a study on ieee 802 21 mih framewaorks in heterogeneous wireless networks

7/29/2019 A Study on IEEE 802 21 MIH Framewaorks in Heterogeneous Wireless Networks

1/5

A Study on IEEE 802.21 MIH Frameworks inHeterogeneous Wireless Networks

Moon Kim, Tae-wook Moon, Sung-joon ChoDept. of Inform. & Telecom. Eng., Graduate School ofKorea Aerospace University

[email protected]

Abstract - In recent years, various wireless accesstechnologies have continuously grown as well as user demandshave. However, such user demands have not been satisfied byeach wireless access technology alone. Therefore, the FutureGeneration Networks (FGNs) are proposed to integrate variousheterogeneous access technologies in order to support bothvertical and seamless handovers. Especially, the IEEE 802.21specifies Media Independent Handover (MIH) services toenhance the mobile user experience by optimizing handoversbetween heterogeneous access networks. In this paper, we focuson the handover framework using MIH messages, and adjust theframework to the integra ted heterogeneous networks byemploying novel messages. We additionally evaluate theperformance of the proposed MIH framework in terms ofhandover latency by using numerical analysis.

Keywords - Heterogeneous networks, 802.21, MIH, FGN,Vertical handover.1. Introduction

In recent years, various wireless access technologies suchas Global System for Mobile communications (GSM), CodeDivision Multiple Access 2000 (CDMA2000), UniversalMobile Telecommunications System (UMTS), Wireless LocalArea Networks (WLAN), and Worldwide Interoperability forMicrowave Access (WiMax) have tremendously evolved anddeployed all over the world. Moreover the user demands forhigher service quality including higher data rate, highermobility, and Quality of Service (QoS) have continuouslygrown in these days. However, such user demands have notbeen fulfilled by each wireless access technology alone. Thecomplementary characteristics ofWLAN, faster but stationary,do not provide high mobility but high data rate, while thecomplementary characteristics of CDMA 2000, slower buthighlymobile, do not provide high data rate but high mobility.Therefore, the Future Generation (or 4G) Networks (FGN) areintegrating those multiple heterogeneous wireless accesstechnologies into a common convergence network [1, 2].The convergence network has been broadly applied to thecommon effort among mobile operators and standards bodiesto achieve the ubiquitous, the key point of the futuregeneration networks. Such ubiquitous networks are expectedto guarantee 'any-service with any-device throughany-network at any-where in any-time'. In order to support

this ubiquitous service, there are crucial requirements whichare very high data rate for 'any-service' , multi-interfacesystems for 'any-device', integrated heterogeneous networksand high mobility for 'any-network', and so on. Consequently,it is essential that multi-interface systems roam seamlesslyacross heterogeneous wireless access networks.

The IEEE 802.21 is proposing the Media IndependentHandover (MIH) Services to enhance the handovers acrossheterogeneous access networks, i.e. vertical handover, and tooptimize the service (or session) continuity during handovers,i.e. seamless handover. For this reason, MIH provides genericlink layer intelligence and other related network informationto upper layers. Particularly, MIH offers a framework of themessage flows between handover-related entities to provideinformation on handover candidate networks and to deliverhandover commands [3, 4].In this paper, we focus on the framework of handovermessage flows in MIH and suit the framework to integratedheterogeneous networks for FGN. We further approach thebalance of the MIH message use. The balance is assumed tomean that the more resources are, the more message capacitiesare. Note that wired networks have much more resources (orbandwidth) than wireless networks have. So the balance isassumed that wired network is given more messages to processthan wireless network. Aiming at offering the balance, wespecify novel messages, the handover profile message and theentrusting message, to improve the handover framework.These messages are designed to provide each user's handoverpolicies to network entities and to reduce the size of the legacymessages respectively.The remaining of this paper is organized as follows. In thenext section, we explain the MIH fundamentals such asfunctions and services. In section 3, we describe theframework of MIH message flows and suit the framework toheterogeneous wireless networks. Section 4 evaluates theperformance of the MIH framework through numericalanalysis, and then we conclude this paper in section 5.

