Статьи 6 семестр / Работы / In what way will wireless systems influence human communication

In what way will wireless systems influence human communication?

Little new technology is needed to make us rely heavily on a single device that will manage all our professional and personal communications needs. This evolution will be based on massively enhanced services, turning the mobile phone into an organiser, entertainment device, payment device, security centre and much more.

To make this happen I predict that one of the greatest changes is that broadcasting and communications will become a seamless network so that any content is available through any channel at any time. He also highlights the areas which will witness significant growth while predicting areas which won’t be so successful in the future.

Ten years ago the mobile phone was purely used for making calls. Today it is a camera, music player, organiser and texting device as well as phone. This is only the start of an evolution over the next twenty years that will turn it into our trusted and indispensable companion in life.

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Predicting the future is an essential element for almost everyone involved in the wireless industry. Manufacturers predict the future when they decide on product lines to develop or research to undertake, operators when they buy licences and deploy networks, and academics when they set PhD topics (doctoral [candidate's] thesis).

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The cellular concept was invented in 1948 by Bell Labs. Cells allow reuse of the frequency. Previously, there could only be 500 mobile phone uses per frequency. In New York City there was a 25 year waiting list for a mobile phone. The FCC didn’t allocate spectrum until 1982. Another major development was the DSP chip. ATT expected up to 1 million cellular subscribers by the year 2000.

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Radio spectrum is used for a wide range of services. These can be broken into the following broad classes:

• Broadcasting services: including short wave, AM and FM radio as well as terrestrial television;

• Mobile communications of voice and data: including maritime and aeronautical mobile for communications between ships, airplanes and land; land mobile for communications between a fixed base station and moving sites such as a taxi fleet and paging services, and mobile communications either between mobile users and a fixed network or between mobile users, such as mobile telephone services;

• Fixed Services: either point to point or point to multipoint services;

• Satellite: used for broadcasting, telecommunications and internet, particularly over long distances;

• Amateur radio; and

• Other Uses: including military, radio astronomy, meteorological and scientific uses.

The number of different devices using wireless communications is rising rapidly. Sensors and embedded wireless controllers are increasingly used in a variety of appliances and applications. Personal digital assistants (PDAs) and mobile computers are regularly connected to e-mail and internet services through wireless communications, and wireless local area networks for computers are becoming common in public areas like airport lounges. However, by far the most important and dramatic change in the use of wireless communications in the past twenty years has been the rise of the mobile telephone.

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Real wireless projects depend on three elements: the device, the network (i.e. the WAN) and the application. If one of those elements isn't up to par, then the project won't work. No one uses cumbersome devices; people give up if they can't connect to the network, and there's no point in doing a project if you can't deliver the data. Until recently, most devices had small screens that made it hard to view data, they ran out of batteries quickly-sometimes wiping out all the information in the process-and they were expensive. Networks, meanwhile, were proprietary and expensive. Those that succeeded fell into predictable categories. They were the companies that had large mobile workforces, depended on data from those workforces and, most importantly, could afford to invest in custom devices, proprietary coverage plans and homegrown applications. Common examples were trucking companies that tracked their drivers with GPS devices, shipping companies offering delivery confirmation, and utility companies whose repair crews collected large amounts of data about problems and fixes in the field.

When it comes to WANs, bandwidth is still limited. When transmitting data, users must sometimes send smaller bits of data so the information moves more quickly. The size of the device that's accessing the information is also still an issue. Even the most recent phones and PDAs have small screens-often only a couple of inches in diameter-and it is hard to read large documents on them.

Many applications need to be reconfigured if they are going to be used through wireless connections. Most client/server applications rely on a persistent connection, which is not the case with wireless. Transactional systems require safeguards for dropped wireless connections. Remedies for all of these shortcomings cost money.

Just because your company can go wireless doesn't mean it should – not every company needs wireless. Critical, time-sensitive applications are the best candidates for WAN projects. If getting information in real-time makes or breaks a sale, give your salespeople access to that data. But remember that WANs are best suited for accessing small pieces of information because of bandwidth constraints.

Wireless LANs are often installed for convenience, such as when an enterprise doesn't want to wire the building, or when an IT staff is dispersed throughout the building. They are often used in hospitals, where doctors and clinicians can check in while on rounds or on the floor. Wireless LANs are faster and more reliable than WANs.

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Wireless communications today covers a very wide array of applications. The telecommunications industry is one of the largest industries worldwide, with more than $1 trillion in annual revenues for services and equipment. (To put this in perspective, this number is comparable to the gross domestic product of many of the world’s richest countries, including France, Italy, and the United Kingdom.) The largest and most noticeable part of the telecommunications business is telephony. The principal wireless component of telephony is mobile (i.e., cellular) telephony. The worldwide growth rate in cellular telephony is very aggressive, and analysts report that the number of cellular telephony subscriptions worldwide has now surpassed the number of wireline (i.e., fixed) telephony subscriptions. Moreover, at the time of this writing in 2003, the number of cellular telephony subscriptions worldwide is reportedly on the order of 1.2 billion. These numbers make cellular telephony a very important driver of wireless technology development, and in recent years the push to develop new mobile data services, which go collectively under the name third-generation (3G) cellular, has played a key role in motivating research in new signal processing techniques for wireless. However, cellular telephony is only one of a very wide array of wireless technologies that are being developed very rapidly at the present time. Among other technologies are wireless piconetworking (as exemplified by the Bluetooth radio-on-a-chip) and other personal area network (PAN) systems (e.g., the IEEE 802.15 family of standards), wireless local area network (LAN) systems (exemplified by the IEEE 802.11 and HiperLAN families of standards, called WiFi systems), wireless metropolitan area network (MAN) systems (exemplified by the IEEE 802.16 family of standards, called WiMax systems), other wireless local loop (WLL) systems, and a variety of satellite systems. These additional wireless technologies provide a basis for a very rich array of applications, including local telephony service, broadband Internet access, and distribution of high-rate entertainment content such as high-definition video and high-quality audio to the home, within the home, to automobiles, and so on. Like 3G, these technologies have spurred considerable research in signal processing for wireless.

