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Organizing a network, composed in many cases of a high number of low-
resourced nodes, is a dicult task since the algorithms and methods have to
save as much energy as possible while offering good performance. Power-saving
has been the main driving force behind the development of several protocols that
have recently been introduced. In this context, perhaps the greatest energy sav-
ings are achieved by protocols whose communications are based on time division
multiple access (TDMA) and synchronization. However, synchronous communi-
cations require the organization of the network nodes in an ecient structure
such as a logical tree. This structure can be used to achieve both, collision-free
communications and minimum end-to-end latency. The network layer is respon-
sible for the dynamic-routing tree creation and topology control using a novel
and interesting routing algorithm.
These kinds of algorithms take into account important node features such
as battery level, number of hops to the sink or link quality; note that if this
information is not considered, problems in the network may occur (interrupted
paths, packet loss or isolated nodes, among others).
Our work integrates the SA-MAC protocol [3], a simple but effective col-
lision resolution protocol as a means to set-up the slot allocations of TDMA
protocols, with NORIA (Network rOle-based Routing Intelligent Algorithm)
[4], a novel routing algorithm for wireless sensor networks. In this paper, we
mainly focus on how SA-MAC and NORIA work together in dense networks
in order to optimize the protocols that control the behaviour of network nodes
in real applications. In our group, we have developed a multisensory indoor
monitoring application, oriented to energy management in intelligent buildings,
where we have encountered a number of problems related to information loss and
packet collisions. Due to this, we have decided to optimize network and medium
access protocols and integrate them together in order to improve the overall
performance.
The rest of this paper is organized as follows: Section 2 summarizes some
related work. The synchronized medium access protocol, SA-MAC is detailed in
Section 3. Fuzzy logic principles are presented in Section 4, and serve as a basis
to the intelligent routing approach detailed in Section 5. Section 6 presents the
integration of both approaches and details the experiments and obtained results.
Finally, Section 7 gives some concluding remarks.
2 Previous Work
TDMA MAC protocols avoid some important problems such us idle listen-
ing, collisions, overhearing and overhead due to control packets. In addition,
when an ecient global synchronization mechanism is available, the topology is
fairly stable and TDMA protocols are usually the best option for ecient data
communications in WSN [5]. A few relevant MAC protocols that make use of
TDMA channel sharing are worth mentioning in [3]. SA-MAC protocol solves this
set-up phase successfully and performs a second phase of synchronization and
data transmission. Also, it is strongly recommended for a MAC protocol to be
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