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x
x
y
z
y
z
(a)
(b)
FIGURE 5.25: The scenario with three neighboring clients. (a) Master-slave.
(b) Peer-to-peer.
Without loss of generality, let us assume that x is the master while y and z
are the slaves. Specifically, x subscribes to i stripes from the server and sends
them to y and z through the peer interface, as depicted in Figure 5.25(a).
Because the master can broadcast the media content to its slaves, the energy
cost of being a master does not change with the number of slaves. It follows
that the threshold values for both master and slave remain the same, i.e.,
α x ≥α M (i) and α y , α z ≥α S (i).
For the peer-to-peer relationship, all three clients contribute their resources
for media streaming, where x, y, z independently subscribe to i, j, and k
stripes from the server, respectively, as shown in Figure 5.25(b). Because y
and z are generally out of their respective communication ranges, we let x
act as the coordinator. Specifically, y and z periodically send j and k stripes
to x, respectively. Together with the media content received from the server,
x broadcasts (i + j + k) stripes to y and z. This collaboration arrangement
makes each of the three clients effectively subscribe to (i+ j + k) stripes, where
(i + j + k)≤n. Obviously, the type of x should be higher than the others.
Thus, the following condition is necessary: α x ≥α 3 (i), where α 3 (i) is given
by:
E RX
s
(i) + E T X
p
(i + j + k) + E RX
p
(j + k)
α 3 (i) =
(5.55)
E RX
s
On the other hand, y and z have similar type requirements, which depend
on the number of subscribed stripes. In particular, the type of y should satisfy:
α y ≥α 3 (j), where α 3 (j) is given by:
E RX
s
(j) + E T X
p
(j) + E RX
p
(i + k)
α 3 (j) =
(5.56)
E RX
s
Similarly, the type of z should satisfy: α z ≥α 3 (k), where α 3 (k) is obtained
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