Gyanendra Prasad Joshi

Cognitive Radio Wireless Sensor Networks: Applications, Challenges and Research Trends

A cognitive radio wireless sensor network is one of the candidate areas where cognitive techniques can be used for opportunistic spectrum access. Research in this area is still in its infancy, but it is progressing rapidly. The aim of this study is to classify the existing literature of this fast emerging application area of cognitive radio wireless sensor networks, highlight the key research that has already been undertaken, and indicate open problems. This paper describes the advantages of cognitive radio wireless sensor networks, the difference between ad hoc cognitive radio networks, wireless sensor networks, and cognitive radio wireless sensor networks, potential application areas of cognitive radio wireless sensor networks, challenges and research trend in cognitive radio wireless sensor networks. The sensing schemes suited for cognitive radio wireless sensor networks scenarios are discussed with an emphasis on cooperation and spectrum access methods that ensure the availability of the required QoS. Finally, this paper lists several open research challenges aimed at drawing the attention of the readers toward the important issues that need to be addressed before the vision of completely autonomous cognitive radio wireless sensor networks can be realized.

An Efficient MAC Protocol for Improving the Network Throughput for Cognitive Radio Networks

The limitation of spectrum has become a major bottleneck of the development of next generation radio system. One of the key challenges of the emerging opportunistic cognitive radio is how to utilize unused spectrum holes efficiently without interference to incumbent system. Assuming that channel status is known, in this paper, we propose a decentralized adaptive medium access control (AMAC) protocol that has no dedicated global common control channel (CCC) and can utilize available resources efficiently. In AMAC, each cognitive radio maintains channel status table and indexes them frequently. The channel that has more probability to be stable is ranked channel one. The most reliable common channel between communicating pair is selected as a CCC. We proposed two data communication mode according to the channel condition. The simulation results show that the proposed decentralized adaptive medium access control (AMAC) protocol significantly increases cognitive radio networks (CRNs) connectivity and data throughput.

Decentralized Predictive MAC Protocol for Ad Hoc Cognitive Radio Networks

A new problem of spectrum scarcity has emerged due to the incredible technological advances in wireless communication. The spectrum scarcity issue is a bottleneck for the next generation of wireless communications. Therefore, efficient spectrum utilization has attracted considerable attention. This paper proposes a novel method of utilizing the white spaces in the licensed spectrum while ensuring the incumbent licensees’ rights. The protocol predicts the incumbents’ arrival using a historical prediction method and protects the incumbent users from the interference of opportunistic spectrum users. Distributed sensing is used to determine the network wide spectrum opportunity. The channel access delay in the proposed protocol is evaluated by simulation and mathematical analysis. The protocol has the advantages of a decentralized system, flexibility and low computing complexity. The simulations show that the protocol outperforms the existing opportunistic spectrum-sharing, media-access-control protocols in terms of the goodput and delay.

A Reader Anti-collision MAC Protocol for Dense Reader RFID System

In dense reader RFID system, a number of readers in the same interrogation area want to access the channel at the same time suffer from reader collision problem. In this paper, we propose a distributed reader anti-collision MAC protocol (RAMP) for dense reader environment. We extended the pulse protocol by adding multiple data channels and the channel hopping algorithm. The channel hopping algorithm helps to decide whether to hop for new channel or wait in the same channel. Also, channel utilization probability based random backoff mitigates the collision possibility in the control channel. Simulation result shows that our protocol mitigates readers collision, hence decreases waiting time significantly than the existing RFID MAC protocol.

A distributed geo-routing algorithm for wireless sensor networks.

Geographic wireless sensor networks use position information for greedy routing. Greedy routing works well in dense networks, whereas in sparse networks it may fail and require a recovery algorithm. Recovery algorithms help the packet to get out of the communication void. However, these algorithms are generally costly for resource constrained position-based wireless sensor networks (WSNs). In this paper, we propose a void avoidance algorithm (VAA), a novel idea based on upgrading virtual distance. VAA allows wireless sensor nodes to remove all stuck nodes by transforming the routing graph and forwarding packets using only greedy routing. In VAA, the stuck node upgrades distance unless it finds a next hop node that is closer to the destination than it is. VAA guarantees packet delivery if there is a topologically valid path. Further, it is completely distributed, immediately responds to node failure or topology changes and does not require planarization of the network. NS-2 is used to evaluate the performance and correctness of VAA and we compare its performance to other protocols. Simulations show our proposed algorithm consumes less energy, has an efficient path and substantially less control overheads.

A Survey on Node Clustering in Cognitive Radio Wireless Sensor Networks

Cognitive radio wireless sensor networks (CR-WSNs) have attracted a great deal of attention recently due to the emerging spectrum scarcity issue. This work attempts to provide a detailed analysis of the role of node clustering in CR-WSNs. We outline the objectives, requirements, and advantages of node clustering in CR-WSNs. We describe how a CR-WSN with node clustering differs from conventional wireless sensor networks, and we discuss its characteristics, architecture, and topologies. We survey the existing clustering algorithms and compare their objectives and features. We suggest how clustering issues and challenges can be handled.

An Efficient Variable Channel Allocation Technique for Wireless Local Area Network (WLAN) IEEE802.11 Standard

The limitation of existing fixed channel allocation caused the degradation on overall throughput of the Wireless Local Area Network (WLAN). This paper proposes a variable channel allocation technique based on the bandwidth requirement and Quality of Service (QoS) of the network. According to this paper’s proposal, the distributed system (DS) of WLAN distributes the available frequency band to access points (APs) or the access points will get required channel bandwidth, in such a manner that the maximum possible bandwidth efficiency will be achieved. The numerical results of the proposed technique are shown in this paper and compared with the existing fixed channel allocation.

Fuzzy-logic-based channel selection in IEEE 802.22 WRAN

Abstract IEEE 802.22 WRAN standard does not specify algorithm for selecting operating channel from backup channel list and prioritizing the backup and candidate channels. Because all the channels in the backup and candidate channels list are not with the same properties, selecting channels randomly from the list may decrease the networks performance. We propose an approach of ranking channel according to behavior of primary users on the channel and RSSI value. It utilizes fuzzy-logic-based algorithm for prioritizing channels in the backup and candidate channels list. Performances of the networks with fuzzy-logic-based channel selection and random channel selection are compared.

Adaptive Window Size-Based Medium Access Control Protocol for Cognitive Radio Wireless Sensor Networks

Many existing medium access control protocols for cognitive radio wireless sensor networks waste bandwidth and suffer from delay because of the fixed channel negotiation period in the common control channel. In this paper, we propose a medium access control protocol for cognitive radio wireless sensor networks that adjusts the channel negotiation period based on network density. We simulate the proposed approach and compare it to the performance of the fixed channel negotiation period based approaches. The results show that the proposed approach efficiently utilizes white spaces and increases the aggregated goodput.

Applications of cognitive radio networks: recent advances and future directions

1Department of Information and Communication Engineering, Yeungnam University, Gyeongsan 38541, Republic of Korea 2Department of Computer Science, Texas Southern University, Houston, TX 77004, USA 3Department of Electric and Communication Engineering, Cankaya University, 06790 Ankara, Turkey 4Department of Electrical, Electronic and Power Engineering, Aston University, Birmingham B4 7ET, UK 5Department of Computer and Network Science, Telecom ParisTech, 75013 Paris, France