This study describes a system, called Wiffler, to augment 3G with WiFi in mobile environment. We need this because 3G is costly, but more ubiquitous, and WiFi is cheaper and intermittently available. It can cover the poor availability and performance of WiFi by quickly switching to 3G, and it can offload more data on WiFi, if delaying reduces 3G usage.

Question answer session

Questions were asked to know more detail of the paper and to understand the contents of the paper properly.

a) What is leveraging delay tolerance?

The main objective of Wiffler is to transfer data on WiFi when available. It works such as wait to transfer data on WiFi until the delay tolerance threshold. As soon as, the condition satisfies the data is transferred to WiFi.

b) what is c in the Wiffler prediction algorithm?

It is tunning parameter, called conservative quotient, and is a number between zero to infinity. The conservative quotient can be set not only by the system or the application but also by the 3G provider. For example, during peak times when 3G spectrum pressure is high, the provider may decide to offoad more data on WiFi at the expense of application latency and set c to a small value. But during the ooff-peak times, c can be set to a large value to improve application latency.