2. Media Independent Handover ServicesThe IEEE 802.21 draft specification, referred as Media

Independent Handover Services, provides generic link layerintelligence and other related network information to upper

ISBN 978-89-5519-139-4 -242- Feb. 15-18, 20091CACT 2009


2/5

layers. The goal is to enhance the mobile user experience byoptimizing handovers between heterogeneous access networks.This includes media types specified by Third Generation (3G)Partnership Project (3GPP), 3G Partnership Project 2 (3GPP2),and both wired and wireless media in the IEEE 802 family ofstandards.

MIH is an evolution for all media, providing capabilities todetect and initiate handover from one media to another (i.e.vertical handovers). It also offers solutions for service (orsession) continuity while vertical handovers occur (i.e.seamless handover). In order to support both vertical andseamless handovers, MIH provides information on potentialhandover target networks and delivers commands abouthandovers. Furthermore, it reports dynamic events relating tolink layer triggers, measurement reports, and timelyindications of changes in link conditions. These roles speedvertical handovers while helping to keep end-to-end servicecontinuity [3, 4].The IEEE 802.21 Working Group (WG) introduces aframework that defines Media Independent HandoverFunction (MIHF). It is logically designed as a shim layerbetween the link layer (L2) and upper layers in the protocolstack of both the Mobile Node (MN) and network element.Figure 1 shows the placement of MIHF within the mobilitymanagement protocol stack and the interaction of MIHF withthe link layer and upper layers. As using this interaction,MIHF facilitates both vertical and seamless handovers acrossheterogeneous access networks. Especially, MIHF employsthree kinds of services as the key element of the interaction.These services are responsible for provision of handoverrelated information such as link status, link layer intelligence,serving and neighboring access networks information, andopera tion pol ic ies. In addit ion, they help upper layerscoord inate and manage handovers , whi le support ing

UpperLayers

CoMectiorI IIM a p Handover Management

Link LayerI IEEE II ..IEEE II . E. 13GPP.. . ..II3GPP2. I02.3 802.11 16Figure 1. MIHF location and MIH key services

both network-initiated and mobile-initiated handovers. Theabove three services are Media Independent Event Service(MIES), Media Independent Command Service (MICS), andMedia Independent Information Service (MIlS).Media Independent Event ServiceMIES provides event classification, event filtering and eventreporting services corresponding to dynamic changes in linkcharacteristics, links status, and link qualities. It also indicatesthe result of management actions and commands on a part ofnetworks. Furthermore, it allows upper layers to treat allaccess technologies in a generic manner. MIHF registers LinkEvent notifications with the interfaces. Any upper layersentities can register for an MIH Event notification. The lowerlayers will generate a Link Event and send it to the MIHFunction which will report to any entity that has registered anMIH Event.Media Independent Command ServiceMICS allows MIHF to query neighboring link resources, andso helps them manage and control link behavior relevant tohandovers by using a set of primitives and commands. It alsoenables both network-initiated and mobile-initiated handovers.MIH Commands originate from the upper layers down to theMIH Function. It continues down to the link layers as a LinkCommand from the MIH Function. Link Commands arespecific to the access network being used.Media Independent Information ServiceMIlS offers a mechanism for an MIHF entity to access thefundamental information about heterogeneous neighboringaccess networks, network topology, properties, and availableservices in order to facilitate the handover process. It furtherdefines query and response messages to ask and get suchinformation for each available neighbor networks. MIlSspecifies a two way street to share Information Element (IE),which represents the information of heterogeneous accessnetworks, with Information Server (IS) [3-7].

3. Handover Frameworks Using MIHThe IEEE 802.21 MIH offers a framework of the messageflows between handover-related entities to provideinformation on handover candidate networks and to delivercommands about handovers. As shown at Figure 2 and 3, theframework consists of MIH discovery, MIH selection,mobility management, and MIH completion. During the MIHdiscovery phase, both information query to IS and resourceavailability check through neighboring access networks areperformed respectively. The MIH selection phase allows the

handover initiator, i.e. eitherMNor serving network, to decidethe handover target network in result of MIH discovery, andalso requests resource preparation to the target network. Thefollowing phase is the mobility management execution. Itcomes up with both the establishment of link layer connectionand the upper layer handover execution. Lastly, resourcerelease is performed by either MN or target network. Theframework of MIH message flows supports bothmobile-initiated and network-initiated handover process. Themobile-initiated handover process is illustrated in Figure 2,

