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A Hybrid architecture between terrestrial and satellite networks based on Orthogonal Frequency Division Multiplexing (OFDM) is employed here. In hybrid architecture, the users will be able to avail the services through the terrestrial networks as well as the satellite networks. The users located in urban areas will be served by the existing terrestrial mobile networks and similarly the one located in rural areas will be provided services through the satellite networks. The technique which is used to achieve this objective is called Pre-FFT adaptive beamforming also called time domain beamforming. When the data is received at the satellite end, the Pre-FFT adaptive beamforming extracts the desired user data from the interferer user by applying the complex weights to the received symbol. The weight for the next symbol is then updated by Least Mean Square (LMS) algorithm and then is applied to it. This process is carried out till all the desired user data is extracted

Node cooperation is considered in this paper in the existence of two relaying protocols i.e. "Amplify and Forward (AF)" also called "Store and Forward (SF)" and the second relaying protocol is "Decode and Forward". The two stated protocols are different from each other and perform different operations on received data before retransmitting to next hop. Also the selection of each protocol is varying in accordance to the distance of a sensor node from the destination node (RF source). It is suggested in this literature that a relay node close to the source node will employ Decode and Forward and if it is close to the destination node, then Amplify and Forward will be employed. This work is achieved by first modelling an empirical system consists of single relay, source and destination. And the two relaying protocols (SF and DF) were modelled and implemented. This approach is then extended for three relay nodes and the two sets of relaying nodes were implemented again on every single node and then the output performances were compared. Finally using analytical approach, the communication range or the capacity of RF source to charge the sensor nodes in certain area was also evaluated and it is considered that the relay nodes within the prescribed range are successfully charged in charging stage. And in communication stage, the relay node was allowed to keep at various distances from the source node and evaluate the performance of each relaying protocol on a particular distance from source and destination.

In an indoor multiple-input multiple-output (MIMO) visible light communication (VLC) system, line of sight (LoS) channel links are present between a light-emitting diode (LED) based transmitter and a photodetector (PD) based receiver. The PDs in the receiver are closely packed resulting in a high channel correlation. To overcome channel correlation and improve the performance of the MIMO-VLC system, angle diversity receivers (ADRs) are commonly employed. The channel matrix entries depend on the normal vectors of the PDs, which in turn depend on the elevation angle (EA) of the PDs. Thus, by having normal vectors pointing in different directions, the channel correlation can be considerably reduced. In a fixed EA system, the EA for all the PDs is considered to be the same whereas, in a variable EA system, the EA of the PDs is chosen irrespective of other PDs. This paper considers a special type of ADR called pyramid receiver (PR) and employs a 4x4 MIMO-VLC system. In this paper, different MIMO algorithms such as repetition coding (RC) and spatial multiplexing (SMP) are considered to exhibit and compare the bit-error-rate (BER) performance of the fixed and variable EA MIMO-VLC systems. The results show that an SMP employed MIMO-VLC system outperforms the RC employed MIMO-VLC system. SMP results in a spatial multiplexing gain that varies linearly with the number of LEDs whereas RC does not yield any spatial multiplexing gain. To attain the same spectral efficiency i.e. 4 bit/s/Hz, a larger signal constellation size is required for RC employed MIMO-VLC system to achieve the same BER as of an SMP employed MIMO-VLC system. Similarly, the BER performance of variable EA MIMO-VLC systems is better as compared to fixed EA MIMO-VLC system.

The Passive sensor nodes are operated in a very low power regime i.e. -10dBm to -30dBm. Due to this fact, there is a high chance of data to be lost or severely corrupted due to overcome of noisy environment. In order to tackle this problem it was suggested that node cooperation is able to combat this. Node cooperation is very helpful in order to take the data node by node until to the final destination, rather to send directly from source to destination. This work is achieved by first modelling an empirical system consists of single relay, source and destination. And the two relaying protocols (SF and DF) were modelled and implemented. This approach is then extended for three relay nodes and the two sets of relaying nodes were implemented again on every single node. The output performances were compared, and further improvement was seen by channel coding.