Quality of Service (QoS) provisioning in networks requires proper scheduling algorithm. Internet traffic,
especially real-time multimedia applications, is bursty in nature . Hence, in addition to the service rate
which is commonly used to isolate service of sessions, other parameters should be involved. In this paper
a scheduling algorithm is proposed that attempts to provide a balance between bursty and non-bursty
(smooth) traffic. We improve thewell-known packet scheduling algorithm, SCFQ.Our proposed algorithm
is proficient to compensate an adjustable amount of missed service to each session. The average delay of
the proposed algorithm is evaluated by simulation. An important advantage of our algorithm is that
byselecting correct parameter setting for each session, the average delay of a bursty session can be
reduced. Furthermore, compared to SCFQ our proposed algorithm does not necessitate any additional
computation.
Design and implementation of low latency weighted round robin (ll wrr) schedu...ijwmn
Today’s wireless broadband networks are required to provide QoS guarantee as well as fairness to
different kinds of traffic. Recent wireless standards (such as LTE and WiMAX) have special provisions at
MAC layer for differentiating and scheduling data traffic for achieving QoS. The main focus of this paper is
concerned with high speed packet queuing/scheduling at central node such as base station (BS) or router to
handle network traffic. This paper proposes novel packet queuing scheme termed as Low Latency
Weighted Round Robin (LL-WRR) which is simple and effective amendment to weighted round robin (WRR)
for achieving low latency and improved fairness. Proposed LL-WRR queue scheduling scheme is
implemented in NS-2 considering IEEE 802.16 network [1] with real time video and Constant Bit Rate
(CBR) audio traffic connections. Simulation results show improvement obtained in latency and fairness
using LL-WRR. The proposed scheme introduces extra complexity of computing coefficient but its overall
impact is very small.
SELFLESS DISTRIBUTED CREDIT BASED SCHEDULING FOR IMPROVED QOS IN IEEE 802.16 ...ijwmn
Packet and flow scheduling algorithms for WiMAX has been a topic of interest for a long time since the very inception of WiMAX networks. WiMAX offers advantages particularly in terms of Quality of service it offers over a longer range at the MAC level. In our paper, we propose two credit based scheduling schemes one in which completed flows distributes the left over credits equally to all higher priority flows(FDCBSS) and another in which completed flows give away all the excess credits to the highest priority uncompleted flow(SDCBSS). Both the schemes are compatible with 802.16 MAC protocol and can efficiently serve real time bursty traffic with reduced latency and hence improved QOS for real time flows. We compare the two proposed schemes for their latency, bandwidth utilization and throughput for real time burst flows with the basic Deficit Round Robin scheduling scheme.
Design and implementation of low latency weighted round robin (ll wrr) schedu...ijwmn
Today’s wireless broadband networks are required to provide QoS guarantee as well as fairness to
different kinds of traffic. Recent wireless standards (such as LTE and WiMAX) have special provisions at
MAC layer for differentiating and scheduling data traffic for achieving QoS. The main focus of this paper is
concerned with high speed packet queuing/scheduling at central node such as base station (BS) or router to
handle network traffic. This paper proposes novel packet queuing scheme termed as Low Latency
Weighted Round Robin (LL-WRR) which is simple and effective amendment to weighted round robin (WRR)
for achieving low latency and improved fairness. Proposed LL-WRR queue scheduling scheme is
implemented in NS-2 considering IEEE 802.16 network [1] with real time video and Constant Bit Rate
(CBR) audio traffic connections. Simulation results show improvement obtained in latency and fairness
using LL-WRR. The proposed scheme introduces extra complexity of computing coefficient but its overall
impact is very small.
SELFLESS DISTRIBUTED CREDIT BASED SCHEDULING FOR IMPROVED QOS IN IEEE 802.16 ...ijwmn
Packet and flow scheduling algorithms for WiMAX has been a topic of interest for a long time since the very inception of WiMAX networks. WiMAX offers advantages particularly in terms of Quality of service it offers over a longer range at the MAC level. In our paper, we propose two credit based scheduling schemes one in which completed flows distributes the left over credits equally to all higher priority flows(FDCBSS) and another in which completed flows give away all the excess credits to the highest priority uncompleted flow(SDCBSS). Both the schemes are compatible with 802.16 MAC protocol and can efficiently serve real time bursty traffic with reduced latency and hence improved QOS for real time flows. We compare the two proposed schemes for their latency, bandwidth utilization and throughput for real time burst flows with the basic Deficit Round Robin scheduling scheme.
What is Quality of Service?
-Basic mechanisms
-Leaky and token buckets
-Integrated Services (IntServ)
-Differentiated Services (DiffServ)
-Economics and Social factors facing QoS
-QoS Vs. Over Provisioning
Scheduling and Resource allocation in 802.11ax (WIFI 6)RESHAN FARAZ
--> IIITD Course Project.
--> Implementation of Scheduling and Resource allocation in 802.11ax using NS-3.
-->Modified Largest Weighted Delay First.
--> Comparison of Round Robin Scheduling with Modified Largest Weighted Delay First.
-->Source Code:-https://github.com/reshan9b11/MLWDF_WN_PROJECT
Fuzzy-Controlled Scheduling of Route-Request Packets (FSRR) in Mobile Ad Hoc ...A. Sufian
In ad hoc networks, the scheduling of route-request packets should be different from that of message packets, because during
transmission of message packets the location of the destination is known whereas in route discovery this is not known in
most of the cases. The router has to depend upon the last known location, if any, of the destination to determine the center
and radius of the circle that embeds all possible current position of the destination. Route-request packets generated from
the source are directed towards this circle i.e., directional route discovery can be applied. Otherwise, when no earlier location
of the destination is known the route-requested has to be broadcast in the whole network consuming a significant amount of
time than directional route discovery. The present article proposes a fuzzy controlled scheduling of route-request packets inparticular that greatly reduces the average delay in route discovery in ad hoc networks.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Rm literature survey_on_scheduling_and_resource_allocation_for_ieee_80211ax_p...RESHAN FARAZ
IEEE 8021.11 is the standard defined for WLAN(Wireless Local Area Network). It first
came into the picture in 1997 which offer a speed of 2Mbit/s. After that we have different
versions, 802.11b having speed 11Mbit/s, 802.11a/g having 54 Mbit/s, 802.11n having 600
Mbit/s, and even above Gbit/s rates in the latest 802.11ac. These speeds can be achieved
by means of different modulation and coding scheme, wider channel and adaptation of
Multiple Input Multiple Output (MIMO) technologies[7]. The 802.11ax will provide outstanding average throughput in the dense environment. Many clients connect with the
Access Point (AP) simultaneously using the Orthogonal frequency-division multiple access
(OFDMA) where AP divides the entire frequency band into multiple subsets of orthogonal
sub carrier called as Resource Unit (RU),These RUs are assigned to different user to transit
in parallel which make 802.11ax different from all other versions of 802.11 so we need some
scheduling and resource allocation mechanism to utilize the features of 802.11ax. Before
going to scheduling and resource allocation, let us discuss some features of 802.11ax
Fuzzy-controlled Scheduling of Real Time Data Packets (FSRP) in Mobile Ad Hoc...A. Sufian
Abstract—In ad hoc networks, the data packets can be mainly classified into two categories – real time and
non-real time. Definitely the scheduling of real time data packets is going to be different from non-real time
ones. The deadline of delivery is a very important criterion to be met in case of real time packets. The other
requirements like velocity and energy concerns are enforced by the inherent dynamic nature of ad hoc
networks. Sometimes it becomes completely unnecessary to forward a real time data packet when the deadline
is impossible to meet or when the destination is on the verge of death. Also if the source nodes start sending
real time packets at a very high rate, then it will not only increase congestion in the network but also hamper
the forwarding of non real time packets since non real times have priority lesser than the real time packets.
