Incentives - Peer-to-Peer Computing: Applications, Architecture, Protocols, and Challenges - page 97

Server

Different
request
times

Internet

Dial-up

Ethernet

Cable
Modem

ADSL

FIGURE 5.11: Asynchrony and heterogeneity of media streaming peers [Cui
and Nahrstedt, 2003].

00:00 00:01 00:02 00:04 00:08

Request
Time

H 0 has: 0 1 2 3 H 1 has: 0 1 H 2 has: H 3 has: 0 1 2 H 4 has:

0 1 2 0 1 2 3

2

0 1 1 2

0 1 0 1

H 2

H 0 H 3

H 1

H 4

0

Server

2 3

FIGURE 5.12: Layered streaming with buffering for serving asychronous
requests [Cui and Nahrstedt, 2003].

1

2 i − k .
Thus, P S always grants media streaming requests from a higher class peer
(i.e., one that has a larger uploading bandwidth). Notice that this is similar in
spirit to the incentive approach used in BitTorrent [Cohen, 2003]. For requests
from lower class peers, P S may serve them as governed by the respective
probabilities P r[i] in the vector. If P S has not served any request during a
certain period of time, then the admission probabilities of lower class peers
will be increased.
Similar to the case in BitTorrent, each peer has the incentive to report a
higher uploading bandwidth because doing so will increase its probability of
admission when it needs to initiate a media streaming session. Xue et al. [Xue
et al., 2004] extended the DAC p2p to a wireless environment. The key idea in

•For k < i≤N , P r[i] =