Which of the following is a wireless internet connectivity method that utilizes cellular technology?

Choosing the Right Antenna

Wireless connectivity to the target AP and the wireless client(s) is essential in order for this attack to work. Also, you need to have a strong wireless signal broadcasting from the Host AP access point. Therefore, choosing the right antenna is important. There are two main types of antennas to consider for this attack: directional and omnidirectional antennas.

The directional antenna sends and receives the wireless signal in one direction. Directional antennas are useful when you know exactly where the wireless device is located. For this purpose, the directional antenna isn't a good choice, because you want to broadcast your signal to as many clients as possible. However, if you are targeting specific wireless client(s) gathered in the same general location, directional antennas are a good option

The omni-directional antenna sends and receives the wireless signal in all directions. Again, because you may not know where a wireless client will try to connect from, you want to use an omni-directional antenna.

Increased Connectivity/Computing Options

There is now an abundance of wireless connectivity through various means like cellular mobile networks, wireless LAN, Bluetooth, ZigBee, ultra-wideband networks, Wi-Fi, and satellite networks. Additionally, with the birth of cloud computing, users are now also offered shared resources along with connectivity. The user is no longer tied to a particular location or device to upload, access, or share data. Availability of such a wide variety of connectivity and “shared computing” options has enabled both personal and business users to add more mobile devices/computing on such networks to improve their mobility and reduce infrastructure costs for business/personal data sharing.

Wireless Pluses and Minuses

There are several benefits to having wireless connectivity to your business or home network:

You avoid relying on a wired solution. Your employees can connect from anywhere in your ISP's service area, as well as from your internal network.

Cost is reasonable (comparable to DSL and cable).

Installation and maintenance are simple.

However, there are some significant drawbacks to wireless Internet service as well:

Wireless data rates are significantly slower than wired data rates. Although current wireless services are based on standards that support speeds up to 54 Mbps, actual speeds are significantly slower, as slow as 2 Mbps. The chances of obtaining anywhere near the maximum speed are very slim. (More on this in Chapter 7.)

Service is not available in many areas, and when service is available, it is limited to a relatively small geographic area. The idea that you could have one wireless Internet provider that you could use anywhere in the country is very appealing, but not realistic. For example, Verizon, one of the largest wireless Internet providers in this country, has wireless Internet connectivity in 181 metropolitan areas. They continue to expand their offerings, but they are many years away from nationwide coverage.

Even if you are within a wireless ISP's service area, you may not be able to pick up a wireless Internet signal if there are physical obstacles blocking your line-of-sight to a tower that relays the wireless signal.

Wireless networking has serious security vulnerabilities. (In fact, many people consider these vulnerabilities so serious that this issue should be the first drawback listed, rather than the last.)

Note: We will look at the security issues surrounding wireless networking in some depth in Chapters 7 and 10.

5.5.2 Unmanned Air Vehicle–Based Optical Wireless Communications

The use of UAVs for delivering wireless connectivity is considered by the telecommunication operators and over-the-top service providers in commercial networks. A network of UAVs operating at a certain height above ground can provide wireless service within coverage areas shaped by their optical antennas (integrated in the UAVs) with the UAVs using the existing terrestrial base station network for FSO wireless backhaul to connect to a dedicated optical ground station. Therefore, the UAVs must optimize their connectivity to deliver reliable service to the end user while simultaneously meeting their own wireless backhaul requirements. A low-altitude UAV network above the built-up urban area may be used. Deploying FSO technology for mobile links between UAVs and fixed OGSs also involve several challenges to establish the ability of a mobile FSO system to operate in different atmospheric conditions. UAV FSO communications and different scenarios for free space communication links such as ground-to-UAV mobile FSO channel, UAV-to-ground FSO link, UAV swarms with different architectures such as ring, star, and meshed types and alignment and tracking of an FSO link to a UAV are already discussed [16]. A demonstration of the FSO communication link at 2.5 Gbit/s is presented [27] for a UAV altitude of 15.8–18.3 km using a 200-mW downlink laser at 1550 nm. They reported BER of 10−9, which needed the pointing requirement on the flight terminal of 19.5 μrad and a bias error of 14.5 μrad with a probability of pointing-induced fades (due to turbulence) of 0.1%. UAV links can therefore be effectively used for high-speed connections where terrestrial links are not available [28–31]. Today's network and associated techniques require gigabit capacity data rates with low-cost backhaul solutions. Next-generation mobile networks (5G) driving the need for high capacity backhaul links involve integration of terrestrial and space networks where UAVs can provide last-mile connectivity, which eventually can establish Internet access to remote areas using flexible FSO links.

