Shweta Pandit

Throughput maximization with reduced data loss rate in cognitive radio network

In this paper, we have investigated a technique to eliminate the sensing-throughput trade-off of the conventional method in the cognitive radio network. First, we have discussed the sensing—throughput trade-off caused by the conventional method in the cognitive radio network and then proposes a frame structure for eliminating such an issue which is presented in the conventional approach. However, the proposed method has a drawback, which is solved by the enhancement in the frame structure. We have numerically simulated and compared the throughput of cognitive users for both (conventional and propose) methods. The frame structure enhancement technique decreases the probability of frame collision between the primary and secondary users (SUs) and reduces the data rate loss.

An overview of spectrum sharing techniques in cognitive radio communication system

Abstract As the complexities of wireless technologies increase, novel multidisciplinary approaches for the spectrum sharing/management are required with inputs from the technology, economics and regulations. Recently, the cognitive radio technology comes into action to handle the spectrum scarcity problem. To identify the available spectrum resource, decision on the optimal sensing and transmission time with proper coordination among the users for spectrum access are the important characteristics of spectrum sharing methods. In this paper, we have technically overviewed the state-of-the-art of the various spectrum sharing techniques and discussed their potential issues with emerging applications of the communication system, especially to enhance the spectral efficiency. The potential advantages, limiting factors, and characteristic features of the existing cognitive radio spectrum sharing domains are thoroughly discussed and an overview of the spectrum sharing is provided as it ensures the channel access without the interference/collision to the licensed users in the spectrum.

Backoff Algorithm in Cognitive Radio MAC Protocol for Throughput Enhancement

In this paper, we have explored a novel concept of the medium access control (MAC) protocol for the distributed cognitive radio network. We have implemented the backoff algorithm in the self-scheduled multichannel cognitive radio MAC (SMC-MAC) protocol for the contention solving among the cognitive users and, hence, reserve the licensed channels for data transmission. In this control channel protocol, the cognitive users share the sensing results with each other, and each channel is divided into four intervals such as idle, sensing-sharing, contention, and data transmission. However, the backoff algorithm has been implemented during the contention interval to enhance the number of successful users and, hence, has increased the throughput of cognitive radio network. The backoff algorithm has significantly minimized the competition and, hence, collision among the cognitive users while reserving the unutilized licensed channels.

Channel capacity in fading environment with CSI and interference power constraints for cognitive radio communication system

Abstract In this paper, we have numerically computed the channel capacity in fading environment under average interference power constraint with two different adaptation policies for the spectrum sharing in cognitive radio communication systems such as power adaptation and rate and power adaptation for multilevel quadrature amplitude modulation format. However, the small scale fading effect over the transmit power of the secondary transmitter is explored. The rate and power of secondary transmitter is varied based upon the sensing information and channel state information of the secondary link. The channel capacity is maximized for these two policies by considering the Lagrange optimization problem for average interference power constraint.

Performance analysis of high-traffic cognitive radio communication system using hybrid spectrum access, prediction and monitoring techniques

In this paper, the hybrid spectrum access and prediction techniques are exploited simultaneously in the high-traffic cognitive radio communication system, in order to enhance the throughput and overcome the problem of waiting states. The hybrid spectrum access is responsible for throughput enhancement by escaping the waiting states whereas the spectrum prediction alleviates the sensing errors in the high-traffic communication environment. The closed-form expression for the throughput of cognitive user (CU) communication is derived and validated the proposed approach with the reported literature. Moreover, a new framework is proposed to conquer the sharing issues of conventional and proposed approaches. In addition to this, the performance metrics of proposed framework such as the data-loss, energy-loss of the CU and interference at the PU have been analyzed.

Advanced Frame Structures for Hybrid Spectrum Access Strategy in Cognitive Radio Communication Systems

In this letter, we have exploited a novel hybrid-cum-improved spectrum access technique for significant improvement in the throughput and data-loss rate. This proposed technique comprises of hybrid spectrum access and improved frame structure strategies of the cognitive radio communication system. Also, the closed-form expressions for throughput and data-loss of these approaches are derived. Moreover, the proposed approaches are validated numerically as well as with reported literature.

