The Vault

Chapter 12  TV Whitespace Use Cases
Research Paper / Jan 2011
Chin-Sean Sum, Gabriel Porto Villardi, Richard Paine, Alex Reznik and Mark Cummings

Chapter 12  TV Whitespace Use Cases

12.1  Introduction

In the worldwide quest for more radio spectrum, the use of television whitespace is representative of the more general case of using existing assigned spectrum that is generally unused. Around the world, there are variations in how TVWS is allocated and in the rules for the use of such spectrum. There are, however, some commonalities in the generalized use of TV Whitespace that warrant a generalized set of use cases to pursue the quest. This chapter explores the use of several application use cases. These are, in some respects similar to other wireless use cases. Then, some coexistence use cases for TVWS being used by different Air Interface Standards (AIS’s) and/or crowded or heavy use geographical areas are discussed. This second category of use cases is unique (at this time) to TVWS.

Assumptions

Assumption 1: TV signals are generally broadcast from major population centers and the strength and utility of the reuse of TVWS wireless broadcast signals is gained at increasing distances from those population centers.


Assumption 2: The use of TV Whitespace radio spectrum is available in unoccupied TV channel spectrum or in the whitespace between TV channels.


Assumption 3: The use of TV Whitespace radio spectrum can be available and assigned to geographical areas following rules of the geographical regulatory agency under which the rules apply.


Assumption 4: The TV Whitespace radio spectrum may vary from regulatory authority to regulatory authority and therefore will need access to a set of authority tables that specify approved TVWS frequencies.


Assumption 5: The rules for TVWS access may be assigned by regulatory authority and require access to multiple regulatory rules.

Definitions

TVWS refers to spectrum allocated to a broadcasting service, however, not used locally. It has gained projection after the Federal Communications Commission (FCC) established rules allowing unlicensed devices to use the aforementioned empty spectrum as long as requirements, such as minimizing interference with protected users, are met.


Smart Grid: A smart grid refers to adding communications and machine intelligence to conventional electric distribution systems. It is generally implemented using two-way digital wireless technology. It can (depending on local regulatory decisions) provide real time (or close to real time) usage information, and in some cases to control appliances at consumers' homes to save energy, reduce cost and increase reliability. It overlays the electricity distribution grid with an information and net metering system.

Such a modernized electricity network is being promoted by many governments as a way of addressing energy independence, global warming and emergency resilience issues. Smart meters may be part of a smart grid, but alone do not constitute a smart grid.

A smart grid may include an intelligent monitoring system that keeps track of all electricity flowing in the system. It may also incorporate the use of superconductive transmission lines for less power loss, as well as the capability of easing the integration of renewable electricity such as solar and wind. When power is least expensive the user can allow the smart grid to turn on selected home appliances such as washing machines or factory processes that can run at arbitrary hours. At peak times it could turn off selected appliances to reduce demand.

Cognitive Radio: Cognitive radio is a paradigm for wireless communication in which either a network or a wireless node changes its transmission or reception parameters to communicate efficiently, thus avoiding interference with licensed or unlicensed users. This alteration of parameters is based on the active monitoring of several factors in the external and internal radio environment, such as radio frequency spectrum, user behaviour and network state.

12.2 What Are the Applications for TV Whitespace?

The extension of spectrum occupancy to the TV Whitespace has opened up a new dimension for a variety of potential applications. The merit of TV Whitespace occupancy is essentially two-fold: (a) Providing desirable characteristics to facilitate innovative applications not fully supported by existing technologies; (b) Offering resource expansion to existing applications for enhanced performance.

A list of seven potential applications (APPs), expected to utilize the physical advantages offered by the TV Whitespace is presented and discussed. Table 1 shows the APPs and their respective descriptions.


Table 1 Potential Applications and Descriptions

APP No.
APP Name
Description

1
Metropolitan Area Connectivity
High-data-rate backbone for fixed stations

2
Utility Grid Networks
Connectivity for complexity-constraint fixed stations

3
Transportation and Logistics
Logistics-control for mobile stations

4
Mobile Connectivity
Seamless connectivity for mobile stations

5
High Speed Vehicle Broadband Access
High-data-rate backbone for high-speed mobile stations

6
Office and Home Networks
High-data-rate short-range indoor connectivity

7
Emergency and Public Safety
Mission-critical highly-reliable connectivity




This list is meant to be a simple set of examples that defines the key parameters. It is not all inclusive. For example, it does not include such applications as manufacturing floor networks, processing plant networks, hospital networks, mobile health networks, etc.


APP1 and APP5 establish high-data-rate backbones to support a collective group of end users in one or multiple sub-networks. The main difference between the two is that APP1 targets fixed stations such as buildings, while APP5 targets mobile stations such as autos, trains, and buses. End users within the sub-network supported by the backbones can share the available bandwidth. As compared to APP1, APP2 also supports large area coverage with fixed end nodes, but with a lower data rate for complexity-constraint devices, such as wireless meters in the utility grids. APP2 is suitable for cost-efficient battery-powered end nodes requiring minimum amount of service and maintenance. Another application that operates in low data rate is APP3, where the end nodes such as delivery trucks, are mobile. In APP3, the main operations are identification, tracking and registration of the moving nodes, which do not require large bandwidth resources. APP4 aims to establish seamless connectivity between end users and the base station directly. End users of APP4 are mainly PDAs/Smartphones, tablets, and laptops computers, which are essential to be connected all the time, but require moderate bandwidth less than that required in, for example, APP6. If users of APP4 move into a building or a vehicle, handover can be conducted to local intermediate hubs so that they can be connected as per APP1, APP5 or APP6 for higher communication speed. APP6 primarily supports short-range connectivity targeting mostly high quality multimedia streaming and broadband Internet access. The main coverage of interest is within a building or spaces nearby the building compounds. APP7 addresses the mission-critical connectivity such as networks deployed in rescue operations and public safety networks. Compared to other APPs, the connectivity in APP7 has to achieve security with higher seamlessness, robustness and reliability.

Each APP has a set of unique characteristics to address different needs for respective applications. In turn, these application characteristics determine the requirements that drive the direction of successive system design processes. Among others, the application characteristics and requirements for the APPs are bandwidth, range, mobility, security, reliability, latency tolerance and supported users. Table 2 shows how the APPs with respective characteristics are related to the requirements.


Table 2 Application Characteristics and Requirements for the APPs

APP
Bandwidth
Range
Mobility
Security
Reliability
Latency

Tolerance
Supported users

1
High
High
Low
High
High
High
Medium

2
Low
High
Low
High
Low
High
High

3
Low
Medium
Medium
High
High
High
Medium

4
Medium
High
Medium
Medium
Medium
Medium
High

5
High
Medium
High
Low
Medium
Medium
Low

6
High
Low
Low
Low
Medium
Low
Low

7
Medium
Medium
Medium
High
High
Low
Medium




The required bandwidth to support the APPs is one of the fundamental radio resources in concern. APP1 and APP5 aim to construct the network backbone and thus require high bandwidth. APP6 is specified to support high quality multimedia streaming and thus also require high bandwidth. On the other hand, low data rate applications such as APP2 for wireless utility meters and APP3 for transportation logistics need only low requirement for bandwidth.

