Vertical Handoff Management for Next Generation ...

ITI 5th IEEE International Conference on Information & Communications Technology

Vertical Handoff Management for Next Generation Heterogeneous Networks Ikram SMAOUI, Faouzi ZARAI and Lotfi KAMOUN

ICICT’07 December 16-18 – Cairo EGYPT

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Context (1) The next generation heterogeneous networks represents a new technology that will enable seamless integration of various wireless access systems. Various sophisticated and quality of service (QoS) constraining applications

High-speed data services, video applications, and multimedia services. An efficient mobility management, specifically the vertical handoff (inter system handoff), is essential in the next generation wireless networks. ICICT’07 December 16-18 – Cairo EGYPT

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Context (2) Vertical handoff in the heterogeneous networks, is one of the major challenges for seamless mobility with ubiquitous connectivity. The Inter-IP systems vertical handoff can be done with Mobile IP (MIP) which is a protocol designed to manage Mobile station mobility. Seamless vertical handoff in heterogeneous networks:

Low latency, low packet loss and security services during handoff.


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Our Goal In this work, we focus on a proposition of a novel scheme for reducing handoff delay • Using the concepts of Received Signal Strength (RSS) and thresholds management.

• Supporting QoS guarantees for real time applications.

The proposition of a new secured IP assignment protocol • Based on the clustering algorithm to assign an IP address to the mobile station (MS).

• Ensuring a minimum level of security by running an authentication process between the MS and the Foreign Agent (FA). ICICT’07 December 16-18 – Cairo EGYPT

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Outline Related Works Vertical Handoff Management Approach • Inter-IP systems Vertical Handoff operations • Inter-IP systems Vertical Handoff delay modeling • Thresholds Management • MS-HA Authentication protocol IP-Address Assignment Protocol Performances Evaluation Conclusion and Future Works ICICT’07 December 16-18 – Cairo EGYPT

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Related Works Decreasing signaling delay by re-assigning a new network component closer to the Mobile Station (MS) to serve the Home Agent (HA) function.

• HMIP, Cellular IP, HAWAII. Other schemes: running a pre-handoff mechanism by parallel running of different vertical handoff steps or anticipating some steps of handoff before the handoff condition is attained. • These schemes did not take into account constraints imposed by the heterogeneity of access networks, such as security and temporary IP address assignment. ICICT’07 December 16-18 – Cairo EGYPT

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Vertical Handoff Management Inter-IP systems Vertical Handoff operations: MS

FAnew

HA

(1) HO Request (2) Authentication (3) IPAssignment (4) Registration+Authentication


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Proposed Vertical Handoff Management Scheme Inter-IP systems Vertical Handoff delay modeling: RSS

FAold

FAnew

RHO Rreg Rpre Rdrop Distance

• The inter-IP systems vertical handoff occur when:

RSSold < RSSnewandRSSold < Rdrop ICICT’07 December 16-18 – Cairo EGYPT

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Proposed Vertical Handoff Management Scheme To determine the time instant of the pre-handoff, we are going to determine the Time Handoff Advance (THA): • We use the symbol THO which represents the necessary time duration to run inter-IP systems vertical handoff, • We use the symbol TmaxHO which represents the maximum time duration allowed by the application to do handoff.

The threshold Rpre is determined by the THA which is estimated by:

THA = THO − T max HO ICICT’07 December 16-18 – Cairo EGYPT

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Proposed Vertical Handoff Management Scheme Thresholds Management: • A large difference between the thresholds RHO and Rpre could increase the uncompleted handoff rate (UHR). • A small difference may not provide low handoff blocking rate (HBR). HBR = Blocked Re quests / NumberofHandoff Re quests

(3)

UHR = Uncomplete Re quests / NumberofHandoff Re quests

(4)

If the HBR is so large, then the Rreg should increase. Whereas, if the UHR is larger, the Rreg should decrease. ICICT’07 December 16-18 – Cairo EGYPT

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Proposed Vertical Handoff Management Scheme Authentication protocol

• Prove the MS Identity • Based on the Signature of Random Number Improvement : BU + piggybacked Type

S B D M G r T E Reserved

Life Time

MS Home Address HA Address COA Identification Sig(RANDMS-HA), RANDHA-MS ICICT’07 December 16-18 – Cairo EGYPT

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IP-Address Assignment IP-Address Assignment in related works: • It is based on the concepts of binary split in order to perform dynamic configuration. • It requires a large amount of signaling between network nodes, since each node can assign an IP address to a new node and all nodes need to synchronize from time to time to keep track of assigned IP addresses.


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Proposed IP-Address Assignment Protocol Using a clustering algorithm in the networks without infrastructure. Selects the stations responsible for establishing, organizing the cluster and having the functionalities of DHCP servers. • The new DHCP server sends a multicast message to all its neighboring DHCP servers for a block of available IP addresses. • A neighboring DHCP server receives this request, divides its set of available IP addresses into disjoint subsets. It sends one subset to the new DHCP server and keeps the rest with itself. ICICT’07 December 16-18 – Cairo EGYPT

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Proposed IP-Address Assignment Protocol MS-FA Authentication Protocol: MS

FAnew

DHCP Server

RAND1

Sigk(RAND1),RAND2 Sigk(RAND2)

IP-Address


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Performances Evaluation The proposed inter-IP systems vertical handoff: • Defines two main thresholds that reduce the blocked handoff rate and the uncompleted handoff rate.

The proposed MS-HA authentication protocol: Reduces the signaling messages by combining the authentication in the registration request and acknowledgement.

•

The proposed IP-Address assignment solution: Requires a smaller amount of signaling messages. • Proposes a security approach which it isn’t treated in previous works. •


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Performances Evaluation Performance metrics:

• Handoff Delay • Handoff Blocking Probability Simulated Network:

IP Network

UMTS Base Station WLAN Access Point ICICT’07 December 16-18 – Cairo EGYPT

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Simulation Results 150 Handoff delay (ms) 135 120 105 90 75 60 45 30 15 0 200 400 600

Enhanced Mobile IP

Mobile IP

Number of users 800

1000

1200

1400

1600

1800

2000

Handoff Delay

• The Handoff Delay increases when the number of admitted users increases.

• The enhanced Mobile IP protocol guarantees a handoff delay lower than the standard Mobile IP. ICICT’07 December 16-18 – Cairo EGYPT

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Simulation Results 2

Handoff blocking pobability (%)

1,5 Mobile IP

Enhanced Mobile IP

1

0,5 Number of users

0 50

100 150 200 400 600 800 1000 1200 1400 1600 1800 2000

Handoff Blocking Probability

• The HBR is near zero with around 150 users. This is explained by the fact that the resources for handoff are still available.

• A minimum HBR obtained with the enhanced MIP due to the managed thresholds that satisfy the time required authentication, the IP assignment and the registration . ICICT’07 December 16-18 – Cairo EGYPT

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Conclusion Proposition of an enhanced scheme of the MIP protocol to support QoS guarantees over heterogeneous wireless networks. The proposed scheme provides overall improvement in delay and Handoff Blocking Probability performances by proposing a thresholds study solution for avoiding computer and network performance degradation.

This scheme also guarantees a secure IP-Address Assignment process by proposing an authentication solution.


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Future Works The study of the effects of mobile speed on the handoff and prehandoff thresholds.

The study and the proposition of an enhanced resources reservation mechanism in order to reduce the Handoff Blocking Probability.


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