TSDSI-SG1-WG1-SI11-V0.1.0-20150909
Study Item Report
Radio Network Evolution and Spectrum (RNES)
Waveform Engineering for Cellular IoT System
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TBD
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1
References ............................................................................................................................................ 6
2
Introduction .......................................................................................................................................... 7
3
Purpose ................................................................................................................................................. 8
4
Intended Audience ................................................................................................................................ 9
5
Scope ................................................................................................................................................... 10
6
Definitions, Abbreviations, Acronyms ................................................................................................ 11
7
Justification, Scenarios and Architectural Requirements ................................................................... 12
7.1
Justification ................................................................................................................................. 12
7.2
Use Case Scenarios...................................................................................................................... 12
7.3
CIOT Waveform and Bandwidth study ....................................................................................... 17
7.4
CIOT System Management/Deployment issues ......................................................................... 29
7.5
Requirements/Motivation .......................................................................................................... 30
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Conclusion ........................................................................................................................................... 30
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Document Revision History................................................................................................................. 30
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1 References
[1]. G.Fettweis and S. Alamouti, “5G: Personal mobile internet beyond what cellular did to
telephony,” in IEEE Communications Magazine, Feb. 2014.
[2]. B. Farhang-Boroujeny, “OFDM versus filter bank multicarrier,” in IEEE Signal Processing
Magazine, May 2011.
[3]. V. Vakilian, T. Wild, F. Schaich, S. ten Brink, , and J.-F. Frigon, “Universal-filtered multi-carrier
technique for wireless systems beyond LTE,” in 9th International Workshop on Broadband
Wireless Access (BWA13) co-located with IEEE Globecom13, Dec. 2013.
[4]. M. S. R. Ayadi and I. Kammoun, “Transmit/receive pulse-shaping design in BFDM systems over
time-frequency dispersive AWGN channel,” in Proceedings IEEE International Conference on
Signal Processing and Communications (ICSPC07), Nov. 2007.
[5]. G. M. Krondorf and S. Bittner, “GFDM: Generalized frequency division multiplexing,” in IEEE
Vehicular Technology Conference (VTC Spring09), 2009. [6] N. Michailow, M. Matthe, I. S.
Gaspar, A. Caldevilla, and L. Mendes, “Generalized frequency division multiplexing for 5th
generation cellular networks,”IEEE Trans. Commun., 2014.
[6]. Physical Layer Aspects for Evolved UTRA (Release 8), 3GPP Std. TS 36.211, 2008.
[7]. DoCoMo, “DFT-spread OFDM with pulse shaping filter in frequency domain in evolved UTRA
uplink,” 3GPP TSG RAN1.
[8]. P. Laurent, “Exact and approximate construction of digital phase modualtions by superposition
of amplitude modulated pulses,” IEEE Trans. Commun., vol. 34, pp. 150–160, 1986.
[9]. K. Murota and K. Hirade, “GMSK modulation for digital radio telephony,” IEEE Trans. Commun.,
vol. 29, pp. 1044–1050, 1981.
[10].
B. Picinbono and P. Chevalier, “Widely linear estimation with complex data,” IEEE Trans.
Signal Processing, vol. 43, pp. 2030–2033, Aug. 1995.
[11].
W. Gerstacker, R. Schober, and A. Lampe, “Equalization with widely linear filtering,” in
Proc. IEEE International Symposium on Information Theory, Washington, DC, June 2001, p. 265.
[12].
N. Al-Dhahir, “MMSE decision-feedback equalizers: Finite length results,” IEEE Trans.
Commun., vol. 41, . 961–975, 1995.
[13].
J. Cioffi, EE:379 Stanford Class Notes. [Online]. Available:
