50620130101005

Journal of Computer Engineering & Technology (JCET) ISSN 2347-3908 (Print), ISSN
2347-3916 (Online), Volume 1, Issue 1, July-December (2013)
36
OLCMCR: ORDERED LOAD-BALANCING COOPERATIVE MULTI
CHANNEL ROUTING TOPOLOGY FOR VOICE TRANSMISSION OVER
IP BASED 802.11 WLAN
Mohammed Sirajuddin1,
Dr D. Rajya Lakshmi2
And Dr Syed Abdul Sattar3
1
Royal Institute of Technology and Science, Chevella, Hyderabad, India
2
Gitam Institute of Technology, Gitam University, Vizag, India
3
Royal Institute of Technology and Science, Chevella, Hyderabad, India
ABSTRACT
In this paper, we propose a cooperative multi channel VoIP routing protocol for 802.11
WLAN networks that handles the congestion to improve the Quality of routing service. Part of
the proposed protocol introduced a MAC layer level solution called Cooperative Multi Channel
Routing (CMCR) that effectively handles the multi channel transmission at one hop relay node
level cooperative multi channel group. The proposed model controls the congestion in
hierarchical order to minimize the resource utilization. Limited bandwidth and a high degree of
mobility require that routing protocols for ad hoc networks be adaptive, trouble-free, and energy
saving. Here we proposed a new Ordered Load-balancing Cooperative Multi Channel Routing
Topology (OLCMCR) for 802.11 WLANs, which handles congestion state. OLCMCR capable
to adopt a any WLAN structure with enhanced similar resilience against mobility. And
OLCMCR utilizes CMCR to reduce the overhead of route failure recovery, improve route
efficiency and reduce data transmissions. Our simulation results show that OLCMCR handles
congestion with reduced control overhead in various environments. Also can observe improved
packet delivery ratio.
Keyword: 802.11, WLAN, congestion control, OLCMCVR
1. INTRODUCTION
The proposed model controls the congestion in hierarchical order to minimize the resource
utilization. Limited bandwidth and a high degree of mobility require that routing protocols for
ad hoc networks be adaptive, trouble-free, and energy saving. Here we proposed a new Ordered
Load-balancing Cooperative Multi Channel Routing Topology (OLCMCR) for 802.11 WLANs,
which handles congestion state. OLCMCR utilizes CMCR to reduce the overhead of route
JOURNAL OF COMPUTER ENGINEERING & TECHNOLOGY
(JCET)
ISSN 2347-3908 (Print)
ISSN 2347-3916 (Online)
Volume 1, Issue 1, July-December (2013), pp. 36-45
© IAEME: http://www.iaeme.com/JCET.asp
JCET
© I A E M E

37
failure recovery, improve route efficiency and reduce data transmissions. Our simulation results
show that OLCMCR handles congestion with reduced control overhead in various
environments. Also can observe improved packet delivery ratio.
The projected model [1] uses a Markov process to model DCF to evaluate the channel
throughput, and frame loss at wireless stations. The initiators [2],[3] to study the performance of
real-time applications over 802.11. The inherent limitations of the 802.11 a/b DCF [4] in
supporting VoIP calls over a WLAN. The research works projected by [5] and [6], the
references they used and the enhanced DCF (EDCF) [7], [8] tend to afford distinguished service
instead of stern QoS guarantee analyzed the interference model [9] in wireless mesh network
and projected a call admission control with interference capacity. Several performance
optimization schemes [10], [11], [12] are proposed for WLANs to improve the VoIP quality.
Projected model [10] uses a dual queue of 802.11 MAC to provide priority to VoIP. In this
regard [11] proposed packet aggregation to increase capacity and [12] proposed an adaptive
transmission algorithm over an IEEE 802.11 WLAN, which supports integrated voice and data
services, under this adaptive transmission model [12] the data traffic is transmitted with DCF,
while voice transmission is carried out with PCF.
The paper is organized as follows: Section 2 briefly describes the OLCMCR.
Section 3 describes cooperative multi channel Group Clogging Estimation (CMCGCE).
Section 4 briefly describes cooperative multi channel Group Egress Load-balancing
(CMCGEL) Algorithm Section 5 describes the simulation and results Section 6 concludes
the paper.
2. OLCMCR
The frame dropping often occurs in WLAN. The reasons for this frame dropping are as below
• Transmission Link failure.
• Inferred Transmission due to overwhelming Inflow that leads Inflow load to low. This also
can claim as frame dropping due to clogging at routing.
An ordered order is used to handle the clogging state as follows
• The Status of clogging within cooperative multi channel Group
• The status of clogging between cooperative multi channel Groups
This helps in minimizing of source level outflow regulation cost and balances the power
consumption.
A. Network and Node activities under proposed protocol:
The network is to be split into cooperative multi channel groups with respect to nodes
participating in multi channel routing such that multicast nodes as multi channel group heads
For each multi channel group i where MGi ,.....1= ; ( MG is the total number of multi channel
groups)
Find transmission load threshold nζ for each multi channel group i .By using nζ of each
multi channel group Transmission load threshold for entire network can be measured.
B. Information sharing within cooperative multi channel Group
Each node nthat belongs to multi channel group iMCG verifies the outflow load and
shares degree of outflow load ( )nold with multi channel group head. Once ( )kolnd received