The present algorithm FSRP is designed considering all these factors and the performance improvement it
produces is very significant compared to other state of the art scheduling protocols.
Fuzzy Route Switching for Energy Preservation(FEP) in Ad Hoc NetworksA. Sufian
Nodes in ad hoc networks have limited battery power. Hence they require energy-efficient technique to improve average
network performance. Maintaining energy-efficiency in ad hoc networks is really challenging because highest energyefficiency
is achieved if all the nodes are always switched off and energy-efficiency will be minimum if all the nodes are
fully operational i.e. always turned-on. Energy preservation requires redirection of data packets through some other routes
having good performance. This improves data packet delivery ratio and number of alive nodes decreasing cost of messages.
Mobile Ad hoc Networks (MANETs) have drawn considerable attentions of the researchers for the last few years. MANETs, consisting of mobile nodes, are self-organizing and self-configuring and hence can be deployed without any infrastructure support. MANETs also have some limitations including short-life, unreliability, scalability, latency, high interference, and limited resources. In order to overcome these limitations many innovations and researches have been done in this field. Incorporating smart antenn system with the mobile nodes is one of them. It has been shown in the literatures that smart antenna can improve network capacity, increase network lifetime, reduce delay, and improve scalability by using directional radiation pattern. But, there are some unsolvedissues too. Smart antenna requires a large
number of antenna elements that a resource constraint mobile node can hardly handle. Hence, one major
design issue is to achieve a desired radiation pattern by using minimum number of antenna elements. Another important issue is the arrangement of antenna elements. Antenna elements can be arranged in linear, planar, and circular manners. In this paper we have addressed these issues. We have proposed a window based smart antenna design for MANETs. Our target is to improve the routing performance of
MANETs. We have shown that by using appropriate window function a desired radiation pattern can be achieved with a minimum number of antenna elements.
What is Quality of Service?
-Basic mechanisms
-Leaky and token buckets
-Integrated Services (IntServ)
-Differentiated Services (DiffServ)
-Economics and Social factors facing QoS
-QoS Vs. Over Provisioning
Scheduling and Resource allocation in 802.11ax (WIFI 6)RESHAN FARAZ
--> IIITD Course Project.
--> Implementation of Scheduling and Resource allocation in 802.11ax using NS-3.
-->Modified Largest Weighted Delay First.
--> Comparison of Round Robin Scheduling with Modified Largest Weighted Delay First.
-->Source Code:-https://github.com/reshan9b11/MLWDF_WN_PROJECT
Fuzzy-Controlled Scheduling of Route-Request Packets (FSRR) in Mobile Ad Hoc ...A. Sufian
In ad hoc networks, the scheduling of route-request packets should be different from that of message packets, because during
transmission of message packets the location of the destination is known whereas in route discovery this is not known in
most of the cases. The router has to depend upon the last known location, if any, of the destination to determine the center
and radius of the circle that embeds all possible current position of the destination. Route-request packets generated from
the source are directed towards this circle i.e., directional route discovery can be applied. Otherwise, when no earlier location
of the destination is known the route-requested has to be broadcast in the whole network consuming a significant amount of
time than directional route discovery. The present article proposes a fuzzy controlled scheduling of route-request packets inparticular that greatly reduces the average delay in route discovery in ad hoc networks.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Rm literature survey_on_scheduling_and_resource_allocation_for_ieee_80211ax_p...RESHAN FARAZ
IEEE 8021.11 is the standard defined for WLAN(Wireless Local Area Network). It first
came into the picture in 1997 which offer a speed of 2Mbit/s. After that we have different
versions, 802.11b having speed 11Mbit/s, 802.11a/g having 54 Mbit/s, 802.11n having 600
Mbit/s, and even above Gbit/s rates in the latest 802.11ac. These speeds can be achieved
by means of different modulation and coding scheme, wider channel and adaptation of
Multiple Input Multiple Output (MIMO) technologies[7]. The 802.11ax will provide outstanding average throughput in the dense environment. Many clients connect with the
Access Point (AP) simultaneously using the Orthogonal frequency-division multiple access
(OFDMA) where AP divides the entire frequency band into multiple subsets of orthogonal
sub carrier called as Resource Unit (RU),These RUs are assigned to different user to transit
in parallel which make 802.11ax different from all other versions of 802.11 so we need some
scheduling and resource allocation mechanism to utilize the features of 802.11ax. Before
going to scheduling and resource allocation, let us discuss some features of 802.11ax
Fuzzy-controlled Scheduling of Real Time Data Packets (FSRP) in Mobile Ad Hoc...A. Sufian
Abstract—In ad hoc networks, the data packets can be mainly classified into two categories – real time and
non-real time. Definitely the scheduling of real time data packets is going to be different from non-real time
ones. The deadline of delivery is a very important criterion to be met in case of real time packets. The other
requirements like velocity and energy concerns are enforced by the inherent dynamic nature of ad hoc
networks. Sometimes it becomes completely unnecessary to forward a real time data packet when the deadline
is impossible to meet or when the destination is on the verge of death. Also if the source nodes start sending
real time packets at a very high rate, then it will not only increase congestion in the network but also hamper
the forwarding of non real time packets since non real times have priority lesser than the real time packets.
The present algorithm FSRP is designed considering all these factors and the performance improvement it
produces is very significant compared to other state of the art scheduling protocols.
Fuzzy Route Switching for Energy Preservation(FEP) in Ad Hoc NetworksA. Sufian
Nodes in ad hoc networks have limited battery power. Hence they require energy-efficient technique to improve average
network performance. Maintaining energy-efficiency in ad hoc networks is really challenging because highest energyefficiency
is achieved if all the nodes are always switched off and energy-efficiency will be minimum if all the nodes are
fully operational i.e. always turned-on. Energy preservation requires redirection of data packets through some other routes
having good performance. This improves data packet delivery ratio and number of alive nodes decreasing cost of messages.
Mobile Ad hoc Networks (MANETs) have drawn considerable attentions of the researchers for the last few years. MANETs, consisting of mobile nodes, are self-organizing and self-configuring and hence can be deployed without any infrastructure support. MANETs also have some limitations including short-life, unreliability, scalability, latency, high interference, and limited resources. In order to overcome these limitations many innovations and researches have been done in this field. Incorporating smart antenn system with the mobile nodes is one of them. It has been shown in the literatures that smart antenna can improve network capacity, increase network lifetime, reduce delay, and improve scalability by using directional radiation pattern. But, there are some unsolvedissues too. Smart antenna requires a large
number of antenna elements that a resource constraint mobile node can hardly handle. Hence, one major
design issue is to achieve a desired radiation pattern by using minimum number of antenna elements. Another important issue is the arrangement of antenna elements. Antenna elements can be arranged in linear, planar, and circular manners. In this paper we have addressed these issues. We have proposed a window based smart antenna design for MANETs. Our target is to improve the routing performance of
MANETs. We have shown that by using appropriate window function a desired radiation pattern can be achieved with a minimum number of antenna elements.
The topology of mobile ad hoc networks (MANETs) change dynamically with time. Connected dominating sets (CDS) are considered to be an effective topology for network-wide broadcasts in MANETs as only the nodes that are part of the CDS need to broadcast the message and the rest of the nodes merely receive the message. However, with node mobility, a CDS does not exist for the entire duration of the network session and has to be regularly refreshed (CDS transition). In an earlier work, we had proposed a benchmarking algorithm to determine a sequence of CDSs (Maximum Stable CDS) such that the number of transitions is
the global minimum. In this paper, we analyze the impact of pause time and static nodes on the performance (CDS Lifetime and CDS Node Size) of the Maximum Stable CDS and degree-based CDS. Pause time refers to the time a node stops at a location before moving again. When a node is declared to be
a static node, it does not move at all during a simulation. We conduct the simulations by varying the
maximum node velocity, the pause time of the mobile nodes and the percentage of static nodes. As we
increase the maximum velocity with which any node could move, we observe to have greater chances of increasing the lifetime of the CDSs (especially the degree-based CDS) by letting all the nodes to move, but pause for an appreciable amount of time every now and then, rather than letting a certain a fraction of the
nodes to remain static all the time, but have the rest of the nodes to move all the time.
