Cognitive Pilot Channel Research Articles

CPC-based backward-compatible network access for LTE cognitive radio cellular networks

Network access plays an important role in LTE cognitive radio (LTE-CR) cellular networks in determining users’ experiences. An overview is first carried out on network access schemes in existing cognitive cellular networks such as IEEE 802.22 and IEEE 1900.4, based on which it can be seen that cognitive pilot channel (CPC)-based network access is a promising scheme for LTECR, which may provide fast network access and put no stringent requirements on terminals. Next, considering the implementation issues of CPC in practical systems, a CPC-based backward- compatible network access scheme should be designed for LTE-CR to facilitate the application of CR in LTE networks, which could exploit existing LTE structures and technologies to carry CPC information. To achieve this, a new system information block (SIB) should be designed to carry CPC on a current physical downlink shared channel with little standards effort. Moreover, load awareness is introduced so that LTE-CR is activated only when the system load is high. The complete process of this SIB-CPC-based backward-compatible and loadaware network access is described, and its performance is evaluated via simulations. It is shown that the blocking ratio of LTE-CR can be reduced notably compared to that of conventional LTE without CR. Moreover, by selecting an appropriate load threshold to activate LTE-CR, the average user throughput of LTE can be improved with near-zero blocking ratio by offloading users to complementary cognitive spectra.

A realisation of broadcast cognitive pilot channels piggybacked on T‐DMB

ABSTRACTThis paper considers the realisation of a broadcast out‐of‐band cognitive pilot channels (CPC) piggybacked on a Terrestrial Digital Multimedia Broadcasting (T‐DMB) platform. The solution satisfies the requirements of coverage‐based CPC schemes. The main goal of these is the enabling of the information transfer to mobile terminals of available knowledge of the wireless network environment, including available radio access networks, frequency bands, network policies and such like information. The proposed CPC solution is first contextualised within the range of CPC concepts, which have been and are being researched. Then, a three‐layer ‘CPC over T‐DMB’ system architectural design is set out. A prototype of the scheme is realised and implemented on a testbed, the design of which is outlined, and through which the key technological concepts are validated and their technical performance evaluated. The results of these system evaluations are presented and discussed. Copyright © 2013 John Wiley & Sons, Ltd.

Interference Aware Routing Game for Cognitive Radio Multi-Hop Networks

In this paper, we introduce a distributed dynamic routing algorithm in multi-hop cognitive radio (CR) networks, in which secondary users (SUs) want to minimize their interference to the primary users (PUs) while keeping the delay along the route low. We employ a cognitive pilot channel (CPC) for SUs to be able to access the information about PUs, including PUs' locations and channel conditions. Medial axis with a relaxation factor is used as a reference path for the routing, along which we develop a hierarchical structure for multiple sources to reach their destinations. We introduce a temporal and spatial dynamic non-cooperative game to model the interactions among the SUs as well as their influences on the PUs, and obtain by backward induction a set of mixed (behavioral) Nash equilibrium strategies. We also employ a multi-stage fictitious play learning algorithm for distributed routing, which minimizes the overall interference from the SUs to the PUs, as well as the average packet delay along the route from the SU nodes to their destinations. Simulation results show that our proposed algorithm can avoid congestion in the CR network and minimize delay while keeping the interference level low.

Fractal theory based dynamic mesh grouping scheme for efficient cognitive pilot channel design

As one of the key characteristics in cognitive wireless networks (CWNs), network environment awareness techniques have received much attention recently. Instead of traditional spectrum sensing technology that suffers from problems of miss detection, false alarm, hidden node, and inefficiency, cognitive pilot channel (CPC) technology has been proposed as one of the candidate solutions for an efficient and accurate network information delivery scheme to user equipment (UE). The aim of the CPC technology is to provide the necessary information for the reconfiguration of the UE using the public signaling channel. To ensure the efficient information delivery, the whole geographical area covered by the CPC is divided into square meshes of the same size. Moreover, two typical network information transmission modes for CPC deployment are also proposed: broadcast CPC mode and on-demand CPC mode. To further improve the efficiency of network information delivery, an efficient dynamic mesh grouping scheme has been designed which is based on the fractal theory for the broadcast CPC mode, where adaptive rectangular sized meshes are used to approximately cover the whole area. Compared to the traditional fixed size mesh division strategy, results show that the proposed dynamic mesh grouping scheme significantly reduces the number of meshes by grouping similar meshes together, and the average delay of receiving CPC information on the UE side is therefore reduced.

