Stanislav Filin

Architecture and enablers for optimized radio resource usage in heterogeneous wireless access networks: The IEEE 1900.4 Working Group

Over the past decade or so, the wireless industry has undergone many significant changes. Radio systems have moved toward forming heterogeneous wireless networks: collaborations of multiple radio access networks, which in some cases operate different radio access technologies, such as second- and third-generation cellular RATs, IEEE 802.x wireless standards, and so on. On the other hand, multimode reconfigurable user devices with the ability to choose among various supported RATs have become a reality, and devices and networks with dynamic spectrum access capabilities, allowing real-time sharing of spectrum resource usage among different systems, are expected to be a part of the future radio eco-space. As a result of these changes, there is a need to develop a standard that addresses the requirements and leverages the opportunities posed by such a versatile radio environment. To this end, IEEE 1900.4 aims to standardize the overall system architecture and information exchange between the network and mobile devices, which will allow these elements to optimally choose from available radio resources. In other words, the standard facilitates the distributed dynamic optimization of the usage of spectrum offered by the heterogeneous wireless network, relying on a collaborative information exchange between networks and mobile devices, thereby acting as a common means to improve overall composite capacity and quality of service for the served networks. This article provides a snapshot of IEEE P1900.4 in its current form, covering the scope and purpose of the standard, reference use cases for which the standard is applicable, its system and functional architectures, and finally, the information model for its main interfaces.

ETSI reconfigurable radio systems: status and future directions on software defined radio and cognitive radio standards

This article details the current work status of the ETSI Reconfigurable Radio Systems Technical Committee, positions the ETSI work with respect to other standards efforts (IEEE 802, IEEE SCC41) as well as the European Regulatory Framework, and gives an outlook on the future evolution. In particular, software defined radio related study results are presented with a focus on SDR architectures for mobile devices such as mobile phones. For MDs, a novel architecture and inherent interfaces are presented enabling the usage of SDR principles in a mass market context. Cognitive radio principles within ETSI RRS are concentrated on two topics, a cognitive pilot channel proposal and a Functional Architecture for Management and control of reconfigurable radio systems, including dynamic self-organizing planning and management, dynamic spectrum management, joint radio resource management. Finally, study results are indicated that are targeting a SDR/CR security framework.

Cognitive communication in TV white spaces: An overview of regulations, standards, and technology [Accepted From Open Call]

This article presents the latest developments in regulatory status and standardization initiatives in the field of TV white space cognitive communication systems. Updates on recent movements of regulatory bodies such as the U.S. FCC, U.K. OFCOM, European CEPT, Japanese MIC, and Singapore IDA in TV white space communications are first presented. The response of the industrial community toward these new regulations is then discussed, focusing on the activities in the IEEE 802 standards association. The latest developments of IEEE 802.11, 802.22, 802.15, 802.19, and DySPAN SC are described. Considerations on system design including PHY/MAC layer design in these standards are then listed and discussed. Lastly, potential usage models of cognitive communications in TV white spaces are presented, with emphasis on required parameters as guiding references to corresponding system design.

A Software Defined Cognitive Radio System: Cognitive Wireless Cloud

This paper introduces the concept, features and architecture of a software defined cognitive radio system: Cognitive Wireless Clouds (CWC) that can realize user-centric and scalable network based on unique cognitive spectrum access, cross-network signaling, network optimization, and fast reconfiguration methods. Then, this paper shows results of feasibility studies on a software defined cognitive radio (SDCR) terminal that can access to the CWC. This includes the configuration of the SDCR terminal and a measurement data for spectrum sensing period and reconfiguration period by using software packages of W-CDMA and IEEE802.11a.

