PAPR Reduction Technique for LTE SC-FDMA Systems Using Root-Raised Cosine Filter

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(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 8, No. 6, September 2010

PAPR Reduction Technique for LTE SC-FDMA
Systems Using Root-Raised Cosine Filter
Md. Masud Rana, Jinsang Kim and Won-Kyung Cho

Deptartment of Electronics and Radio Engineering, Kyung Hee University
1 Seocheon, Kihung, Yongin, Gyeonggi, 449-701, Republic of Korea
Email: mamaraece28@yahoo.com

Abstract—Recently, mobile radio communications have de- rate transmission over mobile wireless channels. In OFDMA
veloped rapidly due to the endless demand for broadband system, the entire channel is divided into many narrow sub-
multimedia access and wireless connection anywhere, and any channels, which are transmitted in parallel, thereby increasing
time. With the emergence of diverse fourth generation (4G)
enabling technologies, signal processing has become ever in- the symbol duration and reducing the intersymbol-interference
creasingly important for small power, small chip resources, (ISI) [4], [8]. Despite many beneﬁts of OFDMA for high speed
and efﬁcient physical implementations of potential multimedia data rate services, it suffer from high envelope ﬂuctuation
wireless communication systems. In this paper, we analytically in the time domain, leading to large PAPR. Because the
derive the time and frequency domain single carrier-frequency high PAPR is detrimental to user mobile equipment (UE)
division multiplexing (SC-FDMA) signals. Simulation results
show that the SC-FDMA sub-carrier mapping scheme has a terminals, SC-FDMA has drawn great attention as an attractive
signiﬁcantly lower peak-to average power ratio (PAPR) compared alternative to OFDMA for uplink data transmission. It can be
to orthogonal frequency division multiplexing (OFDMA). In regarded as DFT-spread OFDMA (DFTS-OFDM), where time
addition, the interleave FDMA (IFDMA) sub-carrier mapping domain data signals are transformed to frequency domain by
scheme with root raised cosine ﬁlter reduced PAPR signiﬁcantly a DFT before going through OFDMA modulation. The main
than localized FDMA (LFDMA) and distributed (DFDMA) sub-
carrier mapping scheme. As a results, improves the mean power beneﬁt of DFTS-OFDM compared to OFDM scheme, is re-
output from a battery driven terminal equipment and power duced variations in the instantaneous transmit power, implying
ampliﬁer efﬁciency. the possibility for increased power-ampliﬁer efﬁciency, low-
Index Terms—CCDF, IFDMA, OFDMA, PAPR, root-raised complexity high-quality equalization in the frequency domain,
cosine, SC-FDMA. and ﬂexible bandwidth assignment [12].
In order to solve the high PAPR problem seen in the
I. I NTRODUCTION uplink of OFDMA, research is now addressing techniques such
The further increasing demand on high data rates in wireless as a SC-FDMA. The most of the previous work related to
communication systems has arisen in order to support broad- 3GPP LTE uplink has been mainly focused on implementation
band services. The third generation partnership project (3GPP) problems in the physical layer [2], [5], [9], [13]. In [10], [12]
members started feasibility study on the enhancement of the proposed raised-cosine pulse shaping method that compare
universal terrestrial radio access (UTRA) in December 2004, PAPR characteristics using the complementary cumulative
to improve the mobile phone standard to cope with future distribution function (CCDF) for different subcarrier mapping.
requirements. This project was called long term evolution PAPR reduction is of the most importance performance
(LTE) [1]. parameter in case of high amplitude signals subject to non
LTE uses single carrier frequency division multiple access linear power ampliﬁcation. This situation more and more occur
(SC-FDMA) for uplink transmission and orthogonal frequency due to the ever-growing demand in high spectral efﬁciency
division multiple access (OFDMA) for downlink transmission advanced mobile telecommunications systems implying multi
[6]. SC-FDMA is a promising technique for high data rate dimensional waveforms considerations for which the PAPR
transmission that utilizes single carrier modulation and fre- is high. Pulse shaping is required for a single carrier sys-
quency domain equalization. Single carrier transmitter struc- tem to bandlimit the transmit signal. This paper addresses
ture leads to keep the peak-to average power ratio (PAPR) a theoretical analysis of the PAPR reduction of LTE SC-
as low as possible that is reduced the energy consumption. FDMA systems when root-raised cosine (RRC) ﬁlter is used.
SC-FDMA has similar throughput performance and essentially RRC is used as the transmit and receive ﬁlter in a digital
the same overall complexity as OFDMA [3], [10], [12]. A communication system to perform matched ﬁltering. The
highly efﬁcient way to cope with the frequency selectivity combined response of two such ﬁlters is that of the raised-
of wideband channel is OFDMA. OFDMA is an effective cosine ﬁlter. In this paper, we analytically derive the time and
technique for combating multipath fading and for high bit frequency domain SC-FDMA signals. Simulation results show

