PAPR Analyses for Broadband OFDM Transmitter
with Digital IF Architecture
Zhenyu Zhang
a, b
, Fengchun Tian
a
, Fanxin Zeng
a, b
, Guixin Xuan
a, b
a. College of Communication Engineering, Chongqing University, Chongqing, China;
b. Chongqing Key Lab. of Emergency Communication, Chongqing Communication Institute, Chongqing, China.
zhenyu.zhang@cqu.edu.cn, fengchuntian@cqu.edu.cn, fzengx@cqu.edu.cn
Abstract-As one of main indexes of orthogonal frequency
division multiplexing (OFDM) system, peak-to-average power
ratio (PAPR) of the time-domain signal has an important effect on
system performance. A larger PAPR has to require a wider linear
range of power amplifier (PA) in system transmitter, which will
greatly decrease the efficiency of PA. In this paper, we introduce a
broadband OFDM communication system which is designed and
implemented on the basis of digital intermediate frequency (IF)
architecture and 1x4 multiple-input multiple-output (MIMO)
technology. The parameters and structure of the 1x4 MIMO-
OFDM communication system are provided, and its frequency
spectrum and time signal are respectively tested. In addition, the
PAPR problem is mainly analyzed, and the corresponding
experimental results and simulation analyses are also presented.
Keywords-OFDM; PAPR; MIMO; digital IF
I. INTRODUCTION
Orthogonal frequency division multiplexing (OFDM) is a
kind of multi-carrier (MC) modulation technique with a high
spectral efficiency and resistance to multi-path fading [1].
When OFDM is combined with multiple-input multiple-output
(MIMO) technique, the obtained MIMO-OFDM technique can
provide higher transmission rate and/or transmission reliability,
which leads to its wide applications in wireless communication
systems, such as WiFi, WiMax, LTE and LTE-A [2]. In
addition to the above public communication networks, MIMO-
OFDM technique was also used to point-to-point transmission
link, e. g., high frequency (HF) radio [3-4], video transmission
[5], emergency service [6] and so on.
For MIMO-OFDM systems, many key technology points had been
researched, such as symbol synchronization [7-8], carrier frequency
offset estimation [9-11], multi-user detection [12-13], channel
estimation [14-15], peak-to-average power ratio (PAPR)
reduction [16-17], etc. These researches can provide helpful
references for realization of specific MIMO-OFDM systems.
In this paper, we focus on the design and implementation of
MIMO-OFDM systems. A set of 1x4 MIMO-OFDM transceiver
with digital intermediate frequency (IF) architecture is
introduced. The transceiver is designed for video transmission
in emergency communication when communication
infrastructure had been damaged in natural disaster. The
designed MIMO-OFDM system consists of a vehicle platform
with four antennas and multiple portable terminals with one
antenna for each terminal. The command control center
equipped with the vehicle platform can receive real-time video
from different portable terminals which can be taken into
disaster scene. Then, such system can be considered as an
alternative to satellite emergency communication. Although
satellite transmission has significant importance on emergency
communication [18], the designed and implemented 1x4
MIMO-OFDM video transmission system can possess lower
cost and larger flexibility.
For the presented 1x4 MIMO-OFDM communication system,
we provide its design parameters and system structure. In
addition, its frequency spectrum and time signal are
respectively tested and analyzed. Also, we discussed the PAPR
problem on the basis of baseband signal amplitude and IF
signal envelope, and the corresponding experimental results
and simulation analyses are also presented.
This paper can be organized as follows. We first introduce
the designed and implemented broadband 1x4 MIMO-OFDM
communication transceiver, where we present the detailed
design scheme, system parameters and key technologies. Then
the PAPR resistance is mainly analyzed in Section III. Finally,
Section IV summarizes the results.
II. T
HE DESIGNED AND IMPLEMENTED BROADBAND MIMO-
OFDM
COMMUNICATION SYSTEM
A. Uplink Structure of the 1x4 MIMO-OFDM System
In order to provide video transmission for emergency
communication, we design and implement a set of 1x4 MIMO-
OFDM system whose uplink block diagram can be shown in
Fig. 1.
Fig. 1 Uplink block diagram of the designed and implemented 1x4 MIMO-
OFDM video transmission system
This work was supported by National Natural Science Foundation of China
(NSFC) under Grants 61471366, 61002034, 61271003, and 61271251, China
Postdoctoral Science Foundation Grants 2015T80959 and 2014M552318,
atural Science Foundation Project of CQ Grant cstc2014jcyjA40050, and
Chongqing Postdoctoral Science Special Foundation Grant Xm2014031.
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