Content delivery in a multi-user cache-aided broadcast network is studied, where a server holding a database of correlated contents communicates with the users over a Gaussian broadcast channel (BC). The minimum transmission power required to satisfy all possible demand combinations is studied, when the users are equipped with caches of equal size. Two centralized caching schemes are proposed, both of which not only utilize the user’s local caches, but also exploit the correlation among the contents in the database. The first scheme implements uncoded cache placement and delivers coded contents to users using superposition coding. The second scheme, which is proposed for small cache sizes, places coded contents in users’ caches and jointly encodes the cached contents of users and the messages targeted at them. The performance of the proposed schemes, which provide upper bounds on the required transmit power for a given cache capacity, is characterized. The scheme based on coded placement improves upon the first one for small cache sizes, and under certain conditions meets the uncoded placement lower bound. A lower bound on the required transmit power is also presented assuming uncoded cache placement. Our results indicate that exploiting the correlations among the contents in a cache-aided Gaussian BC can provide significant energy savings.

中文翻译：

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高斯广播信道上相关内容的集中缓存和传递

研究了多用户缓存辅助广播网络中的内容交付，其中保存相关内容数据库的服务器通过高斯广播信道 (BC) 与用户进行通信。当用户配备相同大小的缓存时，研究满足所有可能的需求组合所需的最小传输功率。提出了两种集中式缓存方案，既利用了用户的本地缓存，又利用了数据库内容之间的相关性。第一种方案实现未编码缓存放置，并使用叠加编码将编码内容交付给用户。第二种方案是针对较小的缓存大小提出的，将编码内容放在用户的缓存中，并对用户缓存的内容和针对他们的消息进行联合编码。所提出的方案的性能为给定的高速缓存容量提供了所需传输功率的上限。基于编码布局的方案在小缓存大小的情况下改进了第一种，并且在某些条件下满足未编码布局下限。假设未编码的缓存放置，还提供了所需发射功率的下限。我们的结果表明，利用缓存辅助高斯 BC 中内容之间的相关性可以显着节省能源。假设未编码的缓存放置，还提供了所需发射功率的下限。我们的结果表明，利用缓存辅助高斯 BC 中内容之间的相关性可以显着节省能源。假设未编码的缓存放置，还提供了所需发射功率的下限。我们的结果表明，利用缓存辅助高斯 BC 中内容之间的相关性可以显着节省能源。