Short Range White Space Utilization in Broadcast Systems for Indoor Environments

Growing demand of reliable and affordable wireless connectivity requires alternative solutions and television white space (TVWS) provides that opportunity. However, the biggest challenge in TV spectrum re-use is to allocate best channels for secondary user while maintaining good Quality of Service (QoS). Allocation of Secondary User (SU) channels with less interference to Primary User (PU) is still a challenge not only to academia research communities but to industry as well. We studied the spectrum selection method of geo-location database (GLDB) that provides certainty in selecting available white space spectrum in the geographical area of request. The Internet Engineering Task Force (IETF) developed a standard communication protocol between the GLDB and white space devices (WSD) in order to establish reliable communication method for WSD. In this paper, a protocol to access white space (PAWS) method combined with analytical hierarchy process (AHP) is proposed for best channel selection from the GLDB. MATLAB simulation platform was used to test the performance of the proposed technique. The results show that the algorithm using proposed AHP based method (with deterministic queuing model within WSD) selects the best operating channel based on a better global priority vector (GPV). The numerical results show that the proposed selection technique is capable of selecting the best channels that satisfy the QoS for SUs profiles as compared to existing techniques.

We propose a novel information market for TV white space networks, where white space databases sell the information regarding the TV channel quality to unlicensed white space devices (WSDs). Different from the traditional spectrum market, the information market demonstrates the positive network externality, as more WSDs purchasing the information from a database will increase the value of the database's information to each of its buyers. We study an oligopoly information market, where two competitive databases compete to sell their information to WSDs, and WSDs decide whether and from which database to purchase the information. Specifically, we first derive the WSD's optimal purchasing behavior under fixed information prices, and show how the market share of each database dynamically evolves over time. We then characterize the market equilibrium, where no WSD has an incentive to change its purchasing behavior. Our analysis indicates that given the prices of databases, there may be multiple market equilibria, and which one actually emerges depends on the initial market shares of both databases. We further show that some equilibria are stable, in the sense that a small fluctuation on the equilibrium will drive the market back to the equilibrium, while some equilibria are not.

One of the many standards developed recently for television white space operation is the IEEE 802.11af wireless LAN in TV white space. This white space device as a secondary user (SU) must not cause damaging interference to an incumbent primary user(PU) such as the ISDB-T digital TV service and even to an existing Analog TV Broadcast. To ensure interference-free coexistence, a keep-out distance, d <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</inf> , between the white space device (WSD) transmitter and the PU within the licensed TV service contour should be strictly observed. However, it is important that this d <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</inf> must neither be overestimated nor underestimated. In this paper, co-channel d <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</inf> between IEEE S02.11af and the ISDB – T DTV and Analog service contours using primarily ITU-R P.1546-6 and ITU–R P.1411-9 recommendations was computed and compared for the eleven analog and digital channels operating in Cebu province, Philippines. Experimental tests conducted show that analog and digital TV broadcast channels are aptly protected from co-channel interference emanating from IEEE 802.11af secondary white space devices operating within its service contour. Interestingly, the study also shows that a pair of IEEE 802.11af devices can establish connectivity within the ITU-R P.1546-based keep-out distance without causing interference to ATV and DTV services.

in television white space networks, secondary users are mandatory to query an accredited geo-location spectrum database (GSDB) in order to determine the vacant channels or white spaces. The recent developments of the Protocol to Access White Spaces (PAWS) by the Internet Engineering Task Force (IETF) have proposed to standardize communication between the GSDB and white space devices. To enable efficient sharing of spectrum, white spaces devices (WSDs) and their related restrictions, the mechanism or channel selection remain open issues in research. In this paper, we proposed use of PAWS and JavaScript Object Notation (JSON) to address the communication between the GSDB and WSDs to enable optimal channel selection decisions in the set-top box making it a smart set-top box.

TV White Spaces (TVWS) has taken a major step forward with the UK regulator Ofcom initiating a pilot of the technology and associated procedures in the UK, and TVWS rules being harmonized at the European level. This paper considers some aspects of our trial within the Ofcom TV White Spaces Pilot, namely, investigation of aggregation in TVWS and the deployment and testing of IEEE 802.11 white space devices that are capable of aggregating up to 4 TV channels, contiguously or non-contiguously. Our trial is the only deployment of these devices, developed at InterDigital in the USA, within the Ofcom TV White Spaces Pilot. This paper discusses the specifics of the InterDigital devices, including their design and capabilities. Further, results are presented highlighting what is possible in TVWS through contiguous aggregation. These results are achieved through per-channel allowed EIRP and capacity analyses based on feedback from a TVWS database within the Ofcom Pilot, using TVWS functionality developed at King's College London. Additional results outline the added benefit of optimal non-contiguous aggregation. Finally, this paper performs a like-for-like comparison of the performance of the InterDigital devices against what is theoretically possible in TVWS through capacity analyses using feedback from the TVWS database.

