![](https://csdnimg.cn/release/download_crawler_static/18810442/bg1.jpg)
IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 61, NO. 7, APRIL 1, 2013 1605
Multi-Block Joint Optimization for the
Peak-to-Average Power Ratio Reduction of
FBMC-OQAM Signals
Daiming Qu, Shixian Lu, and Tao Jiang, Senior Member, IEEE
Abstract—Recently, the filter bank mu lticarrier with offset
quadrature amplitude modulation (FBMC-OQAM) has attracted
increasing attention. However, most peak-to-average power
ratio (PAPR) reduction schemes developed for orthogonal fre-
quency division multiplexing (OFDM) signals are not effective
for FBMC-OQAM signals, due to the overlapping structure
of FBMC-OQAM signals. In this paper, we propose an im-
proved partial transmit sequen ce (PTS) scheme by employing
multi-block joint optimization (MBJO) for the PAPR reduction
of FBMC-OQAM signals, called as MBJO-PTS scheme. In PTS
scheme, one data block is divided into several subblock s and
each subblock is multiplied by a phase rotation factor for the
subblock. The PTS scheme s earches over all combinations of
allowed phase factors to lower the PAPR. Unlike existing PAPR
reduction schemes of independently optimizing the data blocks,
the MBJO-b a se d scheme exploits the overlapping stru cture of
the F BMC -OQAM signal and jointly optimizes multiple data
blocks. Moreover, we develop two algorithms for the optimization
problem in the MBJO-PTS scheme, including a dynamic program-
ming (DP) algorithm to guarantee the optimal solution and avoid
exhaustive search. Theoretical analysis and simulations show
that the proposed MBJO-PTS scheme could provide a significant
PAPR reduction in the FBMC-OQAM system, by exploiting the
overlapping structure of the FBM C-OQAM signal. Employing
the proposed DP algorithm, the FBMC-OQAM system with
theproposedMBJO-PTSschemeevenoutperformstheOFDM
system w ith the conventional PTS scheme by 0.9 dB at CCDF of
in PAPR reduction, under the same number of subcarriers,
modulation type and PTS parameters given in Section V.
Index Terms—Dynamic programming, FBMC-OQAM,
multi- block joint optimization, partial transmit sequence,
peak-to-average power ratio.
I. INTRODUCTION
M
ULTICARRIER modulations (MCM ) have attracted
a lot of attention ranging from wireline to wireless
communicatio ns due t o its cap abil ity to efficiently cope with
frequency selective channels. Much of the attention in the
Manuscript received February 17, 2012; revised October 12, 2012 and De-
cember 13, 2012; accepted December 17, 2012. Date of publication January
14, 2013; date of current version March 08, 2013. The associate editor coordi-
nating the review of this manuscript and approving it for publication was Dr.
Ruixin Niu. T his work was supported by the Natio nal Scien ce Founda tio n of
China by Grants 61271228 and 61172052, the Project-sponsored by SRF for
ROCS, SEM, the National & Major Project by Grants 2012ZX03003004-001
and 2013ZX03003016, and the Fundamental Research Funds for the Central
Universities by Grant HUST:2012TS019.
The authors are with the Wuhan National Laboratory For Optoelectronics,
Department of Electronic and Infor mation, Huazhong U niversity of Sci-
ence and Technology, Wuhan, 430074, China (e-mail: Tao.Jiang@ieee.org;
qudaiming@gmail.com; lushixian2010@gmail.com).
Color versions of one or more of the figures in this paper are available online
at http://ieeexplore.ieee.org.
Dig
ital Object Identifier 10.1109/TSP.2013.2239991
present literature emphasizes on the use of conventional or-
thogonal frequen cy division multiplexing (OFDM). However,
the OFDM system uses rectangular pulse shaping on each sub-
carrier, which leads to high out-of-band radiation. Moreover,
the OFDM s ystem sacrifices data transmission rate because of
the insertion of c ycl ic prefix (CP). To overcome the shortcom-
ings of the OFDM systems, the filter bank multicarrier with
offset quad rature amplitude modulation (FBMC-OQAM) has
attracted increasing attention recently [1]–[3]. Compared with
the conventional OFD M sy stem, the FBMC-OQAM system
provides higher data rate because FBMC-OQAM does not
require the C P. Furthermore, it brings advantages such as ro-
bustness to narrow-b and interferen ce and lower sidelobes [4].
Recently, FBMC-OQAM technology has been considered for
the physical layer of wireless communication systems [4]–[6].
Similar to the OFDM systems, a fundamental d raw back of
the FBMC-OQAM system is its high peak-to-average power
ratio (PAPR) of the transmitted sig nal, which degrades the effi-
ciency of the high pow er amplifier (HPA) [7]. Due to the simi-
larity between the FB M C-OQAM and OFDM system, it is nat-
ural to consider how to employ the PAPR reduction schemes
for OFDM systems to reduce the PAPR of FBMC-OQAM sig-
nals. Existing PAPR schemes of OFDM signals include clipping
[8], [9], tone-reservation (T R ) [10], active constellation exten-
sion (ACE) [11], partial transmit sequen ce (PTS) [12]–[17], se-
lective mapping (SLM) [13], [18] and companding transform
[19], [20]. Overviews of the above schemes can be found in
[21] and [22]. However, some research results showed that it
is not effective to directly em ploy the OFDM PAPR schemes
for FBMC-OQAM systems. The clipping-based method of the
FBMC-OQAM system was discussed in [23] and [24], and it
has been shown that the clipping significantly raises the side-
lobes of the FBMC-OQAM signal. The simulation results in
[25] showed that the direct use of SLM scheme is not as effec-
tive for the FBMC-OQAM system as it is for the OFDM system,
and the major reason is that OFDM and FBMC-O QAM signals
have very different signal structures. The signals of adjacent
data blocks are independent in the OFDM system, while th ey
overlap with each other in the FBMC-OQAM system. A method
called as overlapped SLM (OSLM) was proposed in [25] to
deal with the overlapping of data blocks. Alth ough OSLM im-
proves the original SLM for FBMC-OQAM systems, it still uses
step-by-step optimization that optimizes each data block sepa-
rately. In this paper, we are interested in joi ntl y optimize mul-
tiple data blocks to reduce the peak power of FBMC-OQ AM
signals.
In this paper, we propose an improved PTS scheme by em-
ploying multi-block joint opti mization (MBJO) for the PAP R
1053-587X/$31.00 © 2013 IEEE