Dynamic Pilot Channel Transmission with Adaptive Receive Filter Configuration for Cognitive Radio System

When a cognitive radio system dynamically utilizes a frequency band, channel control information must be communicated over the network in order for the currently available carrier frequencies to be shared. In order to keep efficient spectrum utilization, this control information should also be dynamically transmitted through channels such as cognitive pilot channels based on the channel conditions. If transmitters dynamically select carrier frequencies, receivers must receive the control signal without knowledge of its carrier frequencies. A novel scheme called differential code parallel transmission (DCPT) enables receivers to receive low-rate information without any knowledge of the carrier frequency. The transmitter simultaneously transmits two signals whose carrier frequencies are separated by a predefined value. The absolute values of the carrier frequencies can be varied. When the receiver receives the DCPT signal, it multiplies the signal by a frequency-shifted version of itself; this yields a DC component that represents the data signal, which is then demodulated. However, the multiplication process results in the noise power being squared, necessitating high received signal power. In this paper, to realize a bandpass filter that passes only DCPT signals of unknown frequency and that suppresses noise and interference at other frequencies, a DCPT-adaptive bandpass filter (ABF) that employs an adaptive equalizer is proposed. In the training phase, the received signal is the filter input and the frequency-shifted signal is the training input. Then, the filter is trained to pass the higher-frequency signal of the two DCPT signals. The performance of DCPT-ABF is evaluated through computer simulations. We find that DCPT-ABF operates successfully even under strong interference.

Efficient Mesh Division and Differential Information Coding Schemes in Broadcast Cognitive Pilot Channel

Driven by the inevitable trends of heterogeneous network convergence and cooperation technology innovations have been put forward to improve the spectrum usage efficiency, such as the Cognitive Radio (CR) technology. As one of the candidate solutions for heterogeneous network information delivery for dynamic spectrum sharing in CR environment, the Cognitive Pilot Channel (CPC) techniques are proposed, which greatly improve the efficiency and accuracy of network information delivery to User Equipments. Based on the assumption that the geographical region is divided into meshes and covered by different Radio Access Technologies (RATs), an Efficient Mesh Division (EMD) scheme is brought forward by taking into account both the error probability parameter in the Global Position System localization shift scenario and the information loss ratio parameter in the multi-RATs overlapped scenario. Besides, the impacts of these parameters to the EMD scheme are analyzed and evaluated by using the Analytic Hierarchy Process and Grey Relational Analysis algorithms. Furthermore, in order to improve the efficiency of network information coding among different meshes, the Differential Information Coding (DIC) scheme is put forward, which includes the Homogeneous Meshes Grouping scheme that is based on the frequency occupancy graph and the basic mesh selection strategy with the most popular commonality using image processing techniques. In virtue of the DIC scheme, the duplicate network information in homogeneous meshes is greatly reduced and information coding efficiency is improved by quantizing only the differential information against the basic mesh. Finally, contributions of the proposed EMD and DIC schemes reside in the improvements of the accuracy and efficiency of heterogeneous network information delivery via broadcast CPC channel, which are proved by numerous results.

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.

Novel Research on Cognitive Pilot Channel in Cognitive Wireless Network

With the irreversible trend of the convergence and cooperation among heterogeneous wireless networks, the need for network information awareness of user equipments (UEs) becomes increasingly imperative in the Cognitive Wireless Network (CWN). As one of the candidate solutions for network information delivery for UEs, the Cognitive Pilot Channel (CPC) concept has been brought forward recently, providing UEs with the necessary network information for network selection by using the public signaling channel. Furthermore, the coverage area of CPC is divided into meshes and terminals could receive corresponding information according to their location in mesh. In this paper, an optimal mesh division scheme in CPC is brought forward, trying to analyze the impacts of different parameters such as the delivery information accuracy, information loss and position accuracy to the mesh division scheme. In order to improve the on-demand CPC delivery efficiency, an optimized multicast CPC scheme is designed and evaluated, which remarkably reduces the time delay of information delivery. Numeric experimental results validate the rationality and effectiveness of the proposed scheme and strategy.