UAVs will play a major role in today's connected society by bringing advantages to a wide range of industries, commercial, healthcare, public safety, logistics, and utilities. Current mobile networks need to optimize for flying objects. A UAV traffic management system would help pilots avoid collisions between UAVs and aircraft. All FSO communications can be done using existing optical networks and via secure interfaces on mobile networks. UAV's potential for establishing ultrabroadband connectivity will be able to address the unprecedented growth in demand for mobile and fixed broadband, which will be ready for 5G. Therefore, UAV in combination with FSO will be needed everywhere that large amounts of data have to be delivered in real time. Optical solutions with potential data rates of tens and hundreds of Gbit/s and using OFDM-based multicarrier transmissions have the potential for accomplishing future communication means for UAV scenarios.

For the upcoming 5G wireless network and beyond a reliable and efficient backhaul/fronthaul framework is required. Recently much interest in the unmanned flying platforms of various types including UAVs, drones, balloons, and HAPs can be used to provide wireless communication services based on FSO. Network flying platforms are capable of transporting the backhaul/fronthaul traffic between the access and core network via high data rate point-to-point FSO links. Different mitigation techniques exist for compensating FSO propagation effects distorted by the atmosphere. Emerging backhaul/fronthaul requirements for the 5G+ wireless networks can therefore be met even in the presence of ultradense heterogeneous small cells that are very often necessary to accomplish broadband connectivity without loss. Normally the traffic of small cells is delivered to a central LOS hub. A communication system with UAVs as platforms and the flying altitude can range from a few hundred meters to several kilometers (typically 20 km) depending on the coverage area, weather condition, and the UAV's communication capability, which should be able to provide a potential solution. Some excellent papers are available in the literature discussing UAV platforms for FSO links for communication networks.

Choosing a Wireless Technology for the PIB Device

There are various technologies that could be used to achieve the PIB system. See the brief summary in Table 10.2.

Table 10.2. Wireless Communication Alternatives

The reasons for choosing Bluetooth as the wireless connectivity for the PIB system are:

Its physical size is small, and there are many chip vendors to choose from.

The range is adequate—the lowest power version offers up to a 10 m range, which is sufficient.

The available choice of chip vendors leads to a competitive market, which means the cost will reach less than $5 over the next two to three years.

There is a worldwide acceptance of the ISM band used by Bluetooth, which means that the product design can be sold in markets all over the world.

Products are expected to interoperate if they have been qualified and received a Bluetooth logo. This means that the data terminal side of the Bluetooth link can be implemented with readily available, cost-effective, commercial products.

From Table 10.2, we can see that IrDA is also a good match for the requirements of a Personal Information Base. The advantage of Bluetooth wireless technology is that it is not directional—with infrared technology, the ports on two devices must be lined up, but a Bluetooth device can be accessed while still in the patient's pocket, for example, greatly increasing convenience of use.

20.2.2.2 Wireless Connectivity

The problem of the ever wider use of wireless connectivity, coupled with the increasing ranges for connectivity that are being achieved will inevitably cause increasing problems in the future for the Investigator. The initial problem at the crime scene will be to determine what devices are relevant to the investigation. At any location, there are likely to be a number of access points and the density of these is likely to increase, as there is a greater take-up of wireless connectivity. The next problem is that if the suspect is skilled they may be using a wireless channel that is not in the standard range and which could easily be overlooked. Another problem will be keeping the device isolated during the collection and analysis phases.

