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IEEE 802.22 is the first world-wide standard for wireless regional area networks using cognitive radio technologies. Major drawbacks of these networks are limited network capacity and low energy efficiency. One potential solution for these drawbacks is device-to-device communication, which can be incorporated as D2DWRAN. D2DWRAN features direct intracell communication, reuse of channels, and use of multiple operating channels. In this article, we mainly discuss energy-efficient spectrum sharing in D2DWRAN. We explicate a mechanism to increase energy efficiency for long distance links using relays. Along with energy, channel utilization and fairness are also considered while choosing relays. Thus, significant improvement in both network capacity and energy efficiency can be achieved. The schemes discussed here can also be used in other D2D communication settings.

We present the state-of-the-art system level evaluation of the IEEE 802.22-2011 standard using a highly detailed simulator implementation in NS-2. In the evaluation our attention is focused on the effect of spatiotemporal wireless microphone (WM) activity on the performance of the IEEE 802.22-2011 network, while considering novel spectrum sensing strategies and multimedia traffic with different prioritization in IEEE 802.22-2011. Our general finding is that the IEEE 802.22-2011 standard deals well with WMs and prioritization of simultaneous multimedia traffic using different QoS profiles, while some surprising conclusions follow.

Channel management policy is one of the key functions of any cognitive radio system. The channel management decision in a cognitive radio system depends on various factors such as government regulations, limitations of transmission power between communicating devices, availability of geo-location information, and the quality of various available channels. The main purpose of channel management in a cognitive radio system is to protect the incumbent users (licensed users). The first international standard based on cognitive radio technology is IEEE 802.22, Wireless Regional Area Networks, which aims at providing broadband access in rural areas by effectively utilizing the unused TV channels. This standard aims at describing both PHY and MAC layer functionalities in an infrastructure- based broadband wireless access network for communication between consumer premises equipment using a base station. This article presents the cognitive radio functionality of this standard in detail. The cognitive functionality is provided by the dynamic channel management using channel sensing, channel classification, and maintenance of channel information. Using these techniques, this standard effectively protects the incumbent users and dynamically manages the channel allocation in IEEE 802.22 WRAN systems.

This article presents a high-level overview of the IEEE 802.22 standard for cognitive wireless regional area networks (WRANs) that is under development in the IEEE 802 LAN/MAN Standards Committee.

Cognitive radio techniques are being applied to many different communications systems. They hold promise for increasing utilization of radio frequencies that are underutilized today, allowing for improved commercial data services, and allowing for new emergency and military communications services. For example, these techniques are being considered by the U.S. FCC for communications services in unlicensed VHF and UHF TV bands. Although traditionally these techniques are closely associated with software-defined radios, many standards such as WiFi (IEEE 802.11), Zigbee (IEEE 802.15.4), and WiMAX (IEEE 802.16) already include some degree of CR technology today. Further advances are occurring rapidly. IEEE 802.22 will be the first cognitive radio-based international standard with tangible frequency bands for its operation. Standardization is at the core of the current and future success of cognitive radio. Industry stakeholders are participating in international standards activities governing the use of cognitive radio techniques for dynamic spectrum access and coexistence, next-generation radio and spectrum management, and interoperability in infrastructure-less wireless networks. This article provides a review of standardization activities for cognitive radio technologies and comments on prospects and issues for future standardization.

One of the key challenges of the emerging cognitive radio-based IEEE 802.22 wireless regional area networks (WRANs) is to address two apparently conflicting requirements: ensuring QoS satisfaction for WRAN services while providing reliable spectrum sensing for guaranteeing licensed user protection. To perform reliable sensing, in the basic operation mode on a single frequency band (non-hopping mode), one must allocate quiet times, that is, periodically interrupt data transmission that could impair the QoS of WRAN. This critical issue can be addressed by an alternative operation mode proposed in 802.22 called dynamic frequency hopping (DFH), where WRAN data transmission is performed in parallel with spectrum sensing without interruptions. DFH community, as described in this article, is a mechanism that coordinates multiple WRAN cells operating in the DFH mode, such that efficient frequency usage and reliable channel sensing are achieved. The key idea of DFH community is that neighboring WRAN cells form cooperating communities that coordinate their DFH operations