As an access network to the Internet, CATV/HFC network has been widespread recently. Such a network employs a reservation access method under which reservation and data transmission periods appear by turns. Before data transmission, a station must send a request in a random access manner during the reservation period called a request cluster. If the cluster size is large, the probability of request collision occurrence becomes small. A large cluster size however increases the packet transmission delay. Moreover the throughput decreases since vacant duration of reservation period increases. DOCSIS, a de facto standard for the networks, employs the binary back-off method for request cluster allocation. Since that method normally allocates unnecessary large request cluster, the transmission delay increases under heavy load conditions. In this paper, we propose a request cluster allocation method which dynamically changes the cluster size according to the load conditions. In order to evaluate performance of the proposed method, we build a queuing model and execute computer simulation. Simulation result shows that the proposed method provides smaller delay than the binary back-off method.

An ultra-high-sensitivity HDTV color camcorder (camera with VTR) has been developed featuring image intensifiers with GaAsP photocathodes, which provide very high quantum efficiency. To achieve superior performance and a compact camera body, we combined three 1-inch image intensifiers with a 2/3-inch taking lens and three 2/3-inch CCDs by means of a new optical system capable of enlarging and reducing images. The camcorder provides excellent color reproducibility even under low light level conditions (0.2 lx) at an iris setting of f/2, with a signal-to-noise ratio of 55 dB at pedestal level. Its sensitivity is about 400 times greater than that of current HDTV CCD camcorders, making it particularly well suited for capturing images of faint objects in space, aurora, etc., filming the nocturnal activities of animals in their natural settings, and reporting breaking news at night.

In this paper, we propose an algorithm that automatically generates the intermediate scenes using the bidirectional disparity morphing (BDM) from the parallel stereo images. The two-step search strategy is used for speeding up the computation of the bidirectional disparity map and three occluding patterns are used for smoothing the computed disparities more elaborately. Using the bidirectional disparity map, we interpolate the left and the right image to their intermediate scenes. Then we dissolve two interpolated images into the desired intermediate scene which the holes are removed and the effect of the disparity estimation errors is minimized. We implemented the proposed algorithm on TM1300 supported by TriMedia using pSOSytem which enables to do multiprocessing. As a result, we can interpolate the high-quality intermediate scenes with real-time process.

This paper describes an ultra low power, motion estimation (ME) processor for MPEG2 HDTV resolution video. It adopts a Gradient Descent Search (GDS) algorithm that drastically reduces required computational power to 6 GOPS. A SIMD datapath architecture optimized for the GDS algorithm decreases the clock frequency and operating voltage. A low power 3-port SRAM with a write-disturb-free cell array arrangement is newly designed for image data caches of the processor. The proposed ME processor contains 7-M transistors, integrated in 4.50 mm 3.35 mm area using 0.13 µm CMOS technology. Estimated power consumption is less than 100 mW at 81 MHz@1.0 V. The processor is applicable to a portable HDTV system.

The Tokyo Tower is the highest self-supporting steel tower in the world. Since it was built in 1958, the Tower has been a symbol of Tokyo and a well-known, major tourist attraction in Japan. The number of visitors reached 130 million in 1998. The highest number of visitors in one day was 40,000. The original purpose of the Tower was the transmitting of TV signals to the entire Tokyo Metropolitan area. As time passed, FM radio antennas and other equipment for public use were added to the Tower. Recently digital terrestrial antennas were installed on the Tower, a remarkable moment in its history. Digital broadcasting will start in 2003, using these antennas. This paper introduces the Tokyo Tower and its antennas, giving its construction history and its future in the coming digital broadcasting era.

We have recently developed a programmable composite noise generator (P-CNG) which can easily control noise parameters such as average power, time-based amplitude probability distribution (APD), crossing rate distribution, occurrence frequency distribution and burst duration. Two applications of the P-CNG are demonstrated to show its usefulness. For the first application, Middleton's Class A noise is simulated. A method of setting parameters for Class A noise is demonstrated. The APD of P-CNG output is in good agreement with that of true Class A noise. In the second application, the P-CNG is used for subjective evaluation test (opinion test) of TV picture degradation. Five simple composite noise models with two kinds of APD are used. Other parameters such as average power are kept constant. Experimental results show that the envelope and APD of composite noises do not greatly influence the subjective evaluation. Finally the capabilities of the P-CNG are shown.

