Free Space Optics is a medium with high bandwidth which has maximum data rate. Demand for large data speed capacity has been increasing exponentially due to the massive spread of internet services. So with the growing transmission rate and demand in the field of optical communication, the electronic regeneration has become more expensive. With the introduction of power optical amplifiers the cost of converting optical signals to electronic signals has been brought down immensely. This research paper describes the effect of varying duty cycle on BER performance of the FSO link with hybrid amplifier having different attenuation.Index Terms: FSO (Free space optics), RZ (Return to zero), NRZ (Non return to zero), OOK (On off keying).
In this work physical layer simulation of IEEE 802.15.4 / ZigBee protocol has been done. The proposed work is the implementation of ZigBee system according to the protocol description. In this work we have simulated ZigBee system first with conventional OQPSK modulation technique, then the simulations are performed for MSK modulation, which is through OQPSK modulation. Simulation results for BER showing the average 79.43 % improvement in BER for Proposed MSK compared with OQPSK modulation scheme. For a targ 10-2 the SNR required is 4 dB for this work i.e. for MSK, as compared to 10 dB for conventional OQPSK. Hence, an improvement of 6 dB less SNR. For a target BER of 10-2 the SNR required is 4 dB for this work i.e. for MSK, as compared to 5.2 dB wit [1]. Hence, an improvement of 1.2 dB less SNR.
ZigBee is a low-cost, low-power consumption, wireless mesh networking standard. Firstly, the low cost allows the technology to be widely deployed in wireless control and monitoring applications. Secondly, the low power-usage allows longer life with smaller batteries. Thirdly, the mesh networking provides high reliability and more wide range. ZigBee is a standard which defines a set of communication protocols for low data rate short range wireless networking. ZigBee based on wireless devices operate in 868MHz, 915MHz and 2.4GHz frequency bands for operation. ZigBee is targeted mainly for battery power uses where small data rate, low cost and long battery life are main requirements. In many ZigBee applications, the total time the wireless device is engaged in any type of activity is very limited. The device spends most of its time in power saving mode, also called as sleep mode.
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