Systems Mobile Telephony Network

Published Date: 02 Nov 2017

In 2005, the network technology widely discussed. This mainly refers to a Wi-Fi network or "cloud" on a large scale in a city with a lot of WiFi nodes are connected by a mesh network. There was also a discussion on the current mesh networks, where mobile nodes communicate directly with other mobile nodes, usually in the context of cognitive radio.

The concept behind the mask of technology and the chances of success will be discussed later, not further specified. If successful, 'cloud' of Wi-Fi in a city as a potential replacement for efficiently making mobile convergence for the home and office to expand the urban area. However, it seems that at this time is unlikely that a mesh having the ability to withstand a large number of calls, unless the majority of the cells are connected via wired connections fast. At this point, the cost of the system can not be compared to that of a foam system 3G lead to one of the main reasons for the distribution.

Therefore, I do not think the mobile mesh networks is a serious threat to systems such as 3G, although it can be successful in a number of niche applications.

3.2.4 Cognitive Radio

Another concept in the debate and in 2005 was the cognitive radio. Although there are different definitions of what is a cognitive radio is the basic concept was a device to get to a new environment, "understands" the use of radio frequencies and its behavior accordingly. It was thought particularly useful for the exploitation of the spectrum underutilized. For example, a cognitive radio discover that the emergency services

frequencies currently used light - perhaps because there is little accidents. You can go to these frequencies and a series of units to short, so that the frequencies after each still available. If you can not go to other frequencies, such as those issued so that the material used in the area.

There are obvious military advantages of such a system - that allows devices on a battlefield to operate without central planning, taking into account local radio. In the commercial world, with the promise of cognitive radio to expand the number of available radio frequencies for communication through the use of other frequencies. Studies have suggested that a large part of the light spectrum is used, then it is possible that a significant increase in the amount "effective" of the frequencies of personal communication would

can be obtained. To realize the value of cognitive radio, we must ask if it will work, and the value of this additional spectrum could be.

Will it work? Our vision is that it will not work. One of the key problems in cognitive radio is called the hidden terminal problem. One way that can be done is shown in Figure 3.2.

Figure 3.2 The hidden terminal problem.

A cognitive radio user to measure and there is no activity on the site of a piece of spectrum. However, there may be a legitimate user of that spectrum behind the next building, sending a tower on the hill. Because the building is between the user, the user receives no legitimate cognitive radio signal and then concludes spectrum is uninhabited. But because users can see the tower on the hill, as the user cognitive radio sends this signal is received as an intrusion into the tower. Hidden terminal Problems can also occur in many other cases, including the case where there is no shadow, but the cognitive radio is simply less sensitive than the recipient.

This problem is solved with the tower on the hill of a signal or "lighthouse" for free. A terminal therefore requires the use of the spectrum, and if granted, the tower indicates that the spectrum is occupied. This approach works well, but has a central control of the owner of the tire. Therefore, the choice of the owner of the spectrum, if desired this type of access and, if necessary, under what conditions allow.

The problem of hidden terminal is reduced a little '"issuer in white." TV stations use a particular channel in a city. You can not use the same channel in a nearby town to avoid interference, use only. a place hundreds of miles away from these two transmitters have the possibility to use the frequency to a much lower energy level of the transmission channel without interference because the use of television is relatively static -. assigning frequencies rarely changed - terminals able to determine its location and the database of the spectrum is useful to overcome the problem hidden terminal. The extent to which the white space varies diffusion. In the United States, with its urban sprawl, is common., In the United Kingdom, with a more even distribution of the population and the active use of white program and without transmission equipment, there are fewer opportunities.

Other problems which exist for cognitive radio, including the fact that a cognitive radio could spread in adjacent bands that have not been explored radio interference due to nearby users.

Although these problems can be solved, there is still the question of which cognitive radio. A network of base stations that are able to explore all the possible transmission frequencies would be expensive to build and enormous risk. Find other terminals transmit directly hard and suffer from the problems that are associated with the mesh.

Spectrum is needed? Our opinion is that we should not for this additional spectrum. 3G operators in 2005 is generally only 50% of the equipment used. Promised additional spectrum 3G 2.5 to 2.7 GHz and UHF analog television. As discussed below, the demand for mobile phones eventually fall W-LAN traffic, and there are a lot of spectrum for these in the 5-6 GHz Thus, while the lack of frequencies

a problem in the past, we believe that this problem is diminishing.

