Moby Dick Consolidated System Integration Plan

D0103v1.doc Version 1 6.7.2003
NCP
Set
Network
Preferences
Set
Handover
Preference
Manual
Handover
Network
Environment
Infos
Explicit
Connectivity
Request
MTNM
Set
Network
Preferences
Set
Handover
Preference
Network
Environment
Infos
Network device drivers
TDCDMA WLAN Ethernet
Figure 6: Interactions between MTNM / NCP
The MTNM will update its Network preferences each time it receives a request from the NCP, via the
message SET_NETWORK_PREFERENCES. These preferences will be expressed as for the NCP: first
choice x, second choice y, third choice z; with x,y,z in Ethernet, TD-CDMA, WLAN.
4.1.2.2.2 Set Handover Preference block
The MTNM will update the Handover preference each time it receives a request from the NCP, via the
message SET_HANDOVER_PREFERENCE. This preference will be expressed as for the NCP:
automatic, manual or both. This information will be used to authorize automatic handover, if the
preference is automatic or both.
4.1.2.2.3 Network Environment Info block
This block will analyse information received from the Network device drivers, store them for use by the
automatic handover decision algorithm, attach procedure; and transmit them to the NCP (as already
explained in the description of the corresponding block in the NCP).
The messages received from the device drivers will be ETHERNET_INFO, TD-CDMA_INFO and
WLAN_INFO. The message sent to the NCP will be NETWORK_ENVIRONMENT_INFOS.
First of all, we will not consider every router advertisement or signal level indications received by the
different device drivers. Instead, we will limit ourselves to a “reasonable” time interval between two
consecutive messages from the device drivers to the Network Environment Info block. This will avoid too
frequent handover (backward and forward) if a user moves around the border of two radio coverage areas,
in the case of WLAN or TD-CDMA.
For the three possible network technologies, if we don’t receive an info message at the time we expect
one, we will consider that the technology is not available.
For Ethernet, the message INTERNET_INFO will contain the following information: absent or present,
IPv6 address of the corresponding Access Router, which will be stored locally. The information absent or
present will be transmitted to the NCP, if it changes, via message NETWORK_ENVIRONMENT_INFOS.
For WLAN, the message WLAN_INFO will contain the following information: a list of [signal to noise
ratio, IPv6 address of the corresponding Access Router, IPv6 subnet prefix of Access Router].
Locally, we will keep up to two entries: the current WLAN “access point” if this technology is in use, and
the best candidate for handover (which can be different from the currently used “access point”).
First we will erase the current best candidate for handover, and the following algorithm will be applied to
each element of the list:
• If WLAN is the currently used Network technology and we receive from the WLAN device
driver an update with the same identification and a different signal to noise ratio, we update the
current signal to noise ratio in the MTNM and send an update message
NETWORK_ENVIRONMENT_INFOS to the NCP, with the new signal level.
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