Cooperation among multiple mobile terminals (MTs) can offer higher throughput and improved reliability. With the development of sensors and integrated intelligence, future MTs will have much context awareness of their users, the surrounding environment, and the network. With this consideration, cooperation among MTs with awareness of social and position relationships is becoming attractive. How do the social and position relationships influence the cooperation performance? This paper investigates the cooperation throughput, which is a function of not only the wireless channel but the social and position relationships as well. Embodying the joint effect of the social and position relationships, a vital random variable is derived to give a unified model for the cooperation signal, and it makes the performance analysis feasible. Afterward, we derive a specific expression of the cooperation throughput, where two regions, namely, linear and saturation, are identified. The   generalized degrees of freedom   (GDOF) is then employed to study the behavior of the throughput in the linear region. In particular, an explicit formulation between the GDOF and the social and position relationships is established. It shows that the GDOF provided by each cooperative MT is   $P_i \min \{1,\alpha_i\}$  , where the cooperation probability   $P_i$   and the scaling exponent   $\alpha_i$   are parameters characterizing the social and position relationships, respectively. Simulation results verify the theoretical analysis.
['Hongliang Mao', 'Wei Feng', 'Ning Ge']
Performance of Social-Position Relationships Based Cooperation Among Mobile Terminals