| Recently, mobile social networks(MSNs) have gained tremendous attention, which allow users to share information or keep in touch with their friends through mobile terminals. However, centralized servers and continual Internet connectivity are prerequisites for mobile users to exploit traditional MSN services, even though they are within proximity area, and can directly exchange data through various wireless technologies.Mobile social networking in proximity(MSNP) can alleviate the problems mentioned above. MSNP is a wireless peer-to-peer(P2P) network of spontaneously and opportunistically connected nodes in proximity. However, through thoroughly studying on the existing MSNP development frameworks and applications, we found that the existing schemes can only support single point-topoint(single hop) interactions, and there is lack of work to support multi-hop on commercially available smartphones. This issue greatly limits the coverage of MSNP.Thus, through integrating two typical direct device to device technologies, Wi Fi Direct and Bluetooth, we design and implement a multi-peer connectivity framework on Android platform, BWMesh, by which users can establish multi-hop connection with nearby users without the help of network infrastructure. To illustrate the applicability of BWMesh, a multi-hop chat application, Multi Chat is developed on this framework. Specifically, the contributions of this paper lie in the following aspects.1. This thesis summarizes the existing MSNP schemes, and finds that, most of them only provide single-hop P2 P connection, but few support multi-hop connection which is required to broaden the MSNP coverage in static scenario. Besides, the existing multi-hop applications also have some limitations, for example, ad-hoc mode is not directly supported by off-the-shelf mobile terminals(need mobiles to be rooted), and mobile AP mode and WLAN connection can’t be used at the same time and so on. Therefore, this thesis proposes BWMesh architecture, which can easily support multi-hop networking on the commercial intelligent terminals by combining Bluetooth and Wi Fi direct.2. By integrating Bluetooth and Wi Fi Direct, the thesis designs a multi-hop connectivity framework, BWMesh, which can discover and connect users in proximity, transmit messages, and provide network information. Specifically, the naming and addressing module implements the functions of nodes’ naming and addressing necessary in BWMesh. That is, the user-defined name combined with the intrinsic device serial number is used to uniquely identify an individual at the application level, and also utilized to forward messages at the routing level. The device discovery module searches Bluetooth and Wi Fi Direct devices available in communications range, and displays the found peers on user’s smartphone. The monitor module will monitor the status of Wi Fi Direct and conduct corresponding operations. The device connection and transmission module can complete single-hop P2 P connection and message transmission. The message forwarding module forwards messages to other wireless networks to expand communication range.3. Finally, a simple real-time application, Multi Chat is designed and implemented on BWMesh. Multi Chat can provide multi-peer real-time chat without connecting to the Internet, in multi-hop way. Specifically, the following special scenario is provided by Multi Chat. In proximity area, there exist three mobile devices A, B, and C, in which link AB is a Bluetooth connection, and link BC is a Wi Fi Direct connection. Multi Chat can enable A to chat with C through the intervention in B to save and re-share message using a different communication method. We test several typical scenarios including single-hop with Bluetooth and Wi Fi direct, and and multi-hop case using both Bluetooth and Wi Fi Direct, and show that Multichat can work in all those scenarios. |
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