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One radio frame = 20 Slots = 10 Sub-frames = 10 ms
that the SC-FDMA has a signiﬁcantly lower PAPR compared
1 Slot = 7 OFDM symbols = 0.5 ms 2 Slots = 1 Sub-frame = 10 ms
to OFDMA system. In addition, we comparing the three forms
of SC-FDMA sub-carrier mapping scheme and ﬁnd that the
interleave FDMA (IFDMA) sub-carrier mapping with root 1 2 3 4 ….…… 15 16 17 19 20

raised cosine based pulse shapping method reduced PAPR
Resource block:
signiﬁcantly than localized FDMA (LFDMA) and DFDMA

12 sub-carriers
1 2 3 4 5 6 7 Short CP:

=180 kHz
7 symbols x 12 sub-carriers
sub-carrier mapping scheme. As a results, improves the mean Long CP:
power output from a battery driven terminal equipment and Cyclic prefix 6 symbols x 12 sub-carriers

power ampliﬁer efﬁciency. 7 OFDM symbols 1 resource element
The rest of the paper is organized as follows. We describes Pilot

the 3GPP LTE and LTE SC-FDMA system model in sec-
tion II and III, respectively. In section IV, we describes the Fig. 2. LTE generic frame structure.
different SC-FDMA sub-carrier mapping scheme. In section
V, we describes the PAPR reduction technique for LTE SC-
FDMA systems. In section VI, we simulated and compare blocks ﬁt in a carrier of 1.4 MHz and 100 resource blocks
the proposed method with OFDMA for different sub-carrier ﬁt in a carrier of 20 MHz. Slots consist of either 6 or 7
mapping scheme. Finally, conclusions are made in section VII. OFDM symbols, depending on whether the normal or extended
cyclic preﬁx (CP) is employed. The CP is added in front of
II. 3GPP LTE
each block. The details transmission scheme parameters of
The main purposes of the 3GPP LTE are substantially the 3GPP LTE system are shown in Table I [7]. LTE uses SC-
improved end-user throughputs, low latency, reduced user FDMA scheme for the uplink transmissions and OFDMA in
equipment (UE) complexity, high data rate, and signiﬁcantly downlink transmission.
improved user experience with full mobility. First 3GPP LTE
TABLE I
and LTE-advanced (LTE-A) speciﬁcation is being ﬁnalized LTE SYSTEM PARAMETERS
within 3GPP release 9 and release 10, respectively [1].
Year 2005 2006 2007 2008 2009 2010 2011 2012 Trans. bandwidth (MHz) 1.25 2.5 5 10 15 20
Release 7 study phase (HSPA+) FFT size 128 256 512 1024 1536 2048
Occupied sub-carrier 76 151 301 601 901 1200
Release 8 work phase (LTE)
Sampling frequency (MHz) 1.92 3.84 7.6815.36 23.04 30.72
Release
Release 9 test specs No. of available PRBs 6 12 25 50 75 100
Release 10 (LTE User plane latency (ms) <5
advanced) PRB bandwidth (kHz) 180
Frame duration (ms) 0.5
Release 6 Core First First UE Initially Mass Sub-carrier bandwidth (kHz) 15
market
HSPA uplink specs
drafted
test
specs
certification development Coverage (km) 5-30
Mobility (km/hr) 15-350
Peak data rates (Mbits/s) DL: 100, and UL: 50
Fig. 1. LTE release timeline. Antenna conﬁguration DL: 4x2, 2x2, 1x2, 1x1, and UL: 1x2, 1x1
Spectrum efﬁciency DL: 3-4 x HSDPA, and UL: 2-3 x HSUPA Rel.6
Control plane latency (ms) 100 (idle to active), and 50 (dormant to active)
Speciﬁcally, the physical layer has become quite stable re- Radio resource DL: 3-4 fold higher than Rel.6
cently for a ﬁrst implementation. LTE supports multipule input
multiput output (MIMO) with one, two, four, and eight antenna
elements at base station (BS) and mobile terminal. Both closed III. LTE SC-FDAMA SYSTEM MODEL
and open loop MIMO operation is possible. The target of LTE-
The basic principle of a LTE SC-FDMA transmission sys-
A is to reach and surpass the international telecommunication
tem is shown in Fig. 3.
union (ITU) requirements. One of the important LTE-A ben-
At the transmitter side, a baseband modulator transmits the
eﬁts is the ability to leverage advanced topology networks;
binary input to a multilevel sequences of complex number
optimized heterogeneous networks with a mix of macros with
m1 (q) in one of several possible modulation formats including,
low power nodes such as picocells, femtocells, ensures user
quandary phase shift keying (QPSK), and 16 level-QAM.
fairness, worldwide roaming, and new relay nodes [1].
These modulated symbols are perform a N-point discrete
In 3GPP LTE, the basic unit of a transmission scheme is a
Fourier transform (DFT) to produce a frequency domain
radio frame which is ten msec long. They are divided into ten
representation [3]:
sub-frames, each sub-frame one msec long. Each sub-frame is
N −1
further divided into two slots, each of half msec duration. Fig. 1 ∑ −j2πqn

