Cache-aided interference channels
Cache-aided interference channels
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DOI：
10.1109/isit.2015.7282567
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发表时间：
2015-06
期刊：
影响因子：
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通讯作者：
M. Maddah-ali;Urs Niesen
中科院分区：
文献类型：
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作者：
M. Maddah-ali;Urs Niesen
在过去的十年中，大部分无线流量已从语音转移到内容。这种转变创造了将部分内容缓存在更靠近最终用户的存储器中的机会，例如在基站中。大多数现有文献关注由于缓存而减少回程和核心网络中的负载，即，缓存为源服务器和缓存之间的有线通信链路提供的好处。在本文中，我们感兴趣的是缓存可以为缓存和最终用户之间的无线通信链路提供的好处。为了量化该无线链路的缓存增益，我们考虑了一个干扰通道，其中每个发射器都配备了隔离的缓存存储器。通信分两个阶段进行：内容放置阶段和内容交付阶段。目标是设计放置和交付阶段，以最大限度地提高交付阶段的速率，以响应任何可能的用户需求。着眼于三用户案例，我们表明，通过这些阶段的仔细联合设计，我们可以从缓存中获得三个明显的好处：负载平衡增益、干扰消除增益和干扰对齐增益。在我们提出的方案中，负载平衡是通过特定的文件分割和放置来实现的，从而在缓存中创建特定的内容重叠模式。这种重叠允许实现干扰消除。此外，它允许我们构建多个虚拟发射机，每个虚拟发射机负责所请求内容的一部分，这增加了干扰对齐的可能性。
Over the past decade, the bulk of wireless traffic has shifted from speech to content. This shift creates the opportunity to cache part of the content in memories closer to the end users, for example in base stations. Most of the prior literature focuses on the reduction of load in the backhaul and core networks due to caching, i.e., on the benefits caching offers for the wireline communication link between the origin server and the caches. In this paper, we are instead interested in the benefits caching can offer for the wireless communication link between the caches and the end users. To quantify the gains of caching for this wireless link, we consider an interference channel in which each transmitter is equipped with an isolated cache memory. Communication takes place in two phases, a content placement phase followed by a content delivery phase. The objective is to design both the placement and the delivery phases to maximize the rate in the delivery phase in response to any possible user demands. Focusing on the three-user case, we show that through careful joint design of these phases, we can reap three distinct benefits from caching: a load balancing gain, an interference cancellation gain, and an interference alignment gain. In our proposed scheme, load balancing is achieved through a specific file splitting and placement, creating a particular pattern of content overlap at the caches. This overlap allows to implement interference cancellation. Further, it allows us to construct several virtual transmitters, each responsible for a part of the requested content, which increases interference alignment possibilities.