Architectures for Particle Filtering - Signal Processing Systems - page 647

Tabl e 4 Buffer activity
status conditions of the
PE CU interface

flag AC i =( a 1 a 2 ) Activity condition

00 Inner- and outer-connection available

01 Outer-connection available

10 Inner-connection available

11 No connection available

or a destination (0), and s 4 denotes whether the interface is valid or not. For example,
if S 1 =( , it signifies

that interface 2 is a source and interface 1 is a destination for inter-connection (i.e.,
RTB 2 d to RTB 1 u ). In case of an intra-connection, two independent connections will
be initiated at any given cycle. Since it is possible that only one intra-connection
is available, we have to provide additional information from the priority decoder,
which is s 4 .If s 4 is 11, both S 1 and S 2 are valid. If it is 10, only S 1 is valid, if it
is 01, only S 2 is valid. If it is 00, no connection should be made. In case of intra-
connection, s 3 =

s 1 = 2 , s 2 = 1 , s 3 = 1 , s 4 ) and S 2 =( s 1 = 1 , s 2 = 1 , s 3 = 0 , s 4 )

1 for connection from RTB iu to RTB id ,and s 3 = 0 for connection

from RTB id to RTB iu .
The Exchange Controller establishes connection between a pair of buffers. This is
accomplished by providing signals to the switches that configure the routing. Once
routing is established, the connection is connected at least one particle is transferred.
Otherwise, undesired infinite loop may occur as mentioned previously. As discussed
in the previous section, pairing is only established between RTBs. RTB id to RTB ju
signifies particle transfers between different PE CU interfaces, and RTB iu to RTB id
signifies particle transfers within a PE CU interface. We also indicated that particles
in RB i can be transferred to RTB id . This process conflicts when this RTB id is used
as its own destination (i.e., RTB iu is the source). So the Exchange Controller must
generate appropriate signals to this PE CU interface. On the other hand, when RTB iu
is transferring particles to RB i , there will be no conflict since RTB iu will never
be chosen as a source to its own RTB id . (i.e., short of particles). Since we have
separate data ports, this RTB iu can be a destination for RTB jd .Wehavetomakesure
when both are active and that correct counting is accomplished. This is explained in
Fig. 10 .
The Exchange Controller provides controls and monitors execution of particle
transfer. The Exchange Controller monitors the activity according to flag AC i ,( a 1 , a 2 ),

described in Table 4 . These flags are set and reset by both the Exchange Controller
and PE CU interface controller. a 1 is set if the inner-connection is not available and
a 2 is set if the outer-connection is not available. When the Exchange Controller sets
up a connection, the flags are modified. When the interface controller completes
the buffer access, the flags are again modified. One important note is that since
there is connection from RTB iu to RB i , when there is any particle transfer, the
interface controller signals so that the Exchange Controller makes sure that the
inner-connection is not available. This is only applicable for eliminating conflict
with particle transfers from RTB iu to RTB id .