When a new digital broadcasting system is introduced for the viewers, it is important to be able to include new services and system aspects. That is to give the viewers new experiences and meet the demands they might have in the future. To fulfil the viewers expectations, is a key for success for the introduction of new service and product. It is equally important to look at the long term perspective and have the possibility to gradually develop the digital broadcasting systems we establish today. A fully integrated multimedia system is a hybrid of different media services, distribution paths and display object. The pros and cons of each of them must be examined and each of them used where best suited. This will probably give a more complex media world with fuzzy borders between what is broadcasting, packaged media and what is the on-line information society. In order to balance this, any new digital multimedia system needs to be developed with an open architecture, based on generally agreed standards and possibly follow a non-proprietary approach. IDUN, a prototype system for multimedia broadcasting, is on its way to fulfil these requirements. IDUN combines the powerful point to multi-point emission, domestic data storage and computer processing with the telecommunication network. It is feasible to introduce it in the analogue world of today but could better be utilised in a fully digital future. Some possible services are further proposed. Some of them with a tight relation to what a broadcaster already produces, which could give an evolutionary transfer to the new digital world.

OFDM (Orthogonal Frequency Division Multiplexing) is a useful digital modulation method for terrestrial digital broadcasting systems, both for digital TV broadcasting and digital audio broadcasting. OFDM is a kind of multicarrier modulation and shows excellent performance especially in multipath environments and in mobile reception. Other advantages are its resistance to interference signals and its suitability for digital signal processing. When each carrier of the OFDM signal is modulated with DQPSK, we call it DQPSK-OFDM. DQPSK-OFDM is a basic OFDM system, which is especially suitable for mobile reception. This paper describes how a DQPSK-OFDM system works and shows several experimental and simulation results. The experimental results mainly concern the performance of the DQPSK-OFDM system relative to various disturbances such as multipath (ghost) signals, nonlinearity of the channel, and interference from analog signals. The transmission characteristics of DQPSK-OFDM are investigated and the basic criteria for the system design of DQPSK-OFDM are discussed.

This paper describes an adaptively weighted code division multiplexing (AW-CDM) system, in other words, power controlled spread-spectrum multiplexing system and describes its application to hierarchical digital broadcasting of television signals. The AW-CDM, being combined with multi-resolutional video encoder, can provide such a hierarchical transmission that allows both high quality services for fixed receivers and reduced quality services for mobile/portable receivers. The carrier and the clock are robustly regenerated by using a spread-spectrum multiplexed pseudorandom noise (PN) sounder as a reference in the receiver. The PN reference is also used for Rake combining with signals via different paths, and for adaptive equalization (EQ). In a prototype AW-CDM modem, three layers of hierarchical video signals (highs: 5.91Mbps, middles: 1.50Mbps, and lows: 0.46 Mbps) are divided into a pair of 64 orthogonal spread-spectrum subchannels, each of which can be given a different priority and therefore a different threshold. In this case, three different thresholds are given. The modem's transmission rate is 9.7Mbps in the 6MHz band. Indoor transmission tests confirm that lows (weighted power layer I), middles (averaged power layer II), and highs (lightened power layer III) are retrievable under conditions in which the desired to undesired signal ratios (DURs) are respectively 0dB, 8.5dB, and 13.5dB. If the undesired signals are multipaths, these performances are dramatically improved by Rake combining and EQ. The AW-CDM system can be used for 20-30 Mbps advanced television (ATV) transmission in the 6-MHz bandwidth simply by changing the binary inputs into quaternary or octonary inputs.

