Autor(es):
Severino, Ricardo 
; Batsa, Manish ; Alves, Mário ; Koubâa, Anis
Data: 2010
Identificador Persistente: http://hdl.handle.net/10400.22/3904
Origem: Repositório Científico do Instituto Politécnico do Porto
Descrição
The IEEE 802.15.4 is the most widespread used
protocol for Wireless Sensor Networks (WSNs) and it is being
used as a baseline for several higher layer protocols such as
ZigBee, 6LoWPAN or WirelessHART. Its MAC (Medium
Access Control) supports both contention-free (CFP, based on
the reservation of guaranteed time-slots GTS) and contention
based (CAP, ruled by CSMA/CA) access, when operating in
beacon-enabled mode. Thus, it enables the differentiation
between real-time and best-effort traffic. However, some WSN
applications and higher layer protocols may strongly benefit
from the possibility of supporting more traffic classes. This
happens, for instance, for dense WSNs used in time-sensitive
industrial applications. In this context, we propose to
differentiate traffic classes within the CAP, enabling lower
transmission delays and higher success probability to timecritical
messages, such as for event detection, GTS reservation
and network management. Building upon a previously
proposed methodology (TRADIF), in this paper we outline its
implementation and experimental validation over a real-time
operating system. Importantly, TRADIF is fully backward
compatible with the IEEE 802.15.4 standard, enabling to
create different traffic classes just by tuning some MAC
parameters.