Data gathering in wireless sensor networks using mobile elementsijwmn
In this paper, we investigate the problem of designing the minimum number of required mobile elements
tours such that each sensor node is either on the tour or one hop away from the tour, and the length of the
tour to be bounded by pre-determined value L. To address this problem, we propose heuristic-based
solution. This solution works by directing the mobile element tour towards the highly dense area in the
network. The experiment results show that our scheme outperform the benchmark scheme by 10% in most
scenarios.
T HE I MPACT OF TCP C ONGESTION W INDOW S IZE ON THE P ERFORMANCE E VA...ijwmn
A mobile ad hoc network (MANET) is a temporary coll
ection of mobile nodes randomly moved within a
limited terrain area. The nodes are connected to fo
rm a wireless network without use any communication
infrastructure. Because of the limiting resources o
f MANET nodes, multiple hops
scheme is proposed for
data exchange
across the network. Varieties of mobile ad hoc rout
ing protocols have been developed to
support the multi-hop scheme of ad hoc networks. A
popular Transmission Control Protocol (TCP)
provides a reliable connection in a computer networ
k environment; it sets its congestion window size i
n
response to the behavior of the network to achieve
the best performance. This work aims to investigate
and
compare the MANET protocol
performance, such as DSDV, AODV and DSR in terms of
network
throughput, average routing load, the packet delive
ry ratio (PDR), and average end-to-end delay by
varying the maximum congestion window size. Our si
mulation has been implemented using a well-known
NS-2.35 network simulator. The simulated results sh
ow that the demonstrates of the concepts of MANET
routing protocols with respect to TCP congestion wi
ndow size in MANET environment
O N THE E VALUATION OF G MSK S CHEME W ITH ECC T ECHNIQUES IN W IRELESS S...ijwmn
Wireless sensor nodes are powered by batteries, for
which replacement is very difficult. That is why,
optimization of energy consumption is a major objec
tive in the area of wireless sensor networks (WSNs)
.On
the other hand, noisy channel has a prominent influ
ence on the reliability of data transmission. There
fore,
an energy efficient transmission strategy should be
considered on the communication process of wireles
s
nodes in order to obtain optimal energy network con
sumption. Indeed, the choice of suitable modulation
format with the proper Error Correcting code (ECC)
played a great responsibility to obtain better ener
gy
conservation.In this work, we aim to evaluate the p
erformance analysis of Gaussian Minimum Shift Keyin
g
(GMSK) modulation with several combinations of codi
ng strategies using various analysis metrics such a
s
Bit Error Rate (BER), energy consumption.Through ex
tensive simulation, we disclose that he gain achiev
ed
through GMSK modulation with suitable channel codin
g mechanism is promising to obtain reliable
communication and energy conservation in WSN.
In this paper, the performances of adaptive noise cancelling system employing Least Mean Square (LMS) algorithm are studied considering both white Gaussian noise (Case 1) and colored noise (Case 2)
situations. Performance is analysed with varying number of iterations, Signal to Noise Ratio (SNR) and tap size with considering Mean Square Error (MSE) as the performance measurement criteria. Results show that the noise reduction is better as well as convergence speed is faster for Case 2 as compared with Case 1. It is also observed that MSE decreases with increasing SNR with relatively faster decrease of MSE in Case 2 as compared with Case 1, and on average MSE increases linearly with increasing number of filter
coefficients for both type of noise situations. All the experiments have been done using computer
simulations implemented on MATLAB platform.
Mtadf multi hop traffic aware data for warding for congestion control in wir...ijwmn
In the past few years there is a remarkable change in the field of wireless sensor networks. Congestion occurs when there is a heavy traffic in the network. The heavy traffic in the network leads to wastage of energy and packet loss. Traffic Aware Dynamic Routing algorithm mitigates congestion by using one hop neighbor routing, hence throughput of the network is low. This paper proposed a Multi hop based Data Forwarding Technique to mitigate congestion. Queue length field and depth potential field play a major role to divert the traffic in the network to the alternate paths. The high traffic load leads to data queue overflow in the sensor nodes, these results in loss of important information about important events. Multi hop Traffic-Aware Dynamic Routing algorithm addresses congestion using depth potential field and queue length potential field. The algorithm forwards data packets around the congestion areas and scatters the excessive along multiple paths. The nodes with less load are efficiently utilized in response to congestion. The main aspect of the algorithm is to construct two independent potential fields using depth and queue length. Queue length field solves the traffic-aware problem. Depth field creates a backbone to forward packets to the sink. Both fields are combined to yield a hybrid potential field to make dynamic decision for data forwarding. Simulations are conducted to evaluate the performance of our proposed algorithm and our proposed scheme performs better compared to previous work.
Macro with pico cells (hetnets) system behaviour using well known scheduling ...ijwmn
This paper demonstrates the concept of using Heterogeneous networks (HetNets) to improve Long Term Evolution (LTE) system by introducing the LTE Advance (LTE-A). The type of HetNets that has been chosen for this study is Macro with Pico cells. Comparing the system performance with and without Pico cells has clearly illustrated using three well-known scheduling algorithms (Proportional Fair PF, Maximum Largest Weighted Delay First MLWDF and Exponential/Proportional Fair EXP/PF). The system is judged based on throughput, Packet Loss Ratio PLR, delay and fairness.. A simulation platform called LTE-Sim has been used to collect the data and produce the paper’s outcomes and graphs. The results prove that adding Pico cells enhances the overall system performance. From the simulation outcomes, the overall system performance is as follows: throughput is duplicated or tripled based on the number of users, the PLR is almost quartered, the delay is nearly reduced ten times (PF case) and changed to be a half (MLWDF/EXP cases), and the fairness stays closer to value of 1. It is considered an efficient and cost effective way to increase the throughput, coverage and reduce the latency.
LTE is an emerging wireless data communication technology to provide broadband ubiquitous Internet
access. Femtocells are included in 3GPP since Release 8 to enhance the indoor network coverage and
capacity. The main challenge of mobility management in hierarchical LTE structure is to guarantee
efficient handover to or from/to/between Femtocells. This paper focuses, on different types of Handover
and comparison performance between different decision algorithms. Furthermore, a speed based Handover
algorithm for macro-femto scenario is proposed with simulation results
E NERGY D EGREE D ISTANCE C LUSTERING A LGORITHM FOR W Snsijwmn
Energy consumption is an important parameter in th
e context of the wireless sensor networks (WSNs).
Several factors can cause energy over consumption s
uch as mobility, node position (relay or gateway),
retransmissions... In this paper, we described a ne
w Energy-Degree Distance(EDD) Clustering Algorithm
for the WSNs. A node with higher residual energy,
higher degree and closer to the base station is mor
e
likely elected as a clusterhead (CH). The inter clu
ster and intra cluster communications are realized
on one
hop. The principal goal of our algorithm is to min
imize the energy consumption and balance energy
consumption among all nodes. By comparing EDD clust
ering algorithm with LEACH algorithm,
simulation results have shown its effectiveness i
n saving energy
Realisation of awgn channel emulation modules under siso and simo environment...ijwmn
The testing of a wireless transmitter and receiver in the real-world channel is tedious. So, a channel
emulator using FPGA helps in the testing of transmitter and receiver by providing a test environment that
simulates a real-world wireless channel. Since FPGAs are flexible, cheap and reconfigurable, they are
used in designing an AWGN channel emulator for 4G LTE for Single Input Single Output (SISO) and
Single Input Multiple Output (SIMO) environments. In this paper, three basic modules: transmitter,
channel estimation and receiver modules are synthesized. In the transmitter module, the input data is 64-
QAM modulated and transmitted into the channel. In the channel estimation module, the transmitter data
gets multiplied with the channel coefficients and then added with the noise present in the channel. In the
receiver module, the data is detected using MMSE estimation. These are implemented in Virtex-5 device
using PlanAhead tool and the Resource and Power Estimations are discussed.
