Proactive caching in 5G networks

“Living on the Edge: The Role of Proactive Caching in 5G Wireless Networks” is a paper by Ejder Bastug, Mehdi Bennis and Merouane Debbah that recently won an award for best tutorial article from the IEEE Communications Society, 2016.

The paper outlines a couple of potential use cases for edge computing, with a focus on the potential benefits that the deployment of proactive caching at the network edge could bring.

One of the co-authors, Mehdi Bennis, has written a brief outline of the themes of the paper for Inside 5G. He tells us that his hopes are that the paper will “trigger further research in the topic”.

“Any potential interested parties are more than welcome to reach out for collaboration and funding purposes. We just scratched the tip of the iceberg,” he says.

One interesting aspect of the paper is its proposal for a new class of sub-industry – the Wireless CDN. In the long term, caching/storage will be a commodity and enabler for any 5G vertical, Bennis says. “The entire ecosystem benefits from this, wireless CDN, telcos which now provide OTT services, and MVNOs (who increasingly require stitching and tiling resources for their operation.”

So, without further ado, here is Bennis on his Proactive Caching paper. You can access the full paper here.

By Mehdi Bennis:

In  this  article,  we  propose,  investigate,  and  implement  a  radically  new system  architecture  able  to  exploit  the  above  features  in  order  to  provide  unprecedented  bandwidth spatial reuse gains.

We start from the observation that storage capacity is the fastest growing and cheapest network resource, and can be made widely available in small dedicated “helper” nodes as well as in the user devices. Then, we advocate the use of caching directly at the wireless edge (in contrast with today’s content distribution networks, where caching occurs in the Internet cloud).

In this way, the asynchronous content reuse can be turned into bandwidth spatial reuse, such that the proposed system architecture can turn Moore’s law (the scaling of silicon integration) into a formidable “bandwidth multiplier”.

Peak traffic demands can be substantially reduced by proactively serving predictable user demands, via caching at base stations and users’ devices

This article explores one of the key enablers of 5G wireless networks leveraging small cell network deployments, namely proactive edge caching. Endowed with predictive capabilities and harnessing recent developments in storage, context-awareness and social networks, peak traffic demands can be substantially reduced by proactively serving predictable user demands, via caching at base stations and users’ devices strategic contents.

In order to show the effectiveness of proactive caching, the article examines two case studies which exploit the spatial and social structure of the network, where proactive caching plays a crucial role.

Firstly, in order to alleviate backhaul congestion a mechanism is proposed whereby files are proactively cached during off-peak demands based on file popularity and correlations among users and files patterns. Secondly, leveraging social networks and device-to-device (D2D) communications, a procedure is proposed that exploits the social structure of the network by predicting the set of influential users to (proactively) cache strategic contents and disseminate them to their social ties via D2D communications.

As a result, 1) significant backhaul savings and 2) a higher ratio of satisfied users of up to 22% and 26%, respectively were obtained; 3) more efficient and cost-effective networks can be deployed.

Broader Impact

First, edge caching will radically increase wireless network capacity and significantly improve spectral efficiency, thus unleashing the vision of a wireless broadband revolution in the coming years.  Second, it  will lead  to  the creation  of  a  new  sub-industry,  namely  wireless  content  delivery networks (WCDNs). Third, edge caching will play an important role in current standardisation activity at ETSI led by NOKIA. Fourth, edge caching will be instrumental in making  5G use cases come to fruition. That includes augmented/virtual reality, vehicle to vehicle communication, and other mission-critical applications.

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