## 6 Conclusions, Open Issues and Research Directions
Efficiencyneeds also to be included in cooperative game techniques to use resources that ensure an efficient delivery of information, if not, then the cost of such information delivery will increase, i.e., delays, throughput, integrity of information, etc. The cooperative game methods used that integrate reliability and efficiency, can establish a base on which a quality of service (QoS) model for UASN can be built. * _Motivation_: Since misbehaving (malicious/selfish) that would try to damage, attack, and compromise or degrade the performance of the system nodes might be present in the network, a motivation mechanism is needed to influence and change the behavior of such nodes. Motivation is a way to make nodes react to conditions in order to get more cooperation or to improve network performance. Games have always motivated people based on competition, hence, such motivation can be included so that sensors participate in more cooperative actions for the improvement of network performance. Motivation is very important in cooperative forwarding activities, and providing motivation to misbehaving nodes in UASNs becomes necessary to ensure a successful delivery of data packets among the participating players. These motivations will improve the cooperative performance of regular and misbehaving nodes which will result in improvements in the cooperative packet forwarding processes in UASNs. * _End-to-End authentication_: End-to-End authentication can provide security to the packet forwarding process among participating nodes, and can prevent the data in the packets from being compromised by devious misbehaving nodes. Authentication is important in any network, but when cooperative games are involved, it can be achieved in several contexts. For example, it can be used to authenticate locally in a network by using only previously authenticated one-hop network nodes, but the cooperative games allow to also implement authentication from the perspective of an end-to-end connection. Cooperative games need to be modified to address this context because the process of end-to-end authentication could be accompanied at the same time by reliability (e.g., routing redundancy or delay), by efficiency (e.g., use the right resources that ensures quality) and by motivation (e.g., route competition to choose the best path), in order to deliver a solution with quality to the transmission of information in the network. Authenticating data before forwarding it to the target destination is an important aspect of cooperation that guarantees the security of information forwarding between source and destination in a communication network. This work was supported by the SEP-CONACyT Research Project 255387, the School of Engineering and Sciences and the Telecommunications and Networks Focus Group at Tecnologico de Monterrey. The authors would like to thank the anonymous reviewers for their valuable comments and suggestions to improve the quality of the paper. [PERSON] has written the majority of the manuscript. [PERSON], [PERSON] and [PERSON] have organized the flow of the work and revised and improved the manuscript. [PERSON] has revised and improved the manuscript. The authors declare no conflict of interest.