http://www.stanford.edu/class/ee379a/
[14].
K. Kuchi, “Low PAPR Waveform Design for 5G using Generalized DFT-precoded
Orthogonal Frequency Division Multiple Access”, ISCWS 2015 , Aug 25-28th 2015
[15].
SWIP5 - Waveform Design using Generalized Precoded OFDM (GPO), TSDSI-SI11-SWIP5V1.0.0-20150814
[16]. SWIP18 - Internet of Utillity UE (IoU) for consideration of enhancement to SI, new RACH
procedure and CIoT, TSDSI-SI10-SWIP18-V1.0.0-20150901
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2 Introduction
TBD
7
3 Purpose
TBD
8
4 Intended Audience
TBD
9
5 Scope
This Technical Report describes Cellular IOT aspects including requirements, waveform study and system
aspects.
10
6 Definitions, Abbreviations, Acronyms
TBD
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7 Justification, Scenarios and Architectural Requirements
7.1 Justification
7.2 Use Case Scenarios
7.2.1
CIOT End to End Aspects
This section proposes an end to end requirement for Internet of Utility UE.
Below is brief recap on LTE and SAE following that we provide network architecture and requirement of
Internet of Utility UE.
Recap of LTE and SAE:
LTE or Long term evolution is a 3GPP standard for mobile communication. LTE refers to the Evolved
UMTS Radio Access Network (E-UTRAN), whereas System Architecture Evolution (SAE) refers to the
Evolved Packet Core (EPC).
Network elements in LTE include eNodeB (Base Transceiver Station – BTS), UE (user equipment – used to
connect to eNodeB for accessing or getting voice or data service), Relay Node and Repeater.
Network elements in SAE include MME (Mobility Management Entity), SGW (Serving Gateway), PDN-GW
(Packet Data Network Gateway).
eNodeB is responsible for completing radio resource management when allowing UE to access services.
eNodeB are connected to the EPC using MME for control plane signaling and using SGW for user plane
data.
The SGW is connected to a PDN-GW or PGW for connectivity to external networks including the public
internet.
eNodeB are of various types, e.g. Macro/Wide-area, Micro/local-area, Pico/Small-area, Femto/home,
and can be called, for example as Macro BTS, Femto BTS, etc.
Repeaters are used to extend the coverage of an existing BTS. They re-transmit the uplink and downling
signals without having to decode any of the content. Repeaters have one antenna directed towards the
donor cell, and a second antenna directed towards the target coverage area. The target coverage area
could be an indoor location so the second antenna could be indoors.
12
Relays also rely upon an RF connection to a donor cell, but Relays differ from Repeater because Relays
have their own cells and their own protocol stack. That is, a Relay is similar to a normal BTS but without
a fixed transport connection. Relays decode signals and make radio resource management decisions.
PGW connects to packet data network, which could be an external network (either public or private), or
could belong to the operator.
Other elements like HSS (Home Subscriber Server), EIR (Equipment Identify Register), PCRF (Policy and
Charging Rules Function), etc. and interfaces connecting all the above/preceding elements are also
defined in 3GPP specifications.
All architectures and types of Relay Node specified in 3GPP require enhancements to eNodeB and EPC
elements and therefore in addition to cost of Relay Node, the operators have to pay heavily, for
software and hardware upgrades in eNodeB and EPC elements.
What is Utility UE?
UEs that serve the below applications and the likes:
-
Water meter cannot have grid source and cannot have rechargeable power/battery source.
-
Electricity meter has grid source
-
Always Fixed in location. No mobility.
-
Send 40 bits (or 10 digits) per month and go to sleep/DRX.
Lets call them Utility UE!
The closest that we have in 3GPP is Category 0 UE with capability to exchange1000 bits. We need to
relook this also.
What is needed for such Utility UE?
•
Always OFF
–
LTE follows Always ON
13
–
•
•
•
IP address is reserved
•
S5/S8 bearer is reserved
•
Expensive Core Elements
So we need Always OFF/Dead/Asleep
Fastest SI acquisition
–
Low power UE cannot spend lot of resources
–
No SIB defined in 3GPP for such UE
Fastest Data transfer in Uplink
–
Modify RACH (WCDMA could upload data – not so in LTE)
–
No need of Default bearer; send data (40 bits or low data size) and sleep
–
One Dedicated bearer per application for 1 million to 1 billion devices
–
Is one bearer per UE needed?
Bearer establishment for UE in LTE
14
Proposed solution to handle Internet of Utility UE
-