38
from each node k of the multi channel group iMCG , the multi channel group head ( )hMCGi
calculates the degree of outflow load ( ) iMCGolmcgd at cooperative multi channel Group
( )hMCGi .
i
MCG
k
k
MCG
MCG
olnd
olmcgd
i
i
∑=
= 1
)(
)(
3. Cooperative multi channel Group Clogging Estimation(CMCGCE) Algorithm
Cooperative multi channel Group clogging Estimation (CMCGCE) algorithm is
presented in this section. CMCGCE helps in locating the state of frame dropping due to clogging.
This evaluation occurs under Mac layer. The algorithm CMCGCE follows
CMCGCE Algorithm
At an event of inflow loads at nodei :
Updating Inflow load:
(( ) 0)
' ': 0.5 0.5 ( )
:
(( ) 0)
':
:
f do
t T
il ilcr
T
t
t T til il ilcr TT T T
endif
if dot T
il ilcr T
t
il ilcrT
endif
γ γ
γ
σ σ
γ
γ γγ
γ γγ γ
γ γ
γ
σ
γ
γ
− <
− 
 = × + ×
 
 
   −
   = +
   
   
− ≥
−
=
=
Here in the above conditional statement
tγ : Time between last two transmissions of hop relay node level connected nodes in routing
path
Tγ : Time between two transmissions of hop relay node level connected nodes in routing path
σ ′: Average slop threshold of the inflow load
cril : Current inflow load ratio
T
ilγ : Average inflow load threshold observed for predefined interval Tγ
cril : Current inflow load ratio
ril : Inflow load ratio
ceil : Expected inflow load threshold at current interval

39
Detecting frame drop:
'
( )
due to
loss due to
il il
ce et
T
if il il doce r
packet loss link failure
else
packet congestion
endif
σ γγ= +
<
4. Cooperative multi channel Group Egress Load-balancing(CMCGEL) Algorithm
CMCGEL initiates if clogging found at a node i in routing path. Upon receiving
clogging alerts from Mac layer the routing protocol initiates CMCGEL. Let s be the node
that transmits data to hop relay level nodei . If node i affected by clogging, then CMCGEL
alerts node s . Upon receiving alerts about the clogging state at the hop relay level target node
i , s evaluates ‘ ( ) ( )nd ol mcgd ol
s MCGc
> ’, if true then verifies that ( ( ) ( ) )nd ol mcgd ol
s MCGc
− is
greater than or equal to sε is true or not. If true then the node s balances its outflow load such
that ( )snd ol is not less than ( )mcgd ol
MCGc
Here in the above description sε is outflow threshold at node s , cMCG is current multi
channel group such that cs MCG∈
The node s balances its outflow load by increasing frame such that ( )snd ol is greater or equal
to
( )mcgd ol
MCG MCGc c
ε+
| |
( ) ( ) { and is a node}
1
| |
MCGc
mcgd ol nd ol k MCGMCG k cc
k
MCG MCGc c
ε
− ∈∑
==
k
If ‘ ( ( ) ( ) ) )( ( ) ( ) ) (cs MCG nd ol mcgd ol
s MCG sc
nd ol mcgd ol or ε− <≤ ’ then node s avoids balancing
its outflow load and alerts the ( )MCG h
c
(multi channel group head of the cMCG , cs MCG∈ ).
Then ( )cMCG h alerts all upstream unicast nodes to the node s of the multi channel group
cMG . Upon receiving alerts from ( )cMCG h all upstream unicasting nodes attempts to
balance their outflow load of the node s and updates their ‘ ( )nd ol ’. Each unicasting node
that updated its ‘ ( )nd ol ’ and alerts the ( )cMCG h , then ( )cMCG h estimates ( )mcgd ol
MCGc
and
checks the same with ( )d ol as follows
( ) ( )cMCGmcgd ol d ol ε≥ + is true or not.
Here in this equation ( )d ol is the routing path level degree of outflow load and ε is
outflow load threshold measured at the path level.

