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4G network handover procedure
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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