These UEs include electricity meter, water meter, etc. that need to send meter reading to utility
companies, e.g. BESCOM
-
There will be million or billions such Utility UEs
-
It will be waste of time and network resources to create Point to Point (P2P) EPS bearer for all
Utility UE
-
It will be ideal for the utility company to setup one multipoint to point (MP2P) EPS bearer
constituting of multiple S1 bearers from all eNodeBs that are within the Tracking Area (TA) of a
SGW and one S5/S8 bearer from SGW to PGW
o
We are not saying how the utility company initiates the setting up of MP2P EPS bearer.
It can be via MME or via a special UE (owned only by the utility company) that requests
MME for such setup.
15
-
Once the MP2P EPS bearer is setup, a paging message can be sent to all Utility UE within the TA
to transmit their data
o
Traditionally EPS bearer is setup after the paging message, but here we need to reverse
the function
o
Also we are decoupling the EPS bearer setup from paging message; completion of setup
of MP2P EPS bearer can initiate paging message so that all Utility UEs can transmit, one
at a time or simultaneously.
-
Following the receipt of paging message, these Utility UEs will transmit their data over radio
bearer, one radio bearer for each UE.
-
Data from multiple Utility UE from single eNodeB will be multiplexed within S1 bearer. Data
from multiple S1 bearer will be multiplexed within S5 bearer.
-
Data from all Utility UE will be forwarded to Application Server of Utility company by the PDNGW or PGW.
Please see below illustration of Multipoint to Point EPS bearer.
Table of difference between LTE and the proposal:
16
Sr. no.
In LTE
Probably Not in LTE (?)
1
The paging message and setup of
EPS Bearer are coupled
The paging message and setup of EPS
Bearer are decoupled
2
P2P and P2MP EPS bearers
existed
MP2P EPS bearer is envisaged
3
Always ON: S5 bearer always is
always maintained even if UE
does not have any data to send
Always OFF: the MP2P EPS bearer is
setup only when the Utility company
wants to acquire meter readings from
all Utility UE; once acquired all the
resource associated EPS bearer is
relinquished
4
Consider Low data rate UE
Considers low data size UE or Utility
UE
MP2P EPS bearer is proposed to optimize the number of P2P EPS bearer and to optimize the network
resource requirement for collection of low data size messages from billion of Utility UE
–
Low data size could be 40 bits per month
–
All Utility UE will be identified by alteast two identities
–
•
UE identity
•
Utility Company identity
Case study
Bangalore (40x40 sq.km) with 10 million Utility UE can be served in one day by 10 BTS covering 100 km
radius
7.2.2
CIOT device ecosystem
7.2.3
LTE M2M Vs CIOT Scenario
7.3 CIOT Waveform and Bandwidth study
A waveform with very low peak-to-average-power-ration (PAPR) is proposed. In the proposed
Generalized- precoded-OFDM (GPO) method, data of multiple users is multiplexed in frequency domain
using orthogonal or non-orthogonal subcarrier mapping. The proposed method comprises of:
17
Constellation rotation of user data, DFT precoding and spreading, user specific frequency domain pulse
shaping (FDPS) possibly with certain excess bandwidth. The frequency domain pulse shaping filter
(FDPSF) introduces inter-symbol-interference (ISI) and possibly inter-user interference. For the special
case of binary modulation, we develop waveforms with low PAPR using frequency domain pulse shaping
filters (FDPSFs) that are derived from the linearized Gaussian pulse. To mitigate the ISI and selfinterference caused by the FDPSF, we use conventional and widely linear frequency domain multi-user
user equalization methods that have low-implementation complexity. The proposed method can be
used to develop waveforms with low PAPR, low out of band emission (OBE), and small bit error rate
(BER) penalty.
7.3.1
Waveform Description
Consider the waveform design for a single user case. Generalization to the case of multiple users
simultaneously sharing the available bandwidth will follow. The transmitter sends a block of M i.i.d
real/complex valued modulation alphabets with zero-mean and variance σ2 . Let at (l) denote the
𝑗𝜃(𝑙)
𝑎𝑡 (𝑙 ).
modulation data. We apply a constellation specific phase rotation θ(l) to obtain: 𝑥𝑡 (𝑙) = 𝑒
The DFT precoding of the data stream xt (l) is accomplished using a M -point DFT as
 j 2 lk
x(k )   xt (l )e M
k  0,..., M  1
M 1
l 0
(1)
where l, k denote the discrete time and subcarrier indices, respectively, and 𝑥(𝑀 + 𝑘) = 𝑥(𝑘).
Alternative to (1), a two sided DFT can be taken as.
x(k ) 
M
1
2