Availability is one of the most important concerns in the networking world. For any high available
network, we need to maintain 99.99999% availability. That is why it is one of the most important factors to
find out the single point of failure in the network architecture and eliminate that single point of failure
(SPOF) from physical network and logical network. SPOF in our server infrastructure has been analysed
in terms of communicating with the router for forwarding traffic with multiple routers. We have developed
an algorithm that will automatically select default gateway into the network interface card of virtual
machines. The proposed algorithm will automatically enable Default Gateway Weight settings (DGW)
protocol among routers by configuring Network interface card with default gateway of all routers. The
proposed protocol works based on weight settings for the multiple default gateway configuration in the
host. There will be heartbeat communication and re-convergence will be performed within the shortest
possible time. Lowest weight setting will select the path for packet forwarding through specified routers
related with the default gateway from the virtual machine.
Modulation aware connection admission control and uplink scheduling algorithm...ijwmn
Mobile WiMAX standard defines air interface for mobile broadband wireless access (BWA) systems and aimed to provide high data rate with seamless mobility while maintaining the quality of service (QoS). However, QoS of real-time applications depends on the link quality, which necessitate the channel-aware connection admission control (CAC) and scheduling schemes. In this paper Modulation aware CAC scheme and base station (BS) uplink scheduling algorithm are proposed to improve the system capacity and QoS performance respectively. The proposed CAC scheme aims to increase the admission of higher priority real time services by degrading the bandwidth of admitted lower priority connections on the basis of their channel status without deteriorating their QoS performance much. The performances of proposed algorithms are evaluated through simulation by considering the metrics like throughput, delay and number of connections admitted.
A novel architecture for sdn based cellular network ijwmn
In this paper, we propose a novel SDN-based cellular network architecture that will be able to utilize the
opportunities of centralized administration of today’s emerging mobile network. Our proposed architecture
would not depend on a single controller, rather it divides the whole cellular area into clusters, and each
cluster is controlled by a separate controller. A number of controller services are provided on top of each
controller to manage all the major functionalities of the network and help to make the network
programmable and more agile, and create opportunities for policy-driven supervision and more
automation.
Multiple Downlink Fair Packet Scheduling Scheme in Wi-MaxEditor IJCATR
IEEE 802.16 is standardization for a broadband wireless access in network metropolitan area network (MAN). IEEE 802.16
standard (Wi-Max) defines the concrete quality of service (QoS) requirement, a scheduling scheme and efficient packet scheduling
scheme which is necessary to achieve the QoS requirement. In this paper, a novel waiting queue based on downlink bandwidth
allocation architecture from a number of rtps schedule has been proposed to improve the performance of nrtPS services without any
impaction to other services. This paper proposes an efficient QoS scheduling scheme that satisfies both throughput and delay guarantee
to various real and non-real applications corresponding to different scheduling schemes for k=1,2,3,4. Simulation results show that
proposed scheduling scheme can provide a tight QoS guarantee in terms of delay for all types of traffic as defined in WiMax standards.
This process results in maintaining the fairness of allocation and helps to eliminate starvation of lower priority class services. The
authors propose a new efficient and generalized scheduling schemes for IEEE 802.16 broadband wireless access system reflecting the
delay requirements.
Selfless Distributed Credit Based Scheduling for Improved QOS In IEEE 802.16 ...ijwmn
Packet and flow scheduling algorithms for WiMAX has been a topic of interest for a long time since the
very inception of WiMAX networks. WiMAX offers advantages particularly in terms of Quality of service
it offers over a longer range at the MAC level. In our paper, we propose two credit based scheduling
schemes one in which completed flows distributes the left over credits equally to all higher priority
flows(FDCBSS) and another in which completed flows give away all the excess credits to the highest
priority uncompleted flow(SDCBSS). Both the schemes are compatible with 802.16 MAC protocol and
can efficiently serve real time bursty traffic with reduced latency and hence improved QOS for real time
flows. We compare the two proposed schemes for their latency, bandwidth utilization and throughput for
real time burst flows with the basic Deficit Round Robin scheduling scheme.
Selfless Distributed Credit Based Scheduling for Improved QOS In IEEE 802.16 ...ijwmn
Packet and flow scheduling algorithms for WiMAX has been a topic of interest for a long time since the very inception of WiMAX networks. WiMAX offers advantages particularly in terms of Quality of service it offers over a longer range at the MAC level. In our paper, we propose two credit based scheduling schemes one in which completed flows distributes the left over credits equally to all higher priority flows(FDCBSS) and another in which completed flows give away all the excess credits to the highest priority uncompleted flow(SDCBSS). Both the schemes are compatible with 802.16 MAC protocol and can efficiently serve real time bursty traffic with reduced latency and hence improved QOS for real time flows. We compare the two proposed schemes for their latency, bandwidth utilization and throughput for real time burst flows with the basic Deficit Round Robin scheduling scheme.
A Fair and Efficient Packet Scheduling Scheme for IEEE 802.16 Broadband Wirel...ijasuc
This paper proposes a fair and efficient QoS scheduling scheme for IEEE 802.16 BWA systems that
satisfies both throughput and delay guarantee to various real and non-real time applications. The proposed
QoS scheduling scheme is compared with an existing QoS scheduling scheme proposed in literature in
recent past. Simulation results show that the proposed scheduling scheme can provide a tight QoS
guarantee in terms of delay, delay violation rate and throughput for all types of traffic as defined in the
WiMAX standard, thereby maintaining the fairness and helps to eliminate starvation of lower priority
class services. Bandwidth utilization of the system and fairness index of the resources are also
encountered to validate the QoS provided by our proposed scheduling scheme.
Two-level scheduling scheme for integrated 4G-WLAN network IJECEIAES
In this paper, a novel scheduling scheme for the Fourth Generation (4G)-Wireless Local Area Network (WLAN) network is proposed to ensure that end to end traffic transaction is provisioned seamlessly. The scheduling scheme is divided into two stages; in stage one, traffic is separated into Actual Time Traffic (ATT) and Non-Actual-Time Traffic (NATT), while in stage two, complex queuing strategy is performed. In stage one, Class-Based Queuing (CBQ) and Deficit Round Robin(DRR) are used for NATT and ATT applications, respectively to separate and forward traffic themselves according to source requirements. Whereas in the stage, two Control Priority Queuing (CPQ) is used to assign each class the appropriate priority level. Evaluation of the performance of the integrated network was done according to several metrics such as end-to-end delay, jitter, packet loss, and network’s throughput. Results demonstrate major improvements for AT services with minor degradation on NAT applications after implementing the new scheduling scheme.
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Scheduling is one of the most important fundamental concepts in operating systems. Round
Robin (RR) scheduling is one of the most widely used algorithms in multitasking and real time
environments [1]. In multitasks environments, it is necessary to select the process among a set of
processes. The CPU is allocated to the selected process and controlled by the scheduling algorithm. Each
scheduling algorithm has its own needs, advantages and disadvantages. In this paper we have studied RR
and focused on Dynamic Round Robin algorithm (DRR) and its impact on the processes, which grow in
its burst time in a non-deterministic way with different sets of phenomenon and compared the results.
