Applications of hierarchical constellations for multimedia transmission over fading channels
Date
2003
Authors
Hossain, Md. Jahangir
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Abstract
Hierarchical constellations (known also as embedded, multi-resolution, asymmetrical or nonuniform constellations) are studied for multimedia and multicast transmission over fading channels. Specifically, we propose general design guidelines for multimedia and multicast transmission over fading channels using an adaptive hierarchical phase shift key (PSK) constellation. By computer simulation, we have compared our proposed schemes (for both applications) with a classical time division multiplexing (TDM) that employs uniform PSK of the same order as hierarchical PSK. The adaptive hierarchical PSK, generally, outperforms (in terms of energy) the adaptive uniform PSK in TDM. We also propose a new technique for simultaneous voice and multi-class data transmission over fading channels using adaptive hierarchical M-ary quadrature amplitude modulation (M-QAM). We present closed-form expressions and numerical results for outage probability, achievable spectral efficiency and average bit error rate (BER) for voice and different classes of data transmission over Nakagami-m fading channels. Compared to the schemes employing hybrid binary shift keying (BPSK)/M-ary amplitude modulation (M AM) and uniform M-ary quadrature amplitude modulation (M -QAM), the new hierarchical scheme is spectrally more efficient for data transmission. The new scheme provides also as a byproduct a spectrally efficient way of transmitting voice and single class data.