Introduction

Traditional D2D communications take place among any mobile units to transfer “data.” However, current and emerging mobile applications pose the new challenges of “information” transfer. Typically, information is related to social relations of people. Therefore, social information and social networks have been integrated with wireless and mobile communication to serve the new demand of users for information transfer. When the social information is used or the social network is operated on wireless systems, we can refer to it as a mobile social network [321, 322]. The mobile social network can be integrated or used in D2D communications with the following approaches.

1. • D2D communications to support mobile social network: In this approach, typical social-network applications and mobile social networks will utilize D2D communications to transfer data and information. Instead of using a fixed wireless infrastructure (e.g., a base station of a cellular network) to transfer social-network information, the information can be conveyed through D2D networks. The typical advantages of D2D communications are inherited in this case for the mobile social network, including reducing radio-resource usage, alleviating network overload, and improving the data-and information-dissemination and -delivery performance.

2. • Social-based D2D communications: In this approach, D2D communications supporting other applications can utilize social information of users to improve the efficiency and effectiveness of data and information transfer. For example, packet routing of D2D LAN can be enhanced by taking social ties among devices and users into account to determine an optimal route. Such an optimal route may not only minimize a network cost, but also maximize the social impact, improving the satisfaction of D2D communications and networking.

In this chapter, we focus on the mobile social network and its role in D2D communications. Firstly, Section 10.2 presents an overview of mobile social networks. Their architecture, applications, issues, and approaches are reviewed. Section 10.4 presents some seminal works in the field of social-aware data routing and dissemination. Section 10.5 introduces a detailed formulation for cooperative content delivery in mobile social networks.