A Trellis-Coded 8PSK (TCM) modem has been developed. This modem can transmit HDTV programs at a bit rate of 60Mbps over a satellite channel. In addition to Trellis coding, the (255, 235) Reed-Solomon code is adopted together with an interleaving technique to improve bit error performance. As a result, it has been confirmed that bit error rate of 10^-10 is achievable at a carrier to noise ratio of around 8.5dB over a 30MHz Gaussian noise channel. This TCM modem is also designed to double as a DQPSK modem. We examined the performances of these two modulation methods in a nonlinear channel. It was found that TCM is less disturbed than DQPSK by nonlinear distortion due to TWT. In addition, a limiter amplifier cascaded to TWT improves DQPSK performance and disturbs TCM performance. However it was confirmed that TCM still has a coding gain of 3dB over DQPSK.

We discuss ISDB (Integrated Services Digital Broadcasting) which has a transport structure to meet the technical requirements such as the flexibility and the extensibility of broadcasting in the future. The basic configuration of the ISDB transmission signal for distribution into various transmission channels is shown. Hybrid multiplexing, which uses common fixed-length packets and structured transmission units called "slots," is introduced to construct a transmission signal for low-cost signal processing in ISDB receivers. We show that a fixed packet length of 40-240 bytes results in high transmission efficiency in a diverse range of service arrangements. Furthermore, we use transmission control methods, which show the relationship between programs and packet IDs, to select the desired program with certainty and ease.

Considering the trend towards adopting high efficiency picture coding schemes into digital broadcasting services, we investigate objective picture quality scales for evaluating digitally encoded still and moving pictures. First, the study on the objective picture quality scale for high definition still pictures coded by the JPEG scheme is summarized. This scale is derived from consideration of the following distortion factors; 1) weighted noise by the spatial frequency characteristics and masking effects of human vision, 2) block distortion, and 3) mosquito noise. Next, an objective picture quality scale for motion pictures of standard television coded by the hybrid DCT scheme is studied. In addition to the above distortion factors, the temporal frequency characteristics of vision are also considered. Furthermore, considering that all of these distortions vary over time in motion pictures, methods for determining a single objective picture quality value for this time varying distortion are examined. As a result, generally applicable objective picture quality scale is obtained that correlates extremely well with subjective picture quality scale for both still and motion pictures, irrespective of the contents of the pictures. Having an objective scale facilitates automated picture quality evaluation and control.

In a hybrid coder which employs motion compensation and discrete cosine transform (MC-DCT coder), up to 90% of bits are used to represent the quantized DCT blocks. So it is most important to represent them with as few bits as possible. In this paper, we propose an efficient method for encoding the quantized DCT blocks of motion compensated prediction (MCP) errors, which adaptively selects one of a few scanning patterns. The scanning pattern selection of an MCP error block is based on the motion compensated images which are always available at the decoder as well as at the encoder. No overhead information for the scanning patterns needs to be transmitted. Simulation results show that the average bit rate reduction amounts to 5%.

In the future satellite broadcasting system in 21GHz band, the rainfall attenuation is a most significant problem. To solve this problem, the hierarchical transmission systems have been studied. This paper analyzes the performance of the hierarchical modulation scheme from the view point of power assignment in the presence of the rainfall attenuation. This paper shows an optimum power assignment ratio to maximize the spectral efficiency and the signal-to-noise ratio of received image, and these optimum ratio is varied with the measure of system performance.

Error-correction techniques can be used to reduce the required carrier-to-noise ratio (C/N) in digital satellite news gathering (SNG) systems. The required e.i.r.p. of a digital SNG terminal is smaller than that of conventional analog SNG RF terminals. In this paper, a Ku-band portable SNG RF terminal using a flat antenna is proposed to make the best use of these digital systems. This portable terminal uses 16 planar microstrip subarray antennas, each with a solid-state power amplifier (SSPA) mounted on its backside. The proposed RF terminal is distinctly different from a conventional RF terminal with a parabolic antenna in two ways; it is portable and it has electronic tracking capability. Electronic antenna tracking reduces the terminal setup time because precise alignment of the antenna with the satellite is not required. This paper first describes the system concept and discusses the design concept. Secondly, it then explains phase shifters and feedback loops for electronic tracking. The tracking performance of a feedback system using four subarrays is also presented with some comparisons between theoretical and measured results. Experimental results for the low side-lobe flat antenna and the SSPAs are then presented. These are the most important components of the system. The flat antenna meets the design objectives specified by ITU-R Recommendations. By orthogonally exciting the rectangular patch antenna, the flat antenna is capable of operating dual polarizations and dual frequencies (transmit/vertical polarization: 14GHz; receive/horizontal polarization: 12GHz). The SSPAs have an efficiency of 21% and an output power of 5W.

