The demand for the higher bandwidth is continuously increasing, and to cater to wireless communication can be used. The bandwidth has a close relationship with data-rates in turn has a dependency with channel capacity. In this paper, the channel capacity is estimated when CSI is known/not known at the transmitter and it has been shown that the knowledge of the CSI at the transmitter may not be very useful. The channel capacity for the random MIMO channels is also estimated through simulation and outage capacity is discussed. Finally, MIMO channel capacity in the presence of antenna correlation effect is estimated and obtained results are discussed.

Many optical packet switch (OPS) architectures are proposed and demonstrated. In the design of these architectures, most of the attention is paid on the network layer parameters like high through put (low packet loss probability) and low latency, etc. and to achieve these goals. The structure of the architectures becomes very complex. In real scenarios, these architectures may not work efficiently because of physical layer constraints. Hence, cross layer optimization needs to be considered. This paper addresses the major physical layer constraints, and it has been found that the optical packet switch architecture can work efficiently within the bounded regimes which can be called as an operation window.

In this paper, optical loop buffer based architecture is discussed; with its advantages over other architectures. In general the performance of the switch is measured at physical and network layer. The physical layer analysis deals with power budget analysis, however, at the network layer; the performance is measured in terms of packet loss probability and average delay. To obtain more realistic performance at the network layer the QoS parameters need to be included. In this paper, a QoS parameter which is known as priority of the incoming packets is included and corresponding results are presented, and it has been found that even at the load of 0.7, packet loss probabilities on the order of 10-5 can be achieved.

In wireless communication fading of channels is the serious cause of the received degraded signals. The effect of fading can be minimized by using various time and space domain techniques. However, space domain techniques are preferred over the others due to its advantages. In this paper, comparison of the wireless MIMO system under Almouti's and maximum ratio combining schemes is presented. Basic idea in these schemes is to transmit and receive more than one copy of the original signals. Using two transmitter antennas and one receiver antenna, the scheme provides the nearly same diversity order as the maximal-ratio receiver combining (MRRC) with one transmitter antenna, and two receiver antennas. Results for one transmitter and four receivers under MRRC is also presented and compared. Finally, results are presented while varying the average transmitted power.

In this paper, an all-optical regenerator based, photonic packet switch architecture, which consists of the fiber loop for the storage of the contending packets, is considered. In the loop buffer, the available buffer space may not be fully utilized due to the limited re-circulation count of the data placed on buffer. This limit can be counteracted by placing a pool of regenerators inside the buffer. As optical regenerators are costly devices, hence they should be placed optimally in the buffer. The simulations results are presented by consider Prioritized and non – prioritized traffic. It is shown in the results that regeneration of data is essential if prioritized traffic has to be considered.