2, shows the basic LTE generic frame structure [11]. The sub- s1 (n) = √ m1 (q)e N , (1)
N q=0
carrier spacing in the frequency domain is 15 kHz. Twelve
of these sub-carriers together (per slot) is called a resource where m1 is the discrete symbols, q is the sample index, j is
block therefore one resource block is 180 kHz. Six resource the imaginary unit, and m1 (q) is the data symbol. The output

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Input data
tones. Assume that the channel length of CP is larger than the
Output data
channel delay spread [8].
The transmitted symbols propagating through the radio
Demodulation channel can be modeled as a circular convolution between the
Modulation
channel impulse response (CIR) and transmitted data blocks.
R(k)
m1(q) At the receiver, the opposite set of the operation is performed.
Size-N IDFT The CP samples are discarded and the remaining N samples
Size-N DFT
s3(m) are processed by the DFT to retrieve the complex constellation
s1(n) symbols transmitted over the orthogonal sub-channels. The
Equalization
received signals are de-mapped and equalizer is used to
Subcarrier
mapping compensate for the radio channel frequency selectivity. After
Subcarrier
demapping
IDFT operation, the corresponding output is demodulated and
s2(q)
r(m) soft or hard values of the corresponding bits are passed to the
Size-M IDFT Size-M
decoder.
Channel Noise
DFT
s(m) IV. SC-FDMA SUB - CARRIER MAPPING SCHEME
Cyclic
+
There are two principal sub-carrier mapping modes-
prefix(CP) X Remove CP
insertion localized mode, and distribution mode. An example of SC-
FDMA transmit symbols in the frequency domain for two
Fig. 3. LTE SC-FDMA transceiver system model [6]. user, three sub-carrier per user and six sub-carriers in total
is illustrated in Fig. 4 [6].