The required operating range is set to high for networks targeting a metropolitan area such as in APP1, APP2 and APP4. For applications with high likelihood of intermediate hubs or relay stations being deployed in between the main concentrator and end users such as in APP3, APP5 and APP7, the required range is set to medium. The home and office coverage is set to low range in APP6.

APPs where most of the nodes are either fixed or portable, APP1, APP2 and APP6, are not required to support any mobility. APP5 dealing with high-speed trains and highway buses is required to support high mobility, while APP3, APP4 and APP7 dealing with mostly human and lower-to-moderate speed vehicles, are required to support medium mobility.

Security requirement is set to high in APPs involving logistics, money transaction or emergency situations such as in APP1, APP2, APP3 and APP7. Security requirements for the more consumer-electronics-related APPs, such as multimedia streaming and broadband internet access, are either set to low or medium.

Reliability indicating the network tolerance to possible outages is a mandatory requirement for mission-critical applications such as APP7. Similarly, reliability is also essential in APP1, which is the core-backbone connectivity for a large area, and in APP3, which handles the logistics of transportation and delivery systems. On the other hand, in APP2, reliability can be relaxed except in times of utility emergency response.

The latency tolerance requirement translates to the tolerance against delay in the connectivity. APPs handling time-sensitive data such as video transmission has high requirement in latency tolerance. APP6 and APP7 are typical examples of applications that need to be operated in low latency. For applications such as in APP4 and APP5; comprising a mixture of data, voice, and video; the requirement in latency tolerance is set to medium.

Number of supported users is another important requirement in the APPs. APP2 is required to support up to thousands of wireless utility meters and APP4 is required to support a high number of mobile users, therefore requiring high number of supported users. In a home network, typically, the required number of users is low, as shown in APP6.

12.2.1 APP1: Metropolitan Area Connectivity

The first potential APP for wireless system operating in the TV Whitespace is the Metropolitan Area Connectivity. The metropolitan area connectivity constructs the wireless backbone and intermediate backhaul links interconnecting multiple hubs, where the hubs are further connected to the nodes (hence a sub-network), forming a wireless metropolitan area network (MAN). The MAN can be connected to external entities through a high-speed external backbone. A metropolitan area typically ranges from several hundred meters to several kilometers, covering several buildings to an entire city. Within the metropolitan area all the hubs are interconnected by using air interfaces operating in the TV Whitespace. These hubs are further connected to lower hierarchies of nodes by using the same air interface.
Currently, there are various technologies employed to facilitate connectivity within the MAN. Among others, are cable, optical fiber, radio-wave. and free space optics. Cable and optical fiber are widely used for interconnecting sub-networks. An example is the Metro Ethernet (1) that establishes links among multiple sub-networks (e.g. local area networks or LANs) using cable or optical fiber to form a MAN spanning up to a coverage area of several kilometers. Radio-wave is also a common medium used to establish wireless links within a metropolitan area. The Worldwide Interoperability for Microwave Access (WiMAX) (2) is a protocol that employs radio-wave in the 2-11 GHz and 10-66 GHz bands. In the Wireless Local Area Network (WLAN) a.k.a. Wireless Fidelity (WiFi), range extension on the specification is carried out in the 2.4GHz, 5.15GHz, and 3.6 GHz bands to cover an area of several kilometers (3). Exploiting the flexibility provided by radio-waves, High Altitude Long Operation (HALO) networks (4) are used to provide MAN connectivity to end users from a high elevation angle, therefore, taking advantage of unobstructed line of sight channels by utilizing aircraft circulating in the skies, high above the terrestrial wireless networks. Additionally, free space optical point-to-point links are also used to connect between sub-networks.

All the existing technologies have respective advantages and disadvantages. Transmission using cables and optical fiber is subjected to lower loss as compared to wireless transmission, but require higher installation and maintenance cost and time especially as the coverage area of interest increases. Wireless transmission to facilitate MAN coverage is currently operating mostly in spectrum bands from several GHz up to several tens of GHz, and is therefore subjected to propagation and absorption loss as compared to transmission in the lower spectrum bands such as the very and ultra high frequencies (VHF/UHF). HALO networks have the advantage over obstructions, but are subjected to challenges such as maintaining uninterrupted connectivity to the intended area under the presence of strong wind gusts in the stratosphere, let alone the general concern regarding crashes of large unmanned aeronautical vehicles. Free space optical links provide relatively simple deployment, its stability and quality is highly dependent on atmospheric factors such as rains, fog and dust.
To facilitate connectivity for MAN deployment, the TV frequencies in the VHF/UHF bands offer several encouraging advantages as compared to the current technologies. Compared to the currently employed radio frequencies, the VHF/UHF bands are a valuable networking tool for the same reasons they are desirable for TV broadcasting services, which are the longer reaching and higher obstacle-penetrating capabilities. Compared to the wired connectivity, the TV frequencies offer a more cost-effective solution particularly for coverage of larger areas. The cost and time for installation and maintenance can be reduced significantly. Compared to free space optical links, the TV frequencies are less dependent on atmospheric factors such as the weather. The main setback of the TV Whitespace is the possible unavailability of usable spectrum due to occupancy by incumbents.
The possible physical topologies for the metropolitan area connectivity can be star, tree, mesh, or any combinations of the three. In a typical deployment scenario, all the end nodes in a sub-network are connected to a hub or concentrator via air interface operating in the TV Whitespace. The hubs are interconnected via the same air interface to each other, forming a backbone network. Alternatively, sub-networks can also be connected to the backbone via backhaul connectivity. Additionally, the connectivity between the end nodes to respective hubs may also utilize an air interface other than the TV frequencies, such as Wi-Fi.

Possible application examples of this use case are discussed below.

Campus area connectivity where the end users (e.g. student laptop computers) are connected to hubs in the building. Buildings in the campus area are then interconnected forming a campus area network.
Business enterprise space where the nodes (e.g. company workstations) are connected to hubs. Multiple hubs in the enterprise form a network that is connected to the enterprise central control and management main frame.
Municipal and rural area coverage where end users (e.g. domestic-use computers) are connected to separate household hubs. These household hubs are connected to the backhaul link and then to the main hub in the neighborhood, forming a neighborhood area network. Multiple neighborhood area networks form a MAN.

Industrial site connectivity where the end nodes are the machineries and automotives in the industrial site. These nodes are connected to the intermediate hubs, which are ultimately linked to the main control entity of the industrial plant.
Military premises connectivity where the end users are radios in military premises and military personnel connected to the hub. The hubs are then interconnected and linked to the backbone to the military command center.
Figure 1 illustrates the specific use case of a university campus wireless backbone by means of air interface operating in the TV Whitespace. Fixed directional VHF/UHF antennas professionally installed at the top of faculty buildings provide the necessary TV Whitespace connectivity to support the traffic flow generated within the campus.