CATV networks are considered as promising transmission channels in that they permit wide bandwidth and high quality data communications. In apartment houses, however, the ingress noise in the up-links due to the tree and branch structure of a network deeply degrades the transmission performance of data communication channels. This is a serious problem especially in apartment houses which are often equipped with old coaxial cables. It permits the noise generated from electrical appliances to disturb up-link data communications. In this paper, we propose a wireless CATV system. In the proposed system, the noise generated in the room of a subscriber does not intrude into a trunk line. We analyze the upstream channels of this system. Based on the results of numerical analyses, we found that the proposed system is suitable and practical for up-link operation in CATV networks for apartment houses.

We study the quality of the terrestrial digital video broadcasting (DVB-T) transmission over the cable TV network. Generally, when terrestrial digital TV signals are distributed in the cable TV, a conversion is needed in the head-end, from DVB-T (OFDM) to DVB-C (single carrier). In order to avoid this costly conversion and to transmit DVB-T signal directly in the existent cable channel, many requirements have to be satisfied. It is known that phase noise represents the main limitation for OFDM based systems. In this contribution we demonstrate the sensitivity of the OFDM system for the phase noise effects by using a dynamic model for CATV channel. Then, we conclude by giving the specifications that a converter in the CATV network should have to still allow the functionality of the DVB-T system.

This work presents a frame-structure, referred to as CATM (CATV ATM), to serve as a wireless network infrastructure. The widespread CATV (Community Antenna TV) networks are attractive infrastructures for next generation wireless networks. Providing interactive broadband services over CATV networks is a major trend in communication and ATM (Asynchronous Transfer Mode) networks with broadband communication features well fitted to be the backbone of CATV networks. Based on the proposed network architecture, this work addresses and investigates the problems of call setup and handoff handling. This work also proposes a wireless signaling protocol for establishing mobile connections over the CATM-based wireless networks. To enhance bandwidth utilization, the proposed scheme attempts to keep the path resulting after handoff as short as possible. The protocol also evolves a seamless handoff scheme (denoted as SHSW-CATM), that can preserve data continuity, is transparent to other mobile terminals, and produces a shorter path. Analytical results reveal that the SHSW-CATM has a high probability of obtaining an optimal path (that is, a non-elongated path) following mobility.

This paper proposes the technology of wide passband wavelength-division multiplexing (WWDM) for access networks offering multiplexed services. The technology greatly relaxes the wavelength setting accuracy requirements of the WDM light source and the multiplexer/demultiplexer (MUX/DEMUX) compared to dense WDM (DWDM) technology. A WWDM optical converter that offers the Internet protocol (IP) service is implemented and its performance assessed at temperatures ranging from 0C to 45C. In addition, we assess three channel transmission (cable television (CATV) and IP services) in the 1.5 µm region as a multiplexed service example. Using the proposed WWDM, we confirm the feasibility of a service multiplexing system that offers simultaneous CATV and IP services in access networks. This WWDM technology is expected to provide cost effective service multiplexing systems for access networks.

An MPEG-2 422P@HL encoder chip set composed of a preprocessing LSI, an encoding LSI, and a motion estimation LSI is described. This chip set realizes a two-type scalability of picture resolution and quality, and executes a hierarchical coding control in the overall encoder system. Due to its scalable architecture, the chip set realizes a 422P@HL video encoder with multi-chip configuration. This single encoding LSI achieves 422P@ML video, audio, and system encoding in real time. It employs an advanced hybrid architecture with a 162 MHz media processor and dedicated video processing hardware. It also has dual communication ports for parallel processing with multi-chip configuration. Transferring of reconstructed data and macroblock characteristic data between neighboring encoder modules is executed via these ports. The preprocessing LSI is fabricated using 0.25 micron three-layer metal CMOS technology and integrates 560 K gates in an area of 12.0 mm 12.0 mm . The encoding LSI is fabricated using 0.25 micron four-layer metal CMOS technology and integrates 11 million transistors in an area of 14.2 mm 14.2 mm . The motion estimation LSI is fabricated using 0.35 micron three-layer metal CMOS technology. It integrates 1.9 million transistors in an area of 8.5 mm 8.5 mm . This chip set makes various system configurations possible and allows for a compact and cost-effective video encoder with high picture quality.

