Busy tone based coexistence algorithm for WRAN and WLAN systems in TV white space

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.

A novel 802.11ah transmitter for TV white space (TVWS) band devices is presented. To realize the transmitter meeting the stringent FCC and ETSI TVWS device emission limits for the adjacent channels and FCC restricted bands, a low noise and high linear class- AB voltage- to-current converter (V2I) as the mixer driver and a 2nd -order harmonic notch filter with the frequency tracking capability on the power amplifier (PA) load are newly proposed. The designed transmitter is implemented in a 40nm CMOS process as a part of the TVWS band 802.11ah connectivity System-on-Chip (SoC), and the measured results with the 802.11ah CBW4 signal show −55dBr and −58dBr Adjacent Channel Leakage Ratio (ACLR) at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 3\mathbf{MHz}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 20\mathbf{MHz}$</tex> frequency offset, respectively, and 60dB 2nd harmonic rejection for 470MHz ~ 790MHz TVWS bands. This transmitter is the first SoC level transmitter meeting the FCC and ETSI ACLR requirements.

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?

Localization is the enabling technology of geolocation database assisted Cognitive Radio Networks (CRN) in TV White Space (TVWS), as the location is required in the implementation of geolocation database approach by regulators such as FCC and Ofcom. This paper proposes a novel Sensing enAbled Localization and Tracking (SALT) system, which locates Secondary Users (SUs) and tracks their movements. In particular, the system localize SUs based on their measurement of Primary User (PU) signals in the TV spectrum. SALT also uses the SU movement information to dynamically manage the available spectrum with an optimal spectrum allocation algorithm based on the location estimation, so as to maximize the uplink throughput of the entire network. The performance of the proposed localization and tracking algorithm is verified with field measurement data from complex environment through extensive experimentation.

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 this chapter, Joint Radio Resource Management (JRRM) issues in cognitive networks are discussed presenting the TV White Spaces (TVWS) spectrum exploitation use case. TVWS are portions of UHF spectrum, which will be released and interleaved according to the geographical region due to the gradual switch-off of analogue TV and the adoption of digital TV. With the availability of TVWS and their temporary lease, traditional network planning and RRM design rationale points need to be enhanced. This chapter provides state-of-the-art work for existing cognitive radio network architectures, while a reference architecture for commons and secondary TVWS trading is proposed. Subsequently, JRRM concepts for heterogeneous Radio Access Technologies’ extension over TVWS aiming to continuously guarantee the QoS, the network key performance indicators, and at the same time targeting the overall highest system capacity, are presented. Finally, a thorough classification of existing admission control and scheduling techniques are provided, outlining the need for including continuously more cognitive and context-aware features in JRRM algorithms being applicable in advanced Heterogeneous Networking (HetNet) environments.

In this paper, we propose a novel information market for TV white space networks, where the spectrum database operator sells the information regarding TV white space to secondary users. Different from the traditional spectrum market, the information market processes the unique property of positive externality, as more users purchasing the information service will increase the value of the service to each buyer. We systematically characterize the market equilibrium and the database operator's optimal information pricing strategy. Specifically, we first study how the market share dynamically evolves over time and eventually converge to a market equilibrium. We show that the market equilibrium increases with the initial market share, and there exist several tipping points of the initial market share, around which a slight change will lead to a significant change on the emerging market equilibrium. Based on the market equilibrium analysis, we further study the impact of the database operator's information pricing strategy on the market equilibrium, and derive the optimal information price that maximizes the database operator's revenue. Theoretical analysis and numerical result indicate that this is a promising business model for creating incentives for the database operator in TV white space networks.

We investigate the distributed spectrum management problem in opportunistic TV white space (TVWS) systems using a game theoretical approach that accounts for adjacent-channel interference and spatial reuse. TV band devices (TVBDs) compete to access idle TV channels and select channel “blocks” that optimize an objective function. This function provides a tradeoff between the achieved rate and a cost factor that depends on the interference between TVBDs. We consider practical cases where contiguous or noncontiguous channels can be accessed by TVBDs, imposing realistic constraints on the maximum frequency span between the aggregated/bonded channels. We show that under general conditions, the proposed TVWS management games admit a potential function. Accordingly, a “best response” strategy allows us to determine the spectrum assignment of all players. This algorithm is shown to converge in a few iterations to a Nash equilibrium. Furthermore, we propose an effective algorithm based on Imitation dynamics, where a TVBD probabilistically imitates successful selection strategies of other TVBDs in order to improve its objective function. Numerical results show that our game theoretical framework provides a very effective tradeoff (close to optimal, centralized spectrum allocations) between efficient TV spectrum use and reduction of interference between TVBDs.

