Vishram Mishra

MAC Protocol for Two Level QoS Support in Cognitive Radio Network

The exponential increase in the number of mobile devices using large bandwidth and real-time applications has met with challenges of spectrum scarcity and real-time MAC design. To this end we propose an energy efficient cognitive radio MAC protocol with two-level QoS support, called as TQCR-MAC. We have divided the traffic into two types-real time and non-real time data traffic. The TQCR-MAC protocol utilizes the unused spectrum and provides QoS support for different traffic. The TQCR-MAC exploits the combination of multiple channels and TDMA scheme to further improve the QoS provisioning. The simulation result shows that our proposed protocol improves the network performance significantly, especially when the network is either biased towards real time or non-real time data traffic.

QoS based spectrum decision framework for cognitive radio networks

Recently cognitive radio has gained considerable interest by wireless communication researchers as a viable mean to solve the spectrum utilization problem. The advancement in this area has met with many challenges including in the field of spectrum decision. To this end we propose a QoS based spectrum decision framework for cognitive radio networks which guarantees the QoS to the data packets by allocating the channel which can satisfy the QoS requirement. This is done by categorizing the data packets and channels and then by providing a mapping between them. Four levels of packet priority is supported with this framework. Performance analysis is done to show the effectiveness of the proposed framework.

Energy Aware Spectrum Decision Framework for Cognitive Radio Networks

Recently cognitive radios have been proposed to mitigate the problem of spectrum scarcity and spectrum under-utilization. One of the key aspect of the cognitive radio is the optimal channel selection. The cognitive radio system selects a licensed band which has acceptable availability and also satisfies the system needs in terms of bandwidth and power constraints. To this end we propose an energy aware spectrum decision framework for cognitive radio network (ESDF-CR), which guarantees a certain level of QoS to the system running on low power, by selecting those channels which require lesser power for transmission. Channel selection and packet admission control techniques have been proposed to realize the spectrum decision framework. A comparison is done with random channel selection scheme to show the effectiveness of the proposed framework.

Reconfigurable Channel Selection Technique for Cognitive Radio Network With Heterogeneous Primary Bands

Recently, the Federal Communications Commission has mandated the use of a database to observe the spectral opportunity at a given place over time along with the use of spectrum sensing. It is arduous to obtain the database for spectral opportunity for all places, and since spectral opportunities rapidly vary with location, a new paradigm to obtain the spectral opportunity needs to be determined. We propose a method to obtain the spectral opportunity at a given location for specific channels, such as television (TV) and frequency-modulated (FM) bands, which follow deterministic time usage pattern. Since these channels have a periodic deterministic time usage pattern for every 24 h, learning the spectral opportunities and utilizing these for consequent time periods have better efficiency than other proposed schemes. Once the spectral opportunity is known and if we have multiple channels from which to select, then a decision on the selection of a channel is made. The spectrum decision is done to satisfy the constraints imposed by a user. Since, with our proposed method, the spectral opportunity is known ahead of time, better spectrum decisions can be made. To this end, we propose three different channel selection techniques with different constraints applied. The first channel selection technique provides the selection of channels with a minimum number of channel switching and, thus, reduces the jitters, switching delays, and packet losses. This channel selection technique is appurtenant to real-time applications such as voice over Internet Protocol. The second channel selection technique provides the selection of channels that maximizes the overall throughput of the system and is particularly useful for bandwidth-intensive applications such as BitTorrent. The third channel selection technique provides a compromised value between minimal channel switching and maximal throughput, thus providing a control over the bandwidth demand and real-time requirement. A comparison of these channel selection techniques is done with three other studies to demonstrate the competency in terms of a number of channel switching and throughput obtained in the system.

Deterministic time pattern based channel selection in cognitive Radio network

The exponential increase in the number of mobile devices using large bandwidth and multiple channels has met with challenges of spectrum scarcity and optimal channel selection. To this end we propose a heuristic method based channel selection mechanism in cognitive radio network which utilizes the linked list as a learning mechanism for the network to choose a channel. Some of the standardized channels used by primary user follow a time deterministic pattern in real world scenario. The described mechanism utilizes these time-patterns for detecting the spectral hole in advance and thus achieving the goal of minimal channel selection or of increasing the throughput of the system.

TQCR-media access control: two-level quality of service provisioning media access control protocol for cognitive radio network

Recently cognitive radio has been proposed to solve the problem of spectrum scarcity with the help of an opportunistic utilisation of unused spaces in the spectrum. The implementation of cognitive radio for real-time application faces with the challenge of real-time media access control (MAC) design. To this end the authors propose an energy efficient cognitive radio MAC protocol with two level of quality of service (QoS) support: two level quality of service provisioning in cognitive radio (TQCR)-MAC. The data traffic in the cognitive radio network is classified as real-time traffic and non-real-time traffic, with former having higher priority over latter. The proposed protocol utilises variable interframe spaces for implementing different priorities to data and also exploits the combination of multiple channels and time division multiple access (TDMA) scheme to further improve the QoS provisioning. The TDMA slots in different channels are used as the data carrier segment, in which a real-time data can take over the time slots reserved by non-real-time data. Thus, non-real traffic may suffer from starvation, and hence a guarantee on the non-real-time data is provided with the help of a starvation prevention algorithm. The performance analysis of the proposed MAC protocol is done against two similar MAC protocols, which shows that the performance is improved significantly, especially when the network is either biased towards real-time or non-real-time data traffic.

A QoS provisioning MAC protocol for Cognitive Radio Network

Recently cognitive radio has been envisioned to solve the problem of spectrum scarcity and spectrum under-utilization. A cognitive radio performs communication by selecting a channel on an opportunistic basis. Thus the implementation of a cognitive radio for real-time application faces the challenge of sharing of a constantly varying sporadically available channel among multiple users. To this end we propose an energy efficient medium access control scheme for single-hop cognitive radio network (QCR-MAC) which provides four levels of QoS support with complexity equivalent to that of a single transceiver node. The scheme imparts QoS through the usage of different interframe spaces, which allows different priorities of winning a contention by packets from different applications. Two different channel access etiquettes are used according to the type of channel and data traffic. One spectrum etiquette favours stream based real-time data transfer while another favours bursty traffic. The protocol utilizes a beacon based structure for information interchange and thus allows contentions to be distributed on different channels whilst mitigating the control channel saturation problem. Simulation results shows the effectiveness of the proposed scheme over an existing similar work.

Cognitive Radio Network- A Review

As discussed in Chap. 1, the quality of service and energy efficiency of a cognitive radio system depends upon various parameters, including spectrum selection, media access scheme and spectrum sensing order. In this chapter, we provide a review on technologies which facilitates/improves the parameters responsible for QoS and energy management. At the end of this chapter, we will discuss about different cognitive radio platforms and their evolution.

Case Study: Self-coexistence in CRN Framework

The free use of wireless frequency spectrum by cognitive radio network is anticipated to increase its application in a multitude of wireless systems.

QoS Provisioning and Energy Management Framework for CRN

The cognitive radio comprises of the following three important functional components to realize its operation as wireless communication device.