International Conference on Recent Trends in Engineering, Computer, Information Technology and Applications

(ICRTECITA – 2018)

Seventh Sense Research Group www.internationaljournalssrg.org Page 1

Performance Analysis of Various Modulation

Technique in WiMAXB.Prabha,

Dept. of Electronics &

Communication Engg.

Sona College of Technology,

Salem,India.

S.Vijayashaarathi,

Dept. of Electronics &

Communication Engg.

Sona College of Technology,

Salem,India.

A.P.Jayakrishna,

Dept. of Electronics &

Communication Engg.

Sona College of Technology,

Salem,India.

Abstract - In the field of wireless

communication, the Worldwide Interoperability

for Microwave Access (WiMAX) is one of the

upcoming wireless system which uses the standard

of IEEE 802.16. There are various modulation

methods used for the processing of the given signals

in WiMAX which is based on the parameters such

as voice, audio, video and multimedia signals, in

these techniques the problem occurs is the selection

of modulation which is suited for the given input

signal depends on their performance of BER and

SNR/ SQNR. From the different modulation

schemes, the Delta Modulation is having the better

performance of BER and SNR/SQNR value as

4.0065e-07.

Keywords: WiMAX, BER, DM, SNR,

SQNR, AM, ADM.

I. INTRODUCTION

WiMAX can provide broadband wireless

access (BWA) typically 50 Km for Fixed stations and

5-15 Km for Mobile stations. Whereas in contrast, the

Wi-Fi/802.11 wireless local area network standard is

limited in most cases to only 30-100 m. WiMAX is an

IP based, wireless broadband access technology that

provides performance similar to 802.11/Wi-Fi

networks with the coverage and QoS (Quality of

Service) of cellular networks. The schematic

representation of WiMAX network is shown in Fig

1.which has a Base station and Subscriber station of

the network.

The original version of the standard on which

WiMAX is based (IEEE 802.16) specified a Physical

layer operating in the 10 to 66 GHz range. 802.16a

updated in 2004 and its specification range is from 2

to 11 GHz. Then 802.16e updated in 2005 and uses

Scalable orthogonal frequency division multiple

access (SOFDMA) which is a method of encoding

digital data on multiple carrier frequencies.

Fig 1: WiMAX Network

SOFDMA as opposed to the fixed orthogonal

frequency division multiplexing (OFDM) version with

256 sub carriers in 802.16d [3]. More advanced

versions, including 802.16e, also bring multiple

antenna support through MIMO (multiple input

multiple output). This brings potential benefits in

terms of coverage, self-installation, power

consumption, frequency and bandwidth efficiency.

Orthogonal frequency division multiplexing

(OFDM) [4] technique offers promising solution that

has gained tremendous research interest in recent years

due to its high transmission capability and also for

alleviating the adverse effects of Inter Channel

Interference (ICI) and Inter Symbol Interference (ISI).

OFDM is achieved by providing multiplexing on users

data streams on both uplink and downlink

transmission. OFDM is the fundamental building

block of the IEEE 802.16 standard.

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This article integrates into the following chapters: 2.

Literature survey, 3. Proposed work, 4. Result and

Discussion, 5. Conclusion.

II. LITERATURE SURVEY

In WiMAX, the various modulation

technique is applied in order to analyze the

performance of SNR and BER , from that we take

some of the paper as reference that are discussed

below.

From the design of an FPGA based OFDM

STBC transceiver [1], the design and implementation

of Space Time Block Code (STBC) transceiver is a

high level design and the simulation platform they

used here was MATLAB and they implemented in the

FPGA Kintex 7 kit. The main challenge they face in

the implementation process is minimum resource

memory but the system is reliable, the operating

frequency of the system is 100MHz but the bit rate is

3Mbps, in the process while they receive the data bits

in the ideal condition the FFT/IFFT generates an error

condition this can resolved by using the QPSK

mapping condition.

