Information Technology Reference
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3.4.2.2 Suggestion of a Novel Procedure
Traditionally H.245 messages are encoded in a chunk-by-chunk style. Each
chunk corresponds to a submessage under the main message. For each
chunk of input, an encoding process must be called every time and the
chunks are encoded serially. So in this serial and individual encoding pro-
cess for each and every message eventually leads to a high cost of system
time.
We note some important points here:
•
Each main message and its submessages are the same for all the
individual calls.
From our experiment, we observe that some submessages under a
•
main message are also repeated.
Messages the like TerminalCapabilitySet request are no doubt the
•
same for all calls. But still, the response is also very few in number;
it is because, in reality, terminal capabilities are fixed and there are
few numbers of different mobile terminals produced by different
brands. So for most calls, these requests are the same and responses
are just a little varied.
Hence, it seems that the earlier mentioned serial coding process is just an
unnecessary killing of system's CPU time. In contrast, if there is a low-cost
process that serves the same objective of producing the same encoded out-
put then that process is definitely worth adopting. In this scenario, with the
motivation of improving the call handling efficiency of the 3G gateway, we
would like to suggest a more efficient method on an experimental basis. In
this method, we consider the possibility of reusing a replicated encoded
message set that is already compiled from an earlier call, unless the message
data is changed. And if there is any change in the submessages then that
part can easily be handled by dynamically compiling the part and updating
the returned value in the whole encoded message string. We describe the
method in detail as follows.
Considering the programming level of message encoding, it is not neces-
sary to encode the whole H.245 message for each call, rather the produced
binary stream can just be updated with minor changes in a few bits. Here the
precompiled message streams may be saved in a lookup table and that can be
accessed for each call instead of recompilation each time. Eventually it saves
an appreciable amount of encoding compilation time.
A visual description of the above suggested reusable precompiled
message-data set and its lookup table implementation method is compared
to the traditional message encoding method as depicted in the above tables.
Here we suppose that M1, M2, and M3 are H.245 messages and A, B, and
C are their encoded binary streams, respectively. Table 3.2 shows the tradi-
tional approach for H.245 message encoding where each message is encoded