This paper compares three typical system-sharing configurations for FTTH networks that provide narrowband and video distribution services and proposes a remote node locating strategy for each configuration. Two new evaluation factors, required land space and service provisioning effort, are included in the calculation, in addition to facility cost and maintenance effort. By considering these factors together, the total network cost is calculated and the sensitivity to the number of remote nodes is evaluated. Finally, the most economical system-sharing configuration is identified on the basis of the evaluations for two typical service areas in Japan, for both present and future cost environments.

This paper presents an alternative traffic model for an ATM multiplexer providing video, voice, image, and data services. The traffic model classifies the input traffic into two types: real-time and non-real-time. The input process for realtime traffic is periodic and correlated, while that for non-realtime traffic is batch Poisson and independent. This multiplexer is assumed to be a priority queueing system with synchronous servers operating on time-frame basis and with separate finite buffers for each type of traffic. State probabilities and performance measures are successfully obtained using a Markov analysis technique and an application of the residue theorem in complex variable. The results can be applied in the design of an ATM multiplexer.

A queueing model suitable for multimedia packets with Poisson and batch Poisson arrivals is studied. In the queueing model, priority is given to the packets with batch Poisson arrival, and the packets with Poisson arrival, accumulated in a buffer, are routed by utilizing intervals of the packets with priority. The queueing performance of the proposed model is evaluated by the mean system delay. We also consider the effect of batch size and the ratio of the traffic with batch Poisson arrival and the one with Poisson arrival on the mean system delay. It is found that the proposed queueing model is useful to reduce the mean system delay of the packets with Poisson arrival, while maintaining the means system delay of the packets with batch Poisson arrival.

A new rate-controlled queueing discipline, called virtual rate-based queueing (VRBQ), is proposed for packet-switching nodes in connection-oriented, high-speed, wide-area networks. The VRBQ discipline is based on the virtual rate which has a value between the average and peak transmission rates. By choosing appropriate virtual rates, various requirements can be met regarding the performance and quality of services in integrated-service networks. As the worst-case performance guarantee, we determine the upper bounds of queueing delay when VRBQ is combined with an admission control mechanism, i.e., Dynamic Time Windows or Leaky Bucket. Simulation results demonstrate the fairness policy of VRBQ in comparison with other queueing disciplines, and the performance of sources controlled under different virtual rates.

Throughout the paper, the nearest-neighbour (NN) interconnection of switches within a multistage interconnection network (MIN) is analysed. Three main results are obtained: (1) The switch preserving transformation of a 2-D MIN into the 1-D MIN (and vice versa) (2) The rearrangeability of the MIN and (3) The number of stages (NS) for the rearrangeable nonblocking interconnection. The analysis is extended to any dimension of the interconnected data set. The topological equivalence between 1-D MINs with NN interconnections (NN-MINs) and 1-D cellular arrays is shown.

The double-stage threshold-type foreground-background congestion control for the common-store queueing system with multiple nonpreemptive priority classes is proposed to improve the transient performance, where the numbers of accepted priority packets in both foreground and background stores are controlled under the double-stage threshold-type scheduling. In the double-stage threshold-type congestion control, the background store is used for any priority packets, and some parts of the background store are reserved for lower-priority packets to accommodate more lower-priority packets in the background store, whereas some parts of the foreground store are reserved for higher-priority packets to avoid the priority deadlock. First, we derive the general set of coupled differential equations describing the system-state, and the expressions for mean system occupancy, throughput and loss probability. Second, the transient behavior of system performance is evaluated from the time-dependent state probabilities by using the Runge-Kutta procedure. It is shown that when the particular traffic class becomes overloaded, high throughputs and low loss probabilities of other priority classes can be obtained.