Therefore, we believe that cognitive radio is able to keep its promise to provide seamless spectrum utilization underutilized and struggle to get an application in the more expensive phones can be justified find. Will not have a significant impact on our predictions for the future.

3.3 Fixed Wireless

3.3.1 Introduction

Fixed wireless [4] was very popular around 1997, with many postulated that these cellular wood to be. He continued with the result that between 1999 and 2003, many manufacturers and wireless operators still leave the industry. However, there is an avalanche of new technologies and new market entrants.

The basic concept is to provide a wireless connection to the public telephone network (PSTN) or public data network (PDN) for home or business. Fixed wireless may be used:

• Voice communication easier for the home, which is a similar service to landlines in many developed countries are already in most households. This is often referred to as the normal telephone (POTS) and includes voice, fax, data transfer rates up to 56 kbit / s, and offer personalized access additional premises (CLASS) - functions such as emergency calls, three bubbles games and other incentives.

• The improvement of voice and data communications, and provides all the above features, as well as a line of simultaneous voice capabilities and more reliable data. Offer typical of this area is the provision of data to 1 Mbit / s, but is expected to increase in

future.

• Solutions data only for residential and commercial properties. These solutions are currently used for applications such as Internet and LAN interconnect.

• High speed and very high. These links are usually set on a point by point basis, there are data types in the range of 10 Mbit / s to 1 Gbit frequency solutions / s, data systems and optical highest rate very high.

The area is complex, since each of these different applications, there are several competing technologies such as cable modem, DSL modem, powerline technology and other wireless technologies, as there are many contenders fixed wireless technologies such as business houses are not tested, and because the market is embryonic.

A summary of the main issues in this section.

3.3.2 Key factors for fixed wireless

Fixed Wireless is historically as a means of permanent connections at home, and more recently as a means of competing local network. This historical paradigm has mixed results. More recently this has changed with the assumption that the paper of fixed wireless technology is connected to the source of data at high speed. Most homes are interested in high-speed data usually have some kind of connection, such as copper wires.

In this case, fixed wireless competitor can offer a better service, lower costs, or both.

3.3.3 Main competitors fixed wireless

There are a number of implementation mechanisms for quick access to buildings. These include twisted pair cables, coaxial cables (often referred to as "bait"), the fiber and the power supply line. The main mechanisms are briefly described below.

Copper infrastructure, consisting of a pair of copper wire installed and owned by the state of the phone (PTO), have been the traditional access infrastructure for nearly 100 years. For much of his life was not suitable for anything other than voice because of low bandwidth (only 3 kHz). But the deployment of DSL in 1990 the situation has changed drastically. It currently supplies approximately 2 Mbit / s downlink and penetration approaches 30% in developed countries. Future developments ADSL2 + promises data transfer rates up to 20 Mbit / s, although, as with all DSL solutions, data rate with increasing distance from the local exchange. Some users, probably due to reach data transfer rate of 1 Mbit / s, unless there is a series of major infrastructure improvements.

Cable operators have implemented the underground networks, in particular the distribution of television in many countries. As a result, they tend to be used wires in residential areas, but not the business. Cable networks are different in composition. Some are fully coaxial. Others use the fiber in the spine, but the LAN, coaxial, these are often known as fiber to the curb (FTTC) or hybrid fiber coaxial (HFC).

This is not the whole story. For each statement there is one (or two) pairs of copper wire going from the switch to the right on the premise. In a wired network, share it everywhere local branch in which they are connected. In other words anywhere on a branch connected to the cable are all connected to its single pair. This is fine when the services of transmission cable, to be seen by many at the same time, of 50 or more channels. But as each user in a branch wanted a video on demand service, so that only users 50 can be accommodated on a branch, in contrast to the pair using DSL, where many users can be hosted accommodation. Cable operators are currently "shorten" the branches conducting further from the spine to subscribers.

Cable modems are used with high capacity commercial scale implementation of 30 Mbit / s, and a capacity of up to 10 Mbit / s, it is clear that when the cable is already installed, the cable operators are able to deliver converged to give voice, computer and TV all on the same channel.

Overcoming the "final" can direct fiber to the home. Depending on the devices at each end, the bandwidth of the fiber is almost unlimited (of the order of Gb / s). Expansion of the fiber is expensive, it costs about $ 1,500 for the average family, because of the need to dig trenches and laying cables. But in 2006, there have been a number of implementations in the world takes place in Korea, Japan, United States of America and Italy. As the data rate requirements for the increase can be expected that the penetration of the optical fiber increases.