of the DFT is then applied to consecutive inputs of a size-M s1(1) s1(2) s1(3)
inverse DFT (M >N) and where the unused inputs of the IDFT
are set to zero. If they are equal (M=N), they simply cancel
out and it becomes a conventional single user single carrier
system with frequency domain equalization. However, if N is
smaller than M and the remaining inputs to the IDFT are set
to zero, the output of the IDFT will be a signal with ’single- (x)
carrier’ properties, i.e. a signal with low power variations, and
with a bandwidth that depends on N. The SC-FDMA is single- (y)
carrier, not single frequency. The data signal of each user
consists of a lot of frequency. DFT of SC-FDMA is used to
ﬁlter the frequency items and maps them into IDFT to reform (z)
single user waveform. This may justify the reduced peak-to- Zeros User 1
average power ratio (PAPR) experienced in the IDFT output. Complex weight User 3
The details description of the sub-carrier mapping mode are in User 2
section IV . PAPR is a comparison of the peak power detected Time domain Frequency domain
over a period of sample occurs over the same time period. The
PAPR of the transmit signal is deﬁned as [14]: Fig. 4. Multiple access scheme of SC-FDMA: (x) IFDMA mode, (y)
max0<m<T |s(m)|2 DFDMA mode, and (z) LFDMA.
P AP R = ∫ TN , (2)
1
|s(m)| dm
2 In distributed sub-carrier mode, the outputs are allocated
TN 0 equally spaced sub-carrier, with zeros occupying the unused
where T is the symbol period of the transmitted signal s(m). sub-carrier in between. While in localized sub-carrier mode,
PAPR is best described by its statistical parameter, com- the outputs are conﬁned to a continuous spectrum of sub-
plementary cumulative distribution function (CCDF). CCDF carrier [10], [12]. Except the above two modes, interleaved
measures the probability of signal PAPR exceeding certain sub-carrier mapping mode of SC-FDMA (IFDMA) is another
threshold [12], [14]. To further reduce the power variations special sub-carrier mapping mode. The difference between
of the DFTS-OFDM signal, explicit spectrum shaping can be DFDMA and IFDMA is that the outputs of IFDMA are
applied. Spectrum shaping is applied by multiplying the fre- allocated over the entire bandwidth, whereas the DFDMA’s
quency samples with some spectrum-shaping function, e.g. a outputs are allocated every several sub-carriers. If there are
root-raised-cosine function (raised-cosine-shaped power spec- more than one user in the system, different sub-carrier map-
trum). The IDFT module output is followed by a CP insertion ping modes give different sub-carrier allocation [10], [12].
that completes the digital stage of the signal ﬂow. A CP is In order to accommodate multiple access to the system and
used to eliminate ISI and preserve the orthogonality of the to preserve the constant envelope property of the signal, the

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elements of transmitted signal s(m) are mapped, by using the After IDFT operation, time domain signal can be described
LFDMA or IFDMA sub-carrier mapping rule. as follows. Let m = Cq + c, where 0 ≤ c ≤ N − 1 and
Here is output symbol calculation in IFDMA in time 0 ≤ c ≤ C − 1. Then time domain transmitted signal can be
domain. The frequency samples after IFDMA sub-carrier represent as [12], [16]:
mapping is [12], [16]:
{ M −1
1 ∑
0≤n≤N −1
j2πml
s1 (q/C) = 1 s(m) = s2 (q)e M
s2 (q) = M
0 else l=0
N −1
∑
where q = Cn, and C = M/N and it is the bandwidth 1 1 j2π(Cq+c)l

expansion factor of the symbol sequence. If N = M/C = s1 (l)e CN (6)
CN
l=0
and all terminals transmit N symbols per block, the system
can handle C simultaneous transmissions without co-channel if c = 0, then
interference. After M-point IDFT operation (M > N ), time N −1
domain signal can be described as follows. Let m = N c + q, 1 1 ∑ j2πql
s(m) = [ s1 (l)e N ]
where 0 ≤ c ≤ C − 1 and 0 ≤ q ≤ N − 1. The time domain C N
l=0
IFDMA transmitted signal can be express as [12], [16]: 1
M −1 = m1 (q) (7)
1 ∑ j2πmq C
s(m) = s2 (q)e M
∑N −1 −j2πlp
M q=0 Since m1 (q) = m1 (p)e N , and if c ̸= 0, then
p=0
N −1
∑
1 N −1 N −1
1 ∑ ∑
j2πmn
= s1 (n)e N −j2πlp j2π(Cq+c)l
NC s(m) = [ m1 (p)e N ]e CN
n=0 NC p=0
N −1 l=0
1 1 ∑ N −1 N −1
∑ ∑
j2π(N c+q)n
= s1 (n)e N
1
CN n=0
= m1 (p)e(j2π(q−p)/N +c/CN )l
NC
N −1 l=0 p=0
1 1 ∑ j2πqn
N −1
∑
= [
C N
s1 (n)e N ]. (3) 1 1 − ej2π(q−p) ej2πc/C)
= m1 (p)
n=0
NC p=0
1 − e(j2π(q−p)/N +c/CN )
The square backed [.] of the above equation represent the N-
N −1
∑
point IDFT operation. The above equation can be rewritten 1 1 − ej2πc/C
= m1 (p)
as NC p=0
1 − e(j2π(q−p)/N +c/CN )
1
N −1
s(m) = m1 (q),
C
(4) 1 1 ∑ m1 (p)
∑N −1 = (1 − ej2πc/C ) (8)
1 j2πqn
where m1 (q) = N n=0 s1 (n)e N is the N-point IDFT C N n=0 1 − e(j2π(q−p)/N +c/CN )

