International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 4, Issue 4, April 2015
ISSN 2319 - 4847
Performance Evaluation of WIMAX Network
with High QOS Services Incorporating
Different Physical & Mac Layer Standards
1.
Anita Mishra, NehaMarria2, Harsukhpreet Singh3
1
PIT,PTU,Jalandhar,Punjab,India
2
College of Engineering & Management, Assistant Professor, PTU, Kapurthala, Punjab,India
3
CTIT, Assistant Professor ,PTUJalandhar,Punjab,India
ABSTRACT
VoIP application of Worldwide Interoperatability microwave access (WiMAX) is a broadly deployed technology and has a great
impact in field of 4th generation networks. Main advantage of this technology is utilization of existing infrastructure in the
form of internet connection. There are several QoS classes for VoIP application in IEEE 802.16 systems, such as unsolicited
poll grant, rtPS, nrtPS, Ertps and BE. The major issue in VoIP is quality of service. In order to send better quality in voice data
s5ome factors like delay, jitter, throughput, packet delivery ratio and mean opinion score (MOS) need to be improved so as to
maintain the performance of this application in WiMAX.The proposed idea required no modification of the framework of IEEE
802.16 system and we have analyzed and discussed the performance of the quality of service classes recommended in the IEEE
802.16 system and compared it with proposed approach.The approach proposed in the thesis considers the parameters of Peak
Sustained Traffic Rate and Orthogonal Frequency Division Multiplexing (OFDM) frame duration to improve the quality of
service for VoIP. The simulation of VoIP has been done with Peak Sustained Traffic Rate OFDM frame duration with these
parameters values the performance metrics delay, network load and jitter have been improved which in turn has enhanced the
performance of existing Extended Real Time Polling Service.
Keywords:-VoIP, MOS, rtPS, nrtPS, Ertps, QoS, OFDM
1.INTRODUCTION
The increasing demand for large capacity and higher transmission speeds to accommodate for data intensive
multimedia in conjunction with real time applications, the wireless network have experienced an explosive growth in
last few years [1-2]. WiMAX stands for Worldwide Inter- Portability for Microwave Access can be a communication
technologyfor easily delivering high speed data rates to large geographical area using orthogonal frequency division
multiplexing(OFDM) from Base Station(BS) to Subscriber Station(SS) which mitigates noise, multipath and
interference effects[3-4]. The WiMAX network is a combination of BS and SS. Here the packets are transferred from
source node to destination node after following various scheduling, modulation technique and routing technique. In
compliance with IEEE 802.16 the maximum range of WiMAX network is 50 km from the BS, where the responsibility
of the base station of providing the air interface to the master stationwith supplementary functions that may be part of
the BS are micro mobility management functions, traffic classification, tunnel establishment, QoS policy enforcement,
key management, DHCP proxy, multicast group management and session management. The receiver and antenna could
be a small box or personnel computer Memory Card International Association (PCMCIA) card or a laptop[5-6].
With the introduction of 4G technology in WiMAXoffering a metropolitan area network services that can use one or
more BS and each BS provide the service to the users up to 50 km radius for spreading broadband wireless data over
spacious geographical area. WiMAX offer high speed, flexible, inexpensive and last mile services with performance
similar to those of wire line infrastructure T1, DSL, cable modem based connections, optical fiber orcopperware with a
number of QoS needs. WiMAX provide wide area coverage and QoS capabilities for applications ranging from real –
time delay-sensitive Voice Over Internet Protocol(VoIP) to real time streaming video and non-real time downloads,
ensuring that subscribers obtain the performance they expect for all types of communication with a bandwidth support
of up to 10 MHz[7-8].based on IEEE 802.16 standards, WiMAX provide up to 30 miles broadband access to mobile
users having a telecommunication etiquette offering full access to mobile internet across cities and countries with a
wide range of devices. WiMAX technology is offering very high speed broadband access to mobile internet. Generally
10MHz with the TDD scheme provides 3:1 up and down link ratio. The architecture of WiMAX technology is based on
MAC layer which is a connection oriented layer. Through MAC layer a user can perform a variety of functions such as
various types of applications including multimedia and voice can be used. it also supports best efforts for data traffic as
bit, real time, traffic flaws etc. the aim of design WiMAX technology is to facilitate large number of user with a variety
of connection per terminal[9-10].
Volume 4, Issue 4, April 2015
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 4, Issue 4, April 2015
ISSN 2319 - 4847
This paper is divided into five sections. Some introductory application and characteristics area of WiMAX technology
are presented in Section 1 followed by Section 2 that presents the QoS needs and IEEE 802.16 QoS scheduling schemes
of WiMAX technology, proposed methods and flow chart present in section 3 and in section 4 simulations results are
shown and finally, the conclusion is reported in Section 5.
2.QOS AND IEEE 802.16 QOS SCHEDULING SCHEME
QoS is a spacious and unbound term that refers to the “collective effect of service,” as perceived by the user. QoS more
barely refers to meeting certain necessity typically, packet delivery ratio, throughput, network load, packet error rate,
jitter, and delay associated with a given application. WiMAX networks must support a diversity of applications, such as
video, voice, multimedia and data and each of these has different traffic patterns and QoS necessity [20].The QoS is
granted on the basis of type of application and service under consideration. For example, a user sending an email needs
no real-time data stream like another user having a Voice over IP (VoIP) application. To provide the service parameters
respectively, the traffic management is necessary. There are four main service classes named as UGS, rtPS, nrtPS, BE
but there is a fifth type QoS service class which is added in 802.16e standard, named as: extended real-time Polling
Service (ertPS). These services are prioritized in decreasing order. Within all these classes of services resources are
allocated to manage and satisfy the QoS of higher priority services. In general, IEEE 802.16 has five QoS classes [7].