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number of packets throughout the world. This paper proposes a new speculation for distributed traffic
management by availing the presumption of fuzzy logic. The routers are established by using an
IntelRate Controllers to manage the traffic congestion in the networks dynamically. Fuzzy logic is used
to previse the maximum allowable sending rate by observing the queue size of router. The network
traffic control protocol is unique to estimate the network parameter which involves link latency,
bottleneck bandwidth or packet loss rate in order to compute the allowed source sending rate. The fuzzy
logic based controller can measure queue size directly, it neglects various potential performance issues
arising due to parameter estimation as reduce consumption of computation and memory resource in
router. A network parameter, the queue size can be viewed accurately and if action should be taken to
regulate the source sending rate and it increases the resilience of the network to traffic congestion.
Using the fuzzy logic technique, QoS (Quality of Service) can achieve better performance than the
existing protocol that depends on the estimation of network parameter, to make the network more
adaptive for current traffic conditions.
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IT services to user over the Internet. Workflow scheduling is one of the major problems in cloud systems. A
good scheduling algorithm must minimize the execution time and cost of workflow application along with
QoS requirements of the user. In this paper we consider deadline as the major constraint and propose a
score based deadline constrained workflow scheduling algorithm that executes workflow within
manageable cost while meeting user defined deadline constraint. The algorithm uses the concept of score
which represents the capabilities of hardware resources. This score value is used while allocating
resources to various tasks of workflow application. The algorithm allocates those resources to workflow
application which are reliable and reduce the execution cost and complete the workflow application within
user specified deadline. The experimental results show that score based algorithm exhibits less execution
time and also reduces the failure rate of workflow application within manageable cost. All the simulations
have been done using CloudSim toolkit.
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The number of LTE (Long-Term Evolution) users and their applications has increased significantly in the
last decade, which increased the demand on the mobile network. LTE-Advanced (LTE-A) comes with many
features that can support this increasing demand. LTE-A supports Heterogeneous Networks (HetNets)
deployment, in which it consists of a mix of macro-cells, remote radio heads, and low power nodes such as
Pico-cells, and Femto-cells. Embedding this mix of base-stations in a macro-cellular network allows for
achieving significant gains in coverage, throughput and system capacity compared to the use of macrocells only. These base-stations can operate on the same wireless channel as the macro-cellular network,
which will provide higher spatial reuse via cell splitting. Also, it allows network operators to support
higher data traffic by offloading it to smaller cells, such as Femto-cells. Hence, it enables network
operators to provide their growing number of users with the required Quality of Service (QoS) that meets
with their service demands. In-order for the network operators to make the best out of the heterogeneous
LTE-A network, they need to use QoS-based packet scheduling algorithms that can efficiently manage the
spectrum resources in the HetNets deployment. In this paper, we survey Quality of Service (QoS) based
packet scheduling algorithms that were proposed in the literature for the use of packet scheduling in
Heterogeneous LTE-A Networks. We start by explaining the concepts of QoS in LTE, heterogeneous LTE-A
networks, and how traffic is classified within a packet scheduling architecture for heterogeneous LTE-A
networks. Then, by summarising the proposed QoS-based packet scheduling algorithms in the literature for
Heterogeneous LTE-A Networks, and for Femtocells LTE-A Networks. And finally, we provide some
concluding remarks in the last section.
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The number of LTE (Long-Term Evolution) users and their applications has increased significantly in the last decade, which increased the demand on the mobile network. LTE-Advanced (LTE-A) comes with many features that can support this increasing demand. LTE-A supports Heterogeneous Networks (HetNets) deployment, in which it consists of a mix of macro-cells, remote radio heads, and low power nodes such as Pico-cells, and Femto-cells. Embedding this mix of base-stations in a macro-cellular network allows for achieving significant gains in coverage, throughput and system capacity compared to the use of macrocells only. These base-stations can operate on the same wireless channel as the macro-cellular network, which will provide higher spatial reuse via cell splitting. Also, it allows network operators to support higher data traffic by offloading it to smaller cells, such as Femto-cells. Hence, it enables network operators to provide their growing number of users with the required Quality of Service (QoS) that meets with their service demands. In-order for the network operators to make the best out of the heterogeneous LTE-A network, they need to use QoS-based packet scheduling algorithms that can efficiently manage the spectrum resources in the HetNets deployment. In this paper, we survey Quality of Service (QoS) based packet scheduling algorithms that were proposed in the literature for the use of packet scheduling in Heterogeneous LTE-A Networks. We start by explaining the concepts of QoS in LTE, heterogeneous LTE-A networks, and how traffic is classified within a packet scheduling architecture for heterogeneous LTE-A networks. Then, by summarising the proposed QoS-based packet scheduling algorithms in the literature for Heterogeneous LTE-A Networks, and for Femtocells LTE-A Networks. And finally, we provide some concluding remarks in the last section.
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Dynamic Traffic Management Services to Provide High Performance in IntelRate ...IJMER
Traffic is the chief puzzle problem in which every country faces to elaborate sending a
number of packets throughout the world. This paper proposes a new speculation for distributed traffic
management by availing the presumption of fuzzy logic. The routers are established by using an
IntelRate Controllers to manage the traffic congestion in the networks dynamically. Fuzzy logic is used
to previse the maximum allowable sending rate by observing the queue size of router. The network
traffic control protocol is unique to estimate the network parameter which involves link latency,
bottleneck bandwidth or packet loss rate in order to compute the allowed source sending rate. The fuzzy
logic based controller can measure queue size directly, it neglects various potential performance issues
arising due to parameter estimation as reduce consumption of computation and memory resource in
router. A network parameter, the queue size can be viewed accurately and if action should be taken to
regulate the source sending rate and it increases the resilience of the network to traffic congestion.
Using the fuzzy logic technique, QoS (Quality of Service) can achieve better performance than the
existing protocol that depends on the estimation of network parameter, to make the network more
adaptive for current traffic conditions
Congestion Control and QOS Improvement for AEERG protocol in MANET pijans
QOS improvement has been a subject of intensive discussion. The research in the network field for
congestion control is by means of scheduling packets from different traffic flows for processing at a specific
node. When that particular node is selected for the transmission of all traffic flows since it has been chosen
as an emerging node for the shortest path in the adaptive energy efficient algorithm, queue scheduling
disciplines have been used to improve the quality of service. In this paper, we evaluate the performance of
four queuing disciplines (FIFO, PQ, RED and WFQ) which is implemented in the AEERG protocol. This
paper gives the NS-2 simulation results to compare their relative performance based on queuing delay,
packet drop rate and end-to-end delay for the above queuing techniques.
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Email Id: praveen@nexgenproject.com.
www.nexgenproject.com
Mobile: 9751442511,9791938249
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IMPROVING SCFQ TO SUPPORT BURSTY TRAFFIC
1. International Journal of Wireless & Mobile Networks (IJWMN) Vol. 5, No. 2, April 2013
DOI : 10.5121/ijwmn.2013.5202 21
IMPROVING SCFQ TO SUPPORT BURSTY TRAFFIC
Mahmoud Daneshvar Farzanegan1
, Hossein Saidi1
andMehdiMahdavi1
1
ECE Department, Isfahan University of Technology, Isfahan, Iran
m_daneshvar@ec.iut.ac.ir,[hsaidi, m_mahdavi]@cc.iut.ac.ir
ABSTRACT
Quality of Service (QoS) provisioning in networks requires proper scheduling algorithm. Internet traffic,
especially real-time multimedia applications, is bursty in nature . Hence, in addition to the service rate
which is commonly used to isolate service of sessions, other parameters should be involved. In this paper
a scheduling algorithm is proposed that attempts to provide a balance between bursty and non-bursty
(smooth) traffic. We improve thewell-known packet scheduling algorithm, SCFQ.Our proposed algorithm
is proficient to compensate an adjustable amount of missed service to each session. The average delay of
the proposed algorithm is evaluated by simulation. An important advantage of our algorithm is that
byselecting correct parameter setting for each session, the average delay of a bursty session can be
reduced. Furthermore, compared to SCFQ our proposed algorithm does not necessitate any additional
computation.