Each faculty building has its own sub-networks composed by end nodes, e.g. student laptops, desktops and laboratory servers, which are connected to a hub, e.g. an access point. These hubs are then connected to the fixed antenna at the top of the building. Upon connecting to its sub-network, an engineering student, for example, could access the library database archive searching for relevant research publications or directly exchange files with an architecture student by having his/her traffic flow through the TV Whitespace connectivity. If the traffic destination is an external network, e.g. the Internet or another university campus, the traffic is routed through one of the gateways, which connects the MAN to the high-speed external backbone.

The highly penetrating and wide range characteristics of the VHF/UHF bands make it possible to use less transmit power than it would be required with microwave links, to interconnect faculty buildings, i.e. to cover the same campus area. Needless to say, the installation of such campus wireless backbone would be less time consuming and more economically viable than if the same application is established by employing fiber optics. Additionally, a multitude of other possible applications, such as wireless backbone for business enterprises providing connectivity between the headquarters to its branches, or connecting industrial sites machinery could also be envisioned.




Figure 1 Use case of University Campus with TV Whitespace Wireless Backbone

12.2.2 APP2: Utility Grid Networks

The second potential APP for wireless system operating in the TV White Space is the Utility Grid Network. Contributing to the efforts of building the ecologically-friendly Smart Grid, utility services such as electricity, water, gas and sewer should strive to comply with the growing demands of constructing a more efficient utility networking system. In order to increase efficiency in utility networks, information and communication technology has to be incorporated into every aspect of utility metering, monitoring, load-control and demand response. In this potential use case, the utility grid network covers the end-to-end connectivity from the utility provider to utility consumers. At one end of the network, is the utility provider consisting of the systems for monitoring, command and control of utility systems. The main system is connected to a transceiver station serving as the origin of the smart utility network. At the other end, are the utility consumers with smart metering devices connected to the utility transceiver station via air interface operating in the TV Whitespace. In between the utility provider and the consumers, there may be several hierarchies of nodes serving as relays in the information exchange across both ends, also via air interface operating in the TV Whitespace.

Currently, various technologies are used to connect household utility meters to the utility providers. In the existing utility services, touch-based meter reading, power-line cable, optical fiber and telephone line are some of the technologies used for network connectivity. The touch-based meter reading is one of the conventional methods for metering and billing. A meter reader visits the site with a device that automatically collects the reading from a meter if placed in close proximity. In certain places, there are even primitive methods of manual recording by meter readers. Besides, power-line cable and optical fiber are also common methods to connect the utility provider to the consumers (5). Another connectivity attempt applied in utility systems is via telephone line (6). Alternatively, radio-wave connectivity is recently becoming an emerging means of connecting wireless sensors to the control entity (7).

The conventional touch-based method of employing meter readers to conduct on-site tough-and-go metering is expensive and resource consuming. This method will be phased out gradually as new technologies emerge. Besides, human error is inevitable in this method. With power-line cable and optical fiber connectivity, although offering highly reliable networks, the installation and maintenance cost are significantly higher than wireless solutions, especially in the long run. Furthermore, to cover wider areas such as the sparsely populated suburban and rural areas, the disadvantages of cable and optical fiber connectivity become exponentially pronounced. Alternatively, radio-wave connectivity is a more promising solution towards efficient utility networks. Various efforts are mobilized to have a unified direction towards employing this technology in utility network deployment, specifically in (8), or an enhanced extension of (7).

For establishing connectivity in a utility grid network, radio-wave seems to be the more suitable candidate technology. Among other choices, the TV VHF/UHF frequencies offer several inspiring advantages. As compared to the power-line cable and optical fiber solutions, network connectivity employing air interface operating in the TV Whitespace offers larger coverage with lower cost of installation and maintenance. In the dense urban area, the high penetrating characteristics make the TV frequencies a suitable candidate for covering multiple households separated by walls, for example, in a highly populated apartments. In the sparsely populated suburban and rural areas, the long reaching characteristic makes the TV frequencies suitable for connecting households that are far away from the heart of the network.

Figure 2 illustrates the concept of utility grid networks. Smart electricity, gas, and water meters located at the premises of end users are connected to intermediate hubs and then to the main computing systems of utility providers. The smart meters, intermediate hubs and mainframes are equipped with transceivers capable of operating in the TV Whitespace in order to establish connectivity.
Through the TV Whitespace connectivity; electricity, gas, and water consumption data of a specific household can be transferred automatically to the utility provider in a precise, fast and cheap manner. Contrary to the most common approach of nowadays, meter readers are not employed in utility data collection, freeing the personnel to other tasks, thus adding new values to human resource. Under special circumstances, however, personnel could be deployed to manually obtain the utility data in a specific region, in case of intermediate hub faulty operation, or in a specific household, in case of end user device faulty operation. From the perspective of the utility providers, other advantages of utility grid networks are the ability to connect/disconnect service to the end-users remotely, the flexibility to adjust load-balancing according to local and timely demands, and the capability to respond to emergency situations more effectively. In addition, the utility grid networks application has a remarkable resilience to TV Whitespace outage. In the event of instantaneous channel unavailability, utility data could be transferred seconds, or even minutes later since delay is not particularly a major issue.



Figure 2 Use case of Utility Grid Networks operating in the TV Whitespace


12.2.3 APP3: Transportation and Logistics
The third potential APP for wireless system operating in the TV Whitespace is Transportation and Logistics. In order to increase the efficiency of transportation systems and logistics, optimizing resource management is an essential factor. For such a purpose, advanced networking systems should be established between nodes (e.g. vehicles, cargo) and hubs (e.g. data collectors, relays) for identification, tracking, management, transaction and telemetry in transportation and logistics. In such advanced networks, the hubs are connected to the main concentrator (e.g. system mainframes) where the control and management entity is located. The connectivity from nodes to hubs, and hubs to the main concentrator is established via air interface operating in the TV Whitespace.

In the arena of transportation and logistics, an existing and still evolving enabling technology is the radio identification (RFID) [9]. RFID is used in various applications including public transportation management, shipping/freight distribution systems, virtual payment systems, location-based services, and medical-related services. Currently, the frequency bands used for RFID vary depending on national regulatory bodies and institutions. A fraction of the frequency bands employed by RFID fall within the range of VHF/UHF bands [10] [11]. Besides the already-existing enabling features offered by the current RFID technologies, air interface connectivity via the TV Whitespace could also offer several other complimentary advantages. First, the available TV Whitespace is spectrally wider than the spectrum bands accessible by the VHF/UHF RFID, thus providing bandwidth expansion. Second, by using the lower end of the TV frequencies, larger coverage area and higher resilience to mobility (i.e. less impact due to Doppler spread) can be achieved. Together, the hybrid characteristics offered by TV frequencies are able to suit a wider range of application demands. In a nutshell, TV Whitespace is a suitable technology to complement the current effort by RFID to serve as the enabling technology for transportation and logistics.

The possible physical topologies for transportation and logistics can be star, tree, mesh, or any combinations. In a typical deployment scenario, all nodes are connected to a hub in a star topology via air interface operating in the TV Whitespace. The hubs may be interconnected with each other in a mesh network via the same air interface. The hubs are then further connected to the main concentrator, either directly or through several hierarchies of relays.
Possible applications for this use case are discussed in the following.