UI Improvements

For improved manageability, Microsoft has integrated the wireless connectivity configuration from the properties of a wireless network adapter in older versions of Microsoft into the new Network and Sharing Center in Vista. You can manage, set up, and connect using wireless connectivity from the Network and Sharing Center. Figure 7.1 displays the new Network and Sharing Center where wireless connectivity is managed.

You can configure wireless network profiles on a per-user basis. In the Manage Wireless Networks folder inside the Network and Sharing Center, you can configure wireless network profiles that you can apply to all users on your computer or to a specific user. The per-user profile policy is initiated when a user logs on to the computer, and is disconnected when the user logs off or changes to a different username.

The advantage of configuring per-user wireless profiles is that administrators can restrict network security policy based on the user currently logged on to the system. For example, multiple users can share your corporate wireless workstation. A user from the engineering group that logs on will be allowed access to the internal network via its wireless connectivity, as well as to the Internet. However, a guest user that logs on to the same workstation will only be allowed to wirelessly connect to the Internet and surf the Web. Per-user profiles allow wireless workstations to be shared among multiple security policy groups.

In Vista, you can configure a nonbroadcast wireless network. A nonbroadcast wireless network is a wireless network that does not advertise its network name, or Service Set Identifier (SSID). (For further details on SSIDs and broadcasting, refer to the “Wireless Security” section, later in this chapter.) In Windows 2003 and Windows XP, you could not configure a preferred wireless network as a nonbroadcast wireless network.This feature limited users from being able to automatically prefer and connect to wireless networks that had SSID broadcasting disabled.

Nonbroadcast networks are displayed as “Unnamed Network” when scanning for wireless networks. You will have to pick the name when connecting to an unnamed nonbroadcast network.

Vista will now prompt you when you try to connect to an unsecured wireless network before it automatically connects you (see Figure 7.2).This feature helps users be aware of possible wireless security threats before they connect to networks; for example, connecting to a wireless network that does not support encryption.

When connecting to a wireless network, the Network Connection Wizard will list all security methods that the wireless adapter supports. This allows you to pick the best security method available for your wireless adapter.

Digital identity

Our relationship with the Internet is changing. Mobile devices, wireless connectivity, and our increasing virtual presence across multiple social media services have all but collapsed the boundary between being online or offline. Together the virtual and the real form the seamless space in which many of us live out our daily lives. We fashion the self through social interaction, community and network affiliations, and here come to construct our identities as well as interpret the identity of others.7

According to Stephen Fells, President of Follr.com, a digital identity is “the sum of all digitally available information about an individual.”8 (see box). I would add that this definition also applies to a corporation’s digital identity. Another way to look at it is that a digital identity is data available online about a person, place, or thing (like a corporation) that is unique to them or it. One of the key factors of a digital identity is that it also contains information about how these unique factors are in relationships with each other. The words to notice are “unique” and “relationships.” In other words, identity is about you, digital identity is about your relationships to others. For companies, their identities are about them, and their digital identities are about their relationships with employees, customers, the public, etc.

There is much discussion over online identities and how they are, in fact, used. There is nothing to stop an individual from creating multiple personas for completing certain tasks, such as shopping.9 We had one White House Security Council staff who was fired once it was discovered that he was the person behind the Twitter account @NatSecWonk where he released security information and criticized Washington and national political players.10

There is also much discussion as to where all these tidbits of data that form your identity can be found online: search engines, web browsers, Internet service providers, cell phone companies, and our mobile devices (from smartphones to tablets). It is almost impossible to pinpoint all the “input” points of information about ourselves. Even when we think we are only giving certain information for one specific purpose, it seems to get used for a number of other purposes and on other online sites. For example, when you get a driver’s license, your information is put into the registry of potential jurors that is accessed not only by the court system of the county you reside in, but also marketers who purchase this kind of information for targeted marketing efforts.

From a technical standpoint, digital identity consists of certain core elements:

Authentication elements (identification (ID) #, internet provider address, email address, user name, password, etc.).

Data (original content posted by the individual or company).

Identifiers (photographs, avatars, logos, images, etc.).

Digital traces (contributions to blogs, links, etc.).

The difference between data and digital traces is that digital traces are smaller comments in response to someone else’s original content. For example, they could be comments to a blog.