40
If the given condition is true, then CMCGEL process ends, if not ( )cMCG h alerts ( )pMCG h
then CMCGEL initiates at multi channel group pMCG , which is adjacent upstream multi
channel group to cMCG . The CMCGEL process at pMCG is as follows:
Upon receiving the alert from ( )cMCG h , the ( )pMCG h alerts all upstream unicasting nodes
of node ‘ s ’, which belongs to multi channel group pMCG . Then upstream unicasting nodes
of the multi channel group pMCG , which are upstream nodes to node s balance their outflow
load and define ( )nd ol then informs the same to ( )pMCG h .Afterwards the ( )pMCG h
measures ( )mcgd ol
MCGp
and verifies it as follows:
( ) ( )mcgd ol d ol
MCGp
ε≥ +
If above equation is true then CMCGEL process ends at pMCG , if not that continues to next
multi channel group in the upstream level of the pMCG
This process continues till victim node i is free from clogging or if CMCGEL applied at all
upstream multi channel groups of the ‘ cMCG ’.
The process described above is attempting to avoid the clogging by balancing the outflow
load between multi channel groups and the same can be referred as cooperative multi channel
group level outflow load-balancing (CMCGEL).
Once the CMCGEL ends then the source multi channel group evaluates the ( )d ol .Based on
this ‘ ( )d ol ’ value, the transmission source node balances its outflow load.
Cooperative multi channel Group egress Load-balancing (CMCGEL) Algorithm
P1:
| |
( ) ( )
1
| |
MCGc
mgd ol d olMCG kc
k
MCG MCGc c
ε
−∑
==
If ( ) ( )nd ol mcgd ol
s MCGc
> and ( ) ( )nd ol mcgd ol
s MCG MCGc c
ε− ≥ begin
( ) ( )t tD s D s bt= +
Here ( )tD s is delay time at the node s
bt is buffering time threshold
Value of buffering time threshold bt should be decided such that ( ) ( )d ol mcgd ols MCG MCGc c
ε≥ +
Return.
Endif
P2:
Node s alerts multi channel group head ( )cMCG h about the clogging state of the nodei .
( )cMCG h Alerts all upstream unicasting nodes to node s nodes, which belongs to multi
channel group cMCG
Each node of { , ,..., }
1 2
n n n
u u uk MCGc
updates their ‘ ndol ’ and alerts about the same to
( )CMCG h

41
( )cMCG h Measures ( )mcgd ol
MCGc
by the subsequent equation:
| |
( )
1( )
| |
MCGc
nd ol k
kmcgd ol
MCG MCGc c
∑
==
If ( )mgd ol dolMGc
> and ( ( ) )mgd ol dolMGc
ε− ≥ begin
Alert: The victim node i is freed from clogging state
Return.
Endif
P3: ( )cMCG h Alerts ( )pMCG h
( )pMCG h Alerts all unicasting upstream nodes to node s , which are belongs to multi channel
group pMCG
For each upstream unicasting node { | }pn n MCG∈ begin
If ( ) ( )nd ol mcgd ol
n MCGp
> and ( ) ( )nd ol mcgd ol
n MCG MCGp p
ε− ≥ begin
( ) ( )t td n d n bt= +
The Value of buffer threshold bt should be decided such that ( ) ( )nd ol mcgd ol
n MCG MCGp p
ε≥ +
Endif
Find ( )nnd ol and send the same to ( )pMG h
End-of-for each
Then ( )pMCG h measures ( )mcgd ol
MCGp
If ( ) ( )mcgd ol d ol
MCGp
ε− ≥ and 0ε >
Alert: Balancing Outflow load at multi channel group pMCG removed clogging state at node
i .
Return;
Endif
For each upstream multi channel group in sequence
Begin
Consider pMCG as cMCG
Consider immediate upstream multi channel group 'pMCG to multi channel group pMCG as
pMCG
Go to P1
End-of-for each
∈{MCG | transmissioninitiation node is src and src MCG }
1 1
Measures ( )d ol as
| |
( )
1( )
| |
MCG
mcgd ol MCGi
id ol
MCG
∑
==
The transmission initiated node ‘ src ’ that belongs to multi channel group ‘ MCG
1
’, balances
the outflow load such that clogging state will be avoided.

