Jurgen Streit

Adaptive low-rate wireless videophone schemes

The design and performance of a range of wireless videophone transceivers are presented. Highly bandwidth efficient, fixed but with arbitrarily programmable rate, perceptually weighted discrete cosine transform (DCT) based video codecs are proposed for quarter common intermediate format (QCIF) videophone sequences. Perceptually weighted cost/gain controlled motion compensation and quad-class DCT-based compression is applied with and without run-length coding. Specifically, we propose video codecs having transmission rates in the range of 5-11.36 kbps and preselected the 11.36 kbps codec 1, the 8.52 kbps codec 2 and the 8 kbps codec 2a, for which we designed the intelligent reconfigurable systems 1-5. After sensitivity-matched binary Bose-Chaudhuri-Hocquenghem (BCH) forward error correction (FEC) coding the data rate associated with codec 1 and codec 2a became 20.32 kbps, while that of codec 2 was 15.24 kbps. Throughout these systems a partial forced update (PFU) technique was invoked in order to keep transmitter and receiver aligned amongst hostile channel conditions. When using codec 1 in system 1 and coherent pilot symbol assisted 16-level quadrature amplitude modulation (16-PSAQAM), an overall signalling rate of 9 kBd was yielded. Over lower quality channels the 4QAM mode of operation had to be invoked, which required twice as many time slots to accommodate the resulting 18 kBd stream, The systems robustness was increased using automatic repeat requests (ARQ), inevitably reducing the number of users supported, which was between 6 and 19 for the various systems. In a bandwidth of 200 kHz, similarly to the Pan-European GSM mobile radio systems speech channel, using system 1 for example, 16 and 8 videophone users can be supported in the 16QAM and 4QAM modes, respectively. >

Dual-mode vector-quantized low-rate cordless videophone systems for indoors and outdoors applications

Dual-mode reconfigurable wireless videophone transceivers are proposed for noise-, rather than interference-limited indoors and outdoors applications and their video quality, bit rate, robustness, and complexity issues are analyzed. A suite of fixed, but arbitrarily programmable low-rate, perceptually weighted vector quantized (VQ) codecs with and without run-length compression (RLC) are contrived for quarter common intermediate format (QCIF) videophone sequences. The 11.36-kb/s Codec 1 is Bose-Chaudhuri-Hochquenghem (BCH) (127,71,9) coded to a rate of 20.32 kb/s and this arrangement is comparatively studied along with the 8-kb/s Codec 2 and BCH (127,50,13) scheme, which has the same 20.32-kb/s overall rate. The source-sensitivity matched Systems 1-6 characterized in a table were contrived to comparatively study the range of system design options. For example, using Codec 1 in System 1 and coherent pilot symbol assisted 16-level quadrature amplitude modulation (16-PSAQAM), an overall signaling rate of 9 kBd was yielded, if the noise-limited channel had a signal-to-noise ratio (SNR) in excess of about 22 dB in the vicinity of the basestation or in indoors scenarios. In contrast, over lower quality outdoors channels near the fringes of the cell, the more robust 4-QAM mode of operation had to be invoked, which required twice as many time slots to accommodate the resulting 18-kBd stream and hence, reduced the total number of users supported. The robustness of Systems 2-4, and 6 was increased using automatic repeat requests (ARQ), again, inevitably reducing the number of users supported, which was between 6 and 16. In a bandwidth of 200 kHz, similarly to the Pan-European GSM mobile radio systems speech channel, using Systems 1, 3, 4, or 5, for example, 16 and eight videophone users can be supported in the 16- and 4-QAM modes, respectively, while in dual-mode cells the number of users is between eight and 16. The basic system characteristics are highlighted.

Quadtree-based reconfigurable cordless videophone systems

Arbitrarily programmable, but fixed-rate quadtree (QT) decomposed, parametrically enhanced videophone codecs using quarter common intermediate format (QCIF) video sequences are proposed as a direct replacement for mobile radio voice codecs in second generation systems, such as the Pan-European GSM, the American IS-54 and IS-95, as well as the Japanese systems. The corresponding bit rates are 13, 8, 9.6 and 6.7 kb/s, respectively. As an example, the proposed 11.36 kb/s prototype Codec 1 and the 11 kb/s Codec 2 are embedded in the adaptively reconfigurable wireless videophone systems 1-4 featured in a table and their video quality, bit rate, robustness, and complexity issues are investigated. Coherent reconfigurable 16 or four-level pilot symbol assisted quadrature amplitude modulation (PSAQAM) is used and the systems robustness is improved by a combination of diversity and automatic repeat request (ARQ) techniques. When using a bandwidth of 200 kHz, as in the Pan-European GSM mobile radio system, the number of videophone users supported varies between three and 16, while the minimum required channel signal to noise ratio over Gaussian and Rayleigh channels is in excess of 6 and 8 dB, respectively, assuming a noise-limited, rather than interference-limited scenario. The salient system features are also summarized in a table.