ISBN 978-89-5519-139-4 -243- Feb. 15-18, 20091CACT 2009


3/5

while the network-initiated handover process is described inFigure 3 [8].In this paper, we focus on the balance of the MIH messageflows. The balance is assumed tomean that the more resourcesare, the more message capacity are. Note that wired networkshave much more resources (or bandwidth) than wireless

networks have. So the balance is assumed that the networksabove PoAs, i.e. wired networks, is given more messages toprocess than the networks beyond PoAs, i.e. wireless networks.In order to offer the balance, we newly define the handoverframework using MIH messages. It introduces the initiationphase to provide information about not only user's handoverpolicies but also neighboring networks to the serving PoA.The framework also specifies a handover profile message,namely MIH_HO_Profile, to provide each user's handoverpolicies to serving PoA. Thismessage enables the serving PoAto access each user's handover policies in the initiation phaseand to decide target network without further request messagesfor handover information to MN in the discovery phase.Therefore, the entrusting request message, referred asMIH_MN_HO_Entrust_Request, is defined in the networkdiscovery phase, while the response message, calledMIH_MN_HO_Entrust_Response, is used in the networkselection phase. These messages reduce the size of the legacymessages, according as they does not contain the informationof candidate networkswhich MIH_H_Profile has previouslyprovided to serving PoSeThe proposed handover framework is illustrated in Figure 4and 5. Figure4 shows themobile-initiatedMIH message flows

and Figure 5 shows the network-initiated MIH message flowsfor handover. The detailed explain is as follows.Mobile-initiated Handover1. During initiation, MN sends the handover profile messageto Serving PoA and then Serving PoA gets neighboringnetwork information from IS. It is important that the

initiation phase is executed once right after MN is firstattached to serving network.2. In network discovery phase, MN orders serving PoA tocheck the availability of the resource at candidate networksby sending MIH_MN_HO_Entrust_Request. This newlydefined message is analogous toMIH_MN_HO_Candidate_Query_Request except that itdoes not contain the information of candidate networkswhich MN has previously provided using MIH_HO_Profile during initiation. Accordingly, we expect that thesize of the newly defined message is much smaller thanMIH_MN_H0_Candidate_Query_Request.3. Serving PoS queries the availability of resources at theneighboring candidate networks by employing

MIH_N2N_HO_Query_Resources_Request and MIH_N2N_HO_Query_Resources_Response. Note that ServingPoS does not notify the MN of the resulting resourceavailability at the candidate networks. This is because MNentrusts Serving PoS with the target decision by giving thehandover profile so that MN has no reason to get thoseinformation.

4. As explained above, Serving PoS decides the target of thehandover based on the available resource status at candidate

MIH N2N HO Candidate_Query_Resources_Request

MIH_Nat_HO_Candidata_Query_Requa

stMIH_NeCHO_Candidate_Query_Respo

nse

IMNl

MIH Selection - - - t - - - - - - - - - 1 - - - - - - - - I . .

MIH_Net_HO_Commit_RequestMIH Net HO Com

m i t _ R ; s p o ~ s e

MIH Discovery ----1 1 - - - - - -......

MIH_N2N_HO_COmmit_RequestMIH_N2N_HO..Commit_Response

MIH N2N HO Cand i d a t e _ Q u e r y j ~ ~ e s o

urcas_RequestMIH_N2N_HO_Candidate_Query_Rasources_ResponseMIH_MN_HO_Candidale_Query_Response

MIH._MN_HO_Candidale_Query_Request

1-------- MIH_Get_lnformatioo_Request - - - ~ .. .I I

.....------ MIH_GeClnformation_Response ------fIMNI

MIH Discovery - - - -11-- - - - - - -+ -- - - - -1 . . .

