Mobility Management Mobility management enables telecommun ications networks to Locate roaming mobile terminals (MTs) for call delivery Maintain connections.

Mobility Management

Mobility management enables telecommunications networks to Locate roaming mobile terminals (MTs) for c

all delivery Maintain connections with MTs that change

their points of attachment

Introduction (cont.)

What is mobility management doing? 1. Location management

location registration (or location update)

call delivery (or search) 2. Handoff management, caused by

signal strength deteriorationuser mobilityIntracell vs. intercell handof

Introduction (cont.)

Two kinds of handoff soft handoff vs. hard handoff

Three ways to handoff network-controlled handoff (NCHO - AMPS) mobile-assisted handoff (MAHO - GSM,

IS-95) mobile-controlled handoff (MCHO - DECT,

PACS)

Introduction (cont.)

Three-Stage of process for handoff 1. Initiation: the user, a network agent,

or changing network condition 2. New connection generation: finding

new resources and performing routing operation

3. Data flow control : delivery of data according to agreed-upon service guarantees

Introduction (cont.)

Handoff protocols usually rely on routing resource management data delivery systems

Handoff algorithms are network-protocol-dependentIt needs standardized wireless netowork architecture to access regional, national and global services as efficiently as those on the local level

Future Wireless Network Architecture

The ITU has specified IMT-2000Hierarchical cell structure (HCS)Global network roamingExpanding radio spectrum

Future Wireless (cont.)

Hierarchical cell structure (HCS) consisting of Picocells (in-building: high-capacity) Micro- and macrocells (urban and

suburban terrestrial networks) Large satellite cells Base transceiver stations (BSs or BTSs) can

access terrestrial networks (PSTN, ATM, Internet)

Future Wireless (cont.)

Satellite networks communicate with fixed earth stations (FESs)

Mobile terminal (MT) Location area (LA): consist of multiple cells Cell site switch (CSS): govern one or more

BSs and will provide access to the serving mobile network (PLAN, Internet, ATM, or satellite)

Future Wireless (cont.)

Global roamingTerminal mobility, personal mobility,

and service provider mobility

Radio spectrum ITU promotes harmonized utilization

of the radio spectrum and to facilitate the development of global PCS

Next generation network service portability

Mobility Management for PLMN

Architecture: key componentsMobile terminal (MT)Base station (BS)Mobile switching center (MSC)Home location register (HLR)Visitor location register (VLR)

Mobility Management for PLMN (cont.)

Two standards for location management in the PLMN: 1. IS-41 for AMPS, IS-54, IS-136, PACS 2. GSM MAP for GSM, DCS-1800, PCS-

1900

Both standards: two-level database hierarchyThe following figure shows the call delivery procedure

Mobility Management for PLMN (cont.)

Location management research Database architecture

Centralized vs. distributed Location update

Time based (at a constant time interval)Movement based (movement threshold

across cell boundaries) Distance based (distance threshold): best

performance but highest overhead

Mobility Management for PLMN (cont.)

Terminal paging (a tradeoff between paging cost vs. paging delay)Paging under delay constraintsUpdate and paging under delay

constraints

No single scheme that clearly outperforms the others under all system parameters

Location Management in 3G UMTS

The service area is partitioned into Gateway Location Areas (G-LAs)A G-LA is further partitioned into Location Areas (LAs)An LA consists of a group of cellsThe following figure shows a three-tier mobility databases: HLR, GLR (optional), and VLR

Location Management in 3G UMTS (cont.)

Location Management in 3G UMTS (cont.)

An HLR location update is performed when an MT crosses a boundary of a G-LAA GLR location update is performed when an MT crosses a boundary of an LAA VLR location update is performed when an MT completes d movements between cells, where d is the movement threshold (movement-based location update)

Types of Handover in 3G WCDMA Mobile Networks [4]

4 types of handover (HO): Intra-system HO

Intra-frequency HO Inter-frequency HO

Inter-system HO Hard HO

Intra-frequency HO Inter-frequency HO

Types of Handover in 3G WCDMA Mobile Networks [4]

(cont.) Soft HO and softer HO

During soft HO, a mobile simultaneously communicates with two (2-way SHO) or more cells belonging to different BSs of the same RNC (intra-RNC) or different RNCs (inter-RNC)

In softer HO, a mobile is controlled by at least two sectors under one BS (RNC not involved)

SHO and softer HO are only possible within one frequency (intra-frequency HO)

Scenarios of Diff. Types of HO [4]

Mobility Management for Mobile IP

Mobile IP architecture (Figure) Discovery: How an MN finds a new Internet

attachment point when it moves from one place to another

Registration: How an MN registers with its HA (an internet router)

Routing and tunneling: How an MN received datagrams when it is away from home

Mobile IP location management (Figure)

Mobility Management for Mobile IP (cont.)

Location registrationHandoff management Smooth handoff: for maintaing QoS Routing and Tunneling

Open probems Simultaneous binding: MN can maintain several

CoAs at one time Regionalized registration: localize the registration

to the lowest common FAs Security: protect the CoA’s and HA’s

Mobility Management for WATM

It focuses on 4 issuesLatencyMessage deliveryConnection routingQuality of service (QoS)

Mobility Management for WATM (cont.)

Deal with location management, terminal paging, and handoffFor movement from position B.1.2 to position A.2.2, the location registration procedure is shown as follows:

Mobility Management for WATM (cont.)

Handoff management research Full connection re-routing Route augmentation Partial connection re-routing Multicast connection re-routing

maintaining the potential handoff connection in addition to the original connection, reducing the time spent in finding a new route for handoff

Mobility Management for Satellite Networks

Satellite location management research The development of new LA definitions for LEO

satellite networks Coverage area of a single satellite consists of

small-sized cells, which is called as spotbeams

Satellite handoff management research Intersatellite handoff Spotbean handoff (intrasatellite handoff) Link handoff: satellites near to polar regions turn

off their links to other satellites in the neighbor orbits; Ongoing calls passing through these links need to be rerouted

Research Issues for Integrated Wireless Networks

The next generation of wireless networks promises mobility without geographical constraints or being tied to one particular networkAny network equipped for unified operation must be able to support Inter-carrier (or intersystem) handoff Personal mobility Location management for a heterogeneous network

Mobility-related Research Issues for Next Generation Wireless

NetworksSoftware radioLocation managementInter-system handoffAddressing and identificationDatabase issuesRouting issuesStandardization