Spectrum mobility in cognitive radio network using spectrum prediction and monitoring techniques

The spectrum mobility during data transmission is an integral part of the cognitive radio network (CRN) which is conventionally two types for instance reactive and proactive. In the reactive approach, the cognitive user (CU) switches its communication after the emergence of the primary user (PU), where the detection of emergence of PU relies either on spectrum sensing and/or monitoring. Due to certain limitations of the reactive approach such as: (1) loss at least one packet on the emergence of PU and (2) resource (bandwidth) wastage if the periodic sensing is used for mobility, the researchers have introduced the concept of proactive spectrum mobility. In this approach, the emergence of PU is predicted on the bases of pre-available spectrum information, and switching is performed before true emergence of the PU, in order to avoid even the single packet loss. However, the imperfect spectrum prediction is a major milestone for the proactive spectrum mobility. Recently, due to introduction of the spectrum monitoring simultaneous to the data transmission, the reactive approach has come into lime-light again, however, it suffers from the single packet loss and imperfect spectrum monitoring issues. Therefore in this paper, we have exploited the spectrum monitoring and prediction techniques, simultaneously for the spectrum mobility, in order to enhance the performance of cognitive radio network (CRN). In the proposed strategy, the decision results of the spectrum prediction and monitoring techniques are fused using AND and OR fusion rules, for the detection of emergence of PU during the data transmission. Further, the closed-form expressions of the resource wastage, achieved throughput, interference power at PU and data-loss for the proposed approaches as well as for the prediction and monitoring approaches are derived. Moreover, the simulation results for the proposed approaches are presented and validation is performed by comparing the results with prediction and monitoring approach. In a special case, when the prediction error is zero, the graphs of all metric values overlies the spectrum monitoring approach, which further validates the proposed approach.

Spectrum Sensing in Cognitive Radio Networks: Potential Challenges and Future Perspective

Due to the huge number of diverse wireless devices and technologies, spectacular increases in the number of wireless subscribers, advent of new applications and continuous demand for higher data-rates, the radio frequency (RF) spectrum is becoming more and more crowded. This development calls for systems and devices that are aware of their surrounding RF environment, so they can facilitate flexible, efficient, and reliable operation and utilization of the available spectral resources. Thus, the spectrum sensing is becoming progressively more important to recent and future wireless communication systems for identifying underutilized spectrum and characterizing interference, with the goal of achieving reliable and efficient operation. Cognitive radio is an intelligent radio that is aware of its surrounding environment, capable of learning and adapting its behavior and operation to provide a good match to its surrounding environment and to the user’s needs. Spectrum sensing is the key requirement and one of the most challenging issues for the cognitive radio system. This chapter presents a comprehensive survey of the physical layer spectrum sensing techniques for cognitive radios. The major challenges in spectrum sensing are outlined and several techniques for improving spectrum sensing performance are discussed. Further, a hybrid model for non-cooperative spectrum sensing is presented; with this terminology, the proper channelization of the three techniques is introduced, with relevant discussion. This approach helps in detecting the idle spectrum opportunistically, with better spectrum utilization under non-cooperative sensing, resulting in enhanced spectrum efficiency. We also explore sensing under a cooperative environment. The approach presented aids in opportunistically detecting idle spectrum bands (spectrum holes that are the underutilized sub-bands of the radio spectrum), with better utilization of the spectrum than under non-cooperative sensing, and increased overall spectrum efficiency.

Self-scheduled MAC-layer protocol for spectrum sharing in cognitive radio communication

Recently, the spectrum scarcity has become the bottleneck for the development of wireless communication. Therefore, cognitive radio is a promising technology geared to solve the spectrum scarcity problem by opportunistically identifying the unused portions of the licensed users spectrum and establish the communication in the unutilised regime of the spectrum, while ensuring that the licensed or primary users of the spectrum are not affected. However, one of the major aspect and potential challenge is in the licensed channels, the sensing and access decision. In this paper, we have explored the concept of the multiple access control protocol for the distributed cognitive radio network. In this control channel protocol, the secondary users share the sensing results to each other and each channel is divided into four intervals such as idle, sensing-sharing, contention, and transmission. The sensing-sharing and contention interval are further divided into number of slots and throughput of the communication system has been computed.

Frame structures for hybrid spectrum accessing strategy in cognitive radio communication system

In this paper, we have exploited the novel hybrid-cum-improved spectrum access strategy to significant improvement in the throughput and data-loss rate. This proposed strategy is comprise of hybrid spectrum access and improved frame structure strategies for the cognitive radio communication system. In addition to this, the mathematical expressions of throughput for these approaches are also presented. Moreover, the proposed approaches are validated numerically as well as with reported literature.