Incentives - Peer-to-Peer Computing: Applications, Architecture, Protocols, and Challenges - page 122

is given by:

E RX
s

(i) + E T X
p

(i) + E RX
p

(j)

α 2 (i) = (5.53)

E RX
s

Similarly, we require: α y ≥α 2 (j), where α 2 (j) is given by:

E RX
s

(j) + E T X
p

(j) + E RX
p

(i)

α 2 (j) = (5.54)

E RX
s

j = 5

j = 3

j = 1

FIGURE 5.24: Peer-to-peer: number of subscribed stripes versus the type
of a client (n = 10).

Figure 5.24 shows the variation of the number of subscribed stripes with
the type of client x, α x , for j = 1, 3, 5. This means that if α x = 0.5, x will
obtain 7 stripes when j = 3, i.e., i = 4. Let us illustrate the peer-to-peer
relationship with the following numerical example.
Consider two neighboring clients: x and y whose types are 0.75 and 0.55,
respectively. If they independently stream the media from the server, x will
subscribe to 7 stripes while y will subscribe to 5 stripes. However, they may
collaborate and form a peer-to-peer relationship for media streaming, as shown
in Figure 5.22(b). With reference to Equations (5.53) and (5.54), x subscribes
to 6 stripes from the server and y subscribes to another 4 stripes from the
server. Besides that, they periodically exchange media packets via their peer
interfaces. This effectively allows them to receive the complete 10 stripes, i.e.,
the complete media content.
With the peer-to-peer relationship, both clients increase the number of
received stripes without violating their types. Thus, the collaboration between
two neighboring clients would improve the performance of media streaming
under the same energy consumption constraints.

5.3.4.3 Three Neighboring Clients

Next, let us consider the scenario with three neighboring clients:{x, y, z},
where y and z are the neighbors of x but they may not be able to communicate
with each other directly. Similar to the two-client scenario, the collaboration
among the three clients can take on two different forms: master-slave and
peer-to-peer.