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Why does signal distortion caused by fading cause more serious degradation effects compared with a loss in SNR?
CDMA and TDMA are unique in the sense that each of these multiple-access schemes is associated with a property for mitigating one of the fading degradation.
It can he shown [1] that the SNR is maximized when the value of each Di is equal to ti/N. Based on this condition, determine the maximum achievable SNR.
It is assumed that each branch receives an independently Rayleigh-faded signal.
Calculate which branch is output to the detector if the following diversity-combining techniques are used- Selection.
Calculate the approximate amount of memory, Lo. in units of bit intervals required to be included in the Viterbi equalizer.
Explain the Fourier transform and duality relationships among the time and frequency descriptions of these mechanisms.
What are the two degradation categories that characterize signal time-spreading, and what are the two degradation categories.
What techniques can be used for mitigating the effects of frequency-selective fading? What techniques can he used for mitigating the effects of fast fading".
If there is no motion between a transmitter and receiver, how large would the inter-leaver span need to be in order to provide any time-diversity benefits?
What is the relationship between the spaced-frequency correlation function, as measured by the coherence bandwidth A, and the spaced-time.
Consider an indoor narrowband mobile communication system that is characterized by a power density profile made up of four impulse functions.
Consider a mobile wireless system, using QPSK modulation at 24.3 ksymbols/s, and a carrier frequency of 1900 MHz.
For an inter leaver to provide meaningful time diversity, a rule of thumb requires that the span of the inter leaver, TIL.
A transmitted signal having a bandwidth of 5 kHz. and propagating over a channel having a coherence bandwidth of 50 kHz.
Consider a TDMA mobile wireless system, having a carrier frequency of 1900 MHz. that operates on a high-speed train at a speed of 180 km/hr.
In the late 1980's in Japan, a digital portable telephone system. called the Portable Handy phone System (PHS) was specified.
An inter leaver span should be at least 10 times greater than the channel coherence time in order to provide significant time diversity for a mobile wireless.
What is the largest ratio of inter leaver span to channel coherence time. Tuff°. that can be used, for the following cases?
A mobile wireless system is configured to support a data rate of 200 kbits/s using QPSK modulation and a carrier frequency of 1900 MHz.
For a mobile wireless application, a phase-based modulation scheme is particularly susceptible to phase distortion.
Consider a mobile communication system which has a framing and time-slot arrangement as shown below in Figure.
Consider a mobile wireless orthogonal FDM (OFDM) system that is intended to operate in a vehicle with speeds up to 80 km/hr in an urban environment.
A mobile wireless system uses direct-sequence spread-spectrum (DS/SS) signaling to mitigate the effects of a received signal.
Given a mobile wireless system with a carrier frequency of f. = 900 MHz, and a Doppler frequency of ft = 50 Hz.