KEYWORDS
Scheduling, Fair Queuing, QoS, Bursty traffic
1. INTRODUCTION
Different kinds of services in multimedia networks need different kinds of quality of services
(QoS). QoS is usually quantified by end-to-end delay, service rate, delay variation (jitter) and
packet loss rate. QoS provision might be accomplished in different network layers or devices
such as switches or routers. Due to their key role in QoS provisioning, scheduling algorithms
have received much attention in the literature [1]-[6].
In the development of packet scheduling algorithms, with respect to internal structures, there are
two categories of scheduling algorithms: sorted-priority and frame-based [1]. In a sorted-
priority category, a set of potential functions or virtual clocks are defined. When a packet
arrives in or departs from the server, the values of the virtual clock are updated. For each
waiting packet in the queue, a time stamp is calculated from the virtual clocks. The scheduler
sorts packets in order of the time stamps and serves a packet with the highest priority [7]-[8]. A
useful survey can be found in [2].
In the other category i.e. frame-based, a duration of time is defined as the frame which includes
time-slots. Based on the requested service rate, each session reserves some time-slots in the
frame. The round robin family is a major kind of algorithms in this category [9],[10].
In both of the above categories, the reserved or requested service rate is usually applied to
isolate sessions. Many kinds of packet scheduling algorithms e.g. WFQ, SCFQ, GR, DRR etc.
have been proposed to distribute available bandwidth fairly among all backlogged sessions in
terms of requested service rates, hence, this kind of scheduling algorithm is called Rate
Proportional Server (RPS)[1]. However, most of the RPS schedulers do not have acceptable
performance when bursty traffic and non-bursty (smooth) sessions compete. Suppose a bursty
and a smooth session, equal in term of requested service rates are scheduled by an RPS. When
2. International Journal of Wireless & Mobile Networks (IJWMN) Vol. 5, No. 2, April 2013
22
the bursty session starts to send data after having been idle while the smooth session received
regular service, the RPS scheduler serves both sessions similarly. Because only the service rates
are involved in the scheduling algorithm, unused service in idle duration cannot return back to
the bursty session. In the next section, the treatment of bursty traffic and non-bursty traffic
under by an RPS scheduler is studied with an example.
The bursty nature of internet traffic [11] and QoS requirements in multimedia applications
motivate us to consider in addition to the requested service rate, another parameter which would
describe the need for bursty service in the scheduling algorithm. However, the scheduling of
bursty traffic has been an attractive subject for investigation.[12]-[28]. In these studies the
authors attempt to design scheduling algorithms that provide acceptable service for bursty traffic
by involving more parameters such as delay due time, unused credit or burst specification in the
scheduling algorithms. By adjusting the proper parameters, a better QoS can be provided to
each bursty session.
In some studies, traffic is modelled by a series of bursts, and the scheduling algorithm takes into
account its special requirements and specifications [17]-[19]. This model is suitable for
compressed video such as the MPEG format [17], or optical burst switches (OBS)[20]-[21].
Some scheduling algorithms which consider bursty traffic and channel disappearance in
wireless networks are studied in [22]-[24]. In [22] some credit values are proposed to count
number of unavailable or unused service for each session. Some other studies define a due time
threshold for each session and the server tries to send the packets within the timing limit of this
threshold [18]-[25].
There are also other methods which use the delay or jitter (i.e. delay variation) parameter as
their main scheduling parameter [26]-[27], due to jitter importance in multimedia applications.
In this group of schedulers, bursty traffic is treated implicitly.
In this paper, we improve SCFQ[7] the famous RPS scheduling algorithm, to provide fair
service to both bursty and non-bursty flows. A dominant feature of SCFQ is that its fairness
index (which is based on the service rate) is less than twice the minimum value that can be
achieved for a packetized scheduling algorithm [7].
The organization of the paper is as follows. Section II presents our proposed scheduling
algorithm named Burst-Service Self Clock Fair Queuing (BSCFQ). In section III, we study the
performance of the proposed scheduling method by a simulation model. Section IV concludes
the paper.
2. BURST SERVICE SCFQ
In this section, we present a modification of a known scheduling scheme named SCFQ that
provides proper service to burst traffic. First, we define some parameters and criteria which are
used in the remainder of the paper.
2.1. Definitions
Definition 1-The amount of service:
Let Sሺݐଵ, ݐଶሻ denote the amount of service which session fi receives during (t1, t2). The amount
of service is equal to the sum of all packet lengths in fi which are completely served by the
server. The amount of service is measured in term of data unit e.g. bit.
Let ߩ denote the reserved service rate, then the relative service of the session fi is shown by
sොሺݐଵ, ݐଶሻ and defined as follows:
ୗሺ௧భ,௧మሻ
ఘ
.
3. International Journal of Wireless & Mobile Networks (IJWMN) Vol. 5, No. 2, April 2013
23
Definition 2- Postponed service:
Due to lack of data, each session fi may receive service which is less than its reserved service.
We call the amount of service which is not offered to a session due to the lack of data as the
"postponed service".
Definition 3- Compensable service threshold:
Compensable service is defined when a server tries to offer more service to a session which has
some amount of postponed service and finally can compensate it in a limited time period. This
amount of postponed service which can be compensated is called compensable service.
Compensating of service should be carried out in a condition in which other sessions are
backlogged. The maximum amount of service which can be compensated by a server for each
session is called its compensable service threshold.
Let γi denote the compensable service threshold for session fi in this paper.
In packet by packet scheduling algorithms (no preemptive type), the server does not start
serving a new packet before the service of the last packet is finished. Therefore, it is possible to
consider a condition in which one packet is served more than accords with the share of session
fi. Consequently, the amount of service may advance up to Li (the maximum packet length in fi).
Therefore, we can say that if session fi has a postponed service equal to Li, the server can
compensate for it in the assumed condition. With respect to definition 3, in packet by packet
scheduling algorithms we can conclude that the compensable service threshold should be at
least equal to Li or:ߛ ܮ (1)
2.2. Self-Clock Fair Queue
SCFQ [7] is a sorted-priority scheduler that defines the finishing time stamp for each packet as
follows: ܨ
ൌ ݉ܽݔ൛ܨ
ିଵ
, ܨ௨௧ൟ
ೖ
ఘ
(2)
Where ܨ
is the finishing time stamp of the kth
packet of session fi. The virtual clock of the
system in SCFQ is denoted by ܨ௨௧ which is equal to the finishing time stamp of the packet
which is being served when the kth
packet arrives. ܮ
and ݎ are the packet length of the kth
packet
and requested service rate in session fi. This formula estimates the finishing service time of each
packet in a fluid flow system and applies it in packet by packet scheduling. The calculating of
(2) is easier than some other estimations such as those in WFQ.
2.3. Burst-Service Self-Clock Fair Queue
In addition to the request service rate, i.e. ρi, we apply another non-negative parameter in
BSCFQ which is named flash back and denoted by fbi. Flash back is a parameter which adjusts
the amount of compensable service threshold by playing back the virtual time of the system in
the session fi's view, therefore fbi is measured by the duration of the second.