In the design of Address generator using

Different modulation Schemes [2], the various

modulation scheme used in the Adaptive modulation

was QPSK, 16-QAM, 64-QAM. In this paper they

proposed the system with HDL Verilog coding using

the platform as Xilinx ISE. The code rate comparison

for the modulation scheme as taken for QPSK,16-

QAM and 64-QAM and the hardware implementation

is done by using the Xilinx Virtex 4 then the

interleaver depth is taken for the Adaptive modulation.

The Adaptive modulation and Coding in

OFDM for WiMAX [3], is mainly focused on SNR or

BER values from receiving packets. They maintaining

the target in the channel of BER of 0.01 or 0.001, the

modulation scheme used in the system was QPSK

modulation scheme with FFT size of 1024 for

WiMAX. The higher level of modulation scheme

gives higher data rate with the establishment of high

level of BER value, similarly for lower low level of

modulation scheme which gives a better BER value

with a poor throughput performance level. The various

modulation level is taken for the parameters such as

BER, MSE, FFT length.

While passing the signal from transmitter to

receiver path the burst error is occurred, this error can

be removed by using the Forward Error Correction

(FEC) method and this can be analyzed in the

reference of Block interleaver of OFDM based

WiMAX [4], the simulation result was mainly focused

on the performance analysis of BER in different fading

channels such as Rayleigh, AWGN and Rician

channels. The bit interleaver and block code is mainly

focused on the BPSK modulation on the various

channels, the interleaver coding gain for this is about

5 dB for Rayleigh and 10.3 dB for Rician channel.

The various application for the real time long

range signal transmission is referenced in the

Performance analysis of Mobile WiMAX technology

[5] in military application, the performance analysis is

simulated mainly using the platform as MATLAB

software. The mobility of WiMAX is adopted on the

SOFDMA as a modulation technique in the physical

layer of the MIMO system. The long range

transmission of signals around 30 miles in the

theoretical manner but in practical it covers the

distance of 6 miles, the MAC layer is mainly focused

on QOS which includes throughput, packet error rate,

delay, jitters and so on. The signal transmission as

voice, data, video and audio.

III. PROPOSED WORK

WiMAX supports a variety of modulation

and coding schemes and allows for the scheme to

change on a burst-by-burst basis per link, depending

on channel conditions. Using the channel quality

feedback indicator, the mobile can provide the base

station with feedback on the downlink channel quality.

For the uplink, the base station can estimate the

channel quality based on the received signal quality.

A. Adaptive Modulation

Adaptive Modulation is the ability to modify

the modulations scheme based on the characteristics of

the transmission channel and the throughput

requirement of the user. The technique used in the

mobile communication is EDGE, it is used in the link

adaptation. Under this adaptive modulation technique

various modulation technique Fig 2 is carried out in

WiMAX namely 64-QAM, 16-QAM and QPSK. This

Adaptive modulation is undertaken in the Physical

Layer of the WiMAX. During the working process if

the signal condition is good it referred as 64-QAM,

similarly if the signal condition is poor (or)

intermediate it referred as 16-QAM, QPSK, Robust

BPSK. Based on the signal conditioning and code rate

the SNR, BER values is calculated.

B. Physical Layer of WiMAX

In the physical layer of WiMAX, various

modules are used namely signal generator, serial to

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parallel convertor, interleaver, convolutional encoder,

Add cyclic prefix, IFFT, for transmitter and parallel to

serial convertor, reconfigurable De-interleaver,

Viterbi decoder, Remove cyclic prefix, FFT, for

receiver. Using this module to decrease the

interference, Burst error, power consumption and

increase the output.

Fig 2: Block diagram of WiMAX Transceiver

The above is the block diagram

representation of WiMAX transceiver Fig 3, from that

the STP convertor is the block which is used for the

conversion of input serial input data to parallel data

for increasing the speed and decreasing the errors in

transmitter. In the receiver side the parallel data is

converted into serial data by using the Viterbi decoder.

