System and method for transmission and reception of QAM...

Details System and method for transmission and reception of QAM... System and method for transmission and reception of QAM...

2006-09-29

2008-10-07

Vo, Don N (Department: 2611)

Pulse or digital communications

Systems using alternating or pulsating current

Plural channels for transmission of a single pulse train

Reexamination Certificate

active

07433415

ABSTRACT:
The system for transmission and reception of QAM signals for use in telecommunication networks for any data rates at SNR (signal to noise ratio) of below 0 dB comprises two devices. The first device may be used for transmission Units (1)-(4) transform input bit information sequence (17) with the clock frequency ft(18) into two parallel m-level sequences with the clock frequency ft/2kforming the first and second channels, where k=log2(m). Unit (5) forming additional signalsCos⁢ωt⁢t4⁢k,A·Sin⁢ωt⁢t4⁢k,where ωt=2πft. Units (6), (7) multiply m-level sequences of the first and second channels with signalCos⁢ωt⁢t4⁢kfor removal phase ambiguity at reception end, and units (8), (9) adding with signalA·Sin⁢ωt⁢t4⁢k⁢t,defining level of the additional pilot-signal in output spectrum. Filters (10), (11) forming baseband QAM signal spectrum and units (12)-(16) shift of spectrum at intermediate or carrier frequency. The second device may be used for reception. Restoration of the carrier and clock frequencies at reception end performing with used two PLL (phase lock loop) systems using availability in signal spectrum additional pilot-signal. This allows one to set up synchronization for signal to noise ratio below 0 dB. In this case additional losses amounts 0.3-0.7 dB.

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Webb W., Hanzo L. Modern Quadrature Amplitude Modulation. Principles and Applications Fixed and Wireless Communications. IEEE'1 Press-1994, p. 115-128, Pentech Press, London.
Webb W., Hanzo L. Modern Quadrature Amplitude Modulation. Principles and Applications Fixed and Wireless Communications. IEEE Press-1994, p. 101-115, Pentech Press, London.

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