% within the temperature range from -15 to 125 compared to the variations of 40 and 60% for pull-up and pull-down respectively for the conventional output driver. The temperature insensitivity of the reference current generator was achieved by multiplying two current components. one which is proportional to mobility and the other which is inversely proportional to mobility, by using a CMOS square root circuit. The temperature variation of the DC output current of the reference current generator alone was 0.77% within the entire temperature range from -15 to 125.

To evaluate DRAM memory-cell data retention characteristics, measuring the leakage current of the individual memory-cell is important. However, the leakage current of a DRAM memory-cell cannot be measured directly, because its value is on the order of femtoamperes. This paper describes a Plate Bumping (PB) method that can measure the leakage current of a specific memory-cell using the relationship between the shifted value of memory-cell-plate potential and the retention period. By using the PB method, it can be confirmed that the leakage current of the short-retention cell (bad cell) depends on its storage-node potential. With regards to cells with "0" data stored in them ("0" cells), it appears that the relaxed junction biasing (RJB) scheme which can extend refresh interval increases the number of misread "0" cells due to the lowering of the sense amplifier's sensing threshold.

Discussed here is reduction of power dissipation for multi-media LSIs. First, both active power dissipation Pat and stand-by power dissipation Pst for both CMOS LSIs and GaAs LSIs are summarized. Then, general technologies for reducing Pat are discussed. Also reviewed are a wide variety of approaches (i.e., parallel and pipeline schemes, Chen's fast DCT algorithms, hierarchical search scheme for motion vectors, etc.) for reduction of Pat. The last part of the paper focuses on reduction of Pst. Reducing both Pat and Pst requires that both throughput and active chip areas be either maintained or improved.

New interference cancellation technique using time division reference signal is proposed for optical synchronous code-division multiple-access (CDMA) systems with modified prime sequence codes. In the proposed system one user in each group is not allowed to access the network at each time, and this unallowable user's channel is used as a reference signal for other users in the same group at the time. The performance of the proposed system using an avalanche photodiode (APD) is analyzed where the Gaussian approximation of the APD output is employed and the effects of APD noise, thermal noise, and interference for the receiver are included. The proposed cancellation techniqus is shown to be effective to improve the bit error probability performance and to alleviate the error floor when the number of users and the received optical power are not appreciably small.

This paper deals with performance evaluation of CDMA based on DS/SS/GMSK signaling with the differential detection over multipath Rayleigh fading channels. To demodulate DS/SS/GMSK signals, we consider differential detection, which does not need a carrier recovery. The bit-error-rate performance is evaluated in the presence of thermal noise and multipleaccess interferences under the multipath Rayleigh fading environment. To improve the performance, we also consider adoption of a RAKE receiver.

Capacity of Cellular DS/CDMA systems depends on an amount of co-channel interference (CCI). One of the effective schemes to eliminate the CCI and improve the capacity is CCI cancellers which remove the CCI by subtracting all the regenerated signals of the interfering users. These cancellers, however, suffer from the residual interference due to the symbol errors in the initial decision. Therefore, a canceller which employed error correction in the initial decision has been proposed. In this system, two Viterbi decoders per one user are needed. Therefore, the amount of calculation increases and this causes additional signal processing delay which is not preferable, especially for voice transmission. Here we propose three fast decoding methods by simplifying the second Viterbi decoder which is used for decoding after the cancellation. Method-1 uses information of the first Viterbi decoder. Method-2 utilizes information of the second correlator instead of that of the first Viterbi decoder. Method-3 is the combination of method-1 and method-2. It uses information from both the first Viterbi decoder and the second correlator. The results obtained from the computer simulation show that the ACS reduction ratio reaches up to 80% within 0.5 dB degradation in Es/No.

In this paper, we describe effects of oddcorrelation functions and band-limitation filters for direct-wave reception systems using broadband spread-spectrum (B-SS) techniques. The receiver of this system is synchronized to the direct-wave. First, the effects of odd-correlation functions are investigated by using M-sequences and random sequences. The effects of even-correlation functions for those sequences can be easily obtained by using results of effects of odd-correlation functions for random sequences. Here we derive a novel function of odd-correlation variance for M-sequence, which is obtained theoretically. Consequently, we show the advantage of M-sequence which is used as spreading sequence. As a reason, in the odd-correlation function of M-sequence, small values are taken near the synchronous phase where harmful scattered-waves exist, strongly. Next, the effects of both odd-correlation function and band-limitation filter are studied by using several kinds of filters. Here we discuss the difference of characteristics in case that despreading sequence of bandlimited pulse or that of rectangular pulse is used in the correlator of the receiver. The technique despreading by rectangular pulse can be achieved a high speed signal processing and equipment miniaturizing because of utilization of switching circuit. We show the advantage of despreading sequence of rectangular pulse, when the limitation bandwidth of transmitting signal takes a small value. Because the characteristics of the correlation function between transmitting sequence of bandlimited pulse and despreading sequence of rectangular pulse can be kept better than that between the transmitting sequence and despreading sequence of bandlimited pulse. As these results, in severe bandlimited direct-wave reception systems using B-SS techniques, M-sequence of rectangular pulse as despreading sequence is most suitable.

In this paper, the bit error rate (BER) considering tracking performance is evaluated, by theoretical analysis and computer simulation, for a bi-orthogonal system using a synchronizing pseudo-noise (PN) sequence and co-channel interference cancellers. A system that improves on Tachikawa's system is proposed. It is found that the optimum ratio of the information signal energy to the synchronizing signal energy varies with Eb/No, and the canceller is better for small L than for large L (L = length of the sequence). Moreover, it is found that the BER considering synchronization performance improvse as the equivalent noise bandwidth Bn decreases.

In this paper, we introduce a parallel algorithm for parsing context-free languages. Our algorithm can handle arbitrary context-free grammars since it is based on Earley's algorithm. Our algorithm can operate on any loosely coupled multiprocessor which can provide a topology of a one-way ring. Our algorithm uses p processors to parse an input string of length n where 1 p n. It is shown that our algorithm requires O(n3/p) time. The algorithm uses a simple job allocation strategy. However, it achieves high load balancing and uses the processors efficiently.

Memory Sharing Processor Array (MSPA) architecture has been developed as an effective array processing architecture for both reduced data storages and increased processor cell utilization efficiency [1]. In this paper, the MSPA design methodology is extended to the VLSI synthesis of a serial input processor array (Pa). Then, a new bit-serial input multiplier and a new data serial input matrix multiplier are derived from the new PA. These multipliers are superior to the conventional multipliers by their smaller number of logic-gate count.