The convolutional encoder is used in the

block diagram for the purpose of reducing the bit error

rate (BER). The BER is inversely proportional to the

SNR. The decoder which it used for the demodulation

of signal from the mapper. This is a type of error-

correcting code that generates parity symbols via the

sliding application of a Boolean polynomial function

to a data stream. The sliding application represents the

'convolution' of the encoder over the data, which gives

rise to the term 'convolutional coding.'

One of the most popular ways to correct burst

errors is to take a code that works well on random

errors and interleave the bursts to “spread out” the

errors so that they appear random to the decoder. There

are two types of interleaver commonly in use

today, block interleaver and convolutional interleaver.

The block interleaver is loaded row by row with L

code words, each of length n bits. These L code words

are then transmitted column by column until the

interleaver is emptied. Then the interleaver is loaded

again and the cycle repeats. At the receiver, the code

words are DE-interleaved before they are decoded.

The main drawback of block interleaver is the delay

introduced with each row-by-row fill of the

interleaver.

OFDM are performed by the two sequential

blocks, namely mapper and inverse fast Fourier

transform (IFFT). Here the Add cyclic prefix and

Remove cyclic prefix are used, which is to remove the

errors occurred while passing the signal from

transmitter to receiver side.

C. Delta Modulation

By using the delta modulator it is one of the major

challenge to find the step size of the message signal. A

DM is an analog to digital and digital to analog signal

conversion technique used for transmission of

information such as voice. The voice signal is used as

a message input in the delta modulation technique, the

signal is get as an input in the process as using wave

recorder format and the signal is to be plotted. Now

the input audio waveform is to be modulated by using

the delta modulation process in this method the

maximum variation in the message signal which

means the input audio signal and the step size is

calculated,

Fig 3: Process – Delta Modulation

The calculated data is to be

transmitted into the data files of binary form. Again

the modulated signal is demodulated by using the

demodulator process.

IV. RESULT AND DISCUSSION

From the above section it is clear that the

various modulation techniques are used in this work,

now the performance analysis of each modulation

technique is represented and discussed below.

The performance analysis is taken under the

various factors such as Voice, Audio and video, for

that the BER and SNR/SQNR is calculated and

analyzed as shown in the tabulation below

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.

Table 1: Performance analysis of various

parameters.

From the above tabulation value the various

parameters are analyzed such as voice, audio and

video is taken as for comparison of which modulation

technique is better in the WiMAX. In the initial

process the voice is given as the input signal value, in

that the SNR value is considered for AM and SQNR

for the DM, the delta modulation is having the better

performance than SNR. Similarly, for audio and video

is also compared the Delta modulation technique is

having better performance than Adaptive modulation.

Fig 4: Voice parameter for ADM

In the voice parameter the voice is taken in

the real time and then it is modulated, the voice

frequency waveform is calculated and showed in the

above figure, it has been analyzed and the quantization

noise error for the given signal is calculated and SQNR

is measured.

Fig 5: Audio parameter for ADM.

Similarly for audio is also having the same

procedure in calculation of performance of SQNR, the

bit value is high in audio compared with voice. The

video parameter process is also same as the but the bit

rate is high in compared with the other parameters, the

minimum of 32 bit is used in the input signal and the

RGB(3) can be used as a channel. The noise present in

the input signal is considered as quantization noise,

and the SQNR is calculated.

Fig 6: Video parameter for ADM

From the comparison of various parameters,

the Delta modulation is having the better SQNR ratio

as compared with the AM.

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V. CONCLUSION

In WiMAX technology the main problem occurs

is selecting the modulation technique for the desired

input parameter signal, so we can considered the

various parameters and compare the modulation

techniques depends on the performance of BER and

Noise ratio. From the analysis, the Adaptive

modulation is having the BER value as 7.24e-02 for

the 882k bit length, noise ratio is 8.2391 and for the

same number of bits is used for the comparison of

modulation we got the noise ratio as 1.0909. From this

we conclude that the delta modulation is the best

modulation which we used in WiMAX technology.

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