l
M
2
e j t ( l ) xi ,t (l )e
 j 2lk
M
M
M
k
1
2
2
.

 
LM 
~
x (m)  x   m 
 mod M   1
2 
  . Here, the

Consider a L fold periodic extension of x(k ) where
elements of the vector 𝑥̃(𝑚) take the range 𝑚 = −
𝐿𝑀
2
,..,
𝐿𝑀
2
− 1 𝑎𝑛𝑑 𝑀𝐿 = 𝑁, 𝑁 being total
n
~
x t ( n)  xt  
 L  for n  pL where p  0,1,.., M  1 and
number of used subcarriers. In time domain,
~
𝑁
𝑁
𝑁
x t ( n)  0
elsewhere and 𝑛 = − , . . , − 1. Here 𝑥𝑡 (𝑙) = 𝑥̃𝑡 (𝑙𝐿 − ) 𝑓𝑜𝑟 𝑙 = 0, . . , 𝑀 − 1. Let
2
2
~
x ( m) 
2
N
2
 ~xt (m)e
n
N
2
 2mn
N
m
N
N
,,, 1
2
2
(2)
18
 j 2 ( lL 
M 1
=
 x (l )e
l 0
N
)m
2
N
t
M 1
(3)
=e j m  xt (l )e
l 0
 j 2 lLm
N
(4)
𝑁
On line 1 we substitute the variable n with (𝑙𝐿 − 2 ).
Note: Note that the DFT operation in (1) can also be implemented as a two sided DFT with l in the range
[
−𝑀
2
𝑀
, . . , 2 − 1]. Alternatively, swap the left and right halves of x(k) with zero frequency component in
the middle.
Now consider a frequency domain pulse shaping filter
N
1
2
 q ( n )e
q ( m) 
t
n 
N
2
 j 2 nm
N
N
, m   ,..,  1
N
2
2
(5)
Where 𝑞𝑡 (𝑛) are the samples of the time domain pulse shaping filter. Note that 𝑞(𝑚) may take zero
values for certain subcarriers. Alternatively, all N subcarriers need not be modulated with data. In some
cases, some subcarriers at band edges may be nulled out. Applying the pulse shape to the transmitted
data 𝑥̃(𝑚), we have: 𝑥𝑞 (𝑚) = 𝑞(𝑚)𝑥̃(𝑚). The time domain baseband signal 𝑠(𝑡) is obtained using
an inverse discrete time Fourier transform (IDFT).
1
s (t ) 
N
N
1
2

q (m) x(m)e j 2 mf (t TCP ) , t  [0, T  bT ]
N
m 
2
(6)
where T is the useful portion of OFDMA symbol, TC P is the duration of the cyclic prefix (CP) and Δ𝑓 =
1
𝑇
is the subcarrier spacing. Note that b=1 when the system uses CP only and b = 2 when the system uses
cyclic prefix as well as cyclic suffix. Using (4) and (5), the analog signal can be rewritten as
1
s (t ) 
N
1
=
N
=
1
N
N
1
2

m 
e j m q (m) x(m)e j 2 mf (t TCP ) , t  [0, T  bT ]
N
2
(7)
LM
1
2
M 1
 x (l ) 
l 0
t
m
M 1
e 
j (l )
l 0
q ( m )e
1
lL 1
j 2 m ( ( t TCP )   )
T
N 2
 LM
2
at (l )q p (t  TCP 
(8)
lT T
 )
M 2
(9)
19
q p (t )  
where
N
1
2
m 
N
2
q ( m) e
j 2 m
t
T
and t  [0, T  bT ] is the time domain pulse shaping function and
𝑥𝑡 (𝑙) = 𝑒 𝑗𝜃(𝑙) 𝑎𝑡 (𝑙). Note that 𝑞𝑝 (𝑡) = 𝑞𝑝 (𝑡 + 𝑟𝑇), r being an integer. The transmitter sends
successive data blocks serially where each data block is limited to a duration of 𝑇 + 𝑏𝑇𝐶𝑃 seconds. Here,
the time domain signal has a form similar to conventional SC-FDMA with q(t) being the pulse shaping
function.
7.3.2
Multiple Access
Consider the multiple access scenarios where a number of users share the available bandwidth
simultaneously. We consider both non-orthogonal and orthogonal user allocations where the users may
employ distinct pulse shapes with different bandwidth requirements. Assuming there are a total of u
users, let us denote the data of the ith user with 𝑥𝑖 (𝑘) where
xi (k ) 
M i 1
e
jt ( l )
l 0
xi ,t (l )e
 j 2 lk
Mi
, k  0,.., M i  1
(10)
where Mi is the data length of the ith user, 𝜃𝑖 (𝑙) being the constellation rotation employed by the ith user
data 𝑥𝑖,𝑡 . Note that the DFT operation in (10) can be implemented using a two sided DFT as
xi ( k ) 
Mi
1
2