The main difference between SCFQ and BSCFQ is in the calculation of the finishing time
stamp. In BSCFQ the finishing time stamp of the kth
packet in fi is calculated as follows:
ܨ
≜ ൝
0 ݇ ൌ 0
݉ܽݔ൛ܨ
ିଵ
, ܿݒሺܽ
ሻ െ ݂ܾൟ
ೖ
ఘ
݇ 0
(3)
Whereܽ
is the arrival time of the kth
packet and ݂ܾ is the flash back parameter in session fi.
vc(t) is the overall virtual clock of the system and defined as:
ܿݒሺݐሻ ≜ ݉ܽ ݔሼܿݒሺݐିଵሻ, ܨ௨௧ሽ ݐ ݐ ൏ ݐାଵ (4)
4. International Journal of Wireless & Mobile Networks (IJWMN) Vol. 5, No. 2, April 2013
24
FCurrent is the finishing time stamp of the packet that is being served in the server at time t and tn
is the nth
moment in which vc(t) is modified and vc(tn-1) is the previous stored virtual clock . We
assumed that: vc(0)=0.
For each session also we define a virtual clock as follow:
ܿݒሺݐሻ ≜ ܨ
ு
െ
ಹಽ
ఘ
(5)
Where ܨ
ு
and ܮ
ு
are the finishing time stamp and length of the packet which is head of line
in session fi at time t. If a session is not backlogged, i.e. there is no packet as a head of line
packet, then the time stamp of the previous packet is considered as vci(t). We also assumed that:
vci(0)=0. Let ܿݒሺݐଵ, ݐଶሻ denote ܿݒሺݐଶሻ െ ܿݒሺݐଵሻ.
Similar to SCFQ, we assume that by ending a busy period, i.e. when the server has no more
packet in the queue, the algorithm reinitialized by setting all the vc ,vci and packet counts in
each session fi to zero.
Note that when a session becomes backlogged after an idle period, (3) indicates that ܨ
may be
less than ܿݒሺܽ
ሻ. Therefore, it is possible that ܨ௨௧ will be less than the finishing time of the
last served packet . By defining (4), in this case the value of the vc(t) remains constant.
In acondition in which all sessions are regularly backlogged ܨ௨௧is less than or equal to the
finishing stamp of the head of line packet in each session due to the packet selection mechanism
which a packet by the minimum value of the finishing time stamp is selected.
Figure 1. Packet Arrival and Departure Times in Ex.1
2.4. Example
In the following examples, we attempt to illustrate the mechanism of our algorithm. BSCFQ and
SCFQ results are compared to indicate the benefits of this modification.
It is assumed that there are 2 sessions, all packets lengths are the same and the requested service
rates, (ρ1 and ρ2) are equal to 0.5 packet/sec in both Ex. 1 and Ex.2. The flash back of the
5. International Journal of Wireless & Mobile Networks (IJWMN) Vol. 5, No. 2, April 2013
25
sessions f1 and f2 (݂ܾଵ and ݂ܾଶ) are equal to 0 and 6 sec respectively in both examples. Arrivals
in example1 and example2 are different.
Figure 1 indicates the arrivals and departures in Ex.1 for both SCFQ and BSCFQ algorithms. In
each algorithm (for example part A), arrows in the diagrams A-1 and A-2, indicate the arrival
times of packets in f1 and f2. The finishing time stamps of each packet are also indicated above
each packet's arrow. Diagrams A-3 and B-3 indicate the moments of packet departure from the
system. Meanwhile, we indicate the finishing time stamp of the packet above each arrow and
the virtual clock of the system between both departure times is shown in diagrams A-3 and B-3.
In both examples, if the service of f2 is postponed then the BSCFQ scheduler is able to
compensate for only 3 postponed packets. The packet arrivals in Ex.1 indicate that when 3
packets are served from f1, session f2 is backlogged. In SCFQ the service is equally divided
between two sessions after the 3rd
second and cannot compensate for the postponed service. But
in BSCFQ, first the postponed service is served to f2 then the service is equally divided between
the two sessions. Ex.2 shows that the amount of service which can be compensated for by
BSCFQ is limited even if the postponed service is more than 3 packets.
Figure 2. Packet Arrival and Departure Times in Ex.2
Average packet delays in Ex.1 and Ex.2 are collected in Table 1. The average delay of f2 in both
examples is decreased by BSCFQ. The results indicate that it is possible to adjust BSCFQ to
compensate for a desired value of postponed service and thus, to decrease its average packet
delay.
6. International Journal of Wireless & Mobile Networks (IJWMN) Vol. 5, No. 2, April 2013
26
Table 1. Average packet delay in SCFQ and BSCFQ
Example Ex.1 Ex.2
method SCFQ BSCFQ SCFQ BSCFQ
Average Delay
f1 1.00 2.00 0.13 0.88
f2 2.50 1.50 2.33 1.33
3. SIMULATION MODEL
With the aim of evaluating the average packet delay in the performance of the BSCFQ
algorithm, we create a simulation model using SIMULINK®
in MATLAB. The model includes
4 sessions with equal arrival rates but different burstiness parameters. The arrival traffic in the f1
and f4 sessions is considered to be smooth but for the f2 and f3 sessions it is bursty.
In the first scenario, we assumed that the f1 and f4 sessions have a constant packet rate with
packet inter arrival time equal to 4 sec while sessions f2 and f3 have switched (ON-OFF) traffic
models. During ON intervals a constant packet rate is used with inter arrival time equal to 0.1
sec, while no packet is generated during OFF intervals. ON and OFF intervals are constant but
their periods are different in f2 and f3. We assume that the ON interval is 0.7 sec with a 28 sec
period in f2 while it is 0.3 sec with 12 sec period in f3. The mean arrival rates in all sessions are
the same and equal to 0.25 pkt/sec. The capacity of the output link is considered as 1 pkt/sec
and all packets are to have the same length. Figure 3 indicates the arrivals in the first scenario. It
is obvious that the postponed service in sessions f2 and f3 may be respectively 7 and 3 in each
period.
In order to study the effect of random arrival in our discussion, we build another scenario in
which the arrival process in one of the sessions (e.g. f4) is Poisson. In the second scenario, we
assume that in session f4 packet inter arrival time is exponential (with parameter 4) instead of
being constant. All other assumptions are the same as in the first scenario.
Figure 3.Arrivals in simulation model
Table 2. Values of Flash Back in f2 and f3 sessions
Ex. 1 Ex.2
Session
BSCFQ1
BSCFQ2
BSCFQ3
BSCFQ4
BSCFQ5
BSCFQ6
BSCFQ7
BSCFQ8
BSCFQ9
BSCFQ1
BSCFQ2
f2 7 14 21 28 0 0 0 14 28 14 28
f3 0 0 0 0 4 8 12 6 12 6 12
7. International Journal of Wireless & Mobile Networks (IJWMN) Vol. 5, No. 2, April 2013
27
We also examine SCFQ and BSCFQ with various flash back parameters for f2 and f3. A
summary of the parameters for each different case is given in Table 2. For the first example, the
value of flash back for session f2 is increased in 4 steps (BSCFQ1 to BSCFQ4); it is also
increased in another session, f3, in 3 steps (BSCFQ5 to BSCFQ7). Finally, the flash back values
in both f2 and f3 sessions are changed in 2 steps in the first example (BSCFQ8 and BSCFQ9) and
also in the second example (BSCFQ1 and BSCFQ2).
3.1. Simulation Results
The average and maximum delays of each session are computed for 1000 sec in the first
scenario. The delay of each packet is computed during simulation time and simulation results
are shown in Table 3 and depicted by Figures4 and 5 respectively which show the average delay
for different values of flash back in f2 and f3.
