Chinese Journal of Electronics
Vol.26, No.3, May 2017
Phase Noise Pre-correction Sch eme for
SC-FDMA Signals in LTE-Uplink
∗
XU Zijie
1
, REN Guangliang
1
and ZHANG Yang
1,2
(1. State Key Labor atory of Integrated Service Networks, Xidian University, Xi’an 710071, China)
(2. National Mobile Communic ations Research Laboratory, Southeast University, Nanjing 211189, China)
Abstract — This paper proposes a novel carrier Phase
noise (PN) pre-correction scheme with an adaptive PN
prediction algorithm for Single-carrier Frequency-division
multiple-access (SC-FDMA) systems to alleviate degrada-
tion due to the PN. Our proposed PN prediction algorithm
is a modified polynomial fitting algorithm which is based
on receding horizon principle. The parameters of the pre-
diction model are optimized by using the algorithm on PN
samples of the local oscillator signal in a training window.
By using the optimized prediction model parameters and
the latest PN samples, we can predict future PN samples.
Then these predicted PN samples are put into our pro-
posed PN pre-correction scheme and the SC-FDMA sym-
bols at the transmitter are pre-compensated. Due to the
absence of the radio frequency delay device, the proposed
scheme has a low hardware complexity. Simulation results
show that our proposed scheme can greatly reduce the ef-
fect of the PN on the transmitted SC-FDMA signal.
Key words — Phase noise (PN), Single-carrier
Frequency-division multiple access (SC-FDMA), Predic-
tion algorithm.
I. Introduction
To further improve the spectral efficiency, high-
order modulations are preferred in the future Long-term
evolution (LTE) uplink
[1]
. However, the Single-carrier
Frequency-division multiple-access (SC-FDMA) system
with high-order modulations is very vulnerable to Ra-
dio frequency (RF) impairments, such as the Phase noise
(PN) and the Carrier frequency offset (CFO)
[2−5]
.The
compensation of the PN in the system is more difficult
than that of the CFO due to its fast random time-varying
characteristic. Many PN suppression methods were pro-
posed in the literature
[6−12]
.Mostofthemdealtwith
the PN at the receiver
[6−10]
. Several proposals compen-
sated the PN at the transmitter, which can improve the
quality of the transmitted signal and mitigate the out-of-
band interference caused by the PN, and this characteris-
tic is very important for multiuser transmission with the
low multiuser interference in the uplink. The authors in
Ref.[11] proposed a feedback scheme to reduce the trans-
mitter PN. However, the large latency between the uplink
and the downlink greatly degrades the performance of the
scheme. A self-downconversion architecture based trans-
mitter PN compensation scheme was proposed in Ref.[12].
This scheme is effective in mitigating the out-of-band in-
terference caused by the PN, but may be impractical due
to the large insert loss, high cost and complex calibrations
caused by the three RF delay lines in the scheme.
The key contributions of this paper can be summa-
rized as follows. We propose a novel carrier PN pre-
correction scheme for the user terminal in the LTE uplink.
The scheme uses predicted PN samples to pre-compensate
transmitted SC-FDMA signals and does not require RF
delay lines or other complex hardware devices. Therefore,
our proposed scheme has a lower hardware cost and is
easier to implement than the existing PN compensation
scheme in the transmitter. Also, our scheme has a sim-
pler structure than other schemes which deal with PN
at the receiver. Additionally, in order to obtain precise
predictions of PN samples, we propose an adaptive PN
prediction algorithm. The algorithm is a modified polyno-
mial fitting algorithm which is based on receding horizon
principle. By using the proposed PN prediction algorithm
on the latest PN samples in a training window, we can
obtain the optimal model parameters and the precise pre-
dictions of PN samples. Simulation results show that the
quality of the transmitted signal is highly improved and
∗
Manuscript Received Oct. 12, 2016; Accepted Dec. 21, 2016. This work is supported by the National Natural Science Foundation
of China (No.91538105, No.61401321), the National Basic Research Program of China (973 Program) (No.2014CB340206), the Natural
Science Basic Research Plan in Shaanxi Province (No.2015JQ6259), the Open Project of the State Key Laboratory of Integrated Service
Networks (No.ISN16-01), and the Open Research Fund of National Mobile Communications Research Laboratory (No.2015D01).
c
2017 Chinese Institute of Electronics. DOI:10.1049/cje.2017.03.005