Zero Down 24*n Mobile Network Connectivity

International Journal of Innovative Research in Advanced Engineering (IJIRAE) ISSN: 2349-2163
Volume 1 Issue 6 (July 2014) http://ijirae.com
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© 2014, IJIRAE- All Rights Reserved Page - 333
Zero Down 24*n Mobile Network Connectivity
D.Kadhirvelu G.Aghila
Research Scholar, Professor and Head, NIT
Bharathiar university Puducherry,karaikal
Abstract— Today, lots of connectivity problem in wireless mobile communication are due to weak signal strength. To overcome
this problem a novel idea of utilizing and enabling the service mobility between heterogeneous mobile service providers has been
explored. The basic idea behind the work is to make the heterogeneous providers to work together and to establish and extend
the connection in a spontaneous fashion, without making pre-established roaming agreements. At present roaming agreements
are set manually between the providers, but it is costly and time-consuming process. The idea is when the user moves out of the
home coverage area or when the signal gets down in a mobile terminal even when the mobile terminal is not in use, the
connections have to be extended to provide 100 % connectivity to the user by the available foreign network which eliminates the
problem of “not reachable” condition in mobile network. So for, the related works focuses on extension of connectivity only
while the call is in progress. But this paper fully concentrate on 24 hrs * N days connectivity whether the user call is on or off
progress by proposing a model called the PAC(Pre-Authenticated Connection) and it is designed by using HFNF(High
Frequency network first)technique which establish roaming agreements directly between operators before the connection is
disconnected. This architecture ensures the connectivity except in the case of power loss. In future we plan to extend the
connectivity even in power loss by balancing the power in spine hierarchy.
Keywords— PAC, HFNF, CTRESH, DTRESH, Handoff.
I. INTRODUCTION
The GSM systems have the ability to make and receive phone calls to and from other networks. For the consumers to get the
desired service and high coverage the different network agent can join together to give the desired service. At present different
network agent join together via static roaming procedure which is said in [21,22]. As pre-roaming agreements can’t be established
with all possible provider the users will be disconnected if service is unavailable in home network. To overcome the above problem,
“instant agreement” for roaming between different various network agent is proposed so that the users can get services from multiple
network agent. To overcome the same issue PAC mechanism is proposed to establish the connection before the pervious connection
with home network gets disconnected. This paper address the ability to decide correctly the time to call PAC mechanism based on
the strength of signal. This work also proposes a architecture with a modification in an physical layer of OSI model with Pre
authentication connection module which establish an instant connection with foreign network. Knowledge based mechanisms are
proposed to establish spontaneous roaming agreements.
This proposed architecture consists of knowledge based system with the databases that hold profile, intersystem handover control
rules and the network management system. Based on this mechanism a Fuzzy-Based algorithm is designed which identifies the
correct time to do the handover to the other foreign network to extend the service dynamically. The supportive idea of this work is
presented in section 2.The architecture of proposed PAC mechanism is described in section 3.The open trust model is explained in
section 4.The detailed working procedure and handoff is explained in section 5. Algorithm for rules and negotiation is explained in
section 6.Section 7 explains about handoff initiation procedure. Section 8 explains about handoff monitoring procedure. Section 9
concludes the concept with future idea.
II. BACKGROUND AND RELATED WORK
The service portability across network boundaries has been dealt in detail in Reference [1] and the same concept in the virtual
Home Environment [2],[3],[4],[5] has been described by emulating the behavior of the user home network. Reference [6] describes
the access to mobile services over unlicensed network.UMA helps to perform handover between different wireless networks with the
help of dual-mode handsets. The concept of Application-Layer Mobility is introduced by Schulzrinne [7] and Wedlund [8]. The
roaming problem regarding network integration is described in Reference [9]. AMBIENT provide a way for devices to connect to
each other via any network, through the instant agreements. To reduce scanning time Reference [10] is described and to reduce
handover delay time reference [11,12] is used and [13,14] reduce the authentication delay during handover. All the above described
mechanism does not or very weakly consider the weak signal strength problem, which requires a need of the solution. This paper
provides a PAC (Pre Authentication Connection) model based on HFNF (High Frequency Network First) mechanism.

