The Design And Implementation Of IOS Client Of WiFi Phone Covering Mobile Signal Blind Areas

Using mobile phone is a common way of contacting each other at present. But when people are using their mobile phones, they will sometimes suffer from the weakness of mobile signal in some areas, and that will cause inconvenience in mobile communications. These areas are called mobile signal blind areas. In the recent years, the VoIP technology,smart phones and WiFi networks are widely used. Therefore, it is possible to make a solution of covering mobile signal blind areas by these three technologies.According to the background, this thesis designed and implemented a client based on WiFi and VoIP. This client used SIP as VoIP protocol, and implemented by Swift on iOS platform. This thesis analyzed the demand of the client, and divided the client into four modules: SIP stack module,audio processing module, central control module and user interface module.Each module was independent to others. SIP stack module was implemented by self referring to open source stacks, it completed the function of sending and receiving SIP messages. Audio processing module used Audio Queue from iOS system to recording and playing sounds, and to encode and decode sound data. Central control module was designed to be a state machine.This thesis then described the detailed design and implementation of the four modules. SIP stack module consisted of stack layer, dialog layer,transaction layer and transmission layer. This module was one of the core modules. Audio processing module included two Audio Queues, one for playing and another for recording. Central control module implemented four states, and defined the behavior in each state and the transformation between each state.At last, this thesis made functional tests, robustness tests and performance tests for the client. The test result indicated that the client was functional and stable, and reached the expected goal.