Table 3Average and maximum of packet delay in the first scenario
Scheduling
Algorithm
Average of delay ineach session Maximum delay of each session
f1 f2 f3 f4 f1 f2 f3 f4
SCFQ 3.53 9.30 6.49 1.97 10.05 21.40 10.80 4.05
BSCFQ1 3.55 9.09 6.66 1.99 10.05 21.40 10.80 4.05
BSCFQ2 4.59 6.59 7.41 2.69 8.05 18.40 14.80 6.05
BSCFQ3 5.26 4.29 8.16 3.56 9.05 10.40 14.80 7.05
BSCFQ4 5.42 3.81 8.34 3.69 12.05 8.40 14.80 7.05
BSCFQ5 3.10 10.09 6.03 2.07 6.05 22.40 10.80 4.05
BSCFQ6 2.75 13.06 3.72 1.75 4.05 25.40 6.80 3.05
BSCFQ7 3.03 13.36 2.87 2.03 4.05 26.40 4.80 3.05
BSCFQ8 5.02 8.59 4.69 3.00 7.05 21.40 8.80 5.05
BSCFQ9 5.94 8.50 4.14 2.71 11.05 21.40 8.80 5.05
Figure 4The packet delay averagein eachsession at different cases
(The flash backof session f2is changed).
0.00
2.00
4.00
6.00
8.00
10.00
f1 f2 f3 f4
Session
Delay(sec)
SCFQ BSCFQ1 BSCFQ2 BSCFQ3 BSCFQ4
8. International Journal of Wireless & Mobile Networks (IJWMN) Vol. 5, No. 2, April 2013
28
Figure 5The packet delay averagein eachsession at different cases
(The flash back of session f3is changed).
Figure 6The packet delay averagein different sessions at different cases
( The flash back values of both sessions f2 and f4 are changed)
Figure 6shows the average delay of each session when the flash back of both f2 and f3 sessions
are increased (BSCFQ8 and BSCFQ9). SCFQ, BSCFQ4 and BSCFQ7 are shown in this figure for
comparison.
Figure 7 Average delays in the second scenario
Table 4 Average packet delay in the second scenario
Scheduling Algorithm
Average delay of each session
f1 f2 f3 f4
SCFQ 5.78 12.69 6.56 13.18
BSCFQ1 5.80 8.23 4.93 19.06
BSCFQ2 14.21 6.09 5.11 12.98
Table 4 and Figure 7 show the average delay of the second scenario. We consider only two
cases for this scenario where the value of the flash back in sessions f2 and f3 are non-zero.
0.00
5.00
10.00
15.00
f1 f2 f3 f4
Session
Delay(sec)
SCFQ BSCFQ5 BSCFQ6 BSCFQ7
0.00
5.00
10.00
15.00
f1 f2 f3 f4
Session
Delay(sec)
SCFQ BSCFQ4 BSCFQ7 BSCFQ8 BSCFQ9
0.00
5.00
10.00
15.00
20.00
f1 f2 f3 f4
Session
Delay(sec)
SCFQ BSCFQ1 BSCFQ2
9. International Journal of Wireless & Mobile Networks (IJWMN) Vol. 5, No. 2, April 2013
29
3.2. Discussion
With respect to Figure 4 and Figure 5, we can see that by increasing the value of flash back of a
session, (our proposed parameter for the adjustment of the amount of compensable service
threshold) the corresponding average delay is decreased. When the flash back of a session
increases, however, average delays in other sessions may either increase (e.g. f1 , f3 and f4 in
Figure4 and f2 in Figure5) or show no noticeable change ( e.g. f1 and f4 in Figure 5). This effect
is predictable due to the fact that overall average packet delay during a busy period is constant
when the server is in work-conserve mode. A work-conserve server is a server which is busy
during every time period that at least one session is backlogged. Therefore, when the average
delay of a session during a busy period decreases, the average delay in other sessions should be
increased or kept constant to ensure the overall average delay remains constant.
Figure 6 indicates the average delay when we want to provide burst service to both of the bursty
sessions. Delay average in both bursty sessions f2 and f3 are reduced by increasing the flash back
value (compare BSCFQ8 and BSCFQ9 with SCFQ). Although average delay in other sessions
(e.g. f1 and f4) increase in BSCFQ8 and BSCFQ9 in comparison with SCFQ, the growing of
average delay in other sessions is slighter than that in BSCFQ4 and BSCFQ7 where the server
provides burst service only to one session.
These results are satisfied when the arrivals in session f4 are random. The results in Figure 7
show as is the case in the first scenario, the average delays of f2 and f3 are reduced in
comparison with the delay in SCFQ.
We can also observe that the average delay of f4 is increased in scenario2 as compared to
scenario1. The random nature of the arrival process can be considered as the main factor in the
increase in the average delay of f4. Therefore, we conclude that BSCFQ can reduce the average
delay of bursty sessions even when the arrival is random.
4. CONCLUSIONS
In this paper, we have proposed BSCFQ to improve SCFQ, as a known RPS scheduling
algorithm. In addition to request service rate,we introduce a new parameter called flash backfor
each session. The flash back parameter has beenused to measure the amount of postponed
service that should be compensated by the BSCFQ server. Therefore, BSCFQ provides better
service to bursty sessions rather than SCFQ.
An important advantage of BSCFQ vs. SCFQ is that the average delay of a burstysession can be
reduced. To study the average delay in BSCFQ, we constructed a simulation model. Our
simulation results demonstrate that in compare with SCFQ, BSCFQ reduces theaverage delay
in bursty sessions. It is worth pointing out that QoSs of most of multimedia applications e.g.
real-time video streaming depends on such a feature. An upper bound of delay will be derived in
our upcoming publications.in BSCFQ scheduling algorithm.The computational complexity of
our proposed algorithm, is the same as SCFQ. This is because BSCFQ only adds a subtraction
function in calculating the finishing-tag and also a comparison during virtual clock computation.
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Authors
Mahmoud DaneshvarFarzanegan:.received his B.Sc. degree in electrical
engineering from Isfahan University of Technology (IUT), in 1994 and the
M.Sc. degree in electrical engineering (Communication Networks) from Amir-
Kabir (Polytechnique) University of Technology, Tehran, Iran, in 1997. He
joined the Electrical Engineering Islamic Azad University branch of Najafabad
(IAUN)in 1999 where he is a lecturer. He is currently working toward his Ph.D.
His research interests include: Packet scheduling algorithms, QoS and networks
performance evaluations, Network calculus, and Broadband Power Line
Communication.
HosseinSaidi: received the B.S. and M.S. degrees in electrical engineering
(Electronics and Communication Eng.) from Isfahan University of Technology
(IUT), in 1986 and 1989, respectively, and the Ph.D. degree in electrical
engineering from the Washington University in St. Louis, MO in 1994.From
1994 to 1995, he was a research associates at Washington University St. Louis,
and in 1995 he joined the Electrical and Computer Engineering of IUT, where
he is an Associate Professor. His Research interest includes ATM, high speed
networking, QoS guarantees, routing, algorithms and information theory.
Mehdi Mahdavi: received his B.Sc. degree in electrical (Electronics)
engineering from Isfahan University of Technology, the M.Sc. degree in
electrical engineering from Amir-Kabir (Polytechnique) University of
Technology, Tehran, Iran, and the Ph.D. degree in electrical engineering
(Mobile Communication Networks) from the University of Sheffield, Sheffield,
U.K. In 2004, he joined the ICT faculty, Ministry of ICT, Tehran, where he was
an Assistant Professor working on Tele-traffic theory and network quality of
service in the next generation of mobile cellular and wireless networks. Since
2005, he has been with the Department of Electrical and Computer Engineering, Isfahan University of
Technology, as an Assistant Professor. His research interests include tele-traffic theory, network quality
of service, networks performance evaluations, network calculus, traffic source modelling and
measurements, scheduling algorithms, routing algorithms and telecommunication in general.