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III. ARCHITECTURAL DESIGN OF PAC(PRE AUTHENTICATION CONNECTION)
MECHANISM
To enable instant connection with foreign network, the new PAC module is designed and it is illustrated in the following fig 1.
In the architecture a new module named pre-authentication connection is introduced which is used to establish connection before the
connection between the two host gets disconnected.
[3]
((
[1]
[1]- Request Service [2]- PAC Connection
[3]- Negotiation [4]- Connection
Established if
Fig.1. Pre-Authentication Connection with Partnership Negotiation
When the signal strength falls below the level, the EAP-AC passes the request of service to foreign network server. Once when
the foreign network server identifies that the request is not from home network, the first level basic trust is established using the
network id and as the second stage negotiation is done for instant connection.
IV. TRUST ESTABLISHMENT BETWEEN PROVIDERS – OPEN TRUST MODELS
For immediate, on-demand services, basic trust must be established between the providers before the start of the negotiation
procedure .The trust models is used between two providers to establish trust between them to perform negotiation at the faster rate.
If one network receives an request from unknown network for the usage of its service, the beginning level basic trust is established
between the providers before the start of negotiation procedure. Here the network Id is enough to establish trust between the
providers, as every network posses individual Id while establishing the network infrastructure. Once basic trust is established other
negotiation is done in advance before the connection with home network is disconnected. In other words the providers exchange
roaming agreement dynamically for settlement procedure, processes, agreement suspension and termination, airtime charges,
wholesale rate, and other required features [24] .The novelty in this trust establishment is the use of network ID to identify the
network provider.
V. WORKING PAC MECHANISM FOR INSTANT CONNECTION
A . Mobile Information Service and PAC
In Mobile device when signal gets weak while the call is in progress or the call is not in progress, the neighboring available
network is to be identified and communicated to optimize the handover. The information of nearby networks is obtained by MIS
using query-response mechanisms. The MIS information is used to make the decision for handover at appropriate time. Using this
information intelligent handover decisions is done. The MIS represents information by standard XML (Extended Markup Language)
format. MIS discovers information regarding all neighboring networks and exchanges information regarding network id to establish
basic trust in HFNF basis .
Once the base trust is established with a neighboring providers, the other providers will be in FIFO stack. Before making
negotiation with target provider to establish spontaneous connection, the foreign provider will check whether the home provider
belongs to same list of providers to whom the spontaneous connection is already established earlier. If so then the negotiation is
avoided with the home provider and connection is established based on the rules that is accepted in earlier negotiation .This reduces
[3] [3]
[4]
[1]
[1]- Request Servic [2]- PAC Connection
[3]- Negotiation [4]- Connection
Established if Condition satisfied
[2]
FORIGN PROVIDER
PAC
Home Provider
USER
EAP-AC
PAC