A method of predicting disturbances to TV signal reception has been developed in order to workout countermeasures for interference caused by unwanted emissions from information technology equipment (ITE). The prediction parameters were determined by measuring the emission levels from ITE at an open test site, propagation characteristics of unwanted emissions from ITE in a building, the output power of the TV transmitting station, the propagation characteristics of the TV radio waves, and the directivity of the TV receiving antenna. The possibility of disturbances occurring in the Kanto area was predicted and the results show that, in the worst case, a disturbance will appear in about 11% of the areas within 30 m of a building containing such equipment. This also shows that the disturbance can be suppressed by improving the shielding of the equipment or building by as little as 10 dB.

We have developed an experimental 4 K 2 K pixel progressive scan color camera system. This new camera system has a data rate of 297 MHz pixel/sec and 60 frame/sec and we are sure that horizontal and vertical limiting resolution of 1500 TVL (TV lines) can be achieved on a color monitor. Instead of the previous approach of improving resolution simply by increasing the pixel count in a imager, a novel four-sensor pickup method with 2/3 inch 2 million pixel CMD (Charge Modulation Device) imagers is used in this system. These sensors have 1920 (H) 1035 (V) pixels within a 16:9 wide aspect image area and are successfully driven at 148 M pixel/sec in the progressive scan mode. In the four-sensor pickup method, two sensors are used for green and the rest are for red and blue. A spatial offset imaging method in the diagonal direction was applied to the two green sensors to improve the horizontal and vertical resolution effectively. The horizontal and vertical resolution of the red and blue signals become half that of the green signal, because only one 2 M-pixel imager is used for each signal. The resolution of this system, however, is not degraded so much because the luminance signal is mainly composed of green signals.

The statistical behavior of the amplitude probability distribution of intermodulation distortion interference in multichannel optical-cable TV systems was experimentally investigated. In multichannel transmission, the non-linearity of a laser diode (LD) or an electrical amplifier can cause intermodulation distortion (composite-second-order beat; CSO, composite-triple-beat; CTB, etc. ). Even though it has been discussed as laser-clipping distortion, intermodulation distortion is usually distortion from AM-VSB carriers. The statistical analysis and evaluation of the distortion in transmitted channel is in controversial. We evaluated the distortion in 20 frequency-division-multiplexed 16-QAM channels, with each carrier carrying 80 Mbps for an optical cable TV system. We first enumerated the distortion components causing interference in each transmission channel so as to identify the intermodulation products. Then, in selected channels, we precisely measured the power of each kind of distortion and the amplitude distributions of the intermodulation distortion from sinusoidal and digital-modulated carriers on cable TV as a function of optical modulation depth (OMD) of LD. And we clarified how the probability distribution function (PDF) changed as the OMD increased. Also, the BER performance of a 16-QAM signal was measured and compare to the intermodulation behavior of the different distortion sources. We found evidence that the amplitude distribution of intermodulation distortion from digital carriers differs from that of thermal noise. Experimental results showed that the PDF of the intermodulation distortion changed when the ratio of intermodulation distortion among all undesired signals varied with the OMD. The BER performance varied with intermodulation of both analogue and digital carriers even when the carrier to interference noise power ratio (CIR) is the same.

The statistical behavior of the amplitude probability distribution of intermodulation distortion interference in multichannel optical-cable TV systems was experimentally investigated. In multichannel transmission, the non-linearity of a laser diode (LD) or an electrical amplifier can cause intermodulation distortion (composite-second-order beat; CSO, composite-triple-beat; CTB, etc. ). Even though it has been discussed as laser-clipping distortion, intermodulation distortion is usually distortion from AM-VSB carriers. The statistical analysis and evaluation of the distortion in transmitted channel is in controversial. We evaluated the distortion in 20 frequency-division-multiplexed 16-QAM channels, with each carrier carrying 80 Mbps for an optical cable TV system. We first enumerated the distortion components causing interference in each transmission channel so as to identify the intermodulation products. Then, in selected channels, we precisely measured the power of each kind of distortion and the amplitude distributions of the intermodulation distortion from sinusoidal and digital-modulated carriers on cable TV as a function of optical modulation depth (OMD) of LD. And we clarified how the probability distribution function (PDF) changed as the OMD increased. Also, the BER performance of a 16-QAM signal was measured and compare to the intermodulation behavior of the different distortion sources. We found evidence that the amplitude distribution of intermodulation distortion from digital carriers differs from that of thermal noise. Experimental results showed that the PDF of the intermodulation distortion changed when the ratio of intermodulation distortion among all undesired signals varied with the OMD. The BER performance varied with intermodulation of both analogue and digital carriers even when the carrier to interference noise power ratio (CIR) is the same.