Long term phase noises are characterized for network synchronization using two time domain measurement techniques: the Maximum Time Interval Error (MTIE) and Time Variance (TVAR). First, the characteristics of previously measured fiber delay variations are evaluated. The diurnal and annual delay variations and the long term noise feature of random walk phase modulation are well represented by the TVAR technique. The delay variation due to the AU pointer operation is then measured using commercial SDH demultiplexing equipment and compared with the simulation result; the simulation result agrees well with the experimental result. The delay variation in the SDH equipment is simulated using the thermal fiber delay variation measured in the actual network as the input phase of the equipment. It is shown that the SDH equipment sometimes generates delay steps of 617ns, which are larger than the normal pointer operations of 154ns. The long term delay variation, periods over 10⁷s, due to the threshold spacing between the positive and negative stuffing is described. We also show that TVAR is suitable for evaluating the phase noise feature and MTIE can clearly show the peak value of phase noise. The long term phase noises evaluated in this paper are the dominant sources that degrade network synchronous performance. The results of this paper will be useful in designing the equipment synchronous specification.

This paper presents the results of a study made to determine the line length coverage of the high-bit-rate digital subscriber line (HDSL) present in NTT's local networks. The HDSL carries one bi-directional 784 kbit/s channel per pair and supports the digital interface at 1544kbit/s by using two cable pairs. The primary purpose of this study is to estimate the range limits for candidate transmission schemes considering line installation conditions, and to determine the most promising transmission scheme and its feasibility given the environment of NTT's local networks. Pulse amplitude modulation (PAM) and quadrature amplitude modulation (QAM) transmission schemes are compared for HDSL implementation. It is shown that 2B1Q-PAM and 16-QAM generally achieve better performance than the more complicated PAM and QAM given the presence intra-system crosstalk interference (interference between identical transmission systems). The range limits determined by inter-system crosstalk interference (interference between different transmission systems) with basic rate access (BRA) implementing a burst-mode transmission method are also estimated. This paper concludes that 2B1Q-PAM achieves the best overall performance in NTT's local networks. A feasibility study of 192-6144 kbit/s transmission is also described.

The FDDI-II is a high speed and flexible backbone LAN. It can divide the capacity into one packet-switched channel with flexible bandwidth and up to 16 isochronous channels which may be allocated for a variety of real-time services such as video and voice. How to allocate and maintain isochronous bandwidth is an important issue for supporting good services to users. The FDDI-II standard proposed a centralized scheme to achieve this goal. In this paper, we propose a new scheme in a distributed fashion for the management of isochronous bandwidth. Based on our scheme, the network can support various services in a more efficient way.

The sensitivity degradation due to unmatched quantum efficiencies is theoretically investigated for coherent optical POLSK heterodyne, homodyne and balanced receivers with shot noise, thermal noise and LO intensity noise. This analysis is based on the exact expressions of the probability density function (PDF) of the noise process to calculate the bit-error-rate (BER) considering LO intensity noise and unmatched quantum efficiencies. We derive the optimum LO power to minimize the power penalty for POLSK receivers. The theoretical results clarify the relation between the unmatched quantum efficiencies and sensitivity degradation due to the LO intensity noise. Based on this analysis, it is found that the balanced receiver is preferable for the design of POLSK receivers.

A novel low-power dissipation and high-speed converter-control-IC has been developed for the transmitting amplifier in digital portable telephones. The IC consists mainly of CMOS devices to reduce the bias current. To improve circuit speed, bipolar transistors are used in the output stage of the operational amplifier and in the current sources of the oscillator because they have a larger current capability and smaller parasitic capacitance than CMOS devices. The IC has one-fifth the bias current of a conventional control circuit consisting of discrete devices, and it can operate up to a switching frequency of 3MHz. The small bias current increases converter efficiency, and the high switching frequency reduces converter size. Using this IC, converter loss is 17% less than that with a conventional control circuit.

