Prioritization of Patient Vital Signs Transmission Using Wireless Body Area Networks - E-Healthcare Systems and Wireless Communications - page 286

Quality of Service (QoS): A set of mechanisms
for managing network traffic to satisfy different
application requirements when network capacity
is limited. These mechanisms allow to measure
bandwidth, detect changing network conditions
(such as congestion or availability of bandwidth),
and prioritize traffic. For example, mechanisms
can be applied to prioritize traffic for delay-
sensitive applications (such as voice or video) and
delay-insensitive traffic (such as emails).
Cross-Layer Design: Also called cross-layer
optimization . Traditionally, network communica-
tions follow the Open System Interconnection
(OSI) model, where the communication system
is divided into a stack of layers and information
is transmitted or received by the interactions be-
tween only adjacent layers. As a contrast, in the
cross-layer optimization approach, protocols are
designed by “violating” the reference architecture,
for example, by allowing direct communication
between non-adjacent layers or by sharing vari-
ables between layers.
Reliability: The ratio of the number of received
data packets at the sink (base station) and the
number of total packets sent from a source node.
It is used to measure how reliable the data can be
forwarded to the destination.
Multi-Channel MAC: In this chapter, it re-
fers to medium access control protocol that uses

different radio frequency channels to access the
wireless medium.
Packet Scheduling: In computer networks,
packet scheduling is a function that allocates
network bandwidth to packets.
Cognitive Radio: A form of wireless commu-
nication in which a transceiver can intelligently
detect which communication channels are in use
and which are not, and instantly move into vacant
channels while avoiding occupied ones. This
optimizes the use of available radio-frequency
spectrum while minimizing interference to other
users.
Jain's Fairness: A metric to measure how fair
the protocol serves different users. It is defined
as f x x = ∑

∑

2

( x )

( , , ..., x n )

i

for a set of values

i

1 2

2

n ( x )

i

i

x 1 , x 2 , …, x n . It ranges from 1/n (worst case, i.e.,
most unfair) to 1 (best case, i.e., maximum fair-
ness).

ENDNOTE

1

IEEE 802.15.4 specifies 16 channels within
the 2.4 GHz band, in 5 MHz steps, numbered
11 through 26. Central frequency of channel
n is given by (IEEE Computer Society, 2006):
f c = 2405 + 5( n- 11) MHz, n= 11, 12,…, 26.