Prioritization of Patient Vital Signs Transmission Using Wireless Body Area Networks - E-Healthcare Systems and Wireless Communications - page 280

CVP. Note that when N B is small, the delay of the
CVP data is less than that of PROBE as it can
choose better channels while PROBE cannot.
When N B becomes bigger, the lowest priority of-
fered to the CVP data due to largest delay require-
ment introduces much delay that cannot be offset
by using good LQI channels so the delay is
greater than that with the non-priority PROBE.
As far as the e2e reliability is concerned
(Figure 8(b)), as N B increases, all these protocols
show decreasing reliability due to an increased
interference and a higher number of hops to the
sink, which result in increased PER. Due to similar
reasons as above, MQMAC-CQBR-HS has the
highest reliability while LEAST has the worst,
and data with stricter delay requirement get better
reliability, too.

decreased fairness for distant nodes. PROBE only
has the option to dynamically select routes but not
the channel so its delay fairness lies in between
the other two protocols. Data with stricter delay
requirement obtain better fairness because they
are forwarded in a timely manner.
Similar case happens when reliability fairness
is taken into account as shown in Figure 9(b).
With options to dynamically choose routes (based
on RQI) and channels (based on channel quality),
MQMAC-CQBR-HS gives the best reliability
fairness, while PROBE has the medium perfor-
mance with only one option for dynamic route
selection and LEAST provides the worst fairness
due to the inflexibility with respect to both op-
tions. For a similar reason as above, our solution
provides better fairness to vital signs with strict-
er delay requirement.

Fairness

Effects on Vital Signs

As depicted in Figure 9(a), MQMAC-CQBR-HS
has better e2e delay fairness than the other two
competing protocols. It has more distributive
routes because when certain link or channel be-
comes bad, it can select another one with higher
RQI or LQI to forward packets. On the other
hand, LEAST does not offer such flexibility so
traffic cannot get through so quickly, resulting in

In order to see the effects of our solution on the
patient's vital signs, we compared the received
signals with the generated one. We plot a sample
of the received ECG signals at the sink from the
same node in three different states when N B is 14,
as depicted in Figure 10(a). The delay of these
patient signs can be found by looking at the delay

Figure 8. Delat and reliability comparison