In this paper, we investigate how to acquire spectrum information for accessing the available TV white space quickly. It is known that the load of secondary device can be reduced by utilizing geolocation database. A channel allocation algorithm based on geo-location and positioning accuracy is proposed by using geo-location database in order to further reduce the secondary device's load and sensing cost. Based on the geo-location and positioning accuracy of white space devices (WSDs), the proposed algorithm first allocates the available channels to the WSD which locates outside the keepout region of TV stations. Then, it allocates the channels to the WSDs within the scope of protection of TV station, and in this case the WSD has to sense the allocated channels to determine whether they are idle using the energy detection algorithm. Detailed simulations show that the proposed algorithm effectively reduces the sensing costs and information feedback overhead, and improves the throughput and spectrum efficiency of the whole system.

Motivated by the low utilization of the licensed spectrum across many frequency bands, sensing-based oppor- tunistic spectrum access has recently emerged as an alternative to the outdated exclusive spectrum access policy. Under this new paradigm, a secondary (unlicensed) user monitors a primary (licensed) frequency band for a given and opportunistically transmits if it does not detect any ongoing licensed operations. Evidently, selection of the parameters involves balanc- ing a tradeoff between the speed and the quality with which the secondary user senses the licensed band. With the average throughput as the performance criterion, we obtain the parameters so as to optimize the performance of the secondary user while providing the primary user with its desired level of interference protection. I. INTRODUCTION As evidenced by recent measurements, many frequency bands across the licensed spectrum are significantly under- utilized (1), (2). This finding suggests that the spectrum scarcity, as perceived today, is largely due to the inefficient fixed frequency allocations rather than the physical shortage of the spectrum and has led the regulatory bodies to consider the opportunistic access to the temporally/spatially unused licensed bands (a.k.a. the white spaces) as a means to improve the efficiency of spectrum usage. In the absence of cooperation or signalling between the primary licensee and the secondary users, spectrum availability for the opportunistic access may be determined by direct spectrum where the secondary user monitors a licensed band for a given sensing time and opportunistically transmits if it does not detect any ongoing licensed operations. This approach is particularly appealing due to its low deployment cost and its compatibility with legacy primary users and is being considered for inclusion in the upcoming IEEE 802.22 standard for opportunistic access to the TV spectrum (3). Due to their ability to autonomously detect and to react to the changes in the spectrum usage, secondary users equipped with the spectrum capability may be considered as a primitive form of the cognitive radio (4). Design of any scheme involves balancing a tradeoff between the quality and the speed of through an appropriate selection of the time. As we shall illustrate, in the context of spectrum sensing, may be fine- tuned to enhance the secondary users' perceived quality-of- service (QoS) as long as the regulatory constraint for the protection of the primary users against harmful interference is satisfied. In particular, we will obtain the optimum times at different stages of the spectrum to maximize the average throughput of the secondary user. In this paper, simple energy detection (a.k.a. radiometry) (5) is chosen as the underlying detection scheme. In general, when some information about the structure of the primary signal is available, ad hoc feature-detectors offer a better performance (6). We note, however, that the methodology employed in this paper may be applied to optimize different spectrum sensors once the quality is characterized in terms of the time. The remainder of this paper is organized as follows. The regulatory constraints on spectrum are described in the following section. Section 3 provides an overview of the energy-based spectrum sensing. The optimum times for different stages of the spectrum are derived in Section 4. Finally, this paper is concluded in Section 5.

The aim of this thesis is the study of techniques for efficient management and use of the spectrum based on cognitive radio technology. The ability of cognitive radio technologies to adapt to the real-time conditions of its operating environment, offers the potential for more flexible use of the available spectrum. In this context, the international interest is particularly focused on the “white spaces” in the UHF band of digital terrestrial television. Spectrum sensing and geo-location database have been considered in order to obtain information on the electromagnetic environment. Different methodologies have been considered in order to investigate spectral resources potentially available for the white space devices in the TV band. The adopted methodologies are based on the geo-location database approach used either in autonomous operation or in combination with sensing techniques. A novel and computationally efficient methodology for the calculation of the maximum permitted white space device EIRP is then proposed. The methodology is suitable for implementation in TV white space databases. Different Italian scenarios are analyzed in order to identify both the available spectrum and the white space device emission limits. Finally two different applications of cognitive radio technology are considered. The first considered application is the emergency management. The attention is focused on the consideration of both cognitive and autonomic networking approaches when deploying an emergency management system. The cognitive technology is then considered in applications related to satellite systems. In particular a hybrid cognitive satellite-terrestrial is introduced and an analysis of coexistence between terrestrial and satellite networks by considering a cognitive approach is performed.