Public transportation information system where the nodes (e.g. monitor displays) in the public transports or stations are fed with real-time information such as arrival/departure time and possible delay from the network hubs operated by transport service providers. Additionally, the nodes may also feature multimedia contents such as tourist information, publicity of local events, weather forecasts, traffic condition and news.

Transportation virtual payment system where private vehicle users can conduct payment for highway tolls, parking tickets, and even fines from violation tickets. The same payment system can be applied for public transport payments such as bus, rail, subway, ferries and even airplanes.

Baggage management where the nodes are placed in the baggage and hubs are deployed to perform identification, tracking and handling of the baggage. The information is then sent to the main frame for collective processing.

Freight distribution logistics where the delivery status can be updated in real-time through the connectivity between distributing vehicles (e.g. delivery trucks, ships, trains) and hubs (e.g. access points for monitoring) deployed by the freight service provider in the areas of interest.

Shipping container management in the harbor where the nodes are placed in the containers, which are connected to the hubs in the harbor control center for effective tracking and handling.


Figure 3 illustrates a specific implementation of transportation and logistics employing air interface operating in the TV Whitespace. This example outlines the networking system facilitating logistics in a transportation system that handles freight and shipping services. The logistic-control center is located at the central office of the transportation company. The control center is connected to the data collector network. A data collector network is formed by interconnected hubs (e.g. access points) acting as data collectors deployed in the area of interest. These data collectors are further connected to the mobile nodes (e.g. delivery trucks) that are distributed within the same area. Through the TV Whitespace connectivity between data collectors and delivery trucks, information can be exchanged, therefore, giving the ability to the central office to add various functions to the transportation service. These advanced functions include real-time location tracking of cargo and parcels, protection against cargo theft through surveillance of its trucks during delivery, estimating the best route for delivery based on real-time traffic information collected by its trucks, making predictions on delivery time and others and so on. All aforementioned added functions contribute to reduced delivery time and costs, therefore, leading to increased customer satisfaction. Furthermore, the ability to deploy the connectivity using the VHF/UHF bands complements existing similar services with a wider accessible bandwidth as well as higher resilience to vehicular mobility at the lower end of the TV frequencies. In other words, the use of TV Whitespace to facilitate connectivity brings positive added values to the existing enabling technologies in the current networking systems for transportation and logistics applications.


Figure 3 Use case of Transportation and Logistics operating in the TV Whitespace


12.2.4 APP4: Mobile Connectivity
The fourth potential APP for wireless system operating in the TV Whitespace is Mobile Connectivity. A mobile connectivity network facilitates connectivity for devices that are primarily mobile, portable or nomadic. The network consists of a main concentrator (e.g. base station) and surrounding mobile nodes (e.g. laptops, tablets, PDAs/Smartphones, or transceivers in ships) that are connected via air interfaces operating in the TV Whitespace. The targeted area of coverage spans from several kilometers up to several tens of kilometers. Intermediate relay stations (e.g. access points) may be deployed between the main concentrator and the nodes for range extension. In regions where installation of relay stations requires a higher level of complexity, e.g. the sea, nodes may form ad-hoc based networks to achieve larger coverage. The concentrator is connected to other external networks through a high-speed backbone, possibly with a different means of connectivity.
There are basically two categories of existing systems that support the mobile connectivity networks, mainly targeting applications such as voice telephone, mobile internet access, video calls, and mobile TV. The first category is the cellular technologies, i.e. mobile phone networks. Earlier cellular systems provide mobile telephony (e.g. GSM) [12] and the later amendments (e.g. GPRS, EDGE, CDMAone and etc.) extend to data packet transmission. Besides, there are also further enhancements that support high-speed mobile broadband access, such as the 3G, (e.g., UMTS, TD-SCDMA, W-CDMA, CDMA2000 and etc.) [13] and the “beyond 3G” standard (e.g. LTE) [14]. The LTE-Advanced is envisioned to be the successive 4G standard. The second category is the set of mobile wireless broadband technologies networks. Wireless broadband supports mobile broadband access, primarily formed by the WiMAX family, (e.g., Mobile WiMAX) (2), [15] and Mobile Broadband Wireless Access (MBWA) [16]. The other wireless broadband technology that enables mobile wireless broadband is WiFi. WiFi now has handoff and mobility capabilities that allow handoff and mobility from WiFi AP to WiFi AP and also WiFi to Cellular mobility. It generally supports offloading of high bandwidth applications from cellular to WiFi, but is becoming more capable of standalone mobile connectivity. Generally, these technologies support a wide range of services from voice to data to multimedia.

The main strength able to be offered by the TV Whitespace connectivity is complementary to the existing mobile broadband access applications, particularly in the aforementioned second category of wireless broadband technologies. The TV Whitespace is capable of offering bandwidth extension in the order of tens, if not hundreds of MHz to ease the traffic of current lower bandwidth technologies. Specific use cases are given in the following discussions to emphasize the potentials of the TV Whitespace connectivity.

Figure 4 illustrates one of the envisioned application genres of mobile connectivity using the TV Whitespace, namely, Land Mobile Connectivity. In this use case, PDA/Smartphones, tablet, and laptop/notebook computer users have wireless broadband access to data communications through air interface operating in the TV Whitespace. The end users may be stationary at a location, or moving in a vehicle. Common applications are for example voice telephony, Internet access and web browsing. Compared to connectivity in the GHz band, the VHF/UHF spectrum characteristics offer encouraging advantages to both operators and end users. The longer range and higher penetrating characteristics of the VHF/UHF frequencies translate into a reduced number of base stations deployed over a specific service area, as well as less attenuated signals providing last mile wireless broadband services to end users with higher resilience to service outage. In addition, the higher robustness to mobility inherent to the VHF/UHF bands also results in higher QoS to mobile users using moderate bandwidth-demanding applications, such as video streaming for cellular networks.
Figure 5 illustrates another application genre in Maritime Connectivity using air interface operating in TV Whitespace. Base stations located at the shoreline and the ships/off-shore structures are connected to allow information flow from land to sea and vice-versa. The control center at the shoreline can be connected to conduct data communication, command and control to the ships/off-shore structures. Additionally, by combining the attractive long-range propagation characteristic of the VHF/UHF bands and the implementation of ad hoc mesh networking systems, range extension can be further achieved. Nodes far away from the shoreline can be connected through ad hoc networks formed locally. Alternatively, relay stations built on marine buoys can be deployed for intermediate connectivity. In other words, distant mobile nodes (e.g. deep sea cargo ships) and structures (e.g. oil-gas platforms, sea farm) can be connected to the continent through TV Whitespace connectivity either by employing local ad hoc mesh networks or intermediate marine buoy relays strategically located at some points in the ocean. Furthermore, TV Whitespace connectivity adds significant value to the capacity-limited maritime communication services. Expensive satellite services limited to voice and narrowband data communications available in deep-sea platforms and deep-sea ships will be relieved by the deployment of wireless broadband systems. Such change, allows high-speed data communications (hence inexpensive services such as voice communication, high-speed Internet access and real time video streaming), and improves working environments for personnel dispatched to such remote locations.


