GSM is a wireless digital
signaling network standard designed by
standardization committees from the major European telecommunications
operators and manufacturers. This article introduces the software platform
for GSM network signaling protocol called Mobile Application Part (MAP). We describe
the MAP services, the MAP protocol machine, the MAP dialog model, and then
illustrate the MAP specific service primitives by an example.}
Innovations of modern digital radio technology
has enabled many large mobile and distributed information systems, such as
inventory tracking systems, to provide
readily accessible voice and data services to end users
despite mobility of data servers.
These systems often contain components that are equipped
with radio frequency identification (RFID) tags and
interrogators for wireless connectivity.
However, there are usually large number of these tagged items
in these systems that are highly mobile.
The wireless connections among them are also prone to failure.
In this paper, we evaluate and compare the performance of two RF tag
data access protocols in a single channel per cell implementation:
slotted ALOHA Time Division
Multiple Access (ALOHA/TDMA) and Direct Sequence Code Division
Multiple Access (DS/CDMA).
We use a discrete event simulation model to study the impact of these
protocols on data service under a diversity of highly mobile operating
conditions. Mobile conditions are captured separately by
various levels of burst error, uplink and downlink disconnections,
and tag population.
The results show that performance of (DS/CDMA) dominates in all mobile conditions.
In the most general cases, (DS/CDMA) outperforms (ALOHA/TDMA) by 1.5 times faster
message time.
(DS/CDMA) is particularly superior in the case of pure uplink
disconnections.
For burst error and pure downlink disconnections, (DS/CDMA) renders as
much as 2.0 times and 4.5 times faster message time respectively.
In this paper we consider the use of DECT access for packet data services. DECT systems
are characterized by a dynamic channel selection algorithm which allows to reuse the
available radio resources in a flexible way. The standard channel allocation procedure results
inefficient for packet data applications characterized by short and frequent messages,
which determine fast varying traffic conditions.
We propose an enhanced dynamic channel selection algorithm, which allows to
fulfil the requirements of packet access in a more efficient way. The performance
characteristics of the new and standard algorithm have been evaluated by simulation,
and refer both to a scenario for only packet data services and
an integrated scenario for voice and data services.
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(Tutorial Paper)
Yi-Bing Lin
liny@csie.nctu.edu.tw
Kui W. Moka
Alvin S. Limb
mok@cs.columbia.edu
lim@cc.gatech.edu
bComputer Sciences Department, Clark Atlanta University
Antonio Capone
Luigi Musumeci
capone@elet.polimi.it
musumeci@elet.polimi.it