This paper presents an analysis of the control characteristics of the series resonant converter with a parallel resonant circuit, especially under parallel resonant frequency. Operations of the circuit are classified into several modes. The control characteristics are calculated using the equations derived from equivalent circuits, and are verified by the experiments. From the analysis, the mechanism of a jumping phenomenon in the closed-loop control characteristics is clarified.

This paper describes a design method of stuff synchronization circuit for High-definition Television (HDTV) transmission to reduce stuff jitter, one of the greatest problems in video transmission through plural Synchronous Digital Hierarchy (SDH) networks operating with different frequency sources. First, we determine the quantity of stuff jitter in SDH networks using the pointer mechanism and Administration Unit (AU) pointer bytes. From the results of a subjective test conducted for HDTV, we show that the minimum noticeable jitter is 3.6 nsec in using a color-bar pattern as a test image and a sinusoidal wave as a jitter signal. These results are used to describe the effect of stuff jitter on picture quality. We then introduce a distributed destuffing method at the receiving end, and show that jitter can be reduced by about 32dB in a 622Mbps rate system. Based on these results, we finally show that the cut-off frequency of the clock recovery PLL for distributed destuffing is more than 10 times higher than that required by conventional destuffing. This reduces the pull-in time by more than 99.9%.

The validity of numerical design scheme of CP-PASS (Circularly Polarized Printed Array antenna composed of Strips and Slots) is considered. The strip element of CP-PASS is composed of a strip dipole and a window which increases the frequency bandwidth of the strip element. With the window, however, analysis of the antenna becomes difficult if a simple analytical model is used. The previous design procedure requierd an experimental procedure. By using modern computers, the FDTD (finite-difference time-domain) method becomes powerful tool for the analysis of 3D-structured antennas. In this paper, numerical results of the FDTD analysis for CP-PASS is compared with results from experiments. The characteristics of the unit-radiator of CP-PASS are demonstrated numerically. This paper shows that CP-PASS can be designed numerically and a new path has opened in the study of CP-PASS.

This letter proposes a VP-shaper for ATM networks that controls the VC-level cell clumping. The new shaper is compared with a conventional shaper and is found to significantly increase CAC (Call Admission Control) efficiency and achieve high VP utilization gain. Hardware implementation based on a shared buffer and chained lists is presented and its feasibility is shown.

In their paper[1], Sasase and Mori proposed a method of calculating the resequencing delay for a multiple-server queueing system under a threshold-type scheduling. However, it is found that the result of the proposed method does not converge to the corresponding expression in Ref.[2] for the system with two servers. In this correspondence, we show that the proposed method in Ref.[1] is not correct, and verify it by simulation.

For a CBR (Constant Bit Rate) connection in an ATM (Asynchronous Transfer Mode) network, we determine the CDV (Cell Delay Variation) tolerance for the mapping of ATM cells from the ATM Layer onto the Physical Layer. Our result will be useful to properly allocate resources to connections and to accurately enforce the contract governing the user's cell traffic by UPC (Usage Parameter Control).

This paper proposes a new signaling technique which employs multilevel block codes in conjunction with phase/frequency modulation. The proposed scheme exhibits an increased minimum squared Euclidean distances (MSEDs) and outperforms other conventional schemes in terms of asymptotic coding gain and decoding complexity. The proposed scheme is also considered for non-constant amplitudes, which turned out to show even better performances at small modulation indices in some cases. Examples are given to demonstrate how to optimize the signal set for a given block code to maximize the coding gain.

A simple solution for the right-angle H-plane waveguide double bend is obtained in analytic series form. The simultaneous equations are solved to obtain the transmission and reflection coefficients in fast convergent series forms. The numerical computations are performed to show the behaviors of the transmission coefficient versus frequency.