operation. Therefore in case of IFDMA, every output symbol is
So, the time domain LFDMA sub-carrier mapping signal has
simple a repeat of input symbol with a scaling factor of 1/C in
exact copies of input time signals with a scaling factor of 1/C
time domain. When the sub-carrier frequency allocation starts
in the N-multiple sample positions and in between values are
from f th sub-carrier i.e. q = Cn + f then the frequency
sum of all the time input symbols in the input block with
samples after IFDMA sub-carrier mapping is
{ different complex-weighting (CW) [12].
s1 (q/C − f ) = 1 0≤n≤N −1 Here is output symbol calculation in DFDMA in time
s2 (q) =
0 else domain. The frequency samples after DFDMA sub-carrier
and the time domain transmitted signal can be express as mapping is [12], [16]:
N −1 {
1 1 ∑ j2πqn j2πmf s1 (q/C) = 1 0 ≤ n ≤ N − 1
˜
s(m) = [ s1 (n)e N ]e M s2 (q) =
C N n=0 0 else
1 j2πmf where 0 ≤ c ≤ C − 1, q = Cn, and 0 ≤ C ≤ C. Let
˜
= e M m1 (q). (5)
C m = N q + c where 0 ≤ c ≤ C − 1 and 0 ≤ q ≤ N − 1and
Thus, when the sub-carrier frequency allocation starts from 0 ≤ q ≤ N − 1. The time domain DFDMA transmitted signal
f th instead of zero then there is an additional phase rotation can be express as [12], [16]:
of ej2πmf /M .
M −1
Here is output symbol calculation in LFDMA sub-carrier 1 ∑ j2πml

mapping in time domain. After DFT operation the frequency s(m) = s2 (q)e M
M
l=0
domain sub-carrier mapping signal can be written as
{ N −1
1 1 ∑
0≤l ≤N −1
j2π(Cq+c)l
s1 (l) = 1 = s1 (l)e CN Cl ˜ (9)
s2 (q) =
0 N ≤l ≤M −1 CN
l=0

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TABLE II
if c = 0 and according to the previous procedure, we obtain THE SYSTEM PARAMETERS FOR SIMULATIONS
1 ˜
s(m) = m1 (Cq) (10) System parameters Assumptions
C
∑N −1 −j2πlp System bandwidth 5M Hz
Since m1 (q) = p=0 m1 (p)e N , if c ̸= 0 and according Number of sub-carriers 512
to the previous procedure, we obtain Data block size 16
Roll of factor 0.0999999999
N −1
1 ∑
Oversampling factor 4
1 ˜ m1 (p) 104
s(m) = (1 − ej2πCc/C ) ˜ ˜
(11) Number of iteration
C N n=0 1 − e(j2π(Cq−p)/N +Cc/CN ) Sub-carrier mapping schemes DFDMA, IFDMA, LFDMA
Modulation data type Q-PSK and 16-QAM
So, the time domain symbols of DFDMA sub-carrier mapping Spreading factor for IFDMA 32
Spreading factor for DFDMA 31
have the same structure as those of LFDMA sub-carrier
mapping.
V. PAPR REDUCTION TECHNIQUE FOR LTE SC-FDMA exceeded with probability less than 0.1 percentile PAPR. The
SYSTEMS
PAPR calculation using various sub-carrier mapping schemes
In case of high amplitude signals subject to non linear for SC-FDMA and OFDMA system is shown in Fig. 5. The
power ampliﬁcation, PAPR reduction is one of the most modulation scheme used for the calculation of PAPR is QPSK.
importance performance parameter. This situation more and It can be seen that SC-FDMA sub-carrier mapping schemes
more occur due to the ever-growing demand in high spectral
efﬁciency telecommunications systems implying multi dimen-
0
sional waveforms considerations for which the PAPR is high. 10

