Hand Over in 4G/LTE Networks

HANDOVERIN 4G NETWORKS

Department of Digital SystemsMsc. Digital Communications and

Networks

Oikonomakis Spyridon Pantelopoulou

Charikleia

STRUCTURE OF PRESENTATION

Handover Basics Handover in and between 4G

networks Handover procedures IEEE

802.16m Advanced handover features

IEEE 802.16m Legacy supported handover

IEEE 802.16m Handover Framework 3GPP LTE-

Advanced Interworking between IEEE

802.16m & 3GPP LTE-Advanced Conclusions

THE TERM HANDOVER

The process of transferring an ongoing call or data session from one channel to another in a cellular network.

Basic reasons why a handover might be conducted:The user has moved out of rangeThe base station is full

It is a key component in cellular network mobility management as it requires a specific latency on server interruption time.

HANDOVER FRAMEWORK REQUIREMENTS

Latency and Flexibility Scalability of handover framework to

handle increased handovers without compromising latency performance

Handling networks with heterogeneous BS entities (pico / femtocells)

Optimizations to allow handover to multicarrier-capable devices.

IEEE 802.16M & 3GPP LTE - ADVANCED

Physical layer frame of IEEE 802.16m designed with legacy of IEEE 802.16e allowing operation: Either on separate frequency assignments Or on the same frequency assignment with proper

time-division zone partitioning between them (LZone, Mzone)

Providing legacy access service network (ASN) support mode (plug-and-play)

LTE – Advanced designed with legacy of GSM/EDGE, GERAN and UMTS handover and cell reselection to/from the legacy

systems through treating them as inter-RAT networks.

HANDOVER IN UMTS AND WIMAX

E-UTRAN IEEE – 802.16m

DEPLOYMENT SCENARIOS IEEE – 802.16M

a) greenfield deployment (new spectrum) b) mixed deployment, carrier reuse c) mixed

deployment, carrier overlay

IEEE – 802.16E & IEEE – 802.16M COEXISTENCE ARCHITECTURE

OVERALL HANDOVER PROCEDURES

Preparation and Initiation

Execution

Completion Exception Handling

ADVANCED HANDOVER FEATURES IEEE 802.16M

Goal: To reduce latency during handover in physical and MAC layers and provide a better end-user experience

Advanced handover enhancements based on the general handover call flow:Seamless HandoverEBB Handover (Entry Before Break)

Newly introduced in the IEEE 802.16m air interface protocol:Legacy Supported HandoverMulticarrier Handover

EBB HANDOVER PROCEDURES

General EBB handover procedures: a) single-carrier b) multicarrier

LEGACY SUPPORTED HANDOVER IEEE 802.16M (1)

There are four possible scenarios for handover:

Handover from a 16e BS to 16m BS:16e BS to mixed-mode16m BS16e BS to advanced only 16m BS

Handover from a 16m BS to 16e BS :advanced only 16m BS to 16e BSmixed-mode 16m BS to legacy 16e BS

LEGACY SUPPORTED HANDOVER IEEE 802.16M (2)

Handover procedure from an IEEE 802.16e BS to a mixed-mode IEEE 802.16m BS

Handover from a 16e BS to a 16m Only BS (direct handover)Case of the largest interruption time due to

lack of the demanded BSs’ interfacesLegacy ASN :

Security update is a typical intra-16m handover case

Requires capability negotiation and MAC context setup

16m ASN:Requires full network entry

LEGACY SUPPORTED HANDOVER IEEE 802.16M (3)

Handover from a 16m BS to a 16e BSEither the 16m MS performs legacy

handover to the 16e BS through the LzoneOr the 16m MS performs direct handover

to the 16e BS through the MZone

LEGACY SUPPORTED HANDOVER IEEE 802.16M (4)

THE HANDOVER FRAMEWORK OF 3GPP LTE-ADVANCED

Hard handover is similar to IEEE 802.16m

Differences: Allows only BBE (Break Before Entry)

operationHandover initiation and target selection are

more tightly controlled by the networkSupports seamless and lossless handoverUser procedure can be assigned in a per

resource bearer (RB) mannerPacket Data Convergence Protocol (PDCP)

handles differently the data forwarding at the UE and eNodeB sides in different modes

INTERWORKING BETWEEN IEEE 802.16M AND 3GPP LTE-ADVANCED (1)Handover from IEEE 802.16m to 3GPP LTE-Advanced can use tow layer-2 protocols:

IEEE 802.16m generic MAC layer-2 transfer tunnel

IEEE 802.21 media-independent handover protocol

Given these frameworks and MAC layer control signaling there can be support of:

single-radio handoverdual radio handover

INTERWORKING BETWEEN IEEE 802.16M AND 3GPP LTE-ADVANCED (2) Handover from 3GPP LTE-Advanced to

IEEE 802.16 family supports dual radio procedure via layer 3 transport.

The 3GPP Service and Architecture 2 (SA2) specification requires layer 3 handover signaling for UE to preregister with WiMAX network.

Disadvantage: No layer-2 radio access network 2 (RAN2) specification defined to optimize handover

CONCLUSIONS

Reducing service interruption time is becoming more in next-generation wireless systems.

IMT-Advanced Systems provide advanced handover mechanisms in order to provide enhanced user experience during handover.

Important requirement when design IEEE 802.16m and 3GPP systems is:

Legacy supported mobility management

All previously described advanced features of handover mechanisms enhance the user experience by:

Reducing handover interruption timeDiminishing the coverage hole

QUESTIONS???

THANK YOU FOR YOUR ATTENTION