(EN)
The disclosed invention is referred to a method for optimising the random
access procedures in third generation CDMA cellular telephony systems. The
particular embodiment of the example concerns a TD-SCDMA-TDD synchronous
realization. The disclosed procedure includes a preliminary part charged to
the network (BSSC, MSC) only for establishing the following associations
between the configuration parameters of the involved physical channels: one
signature burst (SYNC1) is associated to one forward access channel (P-FACH)
only, in order to avoid any ambiguity in the mobile stations about where to
look for the expected acknowledgement from the network; one random access
common channel (P-RACH) is associated to one forward access channel (P-FACH)
only, in order to reduce collision on the latter (P-RACH); one access grant
channel (P/S-CCPCH, AGCH) only is associated to one random access common
channel (P-RACH), in order to avoid any ambiguity in the mobile stations about
where to look for the expected answer from the network with the indication of
the dedicated service channels (DPCH); and each complete associative link
binding the involved physical channels is included in the system information
and broadcasted into the serving cell to be read by the mobile stations (MS,
UE) when entering an actual part of the procedure charged to exchange protocol
messages with the network (BSSC; MSC) through said associative links that
being signalling at once to the mobile stations the route towards the services
offered by the network, simplifying the access procedure consequently.
Suitable groupings among: Downlink pilot sequences, Uplink pilot sequences,
scrambling codes, basic midambles, are carried out in a cell-discriminating
way and broadcasted into the cell to simplify the serving cell selection
procedure.
