Kentaro Ishizu

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.

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.

A series of trials in the UK as part of the Ofcom TV white spaces pilot

TV White Spaces technology is a means of allowing wireless devices to opportunistically use locally-available TV channels (TV White Spaces), enabled by a geolocation database. The geolocation database informs the device of which channels can be used at a given location, and in the UK/EU case, which transmission powers (EIRPs) can be used on each channel based on the technical characteristics of the device, given an assumed interference limit and protection margin at the edge of the primary service coverage area(s). The UK regulator, Ofcom, has initiated a large-scale Pilot of TV White Spaces technology and devices. The ICT-ACROPOLIS Network of Excellence, teaming up with the ICT-SOLDER project and others, is running an extensive series of trials under this effort. The purpose of these trials is to test a number of aspects of white space technology, including the white space device and geolocation database interactions, the validity of the channel availability/powers calculations by the database and associated interference effects on primary services., and the performances of the white spaces devices, among others. An additional key purpose is to undertake a number of research investigations such as into aggregation of TV White Space resources with conventional (licensed/unlicensed) resources, secondary coexistence issues and means to mitigate such issues, and primary coexistence issues under challenging deployment geometries, among others. This paper describes our trials, their intentions and characteristics, objectives, and some early observations.

Dynamic Spectrum Assignment and Access Scenarios, System Architecture, Functional Architecture and Procedures for IEEE P1900.4 Management System

Implementing dynamic spectrum assignment and access technologies in heterogeneous wireless networks may lead to considerable improvement in spectrum usage. For this purpose, management system shall be added on top of existing heterogeneous wireless system. IEEE P1900.4 working group has been developing such management system. In this paper, we propose different scenarios for IEEE P1900.4 dynamic spectrum assignment and access use cases. We propose enhancements to IEEE P1900.4 system architecture. Also, we propose functional architecture for IEEE P1900.4 management system. Finally, we propose generic procedures to implement proposed scenarios using proposed system architecture.

Bullet-train Network Architecture for Broadband and Real-time Access

New services on trains are attracting a great deal of attention throughout Europe and Asia where trains are one of the most important forms of transportation. We introduced two information services on bullet-trains; Internet access and video. There are three technical challenges posed by seamless handover at 300 hn/h, aggregation of multiple access, and attack-tolerant communications. We proposed a network architecture to solve them based on the requirements of these services. Due to its extendibility and flexibility, new services that will be introduced in the future can be integrated easily. We are currently developing a tested for experimental evaluations.

Some Initial Results and Observations from a Series of Trials within the Ofcom TV White Spaces Pilot

TV White Spaces (TVWS) technology allows wireless devices to opportunistically use locally-available TV channels enabled by a geolocation database. The UK regulator Ofcom has initiated a pilot of TVWS technology in the UK. This paper concerns a large- scale series of trials under that pilot. The purposes are to test aspects of white space technology, including the white space device and geolocation database interactions, the validity of the channel availability/powers calculations by the database and associated interference effects on primary services, and the performances of the white space devices, among others. An additional key purpose is to perform research investigations such as on aggregation of TVWS resources with conventional resources and also aggregation solely within TVWS, secondary coexistence issues and means to mitigate such issues, and primary coexistence issues under challenging deployment geometries, among others. This paper provides an update on the trials, giving an overview of their objectives and characteristics, some aspects that have been covered, and some early results and observations.

Design and Implementation of A Distributed Radio Resource Usage Optimization Algorithm for Heterogeneous Wireless Networks

We have designed and implemented a radio access network selection algorithm for heterogeneous wireless network environment, in which mobile terminals can adaptively and seamlessly handover among different radio access technologies. We propose a radio resource usage optimization algorithm without centralized computation on the network side, which is based on the Hopfield neural network dynamics whose energy function autonomously minimizes by distributed update of each neuron. We have implemented the proposed algorithm on an experimental heterogeneous wireless network system, which includes functionalities defined in IEEE 1900.4. First, we show that the proposed algorithm can optimize fairness of the throughput by numerical simulation. Then, we show that our algorithm works correctly and optimizes radio resource usage also on the experimental wireless network by distributed handover decisions on the terminal side.

Research, Development, and Standards Related Activities on Dynamic Spectrum Access and Cognitive Radio

This paper introduces NICTs two current on-going projects regarding heterogeneous type and spectrum sharing type cognitive wireless network: Project CWC (Cognitive Wireless Cloud) and Project ASTRA (Advanced Spectrum-Management Technology for Radio Access innovation). For both projects, this paper summarizes the scope, usage model, system requirement, system architecture, prototyping, and standard activities.