Slide 1 Effective Noise Figure in Hybrid BF system Date YYYYMMDD Authors July 2015 JiHo Lee Korea University Slide 2 Abstract This contribution presents the theoretical results of ID: 812186
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Slide1
July 2015
Ji-Ho Lee, Korea University
Slide 1
Effective Noise Figure in Hybrid BF system
Date: YYYY-MM-DD
Authors:
Slide2July 2015
Ji-Ho Lee, Korea University
Slide 2
Abstract
This contribution presents the theoretical results of
n
oise
f
igure (NF)
and
gain
in hybrid
b
eamforming systems.
Slide3Motivation
In hybrid
beamforming systems, the received signals from multiple antennas are phase corrected by phase shifter
and then combined in RF combiner, usually before down-converting at RX.The additional RF blocks (i.e., phase shifter and combiner) are added to RF chain, which increases noise figure.
Note that the RF combiner has multiple input signals and single output signals (multi-to-one RF path).
In this case, the NF should be appropriately considered for the calculation of carrier to noise ratio (CNR).Slide 3July
2015Ji-Ho Lee, Korea University
Slide4July 2015
Ji-Ho Lee, Korea University
Slide 4
Block Diagram of Hybrid Beamforming
The received signals from each antenna are phase-shifted by phase shifter
and combined by combiner after LNA.
At baseband, the conventional MIMO space-time processing is performed for multiplexing gain or/and diversity gain.
Baseband
Space-time
processing
Down-converting
Low-pass filter
LNA
Phase
shifter
ADC
Down-converting
Low-pass filter
LNA
Phase
shifter
ADC
Slide5Noise Figure Calculation
Slide 5
John Doe, Some Company
Month Year
RF chain
,
LNA
Phase
shifter
Equivalent
RF chain
Overall Noise Figure
(
Friis
Equation)
Overall Gain
:
RF block’s gain of
RF
path
:
RF block’s
noise figure of
RF path
: Overall gain of
RF path
: Overall noise figure of
RF path
Slide6July 2015
Ji-Ho Lee, Korea University
Slide 6
Multi-to-One Path system
:
Input s
ignal power of
RF path
:
Input
noise
power
of
RF path
:
Overall gain of
RF
path
: Overall noise figure of
RF
path
:
Insertion phase shift of
RF
path
,
,
,
,
,
,
Array output
Combiner
:
Output noise
power of
RF path
: Amplitude combining coefficient of
RF path
: Output signal power of combiner
: Output noise power of combiner
Slide7July 2015
Ji-Ho Lee, Korea University
Slide 7
Equivalent Single-Path system
Array output
,
Array output
For an analysis purpose, a multi-to-one path system is converted into an equivalent single-path system.
We assume that the total input, output power of multi-
to-one
-path system and equivalent single-path system are identical, such that the above two figures are
equivalent.
,
,
,
,
,
,
:
Effective overall gain of single RF
path
: Effective overall noise figure of single RF path
: Effective signal power of single RF path
: Effective
noise
power of single RF path
Slide8July 2015
Ji-Ho Lee, Korea University
Slide 8
Effective Gain
The effective gain of the array system is given to be [1]
If all signal paths are identical (
),
we have
If all the
are 1
(
,
we have
,
Array output
Slide9July 2015
Ji-Ho Lee, Korea University
Slide 9
Effective Noise Figure
The effective noise figure of the array system is given to be [1]
If all signal paths are identical (
,
we have
If all the
are 1
(
,
we have
,
Array output
Slide10July 2015
Ji-Ho Lee, Korea University
Slide 10
Conclusion
We contribute to calculating the noise figure and gain in hybrid beamforming system.
Slide11July 2015
Ji-Ho Lee, Korea University
Slide 11
References
Junghyun Kim, Jinho Jeong, and
Sanggeun Jeon, "Improvement of Noise Performance in Phased-Array Receivers", ETRI Journal, vol. 33, no.2, pp. 176-183, April (2011)