Generalized Frequency Division Multiplexing with

Generalized Frequency Division Multiplexing with Index Modulation Ersin Öztürk1,2, Ertugrul Basar1, Hakan Ali Çırpan1 1Istanbul

Technical University, Faculty of Electrical and Electronics Engineering, 34469, Maslak, Istanbul, Turkey 2Netaş, Department of Research and Development, 34912, Pendik, Istanbul, Turkey

GFDM-IM Transmitter

INTRODUCTION

GFDM-IM Receiver

RESULTS

Driver

Aim

Requirement

High data rate

High spectral efficiency

Description Number of subcarriers Number of subsymbols GFDM demodulator Pulse shaping filter Length of cyclic prefix

Cloud services

Dynamic spectrum usage Low OOB emission

Internet of things

Low power consumption Relaxed synchronization

Exponent of power delay profile

Tactile internet

Cyber physical control

Number of channel taps

Ultra low latency

What are the PHY candidates for 5G? • Asynchronous and nonorthogonal systems have a potential to fullfil the requirements of the new concepts • Promising candidates • Filter Bank Multicarrier (FBMC) • Universal Filtered Multicarrier (UFMC) • Generalized Frequency Division Multiplexing (GFDM)

GFDM - Main Properties & Benefits • Transmits a block composed by subcarriers with

time slots on each of it

: Number of subcarriers,

Step-3: Spatial Modulation • Map each group of bits to a subcarrier group of length • Index selection • Select out of active subcarriers by the first 1 bits of bits sequence , , ,

∈ [1,… ,

.

• Enables low-complexity frequency equalization

• Inspired by the pioneering idea of SM, OFDM with index modulation (OFDM-IM) is a recently proposed novel scheme • OFDM-IM transmits information not only by constellation symbols, but also by the indices of the active subcarriers that are activated according to the corresponding information bits • OFDM-IM has attracted significant attention during recent times due to its appealing advantages over classical OFDM: • Flexible system design with adjustable number of active subcarriers • Improved error performance for low-to-mid spectral efficiencies • Improvements over classical OFDM in terms of ergodic achievable rate • We investigate the combination of the IM technique with GFDM • The main contributions of this study • The construction of the GFDM-IM system model • The evaluation of its BER performance for Rayleigh multipath fading channels RESEARCH POSTER PRESENTATION DESIGN © 2015

www.PosterPresentations.com

, ,

,…,

1, … , and + 1,… ,

, '

,

.

+ ∈ S, for &

1, … ,

.

,

1 ,.

,

,

2 ,...,.



, ,

2

,

. bits 0

1

1, … , , γ 1,…

,'

5

,

6 ∈ {0, S}, for &

1, … ,

,'

,

1

,4

,

1

,

and the forms the data block for

,…,4

,

1 1

4 1, 4 1 , … , 4

symbol as 4

1 1

Step-7: Apply Nq x nq block interleaving to 4 and get 4: Step-8: Modulate the data block 4: is by GFDM modulator C@ ?@


&

,

K

5

,

L4:

L :

,

0, … , ; > 1

transmitter matrix

Step-9: Add a CP with length ;DE in order to avoid ISI

;



;DE

128 5 MMSE RRC 32

n

0.1

;1oE

10

4\

]MMSE O

cd Q Le Pe PL

]``ab

@

4,

Le Pe

Step-3: Block deinterleaving • Apply Nq x nq block deinterleaving to 4\ and get 4\ Step-4: Primary data block splitting • Divide 4\ into groups each containing

,

arg min 4\ 4h,i

,

• •

2,

2, m

samples and get 4\m,q

> 4

,

j

•

• •

Step-7: Combine the outputs of the decision blocks and forms the -bit sequence

•

Bits

Indices

[0 0]

{1,2}

Subcarrier Group [sχ sξ 0 0 ]T

[0 1]

{2,3}

[0 sχ sξ 0 ]T

[1 0]

{3,4}

[0 0 sχ sξ]T

[11]

{1,4}

[sχ 0 0 sξ]T

Error performance of GFDM-IM system becomes slightly worse than GFDM system below 15 dB as in the OFDM-IM system For high SNR values, GFDM-IM provides approximately 5 dB better BER performance than classical GFDM for a target BER value of 10>5 at the same spectral efficiency The reason behind this BER performance improvement of the GFDM-IM scheme can be explained by the improved Euclidean distance spectrum due to IM It is observed that increasing the roll-off factor slightly degrades the performance

BER performance of the GFDM and the GFDM-IM systems for 4QAM transmission in Rayleigh multipath channel using the look-up table given in Table III

CONCLUSION •

In this study, a novel multicarrier modulation scheme, which is constructed by the combination of GFDM and IM, has been proposed

•

It has been demonstrated that the proposed GDFM-IM system provides significant BER improvement compared to classical GFDM system without increasing the transmitter complexity

•

As a result, by using GFDM-IM scheme, it is possible to reduce the transmit power of a mobile terminal in an uplink scenario