3.3.4 Wireless fixed probability of success

Legend fixed wireless success is the ability to offer a competitive copper and, in some cases, and the fiber cable. This has always been a problem for the fixed wireless. Copper technologies tend to be at least as fast as Wi-promotion, that data transmission speed of excess copper wirelessly. The prices for services such as ADSL has continued to fall, making it increasingly difficult for the supply of wire fixed to succeed. Compete with cable and fiber is even more difficult due to its ability to offer triple play of video, voice and data. This inability to provide competitive supply has resulted in the almost all of the time fixed wireless network.

Has not stopped trying to keep operators. Recently, operators are expected to implementations based on WiMax technology. The advantages are claimed to standardization, increased competition and economies of scale and thus the price of equipment. It is also specified that the installation inside is possible, eliminating the need for expensive external antenna.

Our vision is to set wireless as a pure fixed interval (see below), has little chance of success in a niche of users. Copper offers clear advantages in terms of cost savings, speed and data capacity. Wireless systems, shared tubes of data and users, in a capacity yet elongated cell phone subscribers.

Standardization is probably not cost enough with cost ADSL fall of the government. Covert operation will inevitably lead to a reduction in the size of the cell as the building penetration loss of the signal decreases, further increasing the cost of implementation of the network.

In addition, the service will be less reliable, it is possible that the antenna makes coverage areas poor noise sources in the home or as close as appliances. Fixed wireless failed in the past, and we see no fundamental change in the factors that have led.

3.3.5 The expansion of the market with a Nomadic

One possibility considered by some wireless fixed network operators is to use a combination of fixed and portable. Here subscribers can access the service from their homes as a regular system of access to the fixed network, but also the service when you are out of the house, or when you are around the house, or in other areas of coverage areas, as shopping for city use. The service called nomadic rather than mobile phone to indicate that the user is required to provide a service area to try and remain essentially stationary, while access to the system.

This means that the additional function of a value for the user, and can not be obtained with other fixed services. Therefore, it is likely that increase the chances of success some. However, our opinion is that the user will see these benefits as useless and not be willing to have a much higher monthly fee. Therefore, it is unlikely to significantly alter our results fixed wireless vitality.

3.3.6 Forecast fixed wireless

Since its inception in late 1990, Fixed Wireless failed to succeed. Even if the market is big enough to have a couple of small and medium enterprises is still small compared to other wireless solutions such as support for cellular and wireless LAN. At present it is difficult to see what is possible in this situation. Even if the demand is growing for high-speed connections, this question is generally well served by wired solutions. The possibility of an innovative solution technique seems remote as described above and in more detail in Chapter 6 Perhaps in the long run, the requirements relating to the speed of data increases to house above the level that can be supported by ADSL, if the fiber is inserted more depth in the network and technologies, such as wireless network is set as a fixed feasible. But for now it is difficult to see that play an important role in the future of wireless technology.

3.4 Short Range Devices

3.4.1 Introduction

An area of ​​proliferation of standards and technologies in 2000-2005 was a world of short-range devices. And 'one of the few areas of wireless communication detects rapid growth. Shipments of chip Bluetooth and W-LAN devices is growing rapidly year on year, and soon probably in a phase in which the majority of mobile phones comes with integrated Bluetooth, and most laptops have W-LAN options for achieving this goal.

To understand this market, is the first worth understanding why anyone would want a short-range devices. In practice, few people of a particular device, and is within walking distance - for most users, the higher the better scope. Devices are designed to be a short one or more of the following reasons:

• A high data rate is required, which means that the cells both high frequency bands or small, which in turn is less widespread. Cells of small dimensions can also facilitate access protocols less interference and propagation delays that are maintained, the data rate of speed.

• Long battery life is required, resulting in low power transfer.

• Low cost is required, resulting in a low-power RF components are integrated in the chipset.

Different applications have different advantages and disadvantages of each of these axes - for example, some of the data transfer rate higher, another the lowest cost, the other a mixture of each attribute.

This may explain the proliferation of different rules in detail later. The potential applications for short-range devices, which do not lend themselves to the cell one or more of the following reasons:

• cell can not provide enough data transmission speed.

• cell functionality is not needed (eg, ad-hoc networks).

