Joseph Meehan

Robust transmission of MPEG-4 scalable video over 4G wireless networks

Fine-granularity-scalability (FGS) has recently been adopted by the MPEG-4 standard for the efficient and flexible distribution of multimedia over the Internet. The FGS framework is able to perform spatio-temporal-SNR tradeoffs in real-time at transmission or (post-) processing time, depending upon the available bit-rate, sequence characteristics, priority, user preferences or receiver resources, and not at encoding time. This paper investigates the usage of FGS for robust video transmission over wireless networks. To cope with the detrimental channel conditions, we introduce a novel joint source-channel coding scheme that combines FGS and adaptive modulation. Two schemes are presented, one uses hierarchical modulation and FGS and the other uses time division multiplexing and FGS. Both schemes are shown by computer simulation to maintain a stable video quality over a variety of multipath dynamic Rayleigh fading channels. The proposed adaptive modulated FGS algorithms provide a graceful degradation and improvement in picture quality as the channel conditions vary.

Optimal antenna diversity combining for IEEE 802.11a system

IEEE 802.11a/g devices promise to accommodate the increasing consumer demands for high data rate wireless communications. A novel optimal decoding method for receiver antenna diversity combining for a COFDM system is discussed in this paper to provide robust wireless connections for applications such as wireless multimedia communications. The proposed optimal diversity combining integrates the channel equalization, demodulation (bit metrics calculation) and diversity combining in the decoder, which is the maximum likelihood decoding method for the diversity combining for the COFDM system. The proposed method can have about 4-6 dB gain over a single antenna receiver and 2-4 dB gain over a traditional symbol level diversity combining receiver without increasing the implementation complexity.

Fine-granularity-scalability for wireless video and scalable storage

Fine-Granularity-Scalability (FGS) has recently been adopted as the MPEG-4 standard for the efficient and flexible distribution of multimedia over the Internet. The FGS framework allows spatio-temporal-SNR tradeoffs in real-time (not limited to encoding time) at transmission or (post-) processing time, depending upon the available bit-rate, sequence characteristics, priority, user preferences or receiver resources. This paper discusses the versatility of FGS and how it can be used to great advantage in a variety of application domains beyond Internet video streaming, such as robust wireless video transmission and flexible scalable storage. In particular, the focus is on investigating the use of FGS for enabling the Universal Media Access (UMA) paradigm for wireless networks. To cope with detrimental channel conditions, we use several joint source-channel coding schemes for wireless transmission, termed Robust FGS (RFGS). RFGS exploits the FGS property of compressing video data in a set of multi-priority streams, based on the channel characteristics and terminal capabilities, by adapting the channel coding. Our results show that RFGS can provide graceful adaptability to varying network conditions while also offering additional benefits such as flexible Quality-of Service (QoS) management and channel adaptation and allocation. Moreover, the use of FGS for scalable storage of video content in gateways and in-home centralized storage units is also investigated. The results show that the proposed scalable method allows storing ten times or more video data on the same storage device depending on the desired guaranteed minimum quality level.

Antenna diversity for improved indoor reception of US digital terrestrial television receivers

Antenna diversity algorithms are presented and are shown to improve the reception performance of an ATSC A/53 compliant digital terrestrial TV receiver. A maximum ratio combining algorithm is outlined and the results of field tests of a prototype are presented. An improved beamforming algorithm is described and computer simulation results on captured data are presented. Antenna diversity (in many forms) provides many gains over current single antenna digital terrestrial TV receivers, in particular for indoor use.