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the time and cost of negotiation and avoids repetition of same work. All this work will be done in advance once the signal falls
below the D-thresh hold value, the service can be extended without any delay in time and data loss..
If the home provider is not the member of the foreign provider then negotiates.have to be initiated by Open Trust Model by
using network id and negotiation is done between them by instantly framing the rules as needed to establish spontaneous connection
with two network providers. The connection will be established before the connection gets disconnected because of poor signal. Up
to this level the spontaneous connection is established but handoff doesn’t take place. The hand off will occur only when needed,
even though the pre-connection is established between the network. The hand off decision is done by fuzzy algorithm.
B. Handoff Types
The Handoff mechanism keeps the connection of MT active even when the signal strength gets weaker by changing the
coverage area of one network attachment point to another. Here this work uses vertical handoff since handover is done between
different network providers depending on received signal strength (RSS) .Handoffs can also be classified as soft or hard handoff. In
soft handoff or a make before break handoff MT establish the new connection with the target point before the old connection gets
dropped. The proposed work inherits the soft handoff concept since it establishes pre connection with the foreign provider before
the old connection with the home network gets dropped.
C. Handoff Algorithm Features
An efficient handoff algorithm that is used must be fast so that the user must not experience low quality in their service by
interruption. When the signal falls below the thresh value and no handoff is done, user may feel poor quality of service. A handoff
algorithm must be efficient to make correct decision while calling handoff procedure. The user must feel the good quality of service
after handoff procedure is initiated.
D. Handoff Process
The handoff process consists of 5 stages. 1. Network discovery, 2.Pre-Authenticated connection, 3.Handoff decision, and
4.Handoff execution 5. Handoff monitoring
 Network Discovery- The work of network discovery is to identify or search all the available reachable service broadcasted
by different network providers. This process is always active all time even when no packets is transferred .This is because
only then pre connection can be established when the signal of active network falls below the thresh value. This task is
done and active spontaneous connection is established and the handoff will be done only when needed.
 Pre-Authentication Connection -Once the reachable network is discovered it is maintained in the stack in the High
Frequency First order. In FIFO manner basic trust is established between the home network and foreign network. Once
after basic trust is established, negotiation is performed between the providers and if negotiation succeeds connection is
established else negotiation is done with the other network in the stack.
 Handoff Decision and Mechanism- Handoff is the technique of transferring the service from one coverage area to another
coverage area. This transferring must be done only when the signal strength falls bellow and affects the quality of service.
The calling of handoff procedure is invoked based on the signal strength of active network. The mechanism for handoff
must present in the mobile terminal. In this type, the handoff time is of 0.1 sec. The Mobile searches all the available
networks and measures the signal strengths from surrounding BSs and makes the evaluations to makes Pre Authentication
connection.
 Handoff execution-The handoff procedure will be executed only when SNR is less then D Thresh value. If SNR is less then
C Thresh value pre-connection is established with foreign network and communication between the networks will not be
disconnected until SNR falls below the D thresh value. The handoff procedure will be invoked only when SNR value is less
then D thresh value.
 Handoff Monitoring-The monitoring module will be present in both home network and foreign network. Once when the
handoff execution procedure is invoked then monitoring also will be activated to monitor the signal strength of home
network periodically

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© 2014, IJIRAE- All Rights Reserved Page -336
HOME N/W MOBILE TERMINAL MIS
FORIGN N/W
SCAN
BASIC TRUST
ESTABLISHED
CONNECTION
KNOWLEDD ESTALISHED
1
NO
Fig.2. PAC and Monitoring System
WIRELESSN/W
SELECTION &
HANDOFF DONE
HAND OFF TO
HOME N/W
HOME N/W MOBOLE TERMINAL MIS
FOREIGN N/W
BASIC TRUST
ESTABLISHED
CONNECTION
ESTABLISHED
=0
=0
=1
NO NO
YES
CONNECTION ESTABLISHED
SNR<CTR
SNR<DTR
SCAN ALL FORIGN
NETWORK &INPUTS
N/W ID & TRESH VALUE
HFNF
APPLICATION
NEGOTIATE
HOME N/W
TRESH VALUE
PAC
CHECHK 0 OR 1
MONITORING
>CTR <CTR
<CTR
CAPTURE SNR
VALUE
WAIT
PREPARE HOME
N/W CONNECTION
APPLICATION
MONITORING
<CTR
>CTR
WIRELESS N/W
SELECTION & HANDOFF
DONE
DATA BASE
NMS
RULE BASED
CAPTURE SNR
VALUE
WAIT
PREPARE HOME
N/W CONNECTION
Wireless N/W
selection & handoff
Done