These technologies are supported by a number of transmission and channel-assignment techniques, including time-division multiple access (TDMA), code-division multiple access (CDMA), and other spread-spectrum systems, orthogonal frequency-division multiplexing (OFDM) and other multicarrier systems, and high-rate single-carrier systems. These techniques are chosen primarily to address the physical properties of wireless channels, among the most prominent of which are multipath fading, dispersion, and interference. In addition to these temporal transmission techniques, there are spatial techniques, notably beamforming and space-time coding, that can be applied at the transmitter to exploit the spatial and angular diversity of wireless channels. To obtain maximal benefit from these transmission techniques, to exploit the diversity opportunities of the wireless channel, and to mitigate the impairments of the wireless channel, advanced receiver signal processing techniques are of interest. These include channel equalization to combat dispersion, RAKE combining to exploit resolvable multipath, multiuser detection to mitigate multiple-access interference, suppression methods for co-channel interference, beamforming to exploit spatial diversity, and space-time processing to jointly exploit temporal and spatial properties of the signaling environment. These techniques are all described in the ensuing chapters.

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One of the most notable advanced applications for 4G systems is locationbased services. 4G location applications would be based on visualized, virtual navigation schemes that would support a remote database containing graphical representations of streets, buildings, and other physical characteristics of a large metropolitan area. This database could be accessed by a subscriber in a moving vehicle equipped with the appropriate wireless device, which would provide the platform on which would appear a virtual representation of the environment ahead. For example, one would be able to see the internal layout of a building during an emergency rescue. This type of application is sometimes referred to as "Telegeoprocessing", which is a combination of Geographical Information Systems (GIS) and Global Positioning Systems (GPS) working in concert over a high-capacity wireless mobile system. Telegeoprocessing over 4G networks will make it possible for the public safety community to have wireless operational functionality and specialized applications for everyday operations, as well as for crisis management. The emergence of next generation wireless technologies will enhance the effectiveness of the existing methods used by public safety. 3G technologies and beyond could possibly bring the following new features to public safety:

Virtual navigation: As described, a remote database contains the graphical representation of streets, buildings, and physical characteristics of a large metropolis. Blocks of this database are transmitted in rapid sequence to a vehicle, where a rendering program permits the occupants to visualize the environment ahead. They may also "virtually" see the internal layout of buildings to plan an emergency rescue, or to plan to engage hostile elements hidden in the building.

Tele-medicine: A paramedic assisting a victim of a traffic accident in a remote location could access medical records (e.g., x-rays) and establish a video conference so that a remotely based surgeon could provide “on-scene” assistance. In such a circumstance, the paramedic could relay the victim's vital information (recorded locally) back to the hospital in real time, for review by the surgeon.

Crisis-management applications: These arise, for example, as a result of natural disasters where the entire communications infrastructure is in disarray. In such circumstances, restoring communications quickly is essential. With wideband wireless mobile communications, both limited and complete communications capabilities, including Internet and video services, could be set up in a matter of hours. In comparison, it may take days or even weeks to re-establish communications capabilities when a wireline network is rendered inoperable.

Limitations of 4G. Although the concept of 4G communications shows much promise, there are still limitations that must be addressed. One major limitation is operating area. Although 2G networks are becoming more ubiquitous, there are still many areas not served. Rural areas and many buildings in metropolitan areas are not being served well by existing wireless networks. This limitation of today’s networks will carry over into future generations of wireless systems. The hype that is being created by 3G networks is giving the general public unrealistic expectations of always on, always available, anywhere, anytime communications. The public must realize that although high-speed data communications will be delivered, it will not be equivalent to the wired Internet – at least not at first. If measures are not taken now to correct perception issues, when 3G and later 4G services are deployed, there may be a great deal of disappointment associated with the deployment of the technology, and perceptions could become negative. If this were to happen, neither 3G nor 4G may realize its full potential. Another limitation is cost. The equipment required to implement a nextgeneration network is still very expensive. Carriers and providers have to plan carefully to make sure that expenses are kept realistic. One technique currently being implemented in Asian networks is a Pay-Per-Use model of services. This model will be difficult to implement in the United States, where the public is used to a service-for-free model (e.g., the Internet). Conclusions 4G networks may eventually deliver on all the promises. At times, it seems that technological advances are being made on a daily basis. These advances will make highspeed data/voice-over-Internet-protocol (VoIP) networks a reality. In the meantime, it is important for industry to develop a strong 3G offering that is palatable for the general public. Equally as important, industry must ensure that expectations are realistic and that services meet and exceed those expectations. If all goes according to what the industry envisions, it may be sooner, rather than later that we will see wireless communications evolve. This evolution will give the general public as well as the public safety community amazing functionality from the convenience of a single handheld device.