International standardization of cognitive radio systems

The current radio environment is characterized by its heterogeneity. Different aspects of this heterogeneity include multiple operators and services, various radio access technologies, different network topologies, a broad range of radio equipment, and multiple frequency bands. Such an environment has a lot of technical and business opportunities. Examples are joint management of several radio access networks within one operator to balance load of these networks, detecting and using unused spectrum in the allocated frequency bands without interrupting the operation of the primary users of such frequency bands, and spectrum trading between several operators. To exploit such opportunities, the concept of cognitive radio system has been developed. Many CRS usage scenarios and business cases are possible. This has triggered a lot of standardization activity at all levels, including in the International Telecommunication Union, IEEE, European Telecommunications Standards Institute, and European Association for Standardizing Information and Communication Systems; each of these organizations is considering multiple CRS deployment scenarios and business directions. This article describes the current concept of the CRS and shows the big picture of international standardization of the CRS. Understanding of these standardization activities is very important for both academia and industry in order to select important research topics and promising business directions.

Overview of TV White Spaces: Current regulations, standards and coexistence between secondary users

TV White Spaces (TVWS) refer to segments of the TV spectrum not used by licensed users in a given location. In recent years, regulation agencies throughout the world consider the possibility to open TVWS to unlicensed use, which is followed by standardization activities to realize it. One of the important aspects of unlicensed operation in TVWS is coexistence between heterogenous networks. This paper provides an overview of current regulations, standardization activities related to TVWS, while the main focus is IEEE P802.19.1 standardization project to enable coexistence in TVWS.

Adaptive Two Thresholds Based Energy Detection For Cooperative Spectrum Sensing

In cognitive radio networks, secondary users need to conduct spectrum sensing to properly detect the presence of primary signals that may have much lower power than noise plus interference power. In such a case, time-varying noise plus interference, which is briefly called noise uncertainty in this paper, can substantially degrade the sensing reliability of hard information combining (HIC) and soft information combining (SIC). To improve the sensing reliability in the circumstance with heavy noise uncertainty, we propose an adaptive two thresholds based energy detection and a two stage HIC based cooperative decision for cooperative spectrum sensing. The proposed sensing technique has shown better performance than conventional HIC and comparable performance with SIC when a small number of sensing nodes are used in spectrum sensing.

Design and Implementation of Cognitive Wireless Network based on IEEE P1900.4

IEEE P1900.4 is an emerging standard for optimized radio resource utilization where cognitive radio technologies are used for efficient spectrum utilization. In this paper, we design and implement a cognitive wireless network system based on open documents of IEEE P1900.4, and evaluate its performance using UDP streaming and HTTP download. Our experiments show interesting results that total network throughput in the HDP streaming is improved by 30% although some of individual terminals can not necessarily obtain better throughput. Also, it is shown that performance in the HTTP download becomes worse by up to about 40% as the number of handover increases due to the TCP window control. Our analysis is expected to point out importance of higher layer coordination with lower layers for end-to-end performance improvements in cognitive wireless networks.

Research and development on heterogeneous type and spectrum sharing type cognitive radio systems

This paper introduces two cognitive radio (CR) systems: (a) heterogeneous type CR and (b) spectrum sharing type CR regarding its definition, usage model, fundamental system architecture, and developed prototype.

QoS-Oriented Intersystem Handover Between IEEE 802.11b and Overlay Networks

In this paper, we consider the quality-of-service (QoS)-oriented intersystem handover between the IEEE 802.11b network and the overlay network. We propose the handover scheme and algorithm that guarantee to simultaneously meet the three key QoS parameters, that is, the minimum data rate, the maximum data block delay, and the maximum bit error rate, for the arbitrary number of downlink and uplink multiservice connections. In addition to the QoS requirements, our intersystem handover scheme guarantees to keep the call-dropping probability during the handover and the sum of the average number of ping-pong events during the entry to and the exit from the IEEE 802.11b system below the predetermined values. We define the IEEE 802.11b network as the priority network for the mobile station. Thus, we maximize the time during which the mobile station is served by the IEEE 802.11b network while satisfying the QoS requirements in both networks, as well as the maximum call-dropping probability and the maximum average number of ping-pong event constraints. To solve this task, we propose a novel intersystem handover scheme that utilizes the minimum signal-to-noise ratio threshold, entry hysteresis, and exit hysteresis.