Network Initiated Handovers T. Melia, J. Korhonen, R. Aguiar, S. Sreemanthula, V. Gupta Based on draft-melia-mipshop-niho-ps-00
Motivation • Deployment of heterogeneous access systems combined with IP convergence (WLAN, WiMax, 3G) requires enhanced network controlled mobility • Inter system handovers • WLAN deployments lack network control of roaming users • Steering of roaming: NAPs do not belong to mobile operators (inter domain) • We have solutions for Mobile Initiated and network assisted (L2 triggers, FMIv6 alike solutions) • Need to understand Network Initiated Handover i.e. the trigger generates in the network NEED for a flexible framework supporting both kind of handovers
Definition of network initiated handover Action taken in the network to initiate the handover based on: • Link events originated in the mobile node: • radio link variations (e.g. RSSI, SNR) • powering on of new network devices • new service requirements • … • Events generated in the network: • resource management reasons • optimization based on location/services • multi homed devices • …
Assumptions (i) • Reusing existing security mechanisms as much as possible • All mobile nodes within the scope of this document are expected to support at least one (potentially modified) existing or future IP mobility enabling protocol. • MNs and mobility management nodes are expected to understand or support network initiated and assisted handovers. CNs may not. • The network initiated handover concept relies on the presence of a functional entity.
Assumptions (ii) • To provide adequate scalable support, additional distributed functions are required to support the functional entity. • See functional components described in the document • It is envisioned the presence of multi wireless access, such as 802.11, 802.16, UMTS, forming an heterogeneous composition of macro and micro cells. • Performing network initiated handover has the main implication that the network has first to assess the terminal view of the network. Signal level evaluation is a important matter when coming down to user mobility. • Neighborhood discovery relates to the above assumption when neighborhood scanning is requested from the network. It is expected these functions to be available on the terminal side.
Issues to consider for NIHO feasibility: • Mobility Application Area: • Efficiency of measurement functions for signal level reports • Location of decision functions (RTT) • Network can control the handover • Resource Application Area: • Overlapping and Coverage of (different) wireless access technologies • Resource optimization or administrative decisions • Network can trigger the handover • Application for inter-domain handover • Steering of roaming
NIHO with IEEE 802.21 • IS, ES and CS as enablers for network initiated and assisted handover scenarios • Consider the Mobility and Resource Optimization (opportunistic handover) application area • Two steps approach: • Network selection • MIHF at the terminal discovers available networks • MM in the network decides which is favorable • Handover control • MM sends a CS-switch request to initiate the handover Simulation results available on request
Goals • Independent of the IP mobility management mechanism • Work over administrative domains e.g. in inter-domain handover cases or when a multi-homed host is attached to multiple ISPs • Provide inter technology handover • Provide similar degree of security as existing with the current solutions. Non Goals • Designing a new security framework in order to enable network initiated and assisted handover triggering. • Initial bootstrapping problem -- The mechanism to gain the initial access to some network is out of scope of.
ScenariosSingle administrative domain MRMH NIHO Triggers generated in the home network Mobile Operator Home Network ISP NIHO Triggers generated locally in the access network Transparent to the home network NAP A NAP B
ScenariosMultiple administrative domain Mobile Operator Home Network NIHO Triggers generated in the home network also over administrative domain MRMH ISP ISP GMP NIHO Triggers generated locally in the access network Transparent to the home network NAP A NAP B NAP B