All of these together make up the technological definition of identity needed for IT systems to identify and authenticate users to ensure security of data. In the InfoWorld Deep Diver Series about Identity Management, they remind IT professionals that digital identity management can “ensure with reasonable confidence that the people who access your network are who they claim to be and have the access privileges that they are trying to access.”11 Using these elements you can create a system of identifiers, controls, and security attributes.

Industry Interview:

Stephen Fells (Figure 3.1) is the president and founder of Follr.com, a Web site that promises its users smarter professional networking and digital identity control by providing a venue for an end-user to combine all of their online digital footprints into one comprehensive and organized platform.12 During a telephone interview, Stephen and I discussed the importance of digital identity in today’s world for the personal and the professional and some recent trends in identity protection.

FIGURE 3.1. Stephen Fells, CEO of Follr.com.

12.1.6 Bluetooth profiles

Bluetooth profiles assure interoperability of applications in Bluetooth. The profiles define the required functions and features of each layer from PHY to L2CAP and other protocols outside the core specification. A profile defines vertical interactions between layers as well as peer-to-peer interactions of specific layers between devices (Fig. 12.12) [1].

The generic access profile (GAP), the base profile which all Bluetooth devices implement, defines the basic requirements of a Bluetooth device. It describes methods for device discovery, connection establishment, security, authentication, association models and service discovery. In LE, GAP defines the four specific roles of broadcaster, observer, peripheral and central, which are described above. Another inherent profile is generic attribute profile (GATT). GATT defines the way that two Bluetooth Low Energy devices send and receive standard messages.

For two Bluetooth devices to be compatible, they must support the same profiles. There are a number of Bluetooth BR/EDR adopted profiles which describe commonly used application types. Bluetooth LE application developers can use a comprehensive set of adopted profiles, or they can use GATT to create new profiles. A sampling of the more common profiles are described briefly here [3].

11.3.5 Physical layer

Additionally to the previously described software based methods, usually it is worth considering hardware implemented PHY solutions when it comes to wireless connectivity. The wireless channel, due to its random nature, poses a special challenge for the main technical parameters throughput, delay, resilience, and massiveness. Some methods to tackle these challenges found on modern chips and novelties for future developments are briefly introduced in the following:

Basic concepts In the last decades the PHY was mainly designed for ever-increasing data rates, which according to the theorem formulated by Shannon and Hartley, can be achieved by raising the communications bandwidth. As the bandwidth on the historically used carrier frequencies is already heavily occupied, researchers are developing methods to utilize higher frequencies, where more bandwidth is available, e.g., recently also considering the terahertz band [861]. However, the main challenge for utilizing these frequency bands is the high signal attenuation. The second major development for raising the communications bandwidth relates to the number of antennas used. Truly massive numbers of antennas are considered for future base stations, which make the utilization of the spatial domain additional to the time-frequency domain possible [862]. Simultaneously multiple antennas enable the use of beam forming, which allows focusing the energy of the transmission, and therefore help to overcome the pathloss in higher frequency bands. In all cases, when handling such high data rates, the energy demand of the device becomes a major problem. This requires research for more energy-efficient PHY solutions, i.e., by reducing the amplitude resolution of the analog digital converters in the receivers down to a minimum of one bit [863].

Additionally to throughput limitations, wireless transmissions are limited when it comes to resilience. The wireless channel, due to its random fading, has an unreliable nature, which is problematic for the overall resilience of the system. In particular, radiated waves from the transmitter are reflected by scatterers in the environment. These waves interfere with each other and, depending on the location, can sum up constructively or destructively. Hence, when moving through space, the receiver will observe quickly changing conditions in terms of receive power as depicted in Fig. 11.10.

In the event of strong destructive interference, denoted as an outage, the Signal-to-Noise Ratio (SNR) is too low to recover the transmitted information from the received signal. This inevitably results in transmission errors and is a problem for the reliability of the wireless link. The challenge when designing a reliable wireless communications system on the physical layer is to prepare for such fading-induced outages. One approach is to employ redundancy in the form of physical layer multiconnectivity. In multiconnectivity systems, the device is simultaneously connected over multiple links. Both connections to a single transmitter and connections to multiple spatially separated transmitters can be considered [864]. The scenario of a human wearing special clothing connected over multiple wireless links simultaneously is depicted in Fig. 11.11.

