Hiroyuki Kasai

New Optical Access Network Architecture Using Optical Packet Switches

This paper proposes a new optical access network architecture that differs from those of conventional Point-to-Point (PP) and Passive Optical Networks (PON). The proposed architecture, Optical Switched Access Network (OSAN), uses Optical Switching Modules (OSMs) that connect an Optical Line Terminal (OLT) to Optical Network Units (ONUs) in a virtual point to point configuration so that it offers the merits of both PP and PON while overcoming their demerits. Each OSM optically switches packets of variable length one by one under electrical control. To allow the elimination of optical buffers from OSM, OSAN uses the Multi-Point Control Protocol (MPCP) defined in IEEE 802.3ah. We evaluate the transmission distances between OLT and ONUs, and consider a network synchronization scheme and discovery mechanism that supports MPCP.

Design of optical switching module for gigabit ethernet optical switched access network

This paper introduces the design of an Optical Switching Module (OSM) for our newly proposed Gigabit Ethernet Optical Switched Access Network (GE-OSAN) architecture that uses the Multi-Point Control Protocol (MPCP), defined in IEEE 802.3ah. We outline the GE-OSAN architecture to clarify OSMs role in the network. We offer an OSM configuration that has the basic functions needed to realize downstream and upstream high-speed data services in GE-OSAN. We clarify the OSM optical switching time that allows GE-OSAN to achieve the same throughput as GE-PON. Our survey of currently available optical switches identifies the optical packet switches that can meet this switching time requirement. We evaluate OSM insertion loss with these switches. We propose an OSM configuration that has a regeneration function as well as the basic ones to realize wider network configurations that can lead to a reduction in overall system costs. In addition, we present OSM configurations that have broadcast and multicast functions as well as the basic ones so that GE-OSAN can support broadcast and multicast video services to equal and exceed GE-PON.

Novel optical packet switched access network architecture

This paper describes gigabit Ethernet optical switched access network (GE-OSAN) architecture with non-buffered 1xn optical packet switches. It clarifies the role of the key network element, 1xn optical switching module, in realizing the proposed architecture.

Scalable video transmission by separating and merging of MPEG-2 bitstream

In this paper, we propose a scalable video transmission system based on transcoding. First, we focus on the transcoder to reduce the bitrate of MPEG-2 bitstreams. We show that it is realized the layered coding by using the differential data between input and output of a transcoder. Next, we show the coding algorithm of this differential data. This algorithm can improve the coding efficiency by removing unnecessary code for differential data. By simulation experiments, we show that the proposed coding algorithm prevents the loss of coding efficiency in traditional hierachical coding, and show the effectiveness of proposed scheme.

The implementation of an audiovisual transcoding system

Multimedia transcoding technology can provide interoperability between different types of audiovisual terminals and between terminals that connect to different networks. This paper describes a flexible multimedia transcoder that enables service interoperability between different types of terminals across heterogeneous networks.

MPEG-2 multi-program transport stream transcoder

MPEG-2 Multi-program Transport stream (TS) achieves improvement of transmission efficiency by multiplexing several MPEG-2 streams. In this paper, we propose a transcoder which achieves rate reduction of MPEG-2 multi-program TS. For the purpose of realizing MPEG-2 multi-program TS transcoder, this transcoder requires a rate control method and re-multiplexing method: The former improves average SNR values in total of streams, and the latter achieves the evasion from failure of STD buffer. Next, from simulation experiments, we compare the conventional rate control methods to the proposed one. On the other hand, we show the state of STD buffer. Finally, we show the effectiveness for our proposed scheme.

A study on the rate control method for MPEG transcoder considering drift-error propagation

As the transform method of video bit stream to the required bit stream format, the video transcoder has been adopted in various applications. In this paper, we focus on a MPEG video transcoder that can reduce the required bit rate by using re-quantization in the DCT domain. Furthermore, we propose a rate control method for this MPEG video transcoder that takes into consideration the estimation of drift-error propagation. Next, from simulation experiments, we compare the proposed rate control method to the traditional rate control method in terms of complexity, required buffer size and picture quality.

Rate control scheme for MPEG transcoder considering drift-error propagation

As the transform method of video bit stream to the required bit stream format, the video transcoder has been adopted in various applications. In this paper, we focus on a MPEG video transcoder that can reduce the required bit rate by using re-quantization in the DCT domain. Furthermore, we propose a rate control method for this MPEG video transcoder that takes into consideration the estimation of drift-error propagation. First, we show the transcoder architecture with calculation of `Drift-Error Propagation Ratio. Next, we explain the proposed rate control method that uses minimization of the sum of re-quantization Error and drift- error. Finally, from simulation experiments, we compare the proposed rate control method to the traditional rate control method in terms of complexity, required buffer size and picture quality.

A study on the hybrid image coding and structuring methods for multimedia scalability packages communication services

Multimedia communication services based on standard information, such as MPEG-1, MPEG-2, H.261 and H.263, have been demonstrated using multimedia scalability packages, which can provide multimedia information with user functionality and availability. We propose a video information architecture coding method for these packages, called MSP (Multimedia Scalability Packages). The MSP data architecture is defined using hierarchical architectures. We consider in particular temporal feature information. The temporal scalability concept is described by both MSP data and scalability content data. As coding schemes, we consider video hybrid scalability using spatial and temporal scalability and show some scalability profiles. Finally, we explain the new video temporal function by MSP data description.

Video scalability rate control method by dynamic controlling of hierarchical bit allocation ratio

This paper considers the hierarchical video coding system, and proposes a bit allocation rate control method by dynamic control of the hierarchical bit allocation ratio. As the first step, the MPEG-2 SNR scalability method is considered as the hierarchical video coding, and the relation between the hierarchical bit allocation and the basic/enhancement layer quality is analyzed. It is shown that the intermediate bit allocation ratio may degrade greatly the quality in the enhancement layer. The dependency of the image quality on the hierarchical bit allocation is noted, and video coding bit allocation control is proposed, where the hierarchical loss can be suppressed by dynamically controlling the bit allocation ratio for each picture. A control method is proposed particularly, where the optimal bit allocation ratio is calculated so that the characteristic function is maximized under the constraint that the bit allocation ratio for each GOP is kept constant. Lastly, a simulation experiment is presented. It is shown that the hierarchical loss, which is generated in the conventional bit allocation control, can be suppressed by the proposed control method, and the effectiveness of the proposed method is demonstrated.