Figure 4 Use case of TV Whitespace Land Mobile Connectivity



Figure 5 Use case of TV Whitespace Maritime Mobile Connectivity

12.2.5 APP5: High Speed Vehicle Broadband Access
The fifth potential APP for wireless systems operating in the TV Whitespace is High Speed Vehicle Broadband Access. Broadband access in high-speed vehicles can be realized by linking the vehicle to surrounding communication infrastructure via a network. Generally, the high-speed vehicle connectivity is formed by establishing a backhaul between the hubs (e.g. access points along railway tracks or highways) and the high-speed nodes (e.g. autos, trucks, trains, buses) via air interface operating in the TV Whitespace. The hubs are then connected to the main concentrator (e.g. base station) with the same air interface. In the vehicles, the connectivity between the intermediate relay (e.g. access points in the vehicle) and the end users (e.g. PDAs/Smartphones, tablets, and laptops) may utilize either the TV Whitespace or other air interfaces (e.g. WiFi, Bluetooth).
There are several currently available technologies identified as suitable candidates to support such a use case scenario. These potential candidate technologies are WiFi (an other IEEE 802 AIS’s), WiMAX, cellular networks (with a variety of AIS’s), and satellite communications. In WiFi, the Wireless Access in Vehicular Environment (WAVE) [17] can be used for the connectivity between moving vehicles and roadside infrastructure, operating at the licensed intelligent transportation system band of 5.9 GHz. The WiMAX, AIS can be implemented in a wide variety of bands. Currently, it is only used in bands that local regulatory authorities specifically authorize [15]. Cellular networks particularly the enhanced version for high data rate and low latency such as LTE, is another alternative to support this application. Satellite communication is also a prospective candidate that is able to provide seamless signal coverage.
As compared to the potential candidate technologies for the high-speed vehicle broadband access, connectivity utilizing the TV Whitespace offers several inviting advantages. As compared to air interface such as those in WiFi and WiMAX operating mainly in the GHz band, the TV VHF/UHF frequencies are subjected to lower path loss, longer range and higher penetration capabilities. These characteristics outline a significant advantage in terms of area coverage in difficult terrains and crowded buildings. Most importantly, the TV frequencies display a more superior resilience to mobility as compared to the GHz band, addressing the primary concern in connectivity for vehicle moving at high speed. As compared to satellite communications, air interface in the TV Whitespace can support a higher data rate with lower latency. In short, the TV Whitespace connectivity is capable of offering complementary advantages, if not outperforming other technologies in this use case.

Possible physical topologies for the high-speed vehicle broadband connectivity can be the star or tree architecture. In a typical deployment scenario, the main concentrator such as a base station is connected to hubs along the railway tracks or roadside. These hubs then form the backhaul connectivity to the moving vehicles utilizing air interface in the TV Whitespace. In the vehicles, intermediate relays are deployed. All the end nodes (e.g. end user laptops, tablets, and PDAs/Smartphones) in the high-speed vehicle are connected to the intermediate relays, either through air interface in the TV Whitespace or other options.
Possible application use cases are as follows:

Connectivity for high speed trains (e.g. Japanese Shinkansen, Korean KTX, French TGV and etc.) with travelling speed up to a typical 350km/h where the hubs are constructed along the railway tracks, providing broadband access and multimedia entertainment to passengers in the train.

Connectivity to long distance buses where hubs are deployed along the highways, providing the same services to passengers.

Connectivity to subways and underground transportations where cellular and other wireless signal coverage are normally weak or absent. In this scenario, air interface in the TV Whitespace is capable of increasing both the coverage area and resolution, providing broadband access service to passengers.

Figure 6 provides an illustration of High Speed Vehicle Broadband Access application utilizing air interface operating in the TV Whitespace. With the increasing demand for higher data rates and constant need for connectivity imposed by the fast paced society of today, wireless broadband connectivity must be ubiquitous. That is to say, it must be available even in the most technologically challenging scenarios, like the one inherent to a high speed bullet train moving with speed approaching a typical 350 km/h, or even higher in the future. Speed in such magnitude causes problems to the end user data communications due to inadequate transition time between adjacent cells and significant Doppler spread. In addition, high voltage machinery in railway transportation creates strong electromagnetic exposure. In order to circumvent such harsh scenarios, the connectivity for high-speed vehicle broadband access in the TV Whitespace can be established by deploying along the railways, an array of fixed stations (e.g. base stations). The fixed stations are connected to the intermediate portable relays inside the trains. Connecting to the network, a businessperson travelling from Tokyo to the remote city of Kyoto will have a handful of possibilities to spend the commuting time. The broadband connectivity in the trains supports a wide range of applications, from low-bandwidth-demanding applications such as browsing the Internet and e-mailing to bandwidth-hungry applications such as video conferencing and real time video streaming. To realize this connectivity, the use case application relies on the attractive VHF/UHF characteristic of being resilient to Doppler spread, therefore, allowing the system to support high mobility. Additionally, the reduced path loss and high building penetration characteristics of VHF/UHF also allow a reduced number of fixed stations covering the railway, therefore increasing the cost-effectiveness. Coupling with technologies such as fast handover, resource demanding real-time applications such as video conferencing and video streaming can be supported, even in the fastest trains in the world.


Figure 6 Use case of High Speed Vehicle Broadband Connectivity in TV Whitespace


12.2. APP6: Office and Home Networks
The sixth potential APP for wireless system operating in the TV Whitespace is the Office and Home Networks. This use case seeks to establish ubiquitous high speed connectivity within the area of office and home. The office and home networks typically require a coverage ranging from several centimeters up to several tens of meters. The network consists of one or several interconnected hubs (e.g. access points), which are further connected to multiple nodes (e.g. end user devices), all via air interface operating in the TV Whitespace. The connectivity between the hubs to external networks may be via any alternative radio interface including a hybrid interface operating in both the TV Whitespace and other existing means.
There are a number of existing technologies, both wireless and wired, employed for deploying the office and home networks. Among other wireless technologies, the more common ones are such as the Bluetooth, the millimeter-wave wireless personal area network (WPAN) and the WiFi. The Bluetooth [18] is a short-range cable replacement technology establishing wireless connectivity among devices within the personal space. The millimeter-wave WPAN [19] is a short-range high-speed communication protocol that targets up to Giga-bps order to support applications such as uncompressed video streaming and ultra-high speed data exchange. WiFi (3) is another popular technology used to deploy indoor networks. Besides wireless solutions, wired solutions such as Ethernet, power-line cables, and phone wires are also employed for networks in the home environment. Ethernet (1) is a wired protocol connecting nodes either by using CAT5 wire, coaxial cables, or optical fiber. Protocols involving power-line cables (5) and phone wires [20] are also common in providing coverage for a home network.
In the arena of short-range communications, the major advantage able to be harvested from utilizing the TV Whitespace is the expansion of bandwidth. In applications where there are overlaps in functional characteristics between the TV Whitespace connectivity and the existing technologies with similar purpose, the TV Whitespace system can be viewed as a complementary expansion of available bandwidth that further boosts the communication speed in times of normal operation and relieves the traffic in times of congestion. Spectrum occupancy segmentation (i.e. dedication of specific applications to specific bands in a hybrid wireless connectivity with multiple bands) or medium occupancy segmentation (i.e. dedication of specific applications to specific means of communications in a hybrid wired plus TV Whitespace connectivity) can be conducted adapting to respective local and timely demands in order to optimize the use of radio resources. These segmentation schemes will be further discussed in the specific examples following. Generally, the TV Whitespace provides a means for office and home networks to reduce the traffic burden in a specific operation band or medium. In this sense, the TV Whitespace connectivity does not compete, but completes the existing technologies by enhancing the performance of the office and home area networks.
Possible physical topologies for the office and home networks are the star and tree architectures. The hubs installed in the houses or office buildings are connected to the end user devices in a star manner. In the case where intermediate hubs are installed, the tree topology is employed.
There are a variety of possible applications for the office and home area networks:

Personal workspace connectivity where all the peripheral devices such as printers, scanners and display monitors are connected and controlled by the main work station.