l
e
M i
2
j t ( l )
xi ,t (l )e
 j 2lk
Mi
 Mi
M
 k  i 1
2
2
Let 𝑥̃𝑖 (𝑚) denote the Li fold periodic extension of 𝑥𝑖 (𝑘) where 𝐿𝑖 𝑀𝑖 = 𝑁 and let 𝑞𝑖 (𝑙) be the FDPSF
associated with this user that is defined as
qi (m) 
N
1
2

n 
qi ,t (n)e
 j 2 mn
N
N
2
, for m  
Mi
M
,.., i  1
2
2
(11)
= 0 elsewhere
(12)
where 𝑞𝑖,𝑛 (𝑡) are the corresponding time domain samples. Note that the FDPSF takes non-zero values
over M¯i subcarriers where M¯i − Mi is the excess number of subcarriers employed for the ith user. In
this case, (M¯ i − Mi )∆f is denoted as the excess bandwidth employed by the ith user. Further, the users
are frequency multiplexed over the given the band of interest as
1
si (t ) 
N
N
1
2

m 
N
2
qi (m  mi )xi (m)e j 2f (t TCP ) , t  [0, T  bTCP ]
(13)
20
where mi is the frequency shift of the ith user. The proposed method results in a non-orthogonal
̅𝑖 . Note that, the values of mi are
multicarrier signal if the values of mi are set to integer multiples of 𝑀
chosen based on the subcarrier mapping procedure employed by the system.
The transmitted signal can be represented in an alternative form as
si (t ) 
M i 1
1
N
e
j (l )
l 0
ai ,t (l )qi , p (t  TCP 
N
qi , p (t )   2
1
m
 N qi ( m  mi )e
lT T
 ), t  [0, T  bTCP ]
Mi 2
j 2 m
(14)
t
T
2
Where
is the time domain pulse shaping function employed by the
th
i user. Here, 𝑞𝑖,𝑝 (𝑡) = 𝑞𝑖,𝑝 (𝑡 + 𝑟𝑇), where r is an integer.
Let
N
1
2

qi , p (t ) 
m
N
2
qi (m  mi )e
j 2 m
t
T
t  [0, T  bTCP ]
(15)
Using (11) and and substituting m − mi = m1 in (15) we express qi(t) in alternative form as
qi , p (t )  e
 q0,i (t )e
j 2 mi
Mi
1
2
t
T

 Mi
m
2
 j 2mi
t
T
q0,i (t )  
qi (m)e
j 2 m
t
T
(16)
t  [0, T  bTCP ]
Mi
1
2
 Mi
m1 
2
qi (m1 )e
j 2 m
(17)
t
T
and
is the baseband pulse shaping function used by the ith user. Now
we can rewrite the transmitted signal as
si (t ) 
1
N
M i 1
e
l 0
j i (l )
ai ,t (l )q0,i (t  TCP 
lT T
 )e
Mi 2
j 2 mi
( t TCP 
lT T
 )
Mi 2
T
(18)
21
In practice, the total number of subcarriers is N. However, only Nu subcarriers out of N may be used by
the system. The remaining (N-Nu) subcarriers do not carry the data. Furthermore, a number of users are
frequency multiplexed over the Nu subcarriers. The transmitted signal in its general form is given by
si (t ) 
1
j 2f ( t Tcp )
qi (m  mi ) ~
xi (m)e

Nu m

t  0, T  bTcp

Here the transmitted signal spans over a group of subcarriers whose range is dictated by the subcarriers
occupies by the signal of the ith user. Furthermore, the value of mi is a system design feature that can
be used to control the amount of non-orthogonality introduced by the system. The value of mi may be
0

