Cloudlet-based Mobile Computing
A cloudlet is
a new architectural element that arises from the convergence of
mobile computing and cloud computing. It represents the middle
tier of a 3-tier hierarchy: mobile device --- cloudlet ---
cloud. A cloudlet can be viewed as a "data center in a box"
whose goal is to "bring
the cloud closer". A cloudlet has four key attributes:
background information and rationale for cloudlets, see "The Case for VM-based
Cloudlets in Mobile Computing" As the paper explains,
cloudlets are the enabling technology for a new genre of
resource-intensive but latency-sensitive mobile applications that will
emerge in the future. These include new cognitive assistance
applications that will seamlessly enhance a user's ability to
interact with the real world around him or her. Here is an early
thought piece on augmenting
- only soft state:
is does not have any hard state, but may contain cached state from the
cloud. It may also buffer data originating from a mobile device
(such as video or photographs) en route to safety in the cloud.
The avoidance of hard state means that each cloudlet adds close to zero
management burden after installation: it is entirely
- powerful, well-connected and
possesses sufficient compute power (i.e., CPU, RAM, etc.) to offload
resource-intensive computations from one or more mobile devices.
It has excellent connectivity to the cloud (typically a wired Internet
connection) and is not limited by finite battery life (i.e., it is
plugged into a power outlet). Its integrity as a
computing platform is assumed; in a production-quality implementation
this will have to be enforced through some combination of
tamper-resistance, surveillance, and run-time attestation.
- close at hand: It
is logically proximate to the associated mobile devices. "Logical
proximity" is defined as low end-to-end latency and high
bandwidth (e.g., one-hop Wi-Fi). Often, logical proximity
implies physical proximity. However, because of "last mile" effects, the
inverse may not be true: physical proximity may not imply logical
- builds on
standard cloud technology: It encapsulates offload code
from mobile devices in virtual machines (VMs), and thus resembles classic cloud
infrastructure such as Amazon EC2 and OpenStack. In
addition, each cloudlet has functionality that is specific to its cloudlet role.
"Bringing the cloud closer" also improves the survivability of mobile computing in hostile
environments such as military applications and disaster recovery.
Easily-disrupted critical dependence on a distant cloud is replaced by
dependence on a nearby cloudlet and best-effort synchronization with
the distant cloud. The paper "Cloud Offload in Hostile Environments" explores these issues.
The impact of high offload latency on mobile user experience can be seen in these YouTube videos.
The name "Elijah" was inspired by the
mention of cloudlets in the literature.