In a single-carrier communication system, pulse shaping is
required to bandlimit the signal and ensures it meets the
spectrum mask. In this paper, a root raised cosine (RRC) ﬁlter
−1
is used to pulse shape the SC-FDMA signals. RRC is used 10

as the transmit and receive ﬁlter in a digital communication
system to perform matched ﬁltering. The combined response
Pr(PAPR>PAPRo)

of two such ﬁlters is that of the raised-cosine ﬁlter. The raised-
−2
cosine ﬁlter is used for pulse-shaping in digital modulation 10 Proposed DFDMA
Existing DFDMA
due to its ability to minimize intersymbol interference (ISI). Proposed LFDMA
Existing LFDMA
Its name stems from the fact that the non-zero portion of the Proposed IFDMA
frequency spectrum of its simplest form β = 1 (called the Existing IFDMA
OFDMA
−3
roll-off factor) is a cosine function, ’raised’ up to sit above 10

the f (horizontal) axis. The RRC ﬁlter is characterized by
two values; β, and Ts (the reciprocal of the symbol-rate). The
impulse response of such a ﬁlter can be given as:
 −4
10

 1 − β + 4β/π, t = 0
1 2 3 4 5 6 7 8 9 10 11
 √
 β/ 2[(1 + 2/π) sin(π/β4) + (1 − 2/π) cos(π/β4)],
PAPRo dB

h(t) = t = ±T /β4

 sin[πt/Ts (1−β)]+4βt/Ts cos[πt/Ts (1+β)]
s
 Fig. 5. Comparison of CCDF of PAPR for SC-FDMA with OFDMA using
πt/Ts [1−(4βt/Ts )2 ]) , else
QPSK.
It should be noted that unlike the raised-cosine ﬁlter, the
impulse response is not zero at the intervals of ±Ts . However, gives lower PAPR values as compared to OFDMA scheme.
the combined transmit and receive ﬁlters form a raised-cosine In addition, the root raised cosine pulse shaping method has
ﬁlter which does have zero at the intervals of ±Ts . Only in lower PAPR than the case of existing pulse shapping method
the case of β = 0, does the root raised-cosine have zeros at by more than 3dB. Due to the complex-weighting of LFDMA
±Ts . and DFDMA equation would increase the PAPR. Due to the
phase rotation it is unlikely that the LFDMA samples will
VI. PERFORMANCE ANALYSIS all add up constructively to produce a high output peak after
The performance of the aforementioned PAPR reduction pulse shaping. But it is shown that LFDMA has a lower PAPR
technique is explored by performing extensive computer sim- than DFDMA when pulse shaping is applied. Another PAPR
ulations. All simulation parameters of the LTE SC-FDMA simulation using various sub-carrier mapping schemes for LTE
systems are summarized in Table II [6]. SC-FDMA systems is shown in Fig. 6. The modulation scheme
The CCDF)of PAPR, which is the probability that PAPR used for the calculation of PAPR is 16-QAM. It show that
is higher than a certain PAPR value PAPR0, is calculated by IFDMA has lowest value of PAPR at 7.8dB which is 6.7dB in
Monte Carlo simulation. We compare the PAPR value that is case of QPSK as modulation technique. Finally, we conclude

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[3] B. Karakaya, H.Arslan, and H. A. Cirpan, ”Channel estimation for LTE
0
10 uplink in high doppler spread,” Proc. WCNC, pp. 1126-1130, April 2008.
[4] J. Berkmann, C. Carbonelli, F.Dietrich, C. Drewes, and W. Xu, ”On
3G LTE terminal implementation standard, algorithms, complexities and
challenges,” Proc. Int. Con. on Wireless Communications and Mobile
Computing, pp. 970-975, August 2008.
−1
[5] A. Ancora, C. Bona, and D.T.M. Slock, ”Down-sampled impulse response
10
least-squares channel estimation for LTE OFDMA,” Proc. Int. Con. on
Acoustics, Speech and Signal Processing, Vol. 3, pp. 293-296, April 2007.
[6] M. M. Rana, M. S.Islam, and A. Z. Kouzani, ”Peak to average power ratio
analysis for LTE aystems,” Proc. Int. Con. on Communication Software
Pr(PAPR>PAPRo)