Office area connectivity where all work stations can be connected to each other and to a central main frame for purposes of data exchange and centralized management.

Home area networks where the end nodes such as computers, laptops, PDAs/Smartphones, multimedia displays, stereo systems, game console and telephones are connected through the hub to external entities such as the Internet.

Figure 7 illustrates a specific scenario of the Office and Home Networking application utilizing an air interface operating in the TV Whitespace. In this example, all the peripherals in the house including computers, PDAs/Smartphones, game consoles, televisions in the living room, bedrooms and outside the house are connected to a household main hub. The hub is then connected to external systems such as the Internet. The entire home network can be implemented using the TV Whitespace connectivity. Alternatively, it can also be partially coupled with other existing air interfaces (e.g. the 5 GHz WiFi) in a complementary manner. The ‘dual-band’ network can be optimized through the application-based segmentation of spectrum occupancy. For example, when demand out strips the capacity of the available WiFi spectrum TV Whitespace spectrum can be used for overflow. Priority-based segmentation can also be used based on the urgency of the data type, such as handling the less-urgent data-backup operations in the TV Whitespace connectivity, while freeing up bandwidth in the 5 GHz WiFi band for other more urgent applications. If the TV Whitespace is coupled with wired solutions such as the Ethernet, then segmentation of medium occupancy can be conducted in the same manner. Similarly, TVWS can be used for congestion relief in cellular networks.

Like any other ubiquitous WiFi today, networking in the TV Whitespace will provide the necessary wireless connectivity to keep the business and the entertainment applications running with high QoS. The vast amount of TV Whitespace in the VHF/UHF spectrum allows the radios to take advantage of it. This enables the realization of a broad spectrum of pervasive applications, ranging from the low-bandwidth-demanding to the bandwidth-hungry ones. An important remark about Office and Home Networking based on TV Whitespace occupancy is that it is not intended to be a substitute technology for WiFi today, but adds new spectrum resources, therefore soothing the inevitable spectrum crowding faced by congested frequency bands.



Figure 7 Use case of Office and Home Networks in TV Whitespace



12.2.7 APP7: Emergency and Public Safety
The seventh potential APP for wireless system operating in the TV Whitespace is the Emergency and Public Safety network. Emergency and public safety network is a communication network used by emergency response and public safety organizations such as police force, fire department and emergency medical team responding to accidents, crimes, natural disasters and other similar events. This network covers connectivity from the command/control entity of the public safety organizations all the way down to the end nodes through several hierarchies of intermediate hubs or relays, via air interface operating in the TV White Space. The command/control entity may be the headquarters or commanding offices of the police and fire department. The end nodes can take any form from fixed surveillance cameras/sensors on the streets and other potential disaster areas, to radios in police patrol cars, to mobile radios carried by rescue teams at disaster sites. End nodes have the ability to be interconnected to form mesh networks, to facilitate coverage extension to places where propagation is naturally limited, such as in reinforced concrete buildings and the underground of buildings. Intermediate nodes can be relays or repeaters to extend the range or widen the effective coverage area of the network. Generally, the network should be easily initiated, i.e. in a plug and play manner, with devices simple in design, so as to allow secure easy operation under stressful situations.
There are several technologies suitable for deploying the emergency and public safety networks. Besides the government-controlled dedicated bands with specific networking systems for the sole purpose of public safety services, there are also other candidate technologies for building public safety wireless mesh networks such as WiFi (3) and WiMAX (2). The Terrestrial Trunked Radio (TETRA) (21) is a well-established technology for public safety with global presence. It provides voice services with communication security. TETRA release 2 adds higher data rate support in the form of TETRA Enhanced Data Services (TEDS), in the order of hundreds of kbps.
Air interface operating in the TV White Space presents a fundamental advantage as compared to spectrum bands in the GHz order: the wider coverage offered by the VHF/UHF wavelengths. Besides, the VHF/UHF bands also display more favorable characteristics in times of emergency response in disaster sites which may be demanding the highly penetrating feature for critical operations such as victim search party. For example, the need for communication signal with high object penetration characteristics was significantly pronounced in emergency circumstances in the 9/11 and the London bomb attack, when conventional emergency systems had problems maintaining effective communications in the underground of buildings and in the subways. Additionally, the total available TV Whitespace spectrum is in the order of hundreds of MHz, allowing high-bandwidth-demanding applications, such as disaster-site real-time video streaming.
The typical physical topology for emergency and public safety networks is basically the mesh architecture. All nodes should be interconnected with each other for fast communication during critical times. The nodes have to be also seamlessly connected to the control centers for rapid data retrieve and data upload.
Possible applications for this use case are shown as the following:
Public and traffic safety surveillance system where cameras in targeted locations feed real-time photos/videos of traffic condition/mishaps, criminal activities and so on.

Emergency surveillance where cameras/sensors are located at potential disaster sites such as shore-line with probable tsunami events, areas around active volcanoes and areas with possible earthquake occurrence. Most, if not all of these locations are dispersed outside the dense metropolitan area, and thus require connectivity with wide coverage area.

Mobile real-time video sharing for emergency response purposes where the first responders in disaster sites are required to share videos or telemetry of patient vital signs with qualified medical personnel to increase the efficiency of preserving lives of the victims. In the similar manner, real-time video sharing with the fire department can be useful for the firefighters to better prepare and anticipate the magnitude/type of fire that is taking place. In the field, video streaming from cameras attached to the firefighter-helmet can provide the necessary information for the control center to make quick and effective decisions.

Fast database access for law enforcement officers where video files of on-site crime recording, witness statements and etc., can be uploaded to the network server for processing and analysis. Likewise, fast database retrieval where criminal records, traffic records and etc., can be downloaded easily to facilitate efficient police investigations. For example, to enable instantaneous criminal suspect identification, the mobile police force has to be equipped with vehicles/person database lookup tools and the capability of taking/transmitting high quality still pictures and fingerprint scans.

Navigation and on-site operation assistance where digital maps can be download from the main server to assist public safety organizations to effectively plan and control field operations.

Figure 8 illustrates the Emergency and Public Safety Network application utilizing air interface operating in TV Whitespace. The network is composed by end-nodes, e.g., portable devices held by firefighters and paramedics, and the communication hubs installed in the vehicles forming a local mesh network. This network is in turn linked to the ad-hoc command/control unit on-site, and is further connected to the main operational control entity, possibly located in the headquarters. The end-to-end connectivity can be established employing air interface operating in the TV Whitespace connectivity.

