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Due to the high date rate capability of optical transmitters and the advances in laser and optical components technology, free-space optical (FSO) systems for wireless communication channels have attracted considerable attention recently for many different applications, such as ground-ground, ground-to-satellite and inter-satellite links. The advantages of an optical communication system compared with an RF counterpart are (a) greater bandwidth, (b) smaller size and weight, (c) less power consumption (Garcia-Talavera, 2002; Yuang, Tien, & Lin, 2009). Optical wavelength division multiplexing (WDM) has been shown to be successful in providing virtually unlimited bandwidth to support an ever-increasing amount of traffic for future optical networks. Future optical networks, especially the metro and local networks, are expected to flexibly and cost effectively satisfy a wide range of applications having time-varying and high bandwidth demands and stringent delay requirements.
A WDM technology has the enormous amount of bandwidth available in fiber cable. In WDM system, each carries multiple communication channels and each channel operating on different wavelength. Such an optical transmission system has a potential capacity to provide Tera bytes of bandwidth on a single fiber. WDM technology has the capability to provide the bandwidth for the increase in the huge on traffic demand of various applications like audio, video and multimedia, which needs the QoS over the network (Garcia-Talavera et al., 2002).
Scheduling is the basic function which is implemented in Operating system. Operating system give assistance to wireless communication and it is used in variety of applications like laptop’s and mobiles where each device is connected to each other with a single access node (Khan et al., 2007; Ahsen, Hussain, Khadam, Sharif, & Zaman, 2007). Today scheduling is based on parallel and distributed computing methods (Sharif & Khan, 2007). More flexibility is there in wireless network as compared to wired network (Sharif, Azeem, & Haider, 2012; Sharif, Murtaza, Haider, & Raza, 2011). Several researches have been done on hardware and software part of computer (Irum et al., 2012). As advancement is increased in operating system which enhanced its multitasking capability, this increase further by an efficient scheduling algorithm like a round robin. Scheduling is the process of assigning data or process so as to increase channel utilization, throughput and also reduces its delay and response time as explained in Mohanty et al. (2010). Scheduling can be used in real world, like in applications of networking, traffic management systems of air, road and railway. As scheduling algorithm is the strategy for insertion of data in transmitter so that system efficiently manages load and achieve required Quality of Service (QoS) (Mostafa, Rida, & Hamad, 2010).
To have better scheduling, an algorithm must have maximum channel utilization, throughput and efficiency. Scheduling algorithms are classified as preemptive and non-preemptive algorithm. Preemptive scheduling is when high priority data arrive, it aborts all its transmission and take care of high priority, whereas in non-preemptive algorithm it works on First come first serve [FCFS] i.e. even if high priority arrive it continue its transmission. For improving channel utilization, CPU runs several processes at all times. Before transmission all the resources of CPU are scheduled before as in Raijkamal and Vigneshwaran (2010).