An optimal resource allocation based on the location probability for TVWS-assisted backhaul communications

This paper investigates how suitable TV White Space (TVWS) is for use by cellular networks. Unlike in licensed bands, transmit power in TVWS is limited and considerable interference from TV towers exists. This suggests that evaluating TVWS only in terms of available bandwidth can be misleading, since performance of wireless networks in TVWS is likely lower than in the same amount of dedicated spectrum. We quantify TVWS at the example of Germany, using the European methodology developed in CEPT ECC SE 43. In the second step, we determine the performance of a cellular network operating in TVWS using a calibrated multi-cell and multi-user system level simulation tool. This way we also consider interference between TVWS users, which in previous TVWS studies has not been investigated in detail. Not all locally available TV channels are equally useful. We thus compare different channel selection algorithms a TVWS operator could apply to select from the set of available TVWS channels. We found that while the available spectrum for TVWS usage is in theory quite high, its actual utility strongly depends on the channel selection method and the requirements it is based on. Due to the high interference from TV towers, cellular networks based on frequency re-use one (like LTE) have difficulties finding channels that allow good performance at the cell edge. The inner part of a cell can however considerably benefit from TVWS. This indicates that for cellular networks TVWS is primarily suitable for traffic offloading and spotty coverage rather than for building large contiguous coverage networks.

Unlicensed Operations in the Lower Spectrum Bands: Why is No One Using the TV White Space and What Does That Mean for the FCCCs Order on the 600 MHz Guard Bands?

The regulatory framework for secondary utilization of TV white spaces (TVWS) is well underway in the United Kingdom, while important steps in this direction are taken within the European Union and elsewhere. Mobile network operators are interested in the use of TVWS for cellular extension and rural access, where TVWS is seen as a significant new opportunity for operators to provide new wireless services. The government's plan to close the digital divide between the urban and rural communities has motivated the efforts to develop Wi-Fi like operation in TVWS for better coverage in rural areas. The IEEE currently has a working group developing 802.11af amendment which will allow for WLAN operations in the TVWS. This paper presents a quantitative analysis of downlink throughput performance of IEEE802.11af, also known as White-Fi in a rural environment while taking into account realistic modelling of TV channel availability, wireless channel, AP density, and the effect of co-channel interference caused by secondary APs and DVB-T transmitters. The paper shows that the low operating frequency of White-Fi offers a wide coverage in a rural environment, where there is limited cellular coverage due to the cost-inefficiency of base stations deployment. The presented results also show that there are more available TVWS channels and less co-channel interferers in a rural environment, resulting in a significant throughput performance even in high mobility if suitable channel estimation is considered, making it ideal for vehicular communications with White-Fi.

The IEEE 802.22 is a standard for wireless regional area networks to opportunistically operate in TV bands; however, sharing TV White Space (TVWS) spectrum creates a problem of coexistence because no mechanism is defined for coordinating channel usage among secondary networks. We propose a White Space Resource Sharing mechanism (WSRS) for fixed secondary and mobile IEEE 802.22 networks to improve network coexistence and spectrum efficiency. Based on power control and channel allocation, our mechanism allows the TVWS system to serve vehicular networks in scenarios where there are active secondary fixed networks and no more TVWS channels available for opportunistic usage. Unlike state-of-the-art mechanisms for coexistence in TVWS spectrum, our mechanism allocates resources to vehicles even when the density of fixed nodes and the transmission power of the fixed network cause high interference to the vehicular network. Our results show the offered channel capacity increases up to 50% using the proposed WSRS mechanism compared to the recent IEEE 802.22 standard that does not have a defined TVWS channel sharing mechanism. Furthermore, our WSRS mechanism implements a strategy to protect the fixed secondary network from interference caused by vehicular transmissions while promoting fair usage for both secondary networks.

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.

