the ability to store data, and a copy of each data is stored at
each GP when the carriers get there, which ensures that the
data can be further shared at the GP even though the carriers
leave.
To the best of our knowledge, this is the first work that
focuses on data sharing among the gossip community. Com-
paring with the existing work, the main contributions of this
paper can be summarized as follows.
• We first focus on such a group of people that have
common interest but are usually weak in relationship in
data sharing and define them as a gossip community.
• A data dissemination method, GPS algorithm, is proposed
for data sharing which explores the encounter pattern
of users and the aid of gathering points to facilitate the
spreading of data.
• A method to achieve different performance objects in data
dissemination is proposed and three objects are achieved,
i.e., maximizing delivery ratio, minimizing delay and
balancing the tradeoff between them.
The rest of this paper is organized as follows. Section II
provides a review of the related work about data delivery in
mobile social networks, followed with the system model and
basic assumptions of this paper presented in Section III. In
Section IV, the detail of GPS algorithm is proposed, and utility
functions are designed to guide the assignment of the data
carriers in data dissemination aiming at different performance
objects. Then, the theoretical analysis and simulation exper-
iments are presented in Section V and Section VI. Finally,
Section VII concludes this paper.
II. RELATED WORK
The sharing of data is based on data delivery techniques.
In MSN, data delivery methods are widely studied which can
be divided as single-recipient delivery and multiple-recipients
delivery. The first category is also known as socially-aware
routing [5][6][7][8] for the data is forwarded towards a specific
destination node based on opportunistic routing techniques.
A simple approach of this category is Epidemic [5]. In the
approach, the source broadcasts data to all the users in connec-
tion and the users receiving the data then store and broadcast
it to all the users encountered. In this way the data spreads
until it reaches the destination node. It makes the biggest effort
to achieve successful delivery at the cost of a large amount
of network resource consumed. While in Spray&Wait [6], the
number of copy of each data is restricted by the source who
creates a specific number of copies for each data and sprays
them into the network. Then each copy is carried by a relay
node and waits to encounter the destination node during which
no more copies are produced. CAR [7] is another socially-
aware routing approach in which copies of data are carried by
some active users to seek for the destination node. The active
users are selected based on two user metrics, collocation and
degree of connectivity, which respectively indicate the number
and varying pattern of the one-hop neighbors. Before finding
the destination node, if a more active user is encountered,
the current holder of data forwards the data to the user to
earn a larger delivery chance. A recently proposal [8] explores
user gathering point to help routing in which data is also first
disseminated to several relays similar with Spray&Wait. But
in the next phase, instead of waiting for the encounter with
the destination node, the method tries its best to forward the
data towards the user gathering points to seek a larger delivery
chance.
The multiple-recipients case is also known as data dissem-
ination [1][3][9][10][11], for the data is disseminated to all
the users who are interested in it. SocialCast [9] is a typical
example in which the service provider publishes update data
of the services to the subscribers via the help of data carriers.
The assignment of data carriers is based on the knowledge
of the current neighbors of users and their varying pattern. In
literature [10], the service provider first publishes the update
data to a single user which is selected at a certain probability.
Then the update data is shared by users during which the newer
data takes the place of the older one in the buffers of users.
The publishing rate allocated to each user is optimized to
make the data of the users as “fresh” as possible. The method
in [11] focuses on improving delivery ratio. In the method,
a constrained Markov decision process is adopted to model
the data transmission in the network. Transmission policy is
optimized to maximize the number of users that receive the
data. The author of [1] proposes a method for data sharing in
which users with common interest keywords, similar location
histories and nearby current location are recommended as
friends and connect for data sharing. While in [3], data is
shared directly between two users as long as they are one-hop
neighbors regardless of their relationships. However, when the
users are multiple hops away from each other, the sharing of
data is based on Ad hoc On-demand Distance Vector (AODV)
routing protocol which turns out to be invalid in mobile social
network due to the intermittent connection among users in the
network [12].
Among the above approaches, socially-aware routing ap-
proaches are inefficient to support data sharing due to its
end-to-end communication mode. Data dissemination methods
are feasible, but the existing proposals neither consider the
property of the gossip community, nor leverage the gathering
habit of users, thus are also poor for data sharing in gossip
communities. Therefore, we propose GPS to tackle this issue.
III. SYSTEM MODEL
This paper considers a distributed MSN (Fig. 1), in which
data is delivered based on the carrying and forwarding of users
without the help of base stations or APs. Gossip communities
are identified by interests and data related with the interest
is generated (randomly by a member) and shared among
the same gossip community. Gossip communities are formed
once the users set their interests in their social profile. They
just exist potentially and users need not conduct community
detection to discover it out before data sharing. After all, the
relationship among the gossip community members are usually
very weak to rely on.