and Networks, pp. 516-520, February 2010.
Proposed DFDMA
−2
10
[7] A. Ancora, C. B. Meili, and D. T. Slock, ”Down-sampled impulse
Existing DFDMA response least- squares channel estimation for LTE OFDMA,” Proc. Int.
Proposed LFDMA Con. on Acoustics, Speech, and Signal Processing, April 2007.
Existing LFDMA [8] L. A. M. R. D. Temino, C. N. I Manchon, C. Rom, T. B. Sorensen, and
Proposed IFDMA P. Mogensen, ”Iterative channel estimation with robust wiener ﬁltering in
Existing IFDMA
LTE downlink,” Proc. Int. Con. on Vehicular Technology Conference, pp.
−3
10 1-5, September 2008.
OFDMA
[9] J. Zyren, ”Overview of the 3GPP long term evolution physical layer,” Dr.
Wes McCoy, Technical Editor, 2007.
[10] H. G. Myung, J. Lim, and D. J. Goodman, ”Single carrier FDMA for
uplink wireless transmission,” IEEE Vehicular Technology Magazine, vol.
1, no. 3, pp. 30-38, September 2006.
−4
10
2 3 4 5 6 7 8 9 10 11 [11] M. Noune and A. Nix, ”Frequency-domain precoding for single carrier
PAPRo dB frequency- division multiple access,” IEEE Commun. Magazine, vol. 48,
no. 5, pp. 86-92, May 2010.
[12] H.G. Myung, J. Lim, and D. J. Goodman, ”Peak to average power ratio
for single carrier FDMA signals,” Proc. PIMRC, 2006.
Fig. 6. Comparison of CCDF of PAPR for SC-FDMA with OFDMA using [13] S. Maruyama, S. Ogawa, and K.Chiba, ”Mobile terminals toward LTE
16-QAM. and requirements on device technologies,” Proc. Int. Con. on VLSI
Circuits, pp. 2-5, June 2007.
[14] S. H. Han, and J. H. Lee, ”An overview of peak to average power ratio
reduction techniques for multicarrier transmission,” IEEE Transction on
that the higher values of PAPR by using 16-QAM which is Wireless Communications, April 2005.
undesirable because they cause non linear distortions at the [15] H. G. Myung, ”Introduction to single carrier FDMA,” Proc. Int. Con.
transmitter. on European Signal Processing (EUSIPCO), Poznan, Poland, September
2007.
[16] A. Sohl, and A. Klein, ”Comparison of localized, interleaved and block-
VII. C ONCLUSIONS interleaved FDMA in terms of pilot multiplexing and channel estimation,”
The efﬁciency of a power ampliﬁer is determined by the Proc. Int. Con. on PIMRC, 2007.
PAPR of the modulated signal. In this paper, we analysis
different sub-carrier mapping scheme for LTE SC-FDMA
systems. We derive the time and frequency domain signals
of different sub-carrier mapping scheme, and numerically
compare PAPR characteristics using CCDF of PAPR. We come
to the conclusion that the IFDMA sub-carrier mapping with
RRC pulse shaping method has lowest PAPR values compare
to the other sub-carrier mapping methods. As a results, im-
proves the mean power output from a battery driven terminal
equipment and power ampliﬁer efﬁciency. Therefore, SC-
FDMA is attractive for uplink transmissions since it reduces
the high PAPR seen with OFDMA.

ACKNOWLEDGMENT
This research was supported by the Basic Science Research
Program through the National Research Foundation of Korea
(NRF) funded by the Ministry of Education, Science and
Technology (20100017118).

R EFERENCES
[1] Q. Li, G. li, W. Lee, M. Il. Lee, D. Clerckx, and Z. li, ”MIMO techniques
in WiMAX and LTE: a feature overview,” IEEE Commun. Magazine, May
2010.
[2] E. Dahlman, S. Parkvall, J. Skold, and P. Beming, ”3G evolution HSPA
and LTE for mobile broadband,” Academic Press is an Imprint of Elsevier,
2007.

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