Spectrum scarcity demands for additional bandwidth where new services can be deployed on. However, today's spectrum allocation leaves almost no bands unallocated. Thus, Cognitive Radio has been studied to bring relief to the lack of spectrum, moving towards a more efficient and dynamic spectrum access. In this domain TV White Space have been proposed as a possible solution to bring new, valuable spectrum for opportunistic services. However, their availability is quite low in highly populated areas, and thus their viability is limited. This is mainly because the availability of TV White Space is typically considered at the rooftop, through two-dimensional propagation models which do not account for possible spectrum re-utilization policies within a building, or in a small-scale area. In this paper, we show that much more communication opportunities can be found when we consider also the third-dimension, i.e. the height from the terrain, and novel per-floor allocation policies. We propose three main contributions in this paper. First, we describe an analytical model through which we derive the number of available spectrum resources for indoor secondary networks, considering PU protection policies in the same building, and in surrounding buildings. Second, we estimate the number of TV Gray Space (TVGS) over realistic scenarios in candidate cities, considering realistic street topology and buildings locations, and we show that this value can be much higher than what reported in the spectrum database. Finally, we investigate co-existence of secondary networks on TVWS, when novel per-floor spectrum sharing models are used.

In order to implement the interweave cognitive radio solutions, the research for finding sparsely utilized spectrum bands has revealed the VHF and UHF television broadcast bands, known as television white spaces (TVWS) as the foremost candidate. The TVWS quantification and throughput analysis conducted via several measurement attempts and field trials uncover various facets of the TVWS spectrum measurement. Consequently, the conclusions obtained may be processed to get a statistical knowledge about spectrum availability in a particular geographic region and hence utilized for spectrum management. This paper explores inherent methodologies used for TVWS assessment and provides a comprehensive overview of the TVWS regulatory norms, results obtained by TVWS measurement campaigns and field trials conducted worldwide. In addition, research issues, implementation challenges and future directions for TVWS measurement procedure are highlighted.

Many rural and low-income areas around the globe have poor quality (or no) internet service with limited telephone coverage due to a lack of infrastructure, insufficient power supply, and a limited core telecommunications network. Because of limited mobile device propagation capabilities, sparse population density and poor purchasing power, it is not economically feasible for mobile operators to deploy traditional communication networks in these regions. Researchers recently discovered that a portion of the underutilized TV spectrum known as TV white space (TVWS) could be suitable for those areas in terms of bandwidth, improved reception features, good penetration of buildings, and broad reach. This paper presents a comprehensive evaluation of available TVWS channels in Ethiopia using a Geolocation Database front-end (GLSD) aided by the CSIR Calculation Engine hosted by the CSIR Meraka Institute. GLSD and the CSIR calculation engine together are able to quantify the amount of TVWSs through dynamically allocating the TVWS network radio services according to the geographic position of WSDs. The GLSD was developed using the ITU-R P.1546-5 propagation model. Using the GLSD and the CSIR calculation engine, the quantification of TVWS free channels are calculated. The results show that among the 58 VHF and UHF TV channels, 52 of the channels are free (underutilized) in Ethiopia. These free channels can be employed to provide wireless broadband solutions for connecting the rural areas as well as offloading the urban traffic.

The explosive growth of capacity-hungry wireless services are presenting challenges to the scarce spectrum resource. Operating LTE systems on TV white space may meet the capacity demand due to the good propagation characteristic. However, according to the decision on World Radiocommunication Conference 2012, TV white space is unable to be used by LTE systems exclusively in the near further in China. Cognitive technologies throw light on sharing TV white space between LTE and TV broadcasting systems. Taking 470– 806 MHz band as an example, the availability of deploying LTE systems on TV white spaces in China is studied in this paper. Firstly, the separation distance from LTE stations to the edge of TV coverage area is calculated. Then, the inter-site distance between TV and LTE stations are figured out using the separation distance and TV coverage radius. Combining the theoretical calculation with the deployment information of both analog and digital TV stations stored in the national station database, simulation results on the capacity distribution of cognitive LTE system in typical cities are given. The simulation results inferred that approximately 67% of TV channels are unused averaged over the cities. This result confirms quantitatively the often-stated expectation that white spaces can be shared by LTE systems to meet the capacity demand as well as improve the spectrum efficiency.

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.

