| Summary: | 碩士 === 國立清華大學 === 通訊工程研究所 === 104 === The precoding and large scale antennas system are important technology in millimeter
wave for compensating the severe path loss [1–3]. However, the several high cost and high
power consumption of the analog-to-digital converters (ADC) in gigabit per second are
inevitable if the precoder and combiner are all implemented on baseband, because each
antenna should has one RF chain and ADC.Therefore, the hybrid precoding is proposed
to reduce the number of RF chain and ADC in [4–6] owing to the limited scatterings
in mmWave. Furthermore, the low complexity mixed-signal precoding algorithm is
proposed in [7] to reduce the complexity by simplifying the method to find out the
precoder in RF chain with the negligible performance degradation. However, despite
applying the low complexity algorithm, the computation complexity in searching the
bases vector is still high. The propose algorithm in this study can reduce the expected
value of computation complexity by keeping the unchanged precoder in RF chain and
partially updating the precoder in baseband owing to the high correlation between the
neighboring channel state information. The two update condition are also proposed to
make the condition to do the update and one searching algorithm is proposed to limit
the search range if the AoA and AoD change continually. In final, the simulation results
show that the expected value of computation complexity with proposed update condition
and proposed searching algorithm simulated in the extended SV channel model with
channel coefficient in Quadriga can reduce 27.0%∼31.7% in precoder and 52.2%∼58.1%
in combiner according to the different tracks or different velocities. Furthermore, theproposed searching algorithm can reduce 38.3%∼62.4% in precoder and 34.0%∼58.1%
in combiner also indifferent tracks or different velocities.
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