• Phone calls would be too expensive.

• cell technology is too expensive to be integrated into the device.

Membership in one or more of these categories are the following programs:

• Network in the office or at home. This phone is too slow and too expensive. In the future, this area also on planes and trains and network personal networks throughout the body.

• High-speed data transfer. This phone is too slow. Specific applications include the e-mail synchronization of movement points and access broadcast video from a camera to a monitor.

• Cable replacement applications. Here cell technology is too expensive and too expensive. There are many applications known here as wireless headphones, wireless mouse, headphones and PDA connectivity to the computer.

• Machine to machine communication. This cell is expensive and complicated, but the distances, it may be the only option. Specific applications in this field are remote sensing (eg, growth conditions in a field), and the replacement physical keys for security.

Despite the short-range devices to cover the areas where cells inappropriate, in some cases it is useful to work together to integrate the two, for example, the use of the phone in the house through the technology in short-range, or "master" on a machine to machine subnets can signal to the control through the cell. In general, this integration is generally a matter of software of upper layer in place of the standard integrated.

Although there are relatively few applications in short-range at this time, there is great potential for the "point of no return" for some applications a short distance spread. The turning point is a description of a process in which the penetration is above a certain point a positive spiral allows the driver to rapid growth. For example, a manufacturer of sports shoes, if you notice that a significant percentage of the public had computers with Bluetooth, you may want to create a wireless sneakers on the market. This shoe can request data during execution - as the number of steps, weight, etc. - that have an amateur runner can be downloaded to a computer for analysis of driving. If some of these applications have become available to encourage more people to turn on Bluetooth on your computer, which in turn encourage a greater number of applications to obtain, and so on. The trick is to penetrate beyond the turning point where market forces can lead soon. Given the relatively low cost of short-range devices and the widespread belief in them from companies like Sony, there is every possibility that this could happen. The biggest obstacle is the number of short-range standard - like most of the users, which meets the standard itself reaches the point of no return.

In the next section we look at the various standards that have arisen and why the market is so fragmented.

3.4.2 Overview of standards for short-range devices

Several technologies are called short-range available or under development are shown in Table 3.1, in its maximum speed of data.

Table 3.1 Short-range technologies

Standard

User data rate

Range

Approximate price in 2006

Battery Life

>100 Mbits/s

5-10 m

$5-10

Hours to days

5-30 Mbits/s

100 m

$20

Hours

700 kbits/s

10 m

$3

Hours

500 kbits/s

100 m

$5

Days

Zigbee

128 kbits/s

30 m

$1

Weeks to months

RFID

1-200 kbits/s

0.1-10 m

$0.05-1

Weeks to indefinitely

A more detailed description of each of these techniques, but the following general conditions:

Ultra Wide Band (UWB) uses a new modulation format for sending over a very wide bandwidth. Subject to regulatory approval, this makes it possible to operate at frequencies in use. The main advantage is the possibility of very high data rates, it is necessary to work at low current results in a short for many applications.

• The W-LAN standard, including 802.11a primary, b, g, is the technology that W-LAN, 802.11b and widespread. They provide a high data rate and a relatively wide range, but at the expense of cost and battery.

• DECT technology known as wireless voice used throughout Europe. It is also possible to transport information. The advantages are the price range and represents a relatively low rate data and the battery is normal.

• Bluetooth is also known as short interval standard. The main feature is the low price, which is relatively low-speed data transfer, the scope and duration of the battery. It is commonly embedded in different devices.

• ZigBee is a new Bluetooth standard designed to replace the battery in programs much longer duration that may need assistance BlueTooth. For this purpose, a lower data rate, and a lower duty cycle for transmission and reception.

• Radio Frequency Identification (RFID) is a broad category of passive devices, with a special ink printed on paper labels for active transponders. It includes the development of a standard called "Near Field Communication (NFC). Tags are generally inexpensive and can be extremely long battery life (or yes, no battery required), but they offer a very low rate and data interval often only a few centimeters.

The advantage of a wide range of technologies, the designer can choose a specific application, probably well suited to their specific needs.

The disadvantage is that there is to ensure that the user has the same technology embodied in the device that is the other end of the connection module. The key to determining which technologies fail to understand this optimal balance between functionality and high penetration. The last part of this chapter in this balance and makes a series of predictions about the future of short-range devices.

