Li, Na, Ph.D. (2009) Intelligent transmitter/receiver to locate infrared user in environment. PhD thesis, University of Warwick.

Abstract

Infrared (IR) handover is the procedure providing the change from one transmitter to another in an indoor environment. Since each transmitter covers a predefined small geographical area and handles the need of the infrared user for data transfer in that area. The active infrared user needs to change its transmitting point of connection to a wired backbone network while it is moving across the coverage boundaries of the multiple transmitters to which it is connected. For improving overall network performance, the active infrared user must be connected to the most suitable transmitter while accessing the data transfer provided by the fixed network. Therefore, a new smart active IR transceiver system has been described which accommodates handover for mobile infrared communications. A system has been designed and implemented using one receiver and three transmitters within an indoor environment. The system performance has been evaluated, and issues such as position, orientation, and radiation pattern of the signal sources and receiver have been tackled. The desired signal power for the proposed handover evaluation method is given by the average photocurrent that corresponds to the average optical power incident on the photodiode. However, the main limitation to the bandwidth of the IR front-end is the photodiode capacitance, so that the level of received header signal at the sampling point is modified by the front-end transfer function, which may lead to a wrong decision based on the IR channel quality estimation. Thus, in order to reduce the effect of noise and bandwidth aspects, a raised-cosine-output pulse shape to represent the digital baseband signal is the proposed method for optimizing the estimation of the average transmitter power. That is an active IR receiver can automatically make comparison and then selection of a transmitter which has the transmission quality of the greatest preference based on the recognized header pulse from the received and combined header signals, and finally it could only recover one 16-PPM modulated data block in the form of a time-division-multiplexed stream having the greatest quality.

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