As a specific example, a team of firefighters searching for survivors in the underground of a partially collapsed building could communicate with the command/control entity situated nearby the scene, which in turn provide the team with the building digital maps to help navigate them through the debris. Such effective and robust communication could take place owing to the high building penetrating characteristics of the VHF/UHF spectrum allied to meshing capabilities with enhanced signal propagation. Once survivors are safely rescued from the debris, video cameras could immediately transmit images of the victim in the ambulance along with vital signs such as heart and respiratory rates to the medical professionals remotely located in the hospital. Such ambitious features are possible due to the vast amount of bandwidth available in the TV Whitespace, enabling the implementation of high-bandwidth-demanding applications.

Figure 8 Use case of Emergency and Public Safety Networks in TV Whitespace



12.3  How Do TV White Space Operators Coexist?

We have seen some examples of how single applications with only one AIS at a time in one usage block (geographic location) might use TVWS. However, since TVWS is open to all AIS’s and all types of applications, it is likely that there will be multiple AIS’s trying to use the same usage block at the same time. Each AIS has a mechanism to allow multiple users to operate without interfering with each other, but today’s AIS’s don’t provide a mechanism to present users with different AIS’s to use the spectrum without interfering with each other. Before TVWS, the allocation of spectrum to different AIS’s prevented AIS collisions. With TVWS, that solution disappears. In this section of this chapter, we will discuss use cases where there are such AIS collisions. The intent of this discussion is to lay the groundwork for development of mechanisms that will allow different AIS’s and different network operators to operate in TVWS without interfering with each other. One place that these mechanisms are being developed is IEEE 802.19.1.
12.3.1  On a Campus (university, suburban mall, office park)

It is worthwhile to consider what services are provided by each of the Whitespace provider users of frequencies and therefore the following sections allocate some thought space to these topics. There is definitely a lot of overlap of services in the campus and shopping mall scenarios, so they will be covered together.



12.3.1.1 Cellular

By the term “cellular provider” we mean any provider delivering a cellular (wireless mobility-enabled services such as cellular telephony and mobile data). The capabilities may be 3G, 4G, or possibly other cellular technologies, most notably those product standards from 3GPP and 3GPP2.

Currently cellular networks support the following services:

Voice (via the cellular provider’s core network, maybe circuit switched or VoIP based).

Data (internet) access

VoIP(via Internet access)

Messaging

Emergency services

Gaming

Multimedia broadcast

Of particular interest in the case of cellular services is the notion of a femtocell. To illustrate this, consider the figure below. This shows a canonical femtocell deployment architecture and the links involved.


Of note here are the three links:

Link 1: Mobile Equipment –to-Femto-base station link. This is the wireless link of most interest. Currently this is most often a cellular link utilizing licensed cellular spectrum. However, one can envision the cellular operator utilizing other spectra (such as the unlicensed bands and, of most interest to us, the TV whitespaces) to optimize the utilization of their licensed spectrum. There are some existing examples of such an approach.

Link 2: Femto-base station to broadband router link. This is typically a point-to-point wired link. Alternatively, the femto-base station and the broadband router may be a single piece of equipment in which case this is just a logical connection between the two functions.

Link 3: Broadband router to the cellular network. This is a non-trivial link utilizing the broadband provider’s network to establish a connection between the femto-base station and the cellular provider’s network. Here, it is important to distinguish between 4 cases which depend on the following alternatives

Whether the broadband connection is provided by the same entity as the cellular operator of the femtocell (i.e. a single entity offers both types of services) or a third party.

Whether the broadband connection coexists in the same spectrum (notably, whitespace) as the femtocell or is separate from it (wired or a different broadband wireless link).
12.3.1.2  WLAN

The 802.11-based provider of Whitespace services may be operating in the 100 mW range; but is likely to also use the <40mW and <50mW part of the Whitespace regulatory spectrum. In a campus, the 802.11-based service is generally provided by an enterprise on an enterprise campus or by the educational institution if it is an educational campus. In the shopping mall, the 802.11-based service is used sometimes by the mall as an attraction for people to hang out at the mall and at other times by the individual stores to service themselves or themselves and their customers. Internet access is transparent in the 802.11 provider use in that the primary use of 802.11 is for straight Internet access. When a user has straightforward use of the Internet, there is a lot of flexibility in how they might use services, connect to their other providers, and keep their social connections.

The types of service supported by WLAN technologies in the whitespaces include:

Hot spot internet access (pay-per-use controlled access)

Open Internet access with restricted QoS and bandwidth making VoIP and streaming multimedia difficult to impractical.

Open Internet access with unrestricted QoS and bandwidth making VoIP and streaming multimedia possible.

Proprietary multimedia services (e.g. store-based advertising)

Gaming

12.3.1.3 Fixed Wide-area WAN

A fixed WWAN provider use of Whitespace may be similar to the cellular case in providing service directly to end user devices, or it may deliver an access point / femto cell to provide:

Voice (via the provider’s core network, maybe circuit switched or VoIP based).

Data (internet) access

VoIP(via Internet)

Messaging

Multimedia (unicast, multicast or broadcast)

Emergency services

Gaming

The 4Watt Whitespace could be a candidate for the backhaul broadband service provision as well as direct connection to end user devices, especially in rural environments. The technologies utilized are likely to be based on 802.22 and fixed 802.16. However, other technologies, such as proprietary 802.11-like solutions are also known.

12.3.1.4  Control of operations in the Campus/Mall use case

A key feature of the campus/mall use case is the possible presence of a single entity which is either the direct operator of many of the services listed above, or can exercise significant control over individual operators of such services. For example, in the case of a university campus, the university is likely to be the operator of most of the 802.11-based networks and it can impose restrictions on others (those deployed by students in the dorms or in the labs, for example). Moreover, through established contracts it may gain significant control over the installed cellular femto-cells and/or outsource the operation of some or all of the wireless campus network to a cellular operator.

In the case of a mall, the mall owner is likely to exercise significant control over the 802.11 and femto-cell based networks installed in the mall. Any Fixed WWAN covering the mall would likely be operated either by the mall owner or a wireless service operator under a contract from the mall owner. The same WWAN operator may then be providing coordination services or controls for wireless LANs in the mall. In the case of WWAN, such control could be enabled as part of the service provision model. In many cases (e.g. IEEE 802.22), the fixed WWAN base station has to be professionally installed. The necessary controlling equipment and SW may be provided and configured as part of that installation. However, in the case of WLAN, the control on the utilization of peer-to-peer networks will require methods that can be enabled and used by the network operator without the professional assistance of an “installer.”
12.3.2  In and Around an Apartment complex

The macro scenario where there are primarily high density living spaces like apartments is one in which the predominant uses would require small coverage areas, either via WLAN APs and/or femtocells. These 802.11 APs or femtocells would operate under many of the same conditions and delivering similar services as in the campus use case. In the following discussion, only differences between the two use cases are pointed out.