A fractal video communicator

The image quality and compression ratio trade-offs of five different 176/spl times/144 pels quarter common intermediate format (QCIF) fractal image codecs are investigated by simulation. The average peak signal-to-noise ratio (PSNR) ranges from 29 dB to 37 dB, while the coding rate ranges from 0.24 bit/pel (bpp) to 1.22 bit/pel. Two of the candidate codecs, a 0.28 bit/pel and a 1.1 bit/pel codec, were subjected to bit-sensitivity analysis and protected by the source-sensitivity matched shortened binary BCH (122,80,6) and BCH (122,52,11) codes and transmitted using coherent pilot symbol assisted (PSAM) square-constellation 16-level quadrature amplitude modulation (16-QAM). The proposed fractal video communicators required a channel signal-to-noise ratio (SNR) and signal-to-interference ratio (SIR) of about 15 dB in order to maintain a video peak SNR (PSNR) of 31 dB and 35 dB at signaling rates of 39 kBaud and 156 kBaud, respectively, over Rayleigh-fading channels having a propagation frequency of 1800 MHz and a pedestrian speed of 2 mph.<<ETX>>

An adaptive discrete cosine transformed videophone communicator for mobile applications

A highly bandwidth efficient, fixed but arbitrarily programmable rate, perceptually weighted discrete cosine transform (DCT) based video communicator for quarter common intermediate format (QCIF) videophone sequences is presented. Perceptually weighted cost/gain controlled motion compensation and quad-class DCT-based compression is applied without variable rate compression techniques and without adaptive buffering in order to maintain a fixed transmission rate, which can be adjusted to any required value. We opted for a source coded rate of 11.36 kbps and the sensitivity-matched forward error correction (FEC) coded rate became 20.32 kbps. A partial forced update technique was invoked in order to keep transmitter and receiver aligned amongst hostile channel conditions. When using coherent pilot symbol assisted 16-level quadrature amplitude modulation (16-PSAQAM), an overall signalling rate of 9 kBd was yielded. Over lower quality channels 4QAM had to be invoked, which required twice as many time slots to accommodate the resulting 18 kBd stream. Over the best Gaussian and worst Rayleigh channels signal-to-noise ratio (SNR) values in the range of 7 to 20 dB were needed for these modems in order to maintain near-unimpaired image quality. In a bandwidth of 200 kHz, similarly to the GSM speech channel, 16 and 8 videophone users can be supported, when using the 16QAM and 4QAM systems, respectively.

A low-rate multi-level voice/video transceiver for personal communications

A personal communication system (PCS) transceiver is proposed and investigated. A 4.8 kbit/s transformed binary pulse excited (TBPE) linear predictive speech codec, embedded source sensitivity-matched binary Bose-Chaudhuri-Hocquenghem (BCH) block error correction codecs, non-coherent differentially coded 16-level quadrature amplitude modulation (16-QAM) modem and packet reservation multiple access (PRMA) are deployed. The 2.15 kBd transceiver requires a signal-to-noise ratio (SNR) and signal-to-interference ratio (SIR) in excess of about 24 dB over Rayleigh-fading channels in order to support 10–11 nearly un-impaired voice conversations within a bandwidth of 30 kHz. Additionally, by reserving two PRMA time slots for video telephony, an 8.52 kbps videophone user can also be supported.

Comparison of fixed-rate video codecs for wireless videophony

Gain-cost quantised, fixed but arbitrarily programmable rate discrete cosine transformed (DCT) video codecs, vector-quantised (VQ) and quad-tree (QT) coding algorithms are proposed and their video quality, complexity, compression ratio and error resilience trade-offs are comparatively analysed under identical conditions. Our candidate codecs are compared to the standard H261 and MPEG-2 benchmark codecs. The proposed codecs facilitate wireless videophony for quarter common intermediate format (QCIF) video sequences scanned at 10 frames/s at rates around 10 kbps in second-generation mobile systems.

Quadtree-decomposed cordless videophones

Arbitrarily programmable, but fixed-rate quad-tree (QT) decomposed, parametrically enhanced videophone codecs using quarter common intermediate format (QCIF) video sequences are proposed as a direct replacement for mobile radio voice codecs in second generation systems, such as the Pan-European GSM, the American IS-54 and IS-95 as well as the Japanese systems. The proposed 11.36 kbps codec 1 and the 11 kbps codec 2 are embedded in the adaptively re-configurable wireless videophone systems 1-4 featured in a table and their video quality, bit rate, robustness and complexity issues are investigated. Coherent re-configurable 16 or 4-level pilot symbol assisted quadrature amplitude modulation (PSAQAM) is used and the systems robustness is improved by a combination of diversity and automatic repeat request (ARQ) techniques. When using a bandwidth of 200 kHz, as in the pan-European GSM mobile radio system, the number of videophone users supported varies between 3 and 16, while the minimum required channel signal to noise ratio over Gaussian and Rayleigh channels is in excess of 6 and 8 dB, respectively. The salient system features are summarised in a table.

Fixed-rate video codecs for wireless systems

A comparative study of arbitrarily programmable, but fixed-rate videophone codecs using quarter common intermediate format (QCIF) video sequences scanned at 10 frames/s is offered. These codecs were designed to allow direct replacement of mobile radio voice codecs in second generation wireless systems, such as the Pan-European GSM, the American IS-54 and IS-95 as well as the Japanese systems, operating at 13, 8, 9.6 and 6.7 kbps, respectively.

Adaptive SingleCarrier, Multicarrier, and CDMAbased Video Systems

This chapter contains sections titled: Turbo-Equalized H.263-Based Videophony for GSM/GPRS Wideband Burst-by-Burst Adaptive QAM-Based Wireless Videophony A UMTS-Like Videophone System: Turbo-Coded Burst-by-Burst Adaptive Joint Detection CDMA and H.263-Based Videophony H.263/OFDM-Based Video Systems for Frequency-Selective Wireless Networks Subband-Adaptive Turbo-Coded OFDM-Based Interactive Videotelephony Digital Terrestrial Video Broadcasting for Mobile Receivers Satellite-Based Video Broadcasting Summary and Conclusions Wireless Video System Design Principles