Incentives - Peer-to-Peer Computing: Applications, Architecture, Protocols, and Challenges - page 116

5.3.4 Wireless P2P Media Streaming
Yeung and Kwok [Yeung and Kwok, 2008] studied an interesting incentive
protocol for energy e cient wireless P2P media streaming. In a wireless me-
dia streaming application, users obtain media feeds from subscribed servers for
video entertainment or useful information access (e.g., video clips for impor-
tant stock market information). However, such convenience inevitably comes
with a price in that the energy consumption of the device is greatly increased
due to the continuous isochronous nature of media streaming and the high
volume of data involved (e.g., in video streaming). Thus, energy e ciency is
of a prime concern in supporting media streaming applications.
For this problem of providing energy e cient media streaming to mobile
users, an insight is that we can consider the availability of multiple wire-
less networking interfaces in devices nowadays. For instance, it is now quite
common for a commodity wireless gadget to have at least two wireless inter-
faces, e.g., a CDMA2000 cellular interface and an IEEE 802.11x wireless LAN
(WLAN) interface. Here, we call the former kind of interface the server inter-
face while the latter the client interface. A key observation is that the energy
consumption characteristics of the two interfaces are very different [Cisco,
2009, GTRAN, 2009]. Specifically, the peer interface consumes less energy to
deliver the same amount of tra c than the server interface does. Notice that
some higher end devices can even have more than one client interface, e.g.,
having both WLAN and Bluetooth.
Equipped with two heterogeneous networking interfaces, devices can form
a hybrid wireless network in which some devices are connected to wireless
servers (via cellular base-stations) using the server interfaces while connecting
to other devices using the client interfaces. Some devices may only connect to
other wireless peers but not connect to the servers. While this hybrid wireless
networking infrastructure is feasible and interesting, how it can help in sup-
porting energy e cient media streaming is still a largely unexplored research
issue.

5.3.4.1 System Model

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FIGURE 5.20: System model—a media server and a set of mobile clients.