MIH Completion --+---------+------1.. . HOMIH_MN_HO_Complete__Request

MIH_N2N_HO_Complete_RequestMIH N2N HO Complete_Response

MIH_MN_HO_Complete_Response

MIH Completion --I---------1-------L.MIH_N2N_HO_COmplete_Request

MIH_N2N_HO_Complete_Response

Figure 2. Mobile InitiatedMID Message Flow Figure 3. Network Initiated MID Message Flow

ISBN 978-89-5519-139-4 -244- Feb. 15-18, 20091CACT 2009


4/5

MIH_N2N_HO_COmplete_Request


MIH Completion

"-lot-Ifltl' Mar,agemen! Protocols HO

MIH Net HO Commlt_Respo;;-se

MIH_Net_HO_CommiCRequest

Network Discovery -+---------II------i....

Initiation ----+-------1------......

r--MNl

MIH_N2N_HO_Candidate_Query_Resources_RequestMIH N2N HO Candidate_a u ~ r y _,'Resources_Response

Network Discovery - - + - - - - - - - - - - 11 - - - - - - ....MIH_MN_HO_EntruscRequest

MIH_MN_HO_Entrust_Response

Initiation - - - - - t - - - - - - - ~ I _ _ - - - - ......MIH_HO_Profile

MIH CompletionMIH_MN_HO_Complete_Request

MIH N2N HO Complete_Requ.est


MIH_MN_HO_Complete_Response

r--MNl

Figure 4. Proposing Mobile InitiatedMm Message Flow Figure 5. ProposingNetwork Initiated MIH Message Flownetworks.

5. Serving PoS sends MIH_N2N_HO_Commit_Request toTarget PoS to prepare resource at the target network. TargetPoS responds the resul t of the resource preparation bysending MIH_N2N_HO_Commit_ Response.

6. After identifying that resource is successfully prepared,Serving PoS notifies MN to commit handover toward thespecified network type and PoA through MIH_MN_HO_Entrust_Response message.

7. New l ink layer connect ion is establ ished and a certainmobility management protocol procedures are carried outbetween MN and target network.

8. MN may send MIH_MN_HO_Complete_Request to TargetPoSe Target PoS sends MIH_N2N_HO_Complete_Requestto previous Serving PoS to release resource which wasallocated to MN. After identifying that resource issuccessfully released, Target PoS may sendMIH_MN_HO_Complete_Response to MN.Network-initiated HandoverI. During initiation, MN sends the handover profile messageto Serving PoA and then Serving PoA gets neighboringnetwork infonnation from IS. It is important that theini tiation phase is executed once right after MN is firstattached to serving network.

2. In network discovery phase, there is no need for ServingPoS to query handover information to MN since thehandover profile is already given. Serving PoS just sends

MIH_N2N_HO_Query_Resources_Request to one or morecandidate PoSs to check the availability of the resource atcandidate networks. Candidate PoS responds by sendingMIH_N2N_HO_Query_Resources_ Response to ServingPoSe

3. Serving PoS decides the target network and requestsresource preparation to Target PoS by using MIH_N2N_HO_Commit_Request and MIH_N2N_HO_Commit_Response.

4. After identifying that resource is successfully prepared,Serving PoS commands MN to commit handover towardthe specified network type and PoA throughMIH_Net_HO_Commit_Request and MIH_Net_HO_Commit_Response messages.

5. New link layer connection is established and a certainmobility management protocol procedures are carried outbetween MN and target network.6. Target PoS sends MIH_N2N_HO_Complete_Request toprevious Serving PoS to release resource which wasallocated to MN. After identifying that resource issuccessful ly released, previous Serving PoS may sendMIH_N2N_HO_Complete_Response to Target PoSe

4. Performance EvaluationIn this section, we evaluate the perfonnance of the MIH

framework compared with legacy one in tenns of handover

ISBN 978-89-5519-139-4 -245- Feb. 15-18, 20091CACT 2009


5/5

latency. So we derive total handover latency including thedelay of initiation, network discovery, network selection,mobility management, and so on. Equation (1) and (2)describe the total handover latency of legacy mobile-initiatedMIH framework ( ~ l _mob_MIH ) and which of proposed MIHframework ( ~ e w _ m o b _ M I H ), respectively.

message, according as the entrusting message does not containthe information of candidate networks which MN haspreviously provided using MIH_HO_Profile. As the futurework, we will analysis various SAPs and adapt those to FGNenvironment.

