In the mobile advertising ecosystem, the role of ad exchanges to match advertisers and publishers has grown significantly over the past few years. At a mobile ad exchange, impressions (i.e., opportunities to display ads) are sold to advertisers in real time through an auction mechanism. The traditional mechanism selects a single advertiser whose ad is displayed over the entire duration of an impression, that is, throughout the user’s visit. We argue that such a mechanism leads to an allocative inefficiency , as displaying only the winning ad throughout the lifetime of an impression precludes the exchange from exploiting the opportunity to obtain additional revenue from advertisers whose willingness to pay becomes higher during the lifetime of that impression. Our goal in this paper is to address this efficiency loss by offering mechanisms in which multiple ads can be displayed sequentially over the lifetime of the impression. We consider two plausible settings—one where each auction is individually rational for the advertisers and one where advertisers are better off relative to the traditional mechanism over the long run—and derive an optimal (i.e., revenue-maximizing for the ad exchange) mechanism for each setting. To efficiently compute the payment rule, the optimal mechanism for the former setting uses randomized payments. Under this mechanism, whereas the ad exchange always benefits relative to the traditional mechanism, the advertisers could either gain or lose—we demonstrate both these possibilities. The optimal mechanism for the latter setting is a “mutually beneficial” mechanism in that it guarantees a win–win for both the parties relative to the traditional mechanism, over the long run. Happily, for both the mechanisms, the allocation of ads and the payments from the advertisers are efficiently computable, thereby making them amenable to real-time bidding.

中文翻译：

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维持良好的印象：在广告交易平台上销售分区印象的机制

在移动广告生态系统中，过去几年中，广告交易平台与广告商和发布商匹配的作用已显着提高。在移动广告交换中，通过拍卖机制将印象（即展示广告的机会）实时出售给广告商。传统机制选择单个广告客户，其广告会在整个展示期间（即整个用户访问期间）展示。我们认为，这种机制会导致分配效率低下，因为在一次展示的整个生命周期中仅展示获胜的广告会阻止交易所利用机会从广告客户那里获得更多收入，而广告客户在该展示的生命周期内支付意愿会越来越高。本文的目标是通过提供一种机制来解决这种效率下降的问题，在该机制中，可以在展示的整个生命周期内依次显示多个广告。我们考虑了两种可行的设置-一种是针对广告客户而言，每次竞价都是合理的，而长期而言，相对于传统机制而言，广告客户的状况会更好-并得出一种最佳的（即广告交易收益最大化）机制每个设置。为了有效地计算支付规则，前一种设置的最佳机制使用了随机支付。在这种机制下，尽管相对于传统机制而言，广告交易总能带来收益，但广告商却可能会赢或输—我们将展示这两种可能性。后者的最佳机制是一种“互惠互利”机制，从长远来看，它保证了双方相对于传统机制的双赢。幸运的是，对于这两种机制，广告的分配和来自广告主的付款都是可以有效计算的，从而使它们适合实时出价。