M
M
Mi
. Note that the modulation type, the DFT size, and the type of FDPSF used can be varied at
M
i increases
set to i , i or any other value. For example, setting the value of mi in the range
the spectrum efficiency of the system. Another alternative is to choose the value of mi in the range.
M
i
user level.
7.3.3
Symbol Windowing
As the transmit signal is confined to a period of one OFDM symbol duration, effectively it imposes a
rectangular window function that leads to high OBE. In order to reduce OBE we employ alternative time
domain window functions that offer smooth transitions at the OFDM symbol boundaries. The proposed
method includes a cyclic prefix as well as cyclic postfix each of duration TC P . The analog signal can be
rewritten as
1
si (t ) 
N
1
=
N
N
1
2

w(t )qi (m  mi ) xi (m)e j 2 mf (T TCP ) , t  [0, T  bTCP ]
N
m 
2
M i 1
(19)
e
l 0
j i (l )
ai ,t (l ) w(t )qi , p (t  TCP 
lT T
 ), t  [0, T  bTCP ]
Mi 2
(20)
where w(t) is the proposed window function defined over the interval 𝑡 Є [0, 𝑇 + 𝑏𝑇𝐶𝑃 ] (that is
designed as the OFDM symbol block duration). It is common practice to choose the window w(t) such
that is takes a constant value for the duration of the OFDM symbol that excludes cyclic prefix and suffix.
Additionally, the window may take a constant value during a portion of the cyclic prefix and/or suffix
and it tapers to a zero value at the block boundaries. Raised cosine (RC) window is used in this
contribution.
Note:To avoid the dc subcarrier, the transmitted signal si (t) is further multiplied with 𝑒 𝑗𝜋Δ𝑓(𝑡−𝑇𝐶𝑃 ) or
𝑒 −𝑗𝜋Δ𝑓(𝑡−𝑇𝐶𝑃 ).
7.3.4
Frequency Domain Pulse Shaping Filter
This section proposes a design procedure that enables low PAPR waveform design. The PAPR can be
controlled using a suitable choice of constellation rotation factor θ(l), modulation size Q and the FDPSF
22
q(m) given in (5). We let 𝜃(𝑙) =
such as QAM, we let 𝜃(𝑙) =
𝜋(𝑙−1)
2
for real constellations, and for Q-ary complex constellations
𝜋(𝑙−1)
𝑄
. For the special case of Q=2 (that is the focus of this SI), we design
waveforms with nearly constant envelope by selecting 𝜃(𝑙) =
𝜋(𝑙−1)
2
, and by choosing the FDPSF based
on the linearized Gaussian pulse that is obtained as the principal pulse in the PAM decomposition of a
binary CPM signal with modulation index 0.5. The time domain samples of the FDPSF qt (n) can be
chosen as:
qt (n)  p0 (t )
t  0 
nT
s
where p0 (t) is the linearized Gaussian pulse, s is the over-sampling factor, and the factor BT controls
the characteristics of the waveform, and
0
is constant time offset, and n is an integer. Since the pulse is
 sM
sM
n
1
2
2
n
time limited, the values of can be taken in the range
.
𝑠
With an over-sampling rate of s, the Fourier transform of qt (n) is periodic with a period . The FDPSF
𝑇
with a span of sM subcarriers is obtained by taking a sM point DFT of qt (n) as defined in (11).
Alternatively, the FDPSF can be obtained by taking an sM point DFT first as
q~(m) 
sM 1
 qt (n)e
 j 2nm
sM
0  m  sM  1
n 0
Then, the left and right halves of the DFT output can be swapped so that the zero frequency
components in the middle. Alternatively, the FDPSG can be obtained using a two sided DFT as
q ( m) 
sM
1
2
 qt (n)e
n
 sM
2
 j 2nm
sM
 sM
sM
m
1
2
2
For the special case of s=1, we can design PDPSF without excess BW. In this case, the waveform
introduces ISI but has zero multi-user interference. To obtain the time domain samples for s=1, we can
first generate the samples corresponding to s=2, then choose either the even or odd symbol spaced
sample sequence to generate the required FDPSF.
Note: The frequency domain FDPSF can be applied to a selected users who are located at the cell edge
for increasing the transmit power. Remaining users can use conventional QAM modulation without
applying FDPSF.
7.3.5
Linearized GMSK Pulse
The principal pulse p0 (t) is the main pulse in Laurent’s decomposition [9] is given by
23
𝑘=𝐿1
𝑝0 (𝑡) = {∏𝑘=1 𝑐(𝑡 − 𝑘𝑇) 𝑡 Є [0, (𝐿1 + 1)𝑇]
0
𝑜𝑡ℎ𝑒𝑟𝑤𝑖𝑠𝑒
where
𝜋
cos (− 𝑞(𝑡)) 𝑡 Є [0, 𝐿1 𝑇)
2
𝑐(𝑡) =
𝑐(−𝑡)
𝑡 Є (−𝐿1 𝑇, 0]
0
|𝑡| ≥ 𝐿1 𝑇
{
The pulse q(t) is a Gaussian filtered rectangular pulse response defined as
q(t ) 
1
t 1
t 1
[Q( (  ))  Q(  (  ))]
T
T 2
T 2