42
5. SIMULATIONS AND RESULTS DISCUSSION
The experiments were conducted using NS-2. We build a simulation network with hops
under mobility and count of 50 to 200. The simulation parameters described in table 1.
Authentication ensures that the buffer is properly allocated to valid frames. The simulation
model aimed to compare OLCMCR and self-adaptive transmission scheme [12]. The
performance check of these two carried out against to the metrics explored below
Table1: Simulation parameters that we considered for experiments
Number of nodes Range 50 to 200
Dimensions of space 1500 m × 300 m
Nominal radio range 250 m
Source–destination pairs 20
Source data pattern (each) 4 frames/second
Application data payload size 512 bytes/frame
Total application data load range 128 to 512 kbps
Raw physical link bandwidth 2 Mbps
Initial ROUTE REQUEST timeout 2 seconds
Maximum ROUTE REQUEST
timeout
40 seconds
Cache size 32 routes
Cache replacement policy FIFO
Hash length 80 bits
Certificate life time 2 sec
The scalability of Frame Delivery Ratio with respect to the total number of source nodes
that participating in routing and the traffic load emerged from them has been evaluated initially.
When the source node count is up to 20, both self-adaptive transmission scheme and OLCMCR
maintained their frame delivery ratio scalability in similar passion (see fig 1).
During the increase in the source node count more than 20, the self-adaptive transmission scheme
failed to retain its scalability (see fig 1). This is due to rise in the traffic load caused by increase in
source nodes, and the clogging due to the overloaded traffic. The OLCMCR advantage over self-
adaptive transmission scheme in frame delivery ratio observed is as follows:
When node count between 10 to 20, the average 11% is the advantage of OLCMCR over self-
adaptive transmission scheme observed in Frame Delivery Ratio.
When node counts in between 25 to 45 the average 20% is the advantage of OLCMCR
over self-adaptive transmission scheme observed in Frame Delivery Ratio.
When node counts in between 50 to 40 the average 30% is the advantage of OLCMCR over self-
adaptive transmission scheme observed in Frame Delivery Ratio.
With these observations it is evident that self-adaptive transmission scheme is loosing its
scalability an average of 10% per each 20 nodes increment in the cooperative multi channel
routing path.

43
Figure 1: The advantage of OLCMCR over self-adaptive transmission scheme in Frame
Delivery ratio
The evaluation of the Frame Overhead metric (see fig 2) is evident that the OLCMCR is
stable and scalable than self-adaptive transmission scheme. The observations indicate the
following statistics:
Average 73% of frame overhead for each 5 nodes increment in node count observed in
self-adaptive transmission scheme over OLCMCR.
Average 1% is the increment in frame overhead observed for each 5 nodes increment in node
count observed for OLCMCR. Where as average 19% is the increment in frame overhead found
for each 5 nodes increment in node count observed for OLCMCR.
Figure 2: The Scalability and Stability of OLCMCR over self-adaptive transmission scheme
in frame overhead

44
Figure 3: MAC load comparison report
6. CONCLUSION
This paper discussed a cooperative multi channel routing algorithm called “Ordered
Load-balancing Cooperative Multi Channel VoIP Routing Topology for clogging control in
802.11 WLAN networks” in short referred as OLCMCR. This proposed routing strategy aimed
to control clogging in ordered format, In this regard it first tries to control at hop relay node level
outflow load balancing , if failed then attempts to control by group level outflow load balancing,
if still not succeed then finally attempts to control the clogging with outflow load balancing
between groups. Here in this protocol we derived set of algorithms called Cooperative Multi
Channel Group Clogging Estimation (CMCGCE) and Cooperative Multi Channel Group Egress
Load-balancing (CMCGEL). The CMCGCE algorithm is used to assess the state of the clogging
at a group that caused frame dropping. CMCGEL initiates if the clogging state is observed and
controls clogging in ordered order. The OLCMCR is network format independent. Hence it can
work with a group of either tree or mesh. As a part of an experimental study, the proposed
OLCMCR compared with ODMRP. The simulation results indicate that the OLCMCR improved
the PDR and minimized the Frame overhead of self-adaptive transmission scheme in order of
magnitude. With the motivation gained from simulation results of proposed routing topology
OLCMCR, the future direction can be minimizing the energy usage in OLCMCR
implementation.
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