CrowdSwitch: Crowdsensing Based Switch between Multiple Cellular Operators in Subways

Surfing the Internet with mobile phones is a popular fashion to kill time in subways. However, users usually meet the intermittent connectivity caused by the high- speed movement, leading to poor user experience. We observe that almost every city is covered by multiple cellular operators. In addition, more and more mobile phones support multiple SIM cards. These motivate us to leverage multiple cellular operators together for a reliable connectivity, which is also a trend for next generation cellular network. It is challenging to build collaborations between operators, because there is no interaction between different operators and the traditional handover methods would consume much time on cross-operator cellular detection. To address these challenges, we propose a Crowdsensing based Switch (CrowdSwitch) system between multiple cellular operators in subways. CrowdSwitch uses a large number of mobile phones to measure and collect wireless signals from different locations along subway tracks, uploads them to cloud servers for analysis, and finally recommends the optimal switch strategy to users. We implement CrowdSwitch in off-the-shelf mobile phones and conduct extensive experiments on Shanghai Metro. The results show that CrowdSwitch can depict the accurate LTE distribution and recommend the optimal operator for users to connect.