OF THE THESIS Design Methodology for Backhaul and Distribution Networks Using TV White Spaces by Cyrus Gerami Thesis Directors: Narayan Mandayam and Larry Greenstein Since the FCCs approval of unlicensed use of TV white spaces, the issue of how to use these white spaces has led to innovative technologies such as cognitive radios as well as a variety of spectrum policy proposals. There have been proposals to devise alternate rules for spectrum usage citing the overly conservative restrictions on secondary transmissions to protect incumbents. In this thesis, instead, we propose to utilize white spaces for a backhaul network for internet traffic based on existing restrictions. Using the available white spaces and backhaul traffic demands in New Jersey as a case study, we evaluate the feasibility of such backhauling and present a methodology that can be used for other areas as well. Using a basic design involving fixed towers and directional antennas, our results show that the TV white spaces can be an effective medium for radio backhaul as an alternative to the costly laying of optical fiber. Although the most recent FCC ruling does not mandate protection of wireless microphones, we show that meeting the more stringent earlier FCC requirements on sensing and avoiding harm to wireless microphones would have only a minor impact on capacity. Finally, we study the aggregating of multiple data traffic flows at the nodes and show that, with proper engineering, multiple flows have but a slight effect on the need for optical fiber.

Connected vehicle technology provides many potential benefits on the road such as safety applications, effective traffic management, and mobile Internet access. In order to mitigate the resulting high spectrum demands and provide vehicular connectivity with wider communication range, higher transmission rate, and lower data transfer cost, in this article, we exploit the abundant TV white space with superior propagation characteristics and building penetration performance. We first present the application scenarios exploiting TV white space in heterogeneous connected vehicular communication networks, and discuss white space channel availability and characteristics for vehicular communications. We then propose TV white space geolocation database based vehicular communication architectures for vehicle-to-infrastructure (V2I) communications and vehicle-to-vehicle (V2V) communications. Finally, we highlight the key technical challenges and pinpoint future research directions toward exploiting TV white space for vehicular communication networks.

In recent years, as a demand for communication services over the VANET (Vehicle Ad-hoc Network) is increasing drastically, radio frequencies to be assigned to the new communication services are becoming insufficient. In response to this problem, we consider to apply the cognitive radio technology in general, and the cognitive use of TV white space based on the white space database (WSDB) in particular, to the VANET where communication nodes (vehicles) move fast and for a long time. In order to provide stable and efficient communications over TV white space in VANET, (1) the quick acquisition of the status of license/primary users at the location and (2) the dynamic selection of an appropriate data channel are essential. To fulfill those two requirements, in this paper, we propose a database driven data channel selection scheme for VANET over TV white space. Through simulation experiments, we showed that the proposed scheme can reduce not only channel switching but also channel collision rate with a good balance, thereby improving the throughput performance as well.1

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.

Integrating cognitive radio into the current power grid is designed to enable smart communication and decisions within the grid. Communication within the grid is not feasible without channel(s) and most studies have emphasized the use of cellular spectrum. This study proposes a strategy that enables the use of television white space (TVWS) within the grid. To be specific, we propose using a next-generation utility network (Next-GUN), which leverages on the cognitive radio (CR) channel aggregation capability. This strategy enables the aggregation of idle TVWS into a usable channel, thus making the Next-GUN different from the traditional power network. Next-GUN differs in terms of security, reliability, self-awareness, and cross-layer compatibility to the interface, and conveys different traffic classes, thereby making it a hybrid system. It has no dedicated channel assigned to it, and hence, utilizes the idle TVWS opportunistically to transmit data. The proposed scheme was modelled as a Markovian process and analyzed using a continuous time Markov chain (CTMC). Extensive system simulations were performed to evaluate this proposed model and the corresponding comparison with the literature was done to see the improvement. The result of our comparisons shows that when channels are aggregated, more data/information are transmitted. In addition, the use of cognitive radios on a power network enables smart transaction because idle TVWS is utilized instead of congesting the GSM spectrum. Lastly, the power utility establishment can save the cost of paying for a licensed spectrum.