[STDS-802-16] Uniqueness of SFID
Hi,
If I understand correctly, 802.16-2004 requires that SFID is unique
within the scope of a BS, and also within the scope of a network
(although the definition of 'network' is not exact). Furthermore, SFID
is preserved during handover in a mobile system and so, to be sure that
SFID remains unique in each BS, SFID must first be unique within the
network. In this case, 'network' will be the set of BSs that is
interconnected for the purpose of mobile handoff.
SFID is sent over the air interface only in the DSX messages. These are
unicast messages sent on the primary management channel. The CID of the
primary management channel is already associated with an SS MAC address.
Therefore, the air interface could operate satisfactorily providing the
SFID is unique within the scope of a single SS. In other words, the SS
wouldn't know if the same SFID was used in other SSs in the same BS.
Can anybody tell me why DOCSIS specified a globally unique SFID? An
alternative strategy where SFID is unique for a given SS MAC address
could have saved perhaps three octets in most DSX messages.
This is an interesting question in the context of a mobile network.
Suppose that we have a number of SFID allocator entities that operate in
different regions. We will have to design procedures to ensure
non-overlapping allocations, and to ensure release of SFIDs when an SS
transitions to a region served by a new allocator.
Mark