Table 1 broadly classifies various service classes defined in WiMAX and its applications.
Table I.QoS Classes in WiMAX
Service classes
Description
Application
s
Unsolicited Grant
service(UGS)
For constant Bit rate
and delay dependent
applications
VOIP
Real Time Polling
Service (rtPS)
For variable rate and
delay dependent
applications
Streaming
audio , video
Extended Real time
Service (ertPS)
For variable rate and
delay dependent
applications
VOIP and
Silence
Suppression
Variable and non
real time
applications
FTP
Best effort
Email , Web
,Traffic
Non real time
polling service
(nrtPS)
Best Effort (BE)
 UGS:Unsolicited Grant Service is design to support real time service flow which generates the fixed size data packet
periodically. In this algorithms BS assign fixed size grant to the subscriber station. The grants assign are basically of
two type i.e. grant size and grant period. When voice session is initialized then these values are conciliated. These
grants are sufficient for sending data packets.
Advantages of UGS: this service minimize the MAC overhead and uplink access delay which are caused when SS
make request to the BS for bandwidth request to send the voice data packets.
Disadvantages of UGS:UGS assign fixed size grant for sending voice data packets but voice user do not always have
voice data packet to send because they have period of silence and it cause a waste of uplink resources.
 rtPS: Real time polling service are designed to support real time services which generally generates variable size
data packets periodically. BS assign uplink resources to the SS when voice session is initialized then these values are
conciliated.
Advantages: In this algorithm the SS request the BS for bandwidth of suitable size grant so that the rtPS can transport
data more efficiently as compare to UGS algorithms.
Disadvantages: Because the SS always made a request for Bandwidth to the BS which in turn can cause more MAC
overhead and uplink access delay as compare to UGS algorithms.
 ertPS: Extended Real Time Polling Services algorithm is proposed in order to remove the shortcomings of both
UGS and rtPS algorithms. The UGS approach allows BS to assign fixed size grants to voice users which leads to
wastage of uplink resources during the silent period when voice users do not have any datato send. Meanwhile rtPS
Volume 4, Issue 4, April 2015
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 4, Issue 4, April 2015
ISSN 2319 - 4847
although meant for variable size data packets consumes much of the time in polling process and also account for MAC
overhead.
3.PROPOSED METHODOLOGY
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4.SIMULATION SCENARIO AND RESULTS
Using OPNET 14.5 simulator, we have designed and investigated WiMAX scenario with network size of [20*20 km]
with 45 number of fixed nodes. The work is demonstrated using high network traffic load i.e. with VOIP applications
for simulation interval of 5 minutes.
Fig 1: WiMAX Network Scenario
Table II: SIMULATION PARAMETERS for WiMAX
BS Transmit Power (W)
0.5
Traffic Load
VoIP
No. Of subcarrier stations
45
Base Station MAC
22
Address
SS Station MAC Address
Auto Assigned
WiMAX Efficiency Mode
Physical Layer Enable
BS, SS Antenna Gain
15, 14 dBi
Channel Bandwidth
20MHz
OFDM Sub-carriers
512
Frame Duration
5 ms
3.1 Performance Results
After a number of simulations, the following results were gathered. Based upon these results, a detailed analysis is
presented. QoS on WiMAX network is analyzed through simulation metrics. The metrics which we taken are below: Delay: Delay or latency could be defined as the time taken by the packet to reach from source to the destination. The
results are shown graphically as:
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Fig.2 End-to-End Delay Vs Transmission time
 Jitter: packet delay variance or jitter could be termed as the variation in delay or packet delay variation. The value of
jitter is calculated from the end to end delay. It is the variation in the time between packets arriving. The results are
shown graphically as:
Fig.3 WiMAX Voice Jitter Vs Transmission Time
 Network Load: In a computer network the load is a measure of the amount of computational work that a computer
system performs. The aim of the network load balancing to optimize resources use, maximize throughput, minimize
response time and avoid overload of any one of the resources.The results are shown graphically as:
Fig. 4 Network Load Vs Transmission Time
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Table III:Comparison of Proposed Method with the Existing QoS classes
Delay (msec.)
Network Load
(kbps)
BE
ertPS
nrtPS
rtPS
Optimized
ertPS
29.8564
28.29403
30.81272
30.95195
9.426373
1293.727
1320.678
1309.426
1308.483
1157.256
0.112636
0.111381
0.218629
0.150197
0.006079
Jitter (msec.)
5.CONCLUSION
Measurement of Quality of Service is critical for any WiMAX network. The WiMAX network must assemble a
number of quality of service parameters including low delay, jitter , network load, high throughput and packet delivery
ratio. Today in broadband wireless access the observation is that as adoption grows, so does the need for guaranteeing a
good QoS. The issues of QoS there have become a critical area of concern for supplier of broadband wireless access
equipment and their customers too. In this paper we have conducted general simulation to estimate the performance of
WiMAX for supporting VoIP traffic we have analyzed several important critical paramerts such as end-to end delivery,
jitter and network load. Simulation results shows that we have obtained low delay, jitter and network load.
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