WOA With LED Based Android Mobile

Design of Wireless Optical Access System using LED Based Android Mobile

Abstract:- :- 

This report develops a prototype to demonstrate a directional wireless visible light communication (VLC) system based on Android Mobile. In this system, Two android mobiles can transmit local data to each other simultaneously. The system consists of two parts, the hardware and the software. The design of hardware is based on the USB port integrated in the Android Mobile. The development of software utilizes the protocol of AOA (Android Open Accessory) which is a new feature in Android 3.1 or more advanced version whereby a USB host device can connect to the Android device, allowing data transmission between Android devices over USB interfaces. Thus, the driver of the hardware needn’t be added into the kernel of android. Combing with a USB port on one board, it can achieve up to 2Mbps bit rates error free, which is mainly limited to the USB bridge circuit between two mobiles for data transmission such as text, audio and video. The software is used to set the transmission data rate, control bits, check bits so as to achieve real-time and directional transmission between two mobile devices with a USB port. 

Introduction

Nowadays, there is a growing number of scenarios in house domestic applications, traffic lights, hospitals, hotels, etc. where illumination devices based on visible light LED lamps are used. These lamps combine very low power consumption with an extremely long operational life, maintaining during all their operation the same chromaticity without significant changes. This paper is based on the fact that these devices can also be used as communication emitters without losing their main functionality as illumination sources. This technique is known as Visible Light Communications (VLC). The LED as a light emitting element of VLC has attracted great attention due to its fast response and low power consumption. VLC is a communication method by changing the brightness of sources of light such as a illumination. A set of standards for VLC will soon be established and it is likely that VLC will play an important role in the future wireless communication system.

This paper tries to apply the VLC technology on Android Mobile. Android is the first open source software toolkit for mobile environment. The number of mobiles running Google’s Android has risen sharply. Having snared 76% of global smartphone shipments by operating system in the first quarter according to a survey. It is clearly why we choose Android as our development platform.

The traditional wireless communication technologies between mobile phones are Bluetooth and IrDA. They cannot provide a directional wireless channel for two phones. This paper attempts to build a new transport by which the mobile terminal can transfer local data to each other simultaneously. The general interfaces on the mobile phone are audio jack and USB port. However, The Audio interface consists of four lines, namely left and right channels, ground and audio line, and it can’t provide the power to the external physical module by itself. The common USB mounted on the mobile can provide a 5V DC power, but the electric current output from the port is too weak to satisfy the power consumption of a external electrical model. We had better use the mobile that integrates the module of USB OTG. The USB supports OTG can offer higher current by which the interface module may work infallibility.

Testing And Results

 With the VLC system described above, performance of the USB module is measured. In the VLC system, the optical power of the LED would be weaker and weaker with the increase of the distance between the LED with the PD. To restrain this attenuation, we put a lamp cup on the LED. This cup reduces the diffusion angle of the transmitter LED to gather the light and enable the PD receive more luminance. So, the lamp cup can make contribute to the performance of this system. In our experiment, We had tested the optical power of the PD received with a cup on LED or not. The power of the LED in this experiment is 300 mW. The power of the LED is poorly controlled because the mobilephone in practice is a low-power product.

Conclusion

In this paper, we developed a full-duplex optical wireless system prototype to achieve the transmission between two android mobiles using white light LED. The integration of an electronic device with the hardware and software of mobile devices for personal use was presented. This device is able to take advantage of the main features of mobile devices, allowing users to transmit the local data to each other like Bluetooth. The upper limit transmission rate is 2Mbit/s, which is restricted to USB bridge circuit FT230. The transmission bandwidth of the LED also restricts the communication rate The obtained Q-factor of eye diagram at different transmission rates changes distinctively. The higher USB bridge circuit, the more optimizing circuit designs, efficient coding method, advanced modulation techniques and mechanism for correcting errors will be considered to improve the transmission system in our future work.