because the metadata includes the usage rights of the
delivered context information. Furthermore, the
processing power and bandwidth needs correlate
with power consumption. Thus, the P2P model is the
most demanding for the mobile device.
Information security and search efficiency are
best handled by a trusted central actor. In context
dependent services, search efficiency and data
availability are critical, due to the dynamic nature of
the data (e.g. location, presence). In P2P and hybrid
solutions, efficient querying is achieved by dividing
the load considering peers’ capabilities. The peers
with great processing power and bandwidth are set
as superpeers, handling the message routing and the
storage of user information (Gehlen 2005). Skype
has proved a hierarchical P2P approach feasible for
messaging and presence. Presence, which could also
cover other context types, is delivered efficiently
and securely in P2P manner; only the login server is
centralized. (Baset and Schulzrinne 2004)
The centralized management need is the greatest
in the centralized solution. The hybrid and P2P
solutions allow the user to choose more freely his
service and control service provider, and there is no
urgent need for the operator even though it might
maintain the P2P network and authentication
services. However, the more different controllers,
the greater is the standardization need, since
interoperability of the players must be guaranteed.
Table 3: Differences in market structures.
Central’d Hybrid P2P
Nr. of producers Low Medium High
Network size n/m n/m n
Type of services Heterog. Heterog. Homog.
Service freedom Low Medium High
Table 3 presents the main differences in the
market structures. In centralized solution, the
number of producers might be more than “low”, but
as in mobile operator markets, it is likely that the
majority of the market share would be divided
between 3 or 4 companies. The network size of a
company is all the consumers using this kind of
service (n) divided by the market share (m) of the
company in question. In P2P, n is the number of
consumers. The type of services is heterogeneous in
the centralized and hybrid solutions and
homogeneous in P2P, because of service freedom
i.e. service selection available for consumer use.
Considering the three propositions, P2P might
seem a good choice but its downsides are need for
greater amount of metadata and processing power in
mobile devices. Hybrid model, even though little
restricted on service offerings, might be a good
solution for mobile operator market implementation.
4 DISCUSSION
We have now presented a framework for analyzing
the economic implications of technological
solutions. We tested this framework for evaluating
the information-distribution technologies for a
community calendar service. Through utilizing this
framework, we discovered three possible solutions
for the delivery of user context and community
information in this service. Finally, we analyzed the
possible market structures of each solution and
evaluated the differences between these alternatives.
More research is needed to understand the
different economic implications of technology
during its design phase. Also a study of co-existing
technologies and solutions should be conducted.
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