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Handover mechanisms in next generation heterogeneous wireless ...

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MULTI-INTERFACE MOBILE MODEL FOR MEDIA INDEPENDENT HANDOVER<br />

provides a model and correspond<strong>in</strong>g <strong>mechanisms</strong> <strong>in</strong> which MIH entities can gather<br />

network <strong>in</strong>formation to facilitate handover.<br />

Local MIH User<br />

or Higher Layer<br />

Entity<br />

User<br />

Data<br />

Cellular<br />

Network<br />

Interface<br />

L 2<br />

L 1<br />

L 3<br />

MIH _ USER 1<br />

User<br />

Data<br />

LLC<br />

MIH<br />

Local<br />

Events<br />

MAC<br />

PHY<br />

Station<br />

MIH _ USER 2 ... MIH_USER n<br />

Event - based<br />

Triggers<br />

and<br />

Commands<br />

MIH<br />

Commnd,<br />

Event &<br />

Information<br />

Service<br />

Local<br />

Events<br />

802<br />

Network<br />

Interface<br />

MAC Sub-layer<br />

Management<br />

Entity<br />

PHY Sub-layer<br />

Management<br />

Entity<br />

MGT<br />

Remote<br />

Events /<br />

Information<br />

and<br />

Commands<br />

- 139 -<br />

m<br />

e<br />

st<br />

y<br />

S<br />

nt<br />

e<br />

m<br />

e<br />

g<br />

a<br />

n<br />

a<br />

M<br />

k<br />

o<br />

r<br />

w<br />

et<br />

N<br />

802<br />

Access<br />

Network<br />

MIH<br />

LLC<br />

MAC<br />

PHY<br />

MIH<br />

Network<br />

Cellular<br />

l<br />

Network<br />

Figure 7.1 General Media Independent <strong>Handover</strong> reference model [119]<br />

Under IEEE 802.21, a variety of access technologies such as 802.11, 802.16 and 3GPP<br />

can be accommodated on a s<strong>in</strong>gle mobile term<strong>in</strong>al. Work<strong>in</strong>g with handover decision<br />

algorithms for <strong>heterogeneous</strong> <strong>wireless</strong> networks, IEEE 802.21 is able to provide<br />

flexibility <strong>in</strong> facilitat<strong>in</strong>g <strong>in</strong>formation retriev<strong>in</strong>g, network discover<strong>in</strong>g and handover<br />

trigger<strong>in</strong>g of mobile users.<br />

7.3 A Multi-Interface Mobile Term<strong>in</strong>al Model<br />

In Sec. 7.2.1, two multi-access approaches for access<strong>in</strong>g <strong>heterogeneous</strong> <strong>wireless</strong><br />

networks are described. As discussed, the MISU architecture needs the additional<br />

support from upper layers. It causes less service disruption <strong>in</strong> handover due to be<strong>in</strong>g<br />

able to enable multiple data streams simultaneously on mobile term<strong>in</strong>als. In contrast, the<br />

MIAU architecture reduces the complexity of upper layers. But, longer handover<br />

latency is expected as a result of us<strong>in</strong>g multiple network <strong>in</strong>terfaces on a rotate basis.<br />

L2<br />

L1<br />

L3

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