2 BT
1
,
Q( x ) 
(ln(2)) BT is a parameter that controls the pulse shape, and
2

 e
x

u2
2
du.
where
The value of L1 determines the pulse duration. Typically this value is chosen to be in the range 4-6.
7.3.6
Results and Discussion
In Fig 1, the magnitude power spectrum (in dB) of different frequency domain pulse shaping filters is
given as a function of subcarrier index. We consider the case of M=24 and show the magnitude power
spectrum over a span of 72 subcarriers. We consider three cases: BT=0.3, s=2, BT=0.3, s=1, and
$BT=\infty, s=3.
In simulation, the PAPR of the waveform is measured in dB for each OFDM symbol and the cumulative
distribution function (cdf) is plotted in Fig 2 without windowing. We assume M=24. The PAPR at 99 %cdf
point is recorded for different waveforms. MSK corresponds to BT=infinity Withs=3 MSK spans 3M
subcarriers and gives a PAPR of 0.09 dB. The GPO modulator generates a conventional MSK-like signal
with approximately constant envelope. Reducing the BW occupancy of the signal to less than 3M
increases the PAPR to 1.55 dB for s=2 and 1.95 dB for s=1. If the excess BW is restricted to 100 percent
i.e., for s=2, BT=0.3 gives a PAPR of 0.79 dB that is less than of MSK with s=2. If the system does not have
any excess BW i.e., for s=1, BT=0.3 Type-A pulse gives a PAPR of 1.97 dB. The PAPR reduction obtained
for any of these proposed pulses is significantly less than the case of rectangular FDPSF with s=1 that has
a PAPR of 5.16 dB. For reference, the PAPR of QPSK modulation with rectangular FDPSF is shown in
Table-1 as 6.18 dB.
24
In Fig 3, the PAPR cdf with RC windowing Is given. In all cases, use of RC window increases the PAPR by
approximately 1.0 dB.
In Fig 4-7, the average psd of proposed waveform for different BW allocations with and without RC
window is given. It can be seen that the RC window significantly reduces the OBE compared to standard
OFDM case in all cases.
In Fig8, the BER results for the case of rectangular FDPSF and for (BT=0.3, s=2), (BT=0.3, s=1) and
(BT=infinity, s=3) cases is given. The results are averaged over 10000 OFDM symbol realizations with
(M=12). The BER of WL GMMSE receivers [15] for the considered cases are close to that of rectangular
FDPSF. However, the conventional GMMSE with (BT=0.3, s=2) has approximately 1.9 dB loss at 1% BER
and for the case of (BT=infinity, s=3) the loss is 0.9 dB. We see that the WL receiver is able to fully
mitigate both ISI and multi-user interference created by the pulse shaping filters.
Figure-1: Frequency Domain Pulse Shaping Filter Response
25
Figure2: PPAR without windowing
Figure3: PAPR with windowing
26
Figure4: PSD-30KHz without windowing
Figure5: PSD-30 KHz with windowing
27
Figure6: PSD-180 KHz without windowing
Figure7: PSD-180KHz with windowing
28
Figure8: BER
7.4 CIOT System Management/Deployment issues
TBD
29
7.5 Requirements/Motivation
8 Conclusion
TBD
9 Document Revision History
Version
Date
Released by
Change Description
Version 0.1.0
20150909
9th
September,
2015
Champion: Kiran Kuchi, IIT-H
SG1-WG1-MTG1
Contributors: Satish Jamadagni, Reliance;
Vinod Kumar, Tejas Networks, Klutto
Milleth, CEWiT
30