Section III presents proposed features ( ) which are extracted from received signal under the effect of noise (AWGN) and considered channel model (Rayleigh Flat Fading
Rician Flat Fading
To determine the probability of error in the proposed code-time diversity system in frequency selective channel, the same procedure as that used in flat fading
channel case is followed.
where the subscript ff denotes the flat fading
and p(a) is the probability density function of Rayleigh distribution.
refers to eases where the latest copy of the signal arrives at the base station after a time duration that is smaller than the symbol bit period.
Communication environment consists of QAM signals transmitted through a flat fading
The bandwidth used in the DRM+ system, approximately 100KHz, is much smaller than the coherence bandwidth of the channels in typical urban environment that is in the order of 1MHz , which results in a severe flat fading
3.2 Performance of Energy Detection under Flat Fading
In simulation, the channel is assumed to be quasi-static flat fading
. Gray code is employed to map the data bits to MQAM constellations.
The link between PU-Rx and CU-Tx is supposed to be a flat fading
channel with instantaneous channel gain [g.sub.k,n], the channel between CU-Rx and CU-Tx is also a flat fading
channel characterized by instantaneous channel gain [h.sub.k,n].
For a BER of [10.sup.-4] and the mobility of 3 km/h, simulation results show that a gain of 6 dB is achieved by the proposed scheme over both flat fading
and Pedestrian A (Ped A) channels, compared to the conventional CDD-OFDM system.