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VI. ALGORITHM FOR NEGOTIATION.
The Negotiation algorithm is used only after basic trust is established with the high frequency networks. Once the basic level
trust is established with the strongest network which is identified by the mobile terminal the negotiation algorithm is invoked for
performing negotiation with the foreign network. If negotiation gets succeed pre connection will be established else next high
frequency network will taken in to account which available in stack for the negotiation. The process is continued until negotiation
gets succeeded. Spontaneous connection is done in 5 stages as discovery, pre-connection, decision, execution and monitoring
phases. Execution phase is performed using MIP, the concept of decision making and fuzzy logic is applied while performing pre
connection with the foreign network. The algorithm consists of two parts:
 Pre-connection Initiation Algorithm which is present in fuzzy engine establish the connection with the foreign
network before the service gets disconnected.
 An algorithm is present to perform negotiation which selects the Network from the available network.
A . Working Of Fuzzy Handoff Decision Algorithm
Only when the unavailability of an old network service is detected the handoff decision function is called. Then the two-part
algorithm is executed to perform the handoff from old service to new foreign network. The algorithm consists of the following
functional blocks.
 a IPB transforms the received signal strength as the inputs
 a rule base structure block contains a number of IF-THEN rules;
 a database block contains the membership functions which is used the fuzzy rules;
 The decision operation weather to perform negotiation or not are performed by interference engine by using fuzzy
rules;
 A OPB performs the operation of displaying the final output.
VII. HANDOFF INITIATION ALGORITHM
The procedure to calculate and select an appropriate time to transfer the present service to other network for extending the
service without any detonation in QOS is needed. To perform this, fuzzy concept is used for computing the handoff value which is
used to decide whether handoff is needed from UMTS home network to UMTS foreign network. The work consists of two handoff
technique. 1.Handoff from home UMTS provider to foreign UMTS provider, and 2. Handoff from foreign UMTS provider to from
home UMTS provider
A. Handoff From Home UMTS Provider to Foreign UMTS
In mobile terminal, handoff initiation algorithm is implemented which provide rules for decision making. A MT which is
connected to a UMTS network detects a new foreign UMTS network, and calculates the handoff factor to decide whether the MT
should perform the handoff operation to the foreign UMTS. For intelligent handoff decision, parameters such as received signal
strength is sent as input to establish the basic trust between the networks and then the negotiation procedure is invoked to establish
the pre connection .Once after establishing pre connection the handoff initiation algorithm can be called any time to perform the
handoff operation to extent the service without affection the service quality. The RSSI and data rate indicate the availability of the
target network. The values of the RSSI input parameters are given as input to the initiate algorithm.
The algorithm then transforms the frequency value to pre connection function .The Pre connection function checks the
membership of the network in the data base with the set of If-Then rules to identify weather the negotiation is to be initiated or it has
already performed. If the network is the member, no negotiation is needed and pre connection can be established immediately else
negotiation function must be called to perform the negotiation. Once after establishing pre connection the handoff can be performed
any time when needed. If the signal strength falls below the D thresh value the handoff initiation procedure is invoked to perform the
handoff from current network service to foreign network.
The variable Handoff Factor is defined from 0 to 1, with the maximum membership of the sets “Higher” and “Lower” at 0 and
1, respectively. The fuzzy rule base contains IF-THEN rules such as:

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 IF RSSI is weak, network coverage area is bad, data rate is low, QoS is undesirable, THEN handoff factor is higher
 IF RSSI is medium, network coverage area is medium ,data rate is medium, QoS is acceptable, THEN hand off
factor is average and pre-connection is done
 IF RSSI is strong, data rate is high, network coverage area is good, QoS is desirable, THEN handoff factor is lower
The crisp handoff factor computed after defuzzification is used to determine when a handoff and pre-connection is required as
follows:
if handoff factor < 0.15, then initiate handoff;
if handoff factor < 0.60, then initiate Pre connection by negotiation;
if handoff factor > 0.60, do nothing;
B. Handoff from Foreign Network To Home Network
When home network extend its service by establishing spontaneous connection with foreign network, the monitoring module
which is present in foreign network will Searches for home network signal periodically. If SNR value is above C Thresh, MT
switches from foreign UMTS to Home UMTS. Two thresholds defined to avoid “Ping-Pong” effect. An exponential moving average
of the SNR is used. Only SNR of the Home UMTS is monitored as MT prefers home network because of the short term spontaneous
agreement. , we need to have an accurate and timely handoff decision to maintain the connectivity before the loss of service.
VIII. HANDOFF MONITORING
In the work Monitoring module is introduced both in Home and foreign provider which helps the Foreign provider to switch of
the guest user to their home network when SNR value is above the C thresh value. The monitoring module will be initiated once the
hand off is done with foreign provider. Both the Monitoring module that is present in home and foreign provider will ping pong and
communicate each other and exchange the SNR value. The SNR value will be monitored periodically and hand off is initiated
based on the C thresh value
IX. CONCLUSION
The PAC and monitoring architecture work together instantly and securely without pre-established formal roaming agreement.
Instant and dynamic roaming are established through 2 stage process. In step1 only basic trust and pre-connection is established,
handoff is not done. In step 2 handoff is performed only when needed by using fuzzy concepts. Once after initiating handoff
monitoring is done to return the service to home network. As a future work power balancing approach using SPINE hierarchy can be
adopted to avoid the dropping of connection due to power loss.
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Zero Down 24*n Mobile Network Connectivity

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