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Received Signal Model for Wireless Communications in a Netted Sensors Environment. Rob Taylor. Outline. Discrete-time processing of continuous-time signals Synthesizing transmitted signals Frequency-selective slow-fading channels TDL for SISO TDL for MIMO Narrowband specialization.
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Received Signal Model for Wireless Communications in a Netted Sensors Environment Rob Taylor
Outline • Discrete-time processing of continuous-time signals • Synthesizing transmitted signals • Frequency-selective slow-fading channels • TDL for SISO • TDL for MIMO • Narrowband specialization
Discrete-Time Processing of Continuous Signals x[n] y[n,t] + D/C C/D T T T = sampling period
where g(t) is the pulse shaping filter, is the symbol waveform, and is the carrier frequency. Synthesizing Digitally Modulated Signals • Continuous-time RF complex digitally modulated transmitted signal is written as • The symbol waveform can take on many different forms depending on the modulation format employed • where we vary the amplitude, phase, or frequency to create different modulations. • Currently, we have OOK, BPSK, QPSK, FSK, and GMSK.
Frequency-Selective Slow Fading Channel Model • We will use a tapped delay line (TDL) channel model (Proakis, p.841) with the following continuous-time impulse response: LOS NLOS
For a pulse shaping filter with stop-band frequency we can write the digital SISO mapping equation as: TDL for a Single-Input Single-Output system RCVR XMTR
TDL for a Multi-Input Multi-Output system 1 1 2 2 . . . . . . S J • Defining the following terms allows us to compactly write the MIMO mapping as:
Special Case of Narrowband Signal Model • We can specialize the wideband signal model to handle narrowband signals by letting L=0 and : then and consequently we arrive at, which allows us to write the familiar matrix form: