Moby Dick Consolidated System Integration Plan

D0103v1.doc Version 1 6.7.2003
o For TD-CDMA, a decision for handover is taken if the signal level of best candidate for
handover is higher than TD-CDMA_threshold.
o For WLAN, a decision for handover is taken if the signal level of best candidate for
handover is higher than WLAN_threshold.
• WLAN is the current Network Technology: higher preference level Network technologies are
considered.
o For TD-CDMA, a decision for handover is taken if the signal level of best candidate for
handover is higher than TD-CDMA_threshold.
o For Ethernet, a decision for handover is taken if this technology is present.
o If no higher preference Network technology is selected, current signal level is lower
than WLAN_threshold, a best candidate for WLAN “access point” handover is present
in the Network Environment Infos, and the signal levels follow this relation: current
WLAN signal level + delta_WLAN < best candidate WLAN signal level, a decision for
handover is taken. We introduce delta_WLAN, because we don’t want to handover to a
WLAN new “access point”, which signal level is not significantly better.
• TD-CDMA is the current Network Technology: higher preference level Network technologies
are considered.
o For WLAN, a decision for handover is taken if the signal level of best candidate for
handover is higher than WLAN_threshold.
o For Ethernet, a decision for handover is taken if this technology is present.
o If no higher preference Network technology is selected, current signal level is lower
than TD-CDMA_threshold, a best candidate for TD-CDMA “access point” handover is
present in the Network Environment Infos, and the signal levels follow this relation:
current TD-CDMA signal level + delta_TD-CDMA < best candidate TD-CDMA signal
level, a decision for handover is taken. We introduce delta_TD-CDMA, because we
don’t want to handover to a TD-CDMA new “access point”, which signal level is not
significantly better.
In the case of WLAN and TD-CDMA, if no higher or same preference level Network technology is
selected, and if the current signal level is lower to the predefined threshold (respectively
WLAN_threshold and TD-CDMA_threshold), lower preference level network technologies can be
considered if we are in both mode, by executing a manual handover via the NCP (this case will not be
considered in automatic mode, as it can lead to an uncontrolled succession of automatic handovers
between different technologies). The same criteria per current technology in use will be considered, as
when higher preference level Network technologies are considered.
When a decision to execute handover is taken, we enter in a phase common to manual and automatic
handover, which we will call Handover Execution, and that will be described later.
4.1.2.2.7 Handover Execution
This mechanism is a common part of the Manual and Automatic Handover blocks.
The first thing is to decide whether we are about to execute an intra or inter domain handover. The
solution proposed is to use the Router Advertisements to convey this information: two bits in the IP
subnet prefix will identify the domain. The MTNM memorizes the current domain, and extracts the new
domain from the IP address of the target Access Router, and makes the decision by comparing them.
In case we are currently in Paging Dormant mode, we will only execute a L2 handover (no FHO or
registration procedure). So we will only go through the procedure executing Layer 2 handover, which is
detailed below in the fast handover description.
First intra-domain handover is considered, which will result in a fast-handover.
The MTNM sends the message START_FHO to the Fast Handover module, to request fast handover
execution, with the IP address of the new Access Router, the IP address of the old Access Router, the new
interface name, the old interface name, as parameters.
The Fast Handover module will prepare the fast handover by contacting the old Access Router, and will
receive an answer when everything is ready. For the moment, we consider the case where the FHO can be
executed.
The Fast Handover module will send the message L2_REQ, to request the MTNM to execute the layer 2
handover. This will require:
• If Ethernet is the new L2 technology, nothing needs to be done.
• If WLAN is the new L2 technology, the message USE_WLAN_AR must be sent to the WLAN
driver, with parameters IPv6 address of new Access Router and IPv6 subnet prefix of new Access
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