Q-learning based heterogenous network self-optimization for reconfigurable network with CPC assistance

With the irreversible trend of the convergence and cooperation among heterogeneous networks, there emerge some important issues for network evolution. One of them is to reconfigure network elements such as cellular base stations (BSs) or access points (APs) of wireless local area networks (WLANs) according to the real-time network environment, in order to maximize the cooperation gain of different networks. In this paper, we consider cognitive pilot channel (CPC) as an assistant to enable cooperation among heterogeneous networks. Based on the widely used reinforcement learning algorithm, this paper has proposed the heterogeneous network self-optimization algorithm (HNSA) to solve the adaptation problem in reconfigurable systems. In the algorithm, distributed agents perform reinforcement learning, and make decisions cooperatively with the help of CPC in order to reduce the system blocking rate and improve network revenue. Finally our simulation proves the anticipated goal is achieved.

Flexible spectrum and future business models for the mobile industry

The concept of flexible spectrum is often considered as a medium-to-long-term solution to overcome some of the current inefficiencies and high entry barriers plaguing the mobile industry. Increasingly, a cognitive pilot channel (CPC) is regarded as a central enabler for flexible spectrum. This paper outlines the CPC concept from a business point of view and clarifies its current status in the standardization and regulation fields. The idea of a worldwide CPC will be under consideration by the World Radio Conference in 2011. Based on several potential CPC implementations, the paper identifies a number of flexible spectrum business configurations and revenue sharing models. It also performs an initial forward-looking evaluation of these models using a business model scorecard approach, and finds that while the scope appears to be limited for a fully competitive, cross-operator spectrum market, several platform models (e.g. association or consortium models) stand out as feasible options.

Decentralized spectrum and radio resource management enabled by an on-demand Cognitive Pilot Channel

This paper presents a framework to achieve an efficient dynamic and decentralized spectrum and radio resource usage in heterogeneous wireless network scenarios. The envisaged technical solution follows a layered approach, where joint radio resource management (JRRM) and advanced spectrum management mechanisms are identified at both the intra- and inter-operator levels. The importance of cognitive network functionalities is highlighted. An on-demand Cognitive Pilot Channel (CPC) is proposed as radio enabler solution for decentralized operation with decision making processes executed at the mobile terminal side. The suitability of the proposed solution is shown by comparison with a broadcast CPC approach. Finally, the paper presents and evaluates decentralized JRRM algorithms both at the intra- and inter-operator levels using the proposed framework.

The business model impact of flexible spectrum management and cognitive networks

PurposeThis paper aims to give a short overview of European Union policy trends towards more flexible forms of spectrum management.Design/methodology/approachThe paper presents a business modelling analysis, scenario construction, policy analysis and roadmapping. It argues that both flexible spectrum management and the concept of reconfigurability do not eliminate the need for a number of centralised controlling entities, and even introduce a number of new ones, performing regulatory, commercial and technical functions of a diverse nature. One of the most prominent control entities, the Cognitive Pilot Channel (CPC), is presented, and three different configurations of the CPC are outlined. Subsequently, the potential impact of different CPC configurations on business models for wireless services making use of such a channel is explored.FindingsThe paper concludes that a hybrid model combining a meta‐level CPC with operator‐deployed channels might provide the best mix of technical and strategic control for operators, and value for users.Research limitations/implicationsThe study undertaken here is exploratory in nature since, for example, no exact estimations of cost and revenue, or harmonisation feasibility and roadmaps can be made at this time.Originality/valueThe CPC is a recent and potentially crucial concept which is not yet standardised or implemented and for which no business modelling analysis has been performed yet.