## 2 Related Work  
We review related work on MCS that uses RevAuc, the target of this research, and related work on methods for reducing cellular traffic between a server and mobile hosts in MCS. First, we review related work on MCS that uses RevAuc. [PERSON] et al. [8] proposed a method for a server to determine the amount of incentive given to a successful bidder, which they named reverse auction-based dynamic pricing virtual participatory credit. The method provides relatively more incentive to mobile hosts that continue to participate in a RevAuc even if they are not selected as successful bidders so that the number of participating hosts increases beyond a certain threshold value. They did not mention how the server selects mobile hosts that receive a bid invitation for a data request nor how the server communicates with the mobile hosts. [PERSON] et al. [9] proposed an algorithm for a server to determine whether a mobile host is a successful bidder or not on receiving a bid from the mobile host after receiving bids from a certain number of mobile hosts to solve a problem; in other words, it takes a long time to select successful bidders if a server determines the successful bidders after receiving bids from all mobile hosts. They did not mention how the server selects which mobile hosts to send a bid invitation for a data request nor how the server communicates with the mobile hosts. [PERSON] et al. [10] proposed an incentive mechanism based on reverse auction for location-aware sensing, which determines successful bidders so as to increase the number of participating mobile hosts and decrease the ratio of mobile hosts that do not provide data to the server after being selected as successful bidders. They assume that a server sends bid invitations for all data requests to all mobile hosts, and all mobile hosts tender bids for some bid invitations. They also assume that the server communicates with mobile hosts directly through some network, such as a cellular network. [PERSON] et al. [11] proposed an algorithm for a server to select successful bidders in a RevAuc-based MCS. They assume that a server sends bid invitations for all data requests to all mobile hosts, and all mobile hosts tender bids for some bid invitations. They also assume that the server communicates with mobile hosts directly through some network, such as a cellular network. The above studies related to MCS that uses a RevAuc assume that a server sends bid invitations to mobile hosts and receives bids from mobile hosts through some network,such as a cellular network. They do not mention how to reduce traffic between the server and mobile hosts. Next, we review related work on methods for reducing cellular traffic between a server and mobile hosts in MCS, although those related studies do not focus on MCS using RevAuc. [PERSON] et al. [12] proposed D2D extended sensing (D2D-ES) and D2D content dissemination (D2D-CD), which reduce cellular traffic between a server and mobile hosts using D2D communication in MCS. In D2D-ES, REPs receive sensing data from other mobile hosts, and they send sensing data to the server. D2D-ES assumes that REPs that send sensing data to the server are determined in advance. Therefore, cellular traffic used for the mobile hosts to send sensing data to the server can be reduced. In D2D-CD, REPs receive some information from the server, and they send the information to other mobile hosts through D2D communication. D2D-CD assumes that REPs that receive information from the server are determined in advance. Therefore, cellular traffic used for the server to send information to the mobile hosts can be reduced. Even though they do not mention RevAuc, cellular traffic in a RevAuc can be reduced by applying D2D-CD to transmissions of bid invitations from the server to mobile hosts and by applying D2D-ES to transmissions of bids from mobile hosts to the server. However, they do not mention how to apply their method to pull-type RevAuc. [PERSON] et al.