The fundamental idea behind multiconnectivity solutions is that, when connecting over multiple links in parallel, outages only become a problem when they occur on all links simultaneously. The probability of such a critical event is significantly lower compared to the single link case, since every link sees a different fading realization dependent on the correlation between the links. Therefore the correlation becomes crucially important for the performance of the approach. The links in physical layer multiconnectivity scenarios can be separated in frequency, the spatial domain or time. In frequency-separated multiconnectivity approaches, redundant data is served on multiple carrier frequencies simultaneously. Spatially separated multiconnectivity approaches use multiple antennas for redundant data transmission. When using time separation, data simply is retransmitted after a first transmission attempt.

The physical layer also adds latency to the loop due to the extensive processing required, e.g., for employing channel coding and decoding or waveform generation. Low-latency communications on the wireless link has to be considered together with the resilience of the transmission, as there is usually only time for a single transmission attempt within the targeted round trip times. Simultaneously, this also means that some methods to increase the reliability fail when it comes to latency, namely time-separated multiconnectivity approaches.

When designing PHY methods for reliable and low latency wireless communications the question for massiveness becomes important for practical systems. For example, the available bandwidth greatly limits the number of links that can be assigned to each user in multiconnectivity approaches with frequency separation when a massive number of devices needs to be connected. TaHiL-optimized RRM approaches are envisioned to allow for high numbers of devices, and due to channel monitoring capabilities, enable the necessary flexibility between the described specialized methods. By knowing the fading state, the number of resources can be accurately adopted to achieve a certain QoS in terms of reliability and throughput. Moreover, resources that are in outage for one user can be operational for another. Thus the number of servable devices can be optimized if the scheduling decisions are dependent on these state information. Such QoS-aware scheduling is a MAC task, however, it is enabled by the monitoring capabilities of PHY. The problem when monitoring the wireless channel is that from the point of observation to the point of data transmission, the channel continues to vary. In the worst case, a channel is monitored to be operational but is in outage during a transmission attempt shortly after, therefore requiring methods to predict these outages [865]. Since monitoring as well as prediction are subject to error, such predictive methods need to be designed carefully to the needs of the Tactile Internet. The basic idea for TaHiL-envisioned prediction based RRM approach is depicted in Fig. 11.12 (left). By introducing a threshold for the detection of outages greater than the outage threshold, the probability for critical prediction errors, which falsely predict an operable fading state can be reduced. Such missed outages lead to an unreliable system when occurring too often, therefore making it unusable for TaHiL operation. The detection threshold can be flexibly adopted for different reliability requirements to suite varying use cases and system states. As depicted in Fig. 11.12 (right), fading prediction combined with the additional threshold for outage detection Pthr can overcome the monitoring delay and achieve reliable channel monitoring for TaHiL operation. Dependent on the detection threshold, the possible single link reliability is improved by orders of magnitude. With monitoring available, the challenge is now to design a TaHiL–RRM solution achieving the QoS needed by the use cases described in Chapters 2, 3, and 4.

Relevance for the Tactile Internet When it comes to wireless connectivity, transmissions are generally unreliable due to the random nature of the fading. Moreover, the PHY is an additional source for latency as outlined above. Since these parameters are highly important for the realization of the Tactile Internet, the development of novel PHY techniques becomes a major research focus for lowering the overall round trip latency down to a minimum. For the improvement of wireless reliability, detailed information about the channel is only available at the PHY. Therefore methods to increase wireless reliability and to simultaneously achieve an acceptable latency are most effective when employed at the PHY. Simultaneously these PHY nonidealities are relevant during the development of Tactile Internet applications as well. The remaining possibility for packet loss needs to be considered when it comes to controller design and intention prediction. As portable wireless devices need to be battery powered the energy consumption of the PHY becomes highly relevant for the Tactile Internet as well. For the system as a whole, novel wireless chip design and energy optimized PHY can significantly help to generally reduce power consumption.