ABSTRACT
Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 9.2.4 Benefits of Using FBSs for Users and Operators . . . . . . . . . . . . 276 9.2.5 Femtocell Network Architecture and Functionalities . . . . . . . . 277 9.2.6 Deployment Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278 9.2.7 Femtocell Challenges and Open Issues . . . . . . . . . . . . . . . . . . . . . 278
9.3 Mobility Management in Femtocell Networks . . . . . . . . . . . . . . . . . . . . . . . 279 9.3.1 Mobility Management in WBNs . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
9.3.1.1 Location Management . . . . . . . . . . . . . . . . . . . . . . . 280 9.3.1.2 Mobile Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 9.3.1.3 Handoff Management . . . . . . . . . . . . . . . . . . . . . . . . 280
9.3.2 Femtocell Mobility Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282 9.3.2.1 Femtocells vs. Macro/Microcells . . . . . . . . . . . . . 282 9.3.2.2 Finding Neighboring Femtocells . . . . . . . . . . . . . 284
9.3.2.3 Distinguishing Accessible (CSG and Hybrid)
Femtocells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284 9.3.2.4 Handling Allowed List . . . . . . . . . . . . . . . . . . . . . . . 284
9.3.3 Access Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 9.3.4 Paging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 9.3.5 Idle Mode, Cell Selection, and Cell Reselection . . . . . . . . . . . . 286 9.3.6 Connected Mode and Handoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286 9.3.7 Mobility Management Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
9.4 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 9.4.1 Mobility Management Techniques . . . . . . . . . . . . . . . . . . . . . . . . . 289 9.4.2 Evaluation Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 9.4.3 Proposed Mobility Management Schemes . . . . . . . . . . . . . . . . . . 290
9.4.3.1 Handoff Schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290 9.4.3.2 Scanning and Selection Schemes . . . . . . . . . . . . . 297 9.4.3.3 Reselection Schemes . . . . . . . . . . . . . . . . . . . . . . . . . 298
9.5 Conclusion and Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
Current wireless broadband networks (WBNs) are facing several limitations and con-
siderations, such as poor indoor coverage, explosive growth in data usage, and mas-
sive increase in number of WBN subscribers. Various inventions and solutions are
used to enhance the coverage and increase the capacity of wireless networks. Fem-
tocells are seen as a key next step in wireless communication today. Femtocells of-
fer excellent indoor voice and data coverage. As well, femtocells can enhance the
capacity and offload traffic from macrocells. There are several issues that must be
considered though to enable the successful deployment of femtocells. One of the
most important issues is mobility management. Since femtocells will be deployed
densely, randomly, and by the millions, providing and supporting seamless mobility
and handoff procedures is essential. We present a broad study on mobility manage-
ment in femtocell networks. Current issues of mobility and handoff management are
discussed. Several research works are overviewed and classified. Finally, some open
and future research directions are discussed.