The cable TV (CATV) network is an ideal backbone for PCS due to its prevalent and broadcast nature. This significantly reduces the implementation costs and the handoff overheads. This paper proposes two architectures for the CATV-based PCS system. In the first architecture, each base station is equipped with multiple fixed receivers to provide fast and seamless handoffs for mobile users. Nevertheless, the hardware cost for this implementation is relative expensive. To overcome this, in the second architecture, each base station is equipped with only one tunable receiver. This simple and economic architecture suffers from the possibility of offset conflict when mobile terminals handoff between cells. Three offset assignment algorithms based on the concepts of random assignment, neighbor usage, and clustering, respectively are proposed to solve the offset conflict problem. Simulation results indicate the one with the concept of clustering performs much better than the other two schemes in terms of offset conflict probability.

The project of interconnecting CATV in Hyogo Prefecture, Japan has started since March, 1998. In this project, there are three CATV companies in Hanshin area; Kobe, Nishinomiya and Amagasaki. An ATM switch is equipped in each company and these CATVs are connected serially in the above order. Each company provides the video service to the rest of companies using the MPEG2 over ATM. Each MPEG2 stream is sent to the other two CATV companies according to the function of multicast implemented in ATM switch. In the coverage of each CATV, subscribers utilize Internet connection using cable modems as well as standard CATV broadcasting service. In this paper, we present the outline of the research project in Hyogo Prefecture, Japan, and examine the jitter processes of MPEG streams of the testbed network by the simulation. In our testbed network, cells with two types of requirement for QoS are multiplexed; cells for MPEG2 which require the real-time transmission and those for Internet packets which are much more sensitive for the cell loss ratio. We investigate the jitter processes under some scenarios and show how the jitter process is affected by the Internet traffic and the other cell streams of MPEG2. Furthermore, we study the effect of the number of ATM switches on the jitter process when more CATV networks are added serially.

In this paper, a dedicated hardware design for motion estimation LSI of MPEG2 is presented. Combining our bits truncation adaptive pyramid (BTAP) algorithm with Window-MSPA architecture, the hardware cost is tremendously reduced without PSNR performance degradation for mean pyramid algorithm. The core of the test chip working at 83 MHz, performs a search range of 67 for image size of 1920 1152 and achieves video rate of 60 field/s. It can be used for HDTV purpose. The chip size is 4. 8 mm 4. 8 mm with 0. 5u 2-level metal CMOS technology. The result in this paper shows our promising future to realize one chip HDTV MPEG2 encoder.

For Cable-To-The-Air network providing a seamless access network in both indoor and outdoor, direct optical switching CDMA scheme is newly proposed to multiplex any types of radio signals. In two types of connection methods, optical switch connection and optical coupler connection systems, the received carrier-to-interference-plus-noise power ratios are theoretically analyzed. It is clarified that in the optical switch connection connection system, by introducing the additional optical gain at each radio base station, the carrier-to-interference-plus-noise power ratios for all radio base stations and the connected number of radio base stations can be improved compared with the OC connection system.

A single chip motion estimator is described dedicatedly for MPEG2 MP＠HL moving pictures. Adopting a two-level hierarchical searching algorithm in detecting motion vectors, the computational labor can be reduced by 1/70 in comparison with the conventional algorithm. A novel mechanism is introduced into the full-search procedure, which attempts the maximum possible reuse of reference pixels in order to reduce the bandwidth of the frame memory interface. The proposed motion estimator is integrated in a 0.6 µm triple-metal CMOS chip, which contains 1,450 K transistors on a 12.713.7 mm2 die. The input clock rate can be attained up to 133 MHz, which enables the real time motion estimation for MPEG2 MP＠HL.