A survey of mobile social networking
Laura Marcia Villalba MonnHelsinki University of Technology
When the rapid evolution of mobile devices, the massiveadoption of cell phones by the population and the importantgrowth in social networks came together, the mobile socialnetwork was born.
This paper goes through the migration of social networksto mobile devices and the new features that they could pro-vide with the context awareness abilities.
Also, it covers some architectural notes for the mobile so-cial networks and their limitations. In addition this paperstudies some current mobile social networks as Facebook,Dodgeball, Socialight and WhosThat.
KEYWORDS:mobile social networks, Facebook, Dodge-ball, Socialight, WhozThat, context awareness
The definition of social network sites (here in after called so-cial network) based on  firstly is a web-based service thatallows individuals to construct a public or semi-public pro-file within the system, secondly it manage a list of other userswith whom they share a connection, and thirdly is possibleto view and traverse their list of connections.
A social network provides a variety of mechanisms forusers to share data with other users. Also, it has the abilityto search for users with similar interests and to establish andmaintain communication between them . Online socialnetworks have become very popular during in these last fewyears. For example, Facebook had more than 150 millionusers in February 2009 .
The origins of social networks lie in the early 1990s whenthey were simple means of communication between peopleover the Internet, such as forums, discussion groups, profes-sional associations or other places where people could ex-change ideas. Internet technologies evolved together withsocial software. In this evolution, the social networks as weknow them were created; people started to have a profile,and in turn started sharing content in a more active way inthe Internet communities.
According to the definition that it was provided at the be-ginning, the first social network site was launched in 1997,namely SixDegrees.com .
Social networks are part of the Web 2.0 evolving processof the Internet. Web 2.0 was born in a conference brain-storming session between OReilly and MediaLive Interna-tional. They noted that the web was more important thanever and there were a lot of new applications and sites ap-
Figure 1: Evolution of social networks. Based on 
pearing every day. The central concept behind Web 2.0 wasthe power of collective intelligence: sharing data .
One of the main reasons for this evolution into Web 2.0,was that people start participating more actively in the In-ternet . This occurred because the technology started toallow the Internet users to add content to it. Before Web 2.0,few users shared content in the Internet and most of the In-ternet users were typically receivers of that information.
The technology continued evolving and with it the socialsoftware. Nowadays cell phones or other mobile devices aresomething that most of the people have. And mostly all newcell phones have the ability to navigate through the Internet.
Mobile 2.0 is the name given to the transfer of all the cur-rent trends of Web 2.0 to mobile devices . And mobilesocial networking refers to transferring the current trends insocial networking to those mobile devices, adding new fea-tures that the mobility and the context awareness provide.
Nowadays, there are more cell phone users than Internetusers. Also, the cell phone is a personal device that goeswherever owner goes. As a result it can provide a lot ofinformation about the environment of the user. For example,where he is, what music he is listening to, which photos heis taking, etc.
Currently most of the approaches to mobile social net-working are extending the user interface, so they are ableto work in a mobile device. But the fundamental change isto extend the software, using all the information that the mo-bile device provides. These features give a lot of detail of thecontent that the users share in the social networks. For exam-ple, a user can upload a photo and the system automaticallyplaces the photo in a map .
The aim of this paper is to give an introduction to mobilesocial networks, the features that they share with ordinarydesktop based social networking and their differences. Inaddition the paper further examines some architectural notes,concepts on privacy and security and some case studies ofmobile social networks that have been created.
Figure 2: Mobile context. Based on 
2 Relevant features of the mobile so-cial networking
In general mobile social networks are different from thedesktop based social networks, because they have some ad-ditional features such as, contextual information.
As shown in Figure 2, the mobile context can be gen-erated by means of information such as the location of themobile device, the time, tags that describe the environment,information from other devices that surround it, some capa-bilities that the handset has and some preferences providedby the user.
Positioning means knowing the user exactly location. Thepositioning feature is one of the main differences between adesktop device and a mobile device. In contrast to the for-mer, the cell phone can inform where the user is and thisinformation can be used for enriching the information of theuser.
For example,  suggest that is possible to make a list ofthe most visited locations or favorite places. This informa-tion can be gathered from the environment of the cell phone.The most visited locations can be for example the coffeeshop that the user always visits in the mornings, the school orwork the user goes, or the pubs that he goes to on weekends.
Another example is the automatic localization of photos.Thus, a user takes a photo with his cell phone, and automat-ically the cell phone situates the photo on the map where itwas taken.
By knowing the exact location of the user, the mobile so-cial network can provide a lot of interesting features.
2.2 Friend locator
Friend locator is another interesting feature that  mentionsin his paper is the find a friend feature. Also, a similar ap-proach is described in  and . The idea behind all thearticles is to be able to find someone that is in the same placethat the user is. Imagine this situation for instance; if a user isin a bar, he is connected to a mobile social network by meansof mobile technologies such as Bluetooth, through which hecan browse information of all the people in the bar that arealso connected to the same social network. As a result he canif he wants send them a message or check someones profile.
This feature is potentially very attractive, because the ideaof being able to know everybody who is in the same place isreally tempting for the users.
2.3 Capture and tag media
Capture and tag media is a feature is presented in . Theidea behind this feature is to use contextual information toprovide pre-defined / commonly used tags based on locationand proximity to other users or places.
For example, someone takes a picture of one friend infront of the Big Ben. Both friends have mobile network soft-ware, so when one takes this picture, the cell phone automat-ically tags the friend in the picture and locates it in the map.
2.4 Update personal status
The main concept behind update personal status feature isthat personal status can be updated automatically, with con-textual information . For example: where the user is, whatmusic he is listening to, the state of the mobile device (forinstance, in a meeting state), etc. This data all combinedprovide a lot of information that allows the mobile networksoftware automatically updates the status of the user .
2.5 Interact asynchronously
The asynchronous interaction involves other features of thecell phone, like the ability to send a SMS or an email. Thisfeature allows the user to send other kinds of messages to thepeople connected to the network .
Mobile devices have an enormous advertisement potential.Besides being extremely popular, most people carry them allthe time, enabling personalized advertising  .
There are some reasons why mobile advertisement is animportant branch in the mobile business. Firstly, the highpenetration rate of mobile terminals. Secondly, mobile ter-minals are personal communication devices and are individ-ually addressable. Lastly they have multimedia capabilitiesand provide interactivity.
Despite the many advantages of mobile devices, howeverthere are some serious challenges regarding mobile advertis-ing, such as spam, limited user interface, privacy concernsand the cost of mobile communication  .
Figure 3: Example of possible architecture. Based on 
3 Some architectural notes for themobile social networks
The architecture design behind a mobile social networkclient with all the functionality mentioned in the last chapteris not as trivial as having only a web browser. A componentthat is able to manage all the contextual data is needed.
Detailed in Figure 3 is one possible design of architecturefor the mobile device social network client. There are somecomponents as Bluetooth, audio, GPS, etc that are part of themobile device and are in contact with the user environment,but also there are other applications, such as the calendar,that are inside the mobile device but the user interacts withthem. These components provide information of the contextto the mobile social network engine: for example, where theuser is, which activities the user has planned for a particularday. All that info