Image Processing Reference
In-Depth Information
Representative node
Correlation neighbor
Correlation region
E-MAC
Event area
N-MAC
Sink
FIGURE .
CC-MACprotocoloperations.(RedrawnfromVuran,M.C.andAkyildiz,I.F.,
IEEE/ACM Trans.
Network.
, (), , .)
CSMA/CA protocol and use RTS/CTS packets to regulate the channel access. he aim of E-MAC is
to filter out correlated data, while the aim of N-MAC is to give the forwarding packets priority over
the event detection packets. In fact, in order to meet the desired distortion, all the packets filtered by
E-MAC should be received by the sink, so they have to be prioritized. With the E-MAC mechanism
one node at a time can transmit, the representative node, whereas the others stop the transmission
attempts for the duration of the transmission. After the transmission occurs, a new representative
node may be selected. he selection is performed through a simple RTS/CTS/DATA/ACK sequence.
A representation of the E-MAC and N-MAC operations is given in Figure ..
The nodes hearing the data transmission determine if they belong to the same correlation region,
i.e., if their distance from the representative node is smaller than
r
corr
.Ifthisisthecase,theystop
attempting to transmit; otherwise they enter the contention for the medium when a packet has to
be sent. When a representative node is selected, the other nodes belonging to the correlation region
go to sleep. However, they periodically wake-up in order to check if they have to perform some data
forwarding. Furthermore, in the case
r
corr
is larger than the transmission range, the nodes belonging
to the same correlation region can go to sleep only if they do not belong to the path toward the sink
node, otherwise the event detection capabilities may be seriously afected. he N-MAC mechanism
is the classical CSMA/CA, but it is given priority over the E-MAC through the use of smaller values
for interframe spacing and CW
max
.
This protocol has been evaluated through simulations and the results show that it performs bet-
ter than S-MAC, T-MAC, and TRAMA in terms of latency and energy consumption, thanks to the
reduced number of packets together with the decreased nodes' duty cycle. he packet drop ratio on