•

We conclude that GFDM-IM scheme can be considered a promising candidate for future 5G wireless networks

4,

• GFDM-IM transmitter: No multiplication for IM and block interleaving, identical complexity, Interleaver does not insert any latency • GFDM-IM receiver: Complexity increase due to searching for all possible subcarrier index combinations and signal constellation points • The computational complexity of GFDM-IM receiver increases by - @ with the increasing values of -

3,

2, m

Subcarrier Group [0 0] {1,2,3} [sχ sξ sδ 0 ]T Bits Indices

[0 1] {1,2,4}

[sχ sξ 0 sδ]T

[1 0] {1,3,4}

[sχ 0 sξ sδ]T

[1 1] {2,3,4}

[0 sχ sξ sδ]T

[1] [2] [3]

[4] [5]

[6] [7]

TABLE III. Look-Up Table (4,3) for Subcarrier Index Modulation

Computational Complexity

Transmitter Matrix for roll-off factor: 0.1

• The spectral efficiency gain of the GFDM-IM system over OFDM-IM ; 1 Q qr p ; 1 Q qr

4

[8] [9] [10] [11] [12] [13] [14]

• The spectral efficiency gain of the GFDM-IM system over GFDM system ps

Q

log

, -

Transmitter complexity of the GFDM and GFDM-IM systems is identical Therefore, this significant BER improvement of the proposed GFDM-IM system is provided without increasing the transmitter complexity By using GFDM-IM scheme, it is possible to reduce the transmit power of a mobile terminal in an uplink scenario The proposed GFDM-IM receiver requires four times higher complex multiplications The complexity increase at the receiver is not a major concern for an uplink scenario where the base station has relaxed power and space constraints with respect to the mobile terminal However, GFDM-IM system can provide an interesting trade-off between complexity and BER performance for downlink transmission scenarios Furthermore, spectral efficiency gain of the GFDM-IM system over OFDM-IM system for the configurations given in Tables I, II and III is 19%

REFERENCES •



Recover the information bits by applying the inverse mapping process for both modulated symbols and indices of the active subcarriers

•

4

samples and get 4\m

Step-6: Decide active subcarriers and detect their corresponding information symbols • Calculate the Euclidean distances between the 4\m,q and all possible subcarrier index combinations as well as signal constellation points • Make a joint decision on the active indices and the constellation symbols by minimizing the following metric 4f

•

Spectral Efficiency

& 5 ; . exp >I2J N

]

TABLE II. Look-Up Table (4,2) for Subcarrier Index Modulation

Step-8: Combine all the -bit groups and forms the information bits

Step-6: Primary data block creation • Combine the data blocks 4 and forms the main data block for a GFDM

Value

BER performance of the GFDM and the GFDM-IM systems for BPSK transmission in Rayleigh multipath channel using the look-up table given in Table II

Step-2: GFDM demodulation • Joint equalization and demodulation

•

4

Parameter

P : ; N ; circular convolution matrix, R : AWGN samples vector

1, … , and 6 1,… ,

Step-5: Secondary data block creation • Combine the transmit symbol vectors 4 subsymbol & as 4

Step-1: Cyclic prefix removal • Under the assumption that CP is longer than ;ch and perfect synchronization is ensured, the received signal after CP removal can be expressed as O PK Q R

Step-5: Secondary data block splitting • Divide 4\m into groups each containing

Step-4: Subcarrier block creation • Set inactive subcarriers to zero and create the vector of transmit symbols for a 1 5 , 1 ,5 , 2 ,...,5 , subcarrier group &, ' as 4 ,

GFDM with Index Modulation • Spatial modulation (SM) is a novel MIMO transmission technique which extends the two dimensional signal constellations to the spatial (antenna) dimension

1, … ,

-

• Uses only one cyclic prefix (CP) per GFDM block

• Prevents long filter tail

], for &

,

, ,

,

• Q-ary modulation • Select data symbols for the active subcarriers by the remaining

• Can tolerate loose time and frequency synchronization

• Uses circular convolution for filtering

groups each

Step-2: Secondary bit splitting • Divide these bits into groups each containing bits, i.e., = / • Divide the subcarriers of each GFDM subsymbol into groups each containing subcarriers, i.e., /

• Uses circular pulse shaping of individual sub-carriers

• Increase spectral efficiency

: Number of subsymbols, ; =

Step-1: Primary bit splitting: • Take information bits as input and divide these bits into containing bits, i.e., = /

• Permits flexible time and frequency partitioning to reduce the PHY latency • Reduces out-of-band (OOB) emission to serve for fragmented spectrum allocation

DISCUSSION • •

Table I. Simulation Parameters

What are the requirements of 5G?

• •

GFDM-IM and GFDM error performance are nearly identical for low SNR values For high SNR values, GFDM-IM provides approximately 5 dB better BER performance as in BPSK transmission case

[15] [16]

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