&lt;title&gt;Wireless video communication system using PHS&lt;/title&gt;

Sakamaki, Tomoki; Ibaraki, Hisashi; Ichikawa, Takeo; Suzuki, Ritsuro

doi:10.1117/12.263201

Cited by 2 publications

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“…So, the issue of buffer fill-up during re-transmissions will be similar to that discussed in the paper. The study of wireless video on the DECT and PHS systems has been discussed in [9,22], respectively. In this investigation, we will use the typical parameters of the PACS in our simulations, although the same principle can be applied to other systems.…”

Section: Wireless Channelmentioning

confidence: 99%

A rate-control scheme for video transport over wireless channels

Aramvith

Pao

Sun

2001

IEEE Trans. Circuits Syst. Video Technol.

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We investigate the scenario of using the Automatic Repeat reQuest (ARQ) retransmission scheme for two-way video communications over wireless Rayleigh fading channels. Video quality is the major concern of these applications. We show that during the retransmissions of error packets, due to the reduced channel throughput, the video encoder buffer may fill-up quickly and cause the TMN8 rate-control algorithm to significantly reduce the bits allocated to each video frame. This results in PSNR (Peak Signal-to-Noise Ratio) degradation and many skipped frames. To minimize the number of frames skipped, we propose improved rate-control schemes that take into consideration the effects of the video buffer fill-up, an a priori channel model, and the channel feedback information. We also show that a DCT (Discrete Cosine Transform) coefficient soft-thresholding scheme can be applied to further improve the video quality. As a result, our proposed rate control schemes encode the video sequences with less frame skipping and with higher PSNR compared to TMN8.

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Section: Wireless Channelmentioning

confidence: 99%

A rate-control scheme for video transport over wireless channels

Aramvith

Pao

Sun

2001

IEEE Trans. Circuits Syst. Video Technol.

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“…MPEG4, under development, shall play a role in the future. Here the tentative compression algorithms for video and voice signals are H.261 and CELP, respectively, both of which were modified to include an error collection algorithm [7]. The terminal shown in Fig.…”

Section: Digital Bearer Communications Services -mentioning

confidence: 99%

Evolution of personal multimedia communications services in Japan

Murase

Ohyama

1998

IEEE Pers. Commun.

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ecent progress in communications technology is about to bring dramatic changes to business and home life. In 1990, NTT announced the Visual Intelligent and Personal (VI&P) communications services plan as its service vision for the beginning of the 21st century [1], as shown in Fig. 1. We are engaged in wide-ranging research and development aiming at creating service systems for diverse applications. The phase 1 experiments based on this VI&P plan, which were conducted between 1991 and 1993, focused on narrowband integrated services digital network (N-ISDN) services to optimize the use of the existing INS Net. The phase 2 experiments were initiated in April 1993, and focused on perfecting new services and creating new applications based on optical communications and asynchronous transfer mode (ATM) technology [2]. The sudden increase in the number of pagers and cellular phones reflects the rising demand for person-toperson communication, even for private use. The P in VI&P symbolizes this latest trend. Among these VI&P services, personal communication services will become the most advanced and should receive the most attention. Taking this into consideration, the phase 3 experiments are concentrated on personal-use multimedia services based on wireless access by means of the Personal Handyphone System (PHS) and satellites [3]. This article describes the phase 3 experiments and the technology involved. To cope with future demand for wireless personal multimedia services, research and standardization activities are being strongly carried out in many countries, such as advanced Global System for Mobile Communications (GSM) systems in Europe, the IS-95based wideband code-division multiple access (CDMA) system in the United States, and a wideband CDMA system in Japan. International Mobile Telecommunications in the year 2000 (IMT-2000) is to offer capacities of 144 kb/s outdoors and 2 Mb/s indoors. Under the existing wireless environment, the usable bit rate is limited to 28.8 kb/s; however, several interesting multimedia services can be provided using this level of capacity. In Japan, the introduction of Personal Handyphone Service (PHS) has led to an explosion in mobile digital services. In this article, the expectations of personal multimedia communications are introduced. The main subjects discussed in some detail are digital data communication services using PHS terminals, personal mobility using premises intelligent network, and the nomad office using communication satellites. Attractive future personal communication services are also proposed.

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<title>Wireless video communication system using PHS</title>

Cited by 2 publications

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A rate-control scheme for video transport over wireless channels

A rate-control scheme for video transport over wireless channels

Evolution of personal multimedia communications services in Japan

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