An optimized power allocation algorithm for cognitive radio NOMA communication

The primary objective of cognitive radio network is to effectively utilize the unused spectrum bands. In cognitive radio networks, spectrum sharing between primary and secondary users is accomplished using either underlay or interweave cognitive radio approach. Non orthogonal multiple access (NOMA) is the proven technology in the present wireless developments, which allows the coexistence of multiple users in the same orthogonal block. The new paradigm cognitive radio NOMA (CR-NOMA) is one of the potential solutions to fulfill the demands of future wireless communication. This paper emphasizes on practical implementation of NOMA in cognitive radio networks to enhance the spectral efficiency. The goal is to increase the throughput of the secondary users satisfying the quality of service (QOS) requirements of primary users. To achieve this, we have presented the optimized power allocation strategy for underlay downlink scenario to support the simultaneous transmission of primary and secondary users. Furthermore, we have proposed QOS based power allocation scheme for CR-NOMA interweave model to support the coexistence of multiple secondary networks. Also, the changes adopted in implementing superposition coding (SC) and successive interference cancellation (SIC) for CR-NOMA are highlighted. Finally, simulation results validate the mathematical expressions that are derived for power allocation coefficient and outage probability

On-demand Bandwidth and Stability Based Unicast Routing in Mobile Adhoc Networks

Characteristics of mobile ad hoc networks (MANETs) such as lack of central coordination, dynamic topology and limited resources pose a challenging problem in quality of service (QoS) routing. Providing an efficient, robust and low overhead QoS unicast route from source to destination is a critical issue. Bandwidth and route stability are the major important QoS parameters for applications where long duration connections are required with stringent bandwidth requirements for multimedia applications. This paper proposes an On-demand Bandwidth and Stability based Unicast Routing scheme (OBSUR) in MANET by adding additional QoS features to existing Dynamic Source Routing (DSR) protocol. The objective of the OBSUR is to provide QoS satisfied, reliable and robust route for communicating nodes. The scheme works in following steps. (1) Each node in the network periodically (small regular intervals) estimates bandwidth availability, node and link stability, buffer availability, and stability factor between nodes. (2) Construction of neighbor stability and QoS database at every node which is used in route establishment process. (3) The unicast path is constructed by using route request and route reply packets with the help of route information cache, and (4) route maintenance in case of node mobility and route failures. Simulation results show that there is an improvement in terms of traffic admission ratio, control overhead, packet delivery ratio, end to end delay and throughput as compared to Route Stability Based QoS Routing (RSQR) in MANETs.

On-demand QoS and Stability Based Multicast Routing in Mobile Ad Hoc Networks, Journal of Telecommunications and Information Technology, 2014, nr 3

Finding a connection path that remains stable for suciently longer period is critical in mobile ad hoc networks due to frequent link breaks. In this paper, an on-demand Quality of Service (QoS) and stability based multicast routing (OQSMR) scheme is proposed, which is an extension of ad hoc on-demand multicast routing protocol (ODMRP) to provide QoS support for real time applications. The scheme works as follows. Each node in the network periodically estimates the parameters, i.e., node and link stability factor, bandwidth availability, and delays. Next step is creation of neighbor stability and QoS database at every node by using estimated parameters. The last sequence is multicast path construction by using, route request and route reply packets, and QoS and stability information, i.e., link/node stability factor, bandwidth and delays in route information cache of nodes, and performing route maintenance in case of node mobility and route failures. The simulation results indicate that proposed OQSMR demonstrates reduction in packet overhead, improvement in Packet Delivery Ratio (PDR), and reduction in end-to-end delays as compared to ODMRP, and Enhanced ODMRP (E-ODMRP)

On-demand QoS and Stability Based Multicast Routing in Mobile Ad Hoc Networks

Finding a connection path that remains stable for suciently longer period is critical in mobile ad hoc networks due to frequent link breaks. In this paper, an on-demand Quality of Service (QoS) and stability based multicast routing (OQSMR) scheme is proposed, which is an extension of ad hoc on-demand multicast routing protocol (ODMRP) to provide QoS support for real time applications. The scheme works as follows. Each node in the network periodically estimates the parameters, i.e., node and link stability factor, bandwidth availability, and delays. Next step is creation of neighbor stability and QoS database at every node by using estimated parameters. The last sequence is multicast path construction by using, route request and route reply packets, and QoS and stability information, i.e., link/node stability factor, bandwidth and delays in route information cache of nodes, and performing route maintenance in case of node mobility and route failures. The simulation results indicate that proposed OQSMR demonstrates reduction in packet overhead, improvement in Packet Delivery Ratio (PDR), and reduction in end-to-end delays as compared to ODMRP, and Enhanced ODMRP (E-ODMRP)