The television white space (TVWS) spectrum presents a promising opportunity to extend wireless broadband access, particularly in rural, underserved, and hard-to-reach communities. To leverage this potential, low-power radio communication equipment must efficiently utilise the TVWS spectrum on a secondary basis while ensuring strict compliance with regulatory requirements to prevent harmful interference to primary services. This paper presents a comparative performance analysis of TVWS radio equipment from three original equipment manufacturers (OEMs). The equipment under test was identified to reflect each OEM, as follows: OEM 1 and OEM 2 from South Korea and OEM 3 from the USA. We evaluated their performance in two real-world field scenarios, namely outdoor short-distance and outdoor long-distance. The evaluation was based on the following key metrics: (i) spectrum utilisation efficiency (SUE), (ii) received signal strength (RSS), (iii) downlink throughput, and (iv) connectivity to the Geo-Location Spectrum Database (GLSD) in compliance with the South African TVWS regulatory framework. The overall preliminary experimental results indicate that in both scenarios, white space devices (WSDs) based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11af Standard demonstrated better performance than those based on the 3rd Generation Partnership Project Long-Term Evolution-Advanced (3GPP LTE-A) Standard in terms of the SUE, downlink throughput, and RSS metrics. All WSDs under test demonstrated sufficient compliance with the regulatory requirement metric.

TV white spaces offer an exciting opportunity for increasing spectrum availability, but white space devices (WSDs) cannot interfere with primary users, including TV channels and wireless microphones (mics). Mics are particularly challenging because their use is dynamic and it is hard to avoid interference since mic receivers are receive-only devices. For this reason the FCC and other regulatory agencies have made very conservatives rules that require WSDs to vacate any TV channel that is used by a mic. However, our measurements show that mics typically require only 5% of a channel, wasting as much as 95% of the spectrum.

Advent of TV white space digitization has released frequencies from 470 MHz to 790 MHz to be utilized opportunistically. The secondary user can utilize these so called TV spaces in the absence of primary users. The most important challenge for this coexistence is mutual interference. While the strong TV stations can completely saturate the receiver of the cognitive radio (CR), the cognitive radio spurious tones can disturb other primary users and white space devices. The aim of this paper is to address the challenges for enabling cognitive radio applications in WLAN and LTE. In this process, architectural considerations for the design of cognitive radio front ends are discussed. With high-IF converters, faster and flexible implementation of CR enabled WLAN and LTE are shown. The effectiveness of the architecture is shown by evaluating the CR front ends for compliance of standards namely 802.11b/g (WLAN) and 3GPP TS 36.101 (LTE).

The IEEE 802.11af standard is a wireless local area network that operates in the television white space, requiring it to avoid inducing damaging interference to licensed users such as incumbent digital and television services. To achieve this, precise tools for estimating path loss are essential to prevent both underestimation and overestimation, which could either limit the coverage of White Space Devices (WSDs) or fail to adequately shield primary or licensed users from unwanted emissions produced by secondary WSDs. This paper examines and compares the performance of various models for path loss, including Free Space Path Loss (FSPL), relevant portions of Recommendation ITU-R P.1411-11, and the linear and logarithmic regression models, against field measurement data to identify the most suitable path loss estimation model. The findings indicate that the logarithmic regression model exhibits the Root-Mean-Square Error (RMSE) that has the best performance, with a mean estimation error of 5 dB across all experimental locations where measurements were conducted. Additionally, the study suggests that the path loss model for free space can effectively provide a conservative path loss estimate for all sites, with an average overestimation of 18 dB, thereby ensuring adequate protection for primary users against potential interference from secondary users.

In cognitive radio, wireless ad hoc networks, the rapid changes in environment in addition to heterogeneous spectrum availability among the CR users resulted in the connectivity and stability problem of the network. A cluster structure is seen as an effective technique to overcome this problem. Presently, most existing works in cognitive radio focus on forming clusters under the homogenous channel model. Withal, the channels that are situated in vastly isolated frequency bands show a remarkable heterogeneity in transmission ranges. In this paper, we proposed a greedy heuristic algorithm for clustering to identify the effect of channel heterogeneity on cluster formation performance. A new metric for cluster head selection named selection factor is proposed. This metric is computed based on the number of available channels, the number of common channels that a CR user share with each of its neighbors, channel reward (coverage) for the available channels and the number of neighbors. To the best of our knowledge this is the first effort to add the channel heterogeneity into the formulation of cluster head election in cognitive wireless networks. We investigate the clustering formation, performance for the CRAHN under both heterogeneous and homogeneous channel models. Particularly, we evaluate the average number of clusters, cluster size, number of common available channels within each cluster and load balance among clusters. The algorithm has been implemented and tested using Matlab. Simulation results revealed that the performance of clustering is significantly affected by the channel heterogeneity.

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.

This paper proposes a spatial time-division multiple access (STDMA) based scheme (STBS) to enhance the system throughput in cognitive radio wireless networks. Especially, the proposed scheme is suitable for the situation when the available number of channels is far less than the number of secondary users (SUs). The system design includes: 1) a novel criterion based on SINR constraint (SC) to determine the feasibility of spatial reuse of spectrum; 2) a heuristic spectrum allocation and scheduling (HSAS) algorithm. Simulation results show that in comparison with the STBS based on Interference range (IR) criterion proposed in [5], the proposed scheme can improve the system throughput as much as 100% when the number of channels is 1/5 of the number of users as well as guarantee a low outage ratio of system blow 2% in various scenarios.