ACKNOWLEDGMENT

Regard that Dx _y is the message delivery delay between Xand Y, P Net deceision is the process time of target networkdecision, TL2 is the handover latency caused by linkconnection establishment, and TL3 is the handover latencycaused by IP connection establishment. In same manner, thetotal handover latency of both legacy and proposednetwork-initiated MIH framework are represented at equation(3) and (4), respectively.

~ l d _ m o b _ M I H =4DMN- SAR + 6DsAR-TAR+ 2DMN- TAR + 2DMN- 1S + PNet_deceision + T L2 + T L3

Tnew_mob_MIH =3DMN- SAR + 6DsAR-TAR+ 2DMN- TAR + 2DsAR-IS + PNet_deceision + T L2 + T L3

~ l net MIH =4DMN- SAR + 6DSAR-TAR+ 2DSAR-IS + PNet_deceision + T L2 + T L3

T"ew_net_MIH =3 DMN- SAR + 6DSAR-TAR+ 2DSAR-IS + PNet_deceision + T L2 + T L3

(1)

(2)

(3)

(4)

This research was supported by the Internet information RetrievalResearch Center (IRC) in Korea Aerospace University. IRC is aRegional Research CenterofGyeonggi Province, designated by ITEPand Ministry of Knowledge Economy.REFERENCES

[1] C. Yiping, Y. Yuhang, "A New 4G Architecture Providing MultimodeTerminals Always Best Connected Services," IEEE WirelessCommunications[see also IEEE Personal Communications}, Vol. 14,Issue 2, pp. 36- 41, April, 2007.[2] S .Y . Kim, Y . B . Cho, and S. 1. Cho, "PlatformArchitecture for SeamlessMMS Service over WLAN and CDMA2000 Networks," PCM 2004, pp.

720-727, December, 2004.[3] IEEE Std. 802.21, Draft D9.0, "IEEE Standard for Local andMetropolitan Area Networks: Media Independent Handover Services. "[4] L. Eastwood, S. Migaldi, X. Qiaobing, V. Gupta, "Mobility Using IEEE802.21 in a Heterogeneous IEEE 802.16/802.1 I-BasedIMT-ADVANCED (4G) Network," IEEE Wireless Communications,April, 2008.[5] Q.B. Mussabbir, W. Yao, Z. Niu, X. Fu, "Optimized FMIPv6 UsingIEEE802.21 MIH Services in Vehicular Networks," IEEE Transactionson Vehicular Technology, 2007.[6] 1. Stein, "Survey of IEEE 802.21 Media Independent HandoverServices," http://userfs.cec.wustl.edu/-jws2/mihs /index.html.[7] K. N. Choong, V. S. Kesavan, S. L. Ng, F. de Carvalho, A. L. Y. Low andC. Maciocco, "SIP-based IEEE802.21 Media Independent Handover - aBT Intel collaboration," BT Technology Journal, Vol. 25, Num. 2, April,2007.[8] https://mentor.ieee.org/802.21/documents.

From these equations, we verify that the proposed MIHframework reduces handover latency. Especially, thehandover latency over wireless section, i.e. DMN-SAR ' aredecreased by eliminating the wireless signaling overheads inthe proposedMIH framework.

5. ConclusionsThis paper has introduced the IEEE 802.21 MIH andevaluated the handover framework using MIH messages inheterogeneous wireless access networks. In addition, we havespecified novel messages, the handover profile message and

the entrusting message, to improve the handover framework.In result, i t is verified that the handover profile message,namely MIH_HO_Profile, provides each user's handoverpolicies to the serving PoA, it thus allows the serving PoA toaccess each user's handover policies and to decide targetnetwork without any requests for handover information toMN.It is further confirmed that the use of the entrusting message,called MIH_MN_HO_Entrust, reduces the size of the legacy

ISBN 978-89-5519-139-4 -246- Feb. 15-18, 20091CACT 2009

a study on ieee 802 21 mih framewaorks in heterogeneous wireless networks

Documents