In this paper, how to aggregate and allocate idle TVWS (TV White Space) bands for CR (Cognitive Radio) enabled TD-LTE (Time Division Long Term Evolution) system is investigated. Considering the limited spectrum aggregation capability of TD-LTE terminals, a Spectrum Aggregation algorithm with Minimum Spectrum Switch (SAMSS) is proposed to utilize the relatively wide and dynamic TVWS. Based on the theories of semi-Markov process and alternating renewal process, channel usage states of TVWS are constructed as an ON-OFF alternating model. Then, transition probabilities of the channel usage states are calculated and switching probability of the aggregation region is estimated by asymptotic analysis. The proposed algorithm finally selects the aggregation region with the smallest switching probability for UEs to minimize the number of spectrum switches during multiple sensing and transmitting periods. Numerical results show that the proposed algorithm outperforms the traditional methods by effectively reducing the number of spectrum switches in a long span of time, whilst guaranteeing favorable system access performance such as the total number of working UEs.Keywordsspectrum aggregationcognitive radioTD-LTEspectrum accessspectrum switchswitching probability

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.

One of the newest bands allowed for unlicensed device operation is called TV white space. It occupies partially UHF and VHF bands, which were reserved for licensed terrestrial TV broadcasting. New regulations throughout the world enable unlicensed use of TV white space if and only if no harmful interference is created to licensed devices. On the other hand, interference between unlicensed devices is not regulated. There is no doubt that a system which enables coexistence between unlicensed users in TV white space would be beneficial. This paper provides design overview for such a system and research activities conducted to realize it.

Chapter 4 - TV White Space Developments in the European Union

To maintain a high quality of service to the increasing number of smartphone users, additional spectrum is required. The TV white space bands provide a good opportunity to achieve this goal. They can be used as standalone spectrum or aggregated with other licensed bands to increase the total available bandwidth. This paper compares the downlink throughput performance of LTE-Advanced in two different frequency bands. It also addresses the impact of smartphone orientation, with results quoted for three different elevation angles. We consider the higher LTE-Advanced band at 2.6 GHz and the TV white space band at 800 MHz. The radio channel is modelled using a state-of-the-art 3D ray-tracing tool combined with measured 3D radiation patterns for the base station and handset antennas. The throughput performance for a large number of base station and mobile terminal locations is investigated in two different UK cities. We use the computationally efficient received bit information rate algorithm to compute packet error rate as a function of channel structure and SNR. The approach reduces simulation run time by a factor of more than 300. Similar average throughput vs SNR results are observed in both frequency bands. However, higher K-factor and total received power levels are observed when the user equipment is tilted to 45o in elevation. Throughput results show that the efficiency of carrier aggregation between LTE and TVWS bands depends on the cell size and the type of urban environment.

Recent FCC rules allowing unlicensed use on a secondary basis of the Television White Spaces (TVWS) promise a whole new set of possible applications. The first step towards realizing these applications is the creation and adoption of industry standards. In this paper we present the first such standard for personal/portable devices in the TVWS that complies fully with the existing FCC rules while retaining flexibility for use with other regulatory domains. We describe the physical (PHY) and medium access control (MAC) layers specified in the standard and present performance results to demonstrate the robustness and spectral efficiency of the proposed protocols.

TV white spaces (TVWS) can be used by secondary users as long as they do not cause harmful interference to primary users (PUs). Regulatory authorities worldwide have mandated the use of geo-location database (GLDB) for protection of incumbent users. In a wireless TVWS network, interference could be due to either co-channel interference or adjacent channel interference. Recent studies have shown that aggregate adjacent channel interference from a high density of mobile users using low power in multiple adjacent channels is as harmful as co-channel interference even if each single adjacent channel interference stays below the GLDB D/U (desired to undesired) ratio constraint. When there is a high density secondary users (SUs) in a TVWS network, there will high interference among SUs and a possibility of harmful interference to primary users (PUs). Power control is therefore necessary to protect PUs against harmful interference and to reduce the level of interference among SUs. In this paper we propose a firefly algorithm based power control algorithm for a GLDB based wireless TVWS network that take into consideration interference constraints at the primary user (PU) and SU. The algorithm also takes into consideration both co-channel and adjacent channel interference. Simulation results show that the proposed algorithm protects TV receivers against harmful interference and results in an improvement of signal to interference and noise ratio (SINR) for SUs.