12.3.2.1 Cellular

The presence of a large number of femtocell-using cellular users in a congested apartment scenario implies that coexistence strategies will be required to support such a high density of cells. The use of whitespace frequencies would enable more channels to support such high density demand.

12.3.2.2 WLAN

Lots of 802.11 users in a congested apartment scenario implies that the density requires changes in the power levels and channels in order to work together effectively. However, when density reaches critical levels, allocated channels can not be sufficient to provide adequate quality of service and could potentially trigger a move into White Space. The use of indoor whitespace frequencies enables an expansion of the available unlicensed frequencies for such use (2.4 and 5.15GHz). Given the short distance involved, operation of 802.11-based technologies under the <50mW and <40mW rules becomes more likely.

12.3.2.3 Fixed WWAN

In the apartment building case, a fixed WWAN may be the Internet connection and Internet backhaul via fixed 802.22 or 802.16 wireless, including an 802.16-based Whitespaces technology. Non-802 defined technologies may be used as well. Distribution into the apartment building from the single point of the wireless antenna at the apartment complex, may be WLAN-based and the WLAN may be utilizing TV band Whitespaces.

12.3.2.4 Control of operations

In the case of an apartment building, each individual apartment dweller may be a fully independent operator of their own small wireless network. Whether this operator relies on an 802.11 or a femtocell based network extension (or both), each acts independently. Moreover, each apartment dweller may utilize different broadband service providers (in large cities it is not uncommon for 3-4 different cable/fiber providers to service the same building and this may be supplemented by WWAN). Consequently, different ISPs are likely to be used as well. Each apartment dweller may also utilize their own independently selected cellular service provider.

It should be clear that in this case, coordination of whitespace usage through a single point of control for the building as a whole is not likely. Apartment complex owners, however, may attempt to retain central control if coexistence is not possible.


12.3.3  In the Home

The existing providers of home equipment and services may use <40mW and <50mW (sensing) Whitespace devices to extend and multiply their products and services through a new source of frequencies. These will all be addressed separately.

12.3.3.1 Cellular

The cellular providers would like to have Whitespace extensions of the cellular frequencies in the form of additional voice and Internet channels via the cellular 4W regulatory domain in addition to the use of lower-power for Whitespace-based femtocells in the home. The cellular provider use of Whitespace frequencies includes text, voice, Internet, and VOIP. The cellular providers will probably want to provide all their existing services, plus video and some other services that are enabled by either more bandwidth or by more frequencies, including Whitespace frequencies.

12.3.3.2 WLAN

The WLAN providers of home equipment would like to use the Whitespace frequencies to extend and expand the use of currently used unlicensed (2.4 and 5GHz) frequencies for WLAN. The more bandwidth available from Whitespace frequencies could mean more capable delivery of video or other services over 802.11-based services.

12.3.3.3 Fixed WWAN

The Fixed WWAN providers of home equipment would like to use the Whitespace frequencies to extend, improve and expand the use of those frequencies for Fixed WWAN. However, other technologies, such as proprietary 802.11-like solutions are also known to operate as WWANs. In considering Fixed WWAN service in the home use case, it is particularly important to differentiate between the outdoor-outdoor and outdoor-indoor antennae siting configuration for TV band whitespace usage.

The outdoor-outdoor siting corresponds to the likely usage of technologies based on 802.22 and 802.16 standards, as well as non-802 standards, such as DOCSIS. In this case, broadband access, including video service, is provided using up to 4W EIRP Whitespace channels to service fixed access points. Installation of such equipment may be professionally done.

The outdoor-indoor solution siting corresponds to the use of small indoor equipment communicating with an outdoor base-station to provide service into the home. This equipment may be sited by the customer, much like WLAN access points are today. For example, modified 802.11-based solutions can presently reach the kinds of distances discussed in 4W Whitespace FCC specifications by using 1W unlicensed frequencies in the 2.4 and 5GHz bands. It is possible to use TV whitespace frequencies for wireless backhaul from femto-cells and WLAN access points.

12.3.3.4 Control of operations in the Home use case

It is possible that in this use case the home operator becomes a single point of control for a significant number of use case players, including femtocells, 802.11, smaller non-802 devices (e.g. microphones). However, other whitespace players (e.g. cellular and whitespace TV) remain outside of the space of control of the home user. However, proximity of neighbors may result in a need for a much more complex and distributed spectrum management model, more like the case of the apartment complex rather than the campus use case.

12.4 TV White Space and US Broadband Initiative

TVWS will fill a substantial role in the US Broadband Initiative. The need is for the US’s Federal Communications Commission (FCC) to allow more radio spectrum to be used for broadband access in the limited spectrum available. The FCC has made previous attempts to define and allocate licensed spectrum that is not used efficiently within geographical areas. One such attempt was the use of lightly licensed spectrum in the 3650MHz band where there is an authority that manages the light license of the dependent station. Such a functionality is used in WLANs via 802.11y. In TVWS, a portion of spectrum may be used in a metropolitan area and not used at all in a rural area. Up until the TVWS initiative, there has not been an efficient way to share that spectrum based on the geographical area of use. The use of a shared database with geographical information, and the ability to reserve a channel through the use of that database, is a major step forward in the extension and expansion of unlicensed or lightly licensed spectra, envisioning use even in currently licensed or government designated spectrum and in geographical areas where the spectra cannot presently be used. The TVWS is representative and predictive of this trend and the expectation is that most spectrum will eventually fall under the category of lightly licensed, databased, geographical information for broadband use.

Some argue that TVWS will not be needed if the TV broadcasters are cosnolidated into a small portion of the existing TV allocation and the remaining spectrum is auctioned off. This is not true for several reasons including timing, openness to future changes, geographic independence, and relationship to a larger White Space spectrum strategy.

The Broadband Initiative, if it is approved, will take some time to achieve that approval. The financial and political forces arrayed are quite substantial. It is difficult to predict exactly how long it would take to achieve approval, but it is likely to be measured in years. In the meantime, TV White Space systems could be operating in the public interest convenience and necessity. If the Broadband Initiative is approved, even its proponents say that it is likely to take ten years to implement. It is also likely that the implementation process will involve multiple steps, in different locations, over an extended time period. In this case, TV White Space could play a key role in the migration process. Given these time periods, it is likely that several generations of TV White Space equipment and services could be profitably deployed. Finally, the Even with full implementation of the Brodaband Plan, there is likely to be demand for additional spectrum. What is learned in the TVWS bands can be applied to other bands that are not fully utilized.


12.5 A New Trend:  Other Cognitive Spectra

Other cognitive spectra are really the entire radio spectrum. Once a workable concept is proven, then the entire radio spectrum falls into the category of usable if it is not being used by a licensee or a lightly licensed use through a database.

12.6 Conclusion

TVWS is one of the projects that expands the use of the radio spectrum in a more efficient and effective manner. The applications that it can support are the applications of any radio technology; no wires and no interference to the others in the spectra. This chapter started with a discussion of somewhat generic application use cases applied to TVWS. Then the discussion turned to coexistence use cases. Finally, how TVWS might fit into the Broadband Plan and be applied to other parts of the radio spectrum was discussed. With this as background, it is clear that TVWS can play an important role in providing the capability that the public is demanding for more and more wireless service.



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