3.4.3 Ultra Wide Band (UWB)

The idea of ​​a W-PAN technology occurred in 2002 in the group and called IEEE 802.15.3 WiMedia. This technology is widely centered distribution of audio-visual information in the home. Thus, for example, can be used for wireless connection DVD player with monitor and speakers, can not be in the same room. To do this, you should be capable of data transfer rates of 20 Mbit / s, to provide a high quality service. It is not easy to achieve with the current WLAN standards

time intervals which are not reserved, and then the clear need for a new standard.

Initially seen WiMedia forum in a number of different air interface standard with different data transfer speeds. In 2004 they decided to focus on UWB technology as their major.

UWB allows data rates of 100 Mbit / s, 1 Gbit / s, but this can be detrimental to a small area can be limited to within a single room. If this data rate higher, but the lower range will be of great value to users is not yet clear.

In 2006, the WiMedia still a developing technology, chipsets and devices appear. Success will depend on the adoption by manufacturers of home audio-visual equipment.

3.4.4 Wireless LAN

Almost all of the W-LAN solutions are compliant with the IEEE 802.11 standard. Thus, in the remainder of this section concentrate 802.11 and many variations.

A WLAN 802.11 system typically comprises one or more base stations or access points, and a variety of mobile devices. W-LAN devices may operate without a base station in ad-hoc mode via Bluetooth (see below), but this way of working is much less common. IEEE 802.11 protocol stack is the lowest physical layer, and then a single layer protocol three.

There are many variations or modifications of 802.11 - at the time of writing the most important of these were:

• 11a fast version of the operating system 802.11 in 5 GHz band

• 11b is considered the standard W-LAN solution that operates at 2.4 GHz

• 11g a high-speed version, but in Ghz 2.4.

They all have the same multiple access method - Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA).

W-LAN suffer the hidden terminal problem same as cognitive radio, and this approach tries to solve the problem, albeit with some interference between users.

In essence, the control of a device that wants to transmit a packet radio channel. If no activity is detected is released. If it is considered that there is no activity waits a random time before packaging. E 'possible that a different device is a packet transmitted simultaneously.

To overcome this, the base station sends an acknowledgment for each packet received. If the station does not receive an acknowledgment wait a random time before forwarding the packet.

The technologies are different in its physical layer. A summary of the similarities and differences between the standards set out in Table 3.2.

Table 3.2 A comparison between different variants of 802.11

Characteristic

802.11a

802.11b

802.11g

Spectrum

5 GHz

2.4 GHz

2.4 GHz

Max physical data

54 Mbits/s

11 Mbits/s

54 Mbits/s

Max user data rate

25 Mbits/s

5 Mbits/s

25 Mbits/s

Physical layer

OFDM

DSSS

OFDM

At first glance, it looks like a problem with the spread of WLAN standards, resulting in confusion for the user to stop and, after the lack of success in the market. In practice this does not happen, because the rule 11b has a moment to set the de-facto standard. Currently, if manufacturers make in 11th 11g or add a product beyond 11b. This provides some stability in the market and ensure that all the products work together and use a version of higher speed as they are available in both the base station and the mobile phone.

One of the most important developments in wireless communications since 2000 is the success, W-LAN. In 2000, it was not clear how wide it would be accepted, but in 2006 almost all laptops and PDAs have many features W-LAN. W-LAN base stations for home and offices were also increasing at a rapid pace. Hence the success of W-LAN in the home and in the office seemed assured.

Less obvious is the hotspot market, where it is used W-LAN in public places such as airports to high data rate. This is a market that had fought in 2000 in the United States, where the two main actors - Metricon and Mobile Star - has failed. In 2006, the market turned out to be repaired with some of the largest mobile operators and major investments of T-Mobile and Swisscom and W-LAN access point devices, such as the Large Cloud of installations in progress. However,

in 2006, it was not clear whether the public W-LAN would be successful, and what the current business model would be.

Our vision is that the public W-LAN is a very good match for the needs of notebook users.

With W-LAN in the laptop without integrated devices are needed. W-LAN in a fast and efficient way to send e-mail to use and browse the web and has been implemented in the main tourist sites. This seems to be a viable market, but is not large. But when integrated with other services as part of a process of convergence their value. We hope that the points of W-LAN are increasingly accepted by the main fixed and mobile operators worldwide.

3.4.5 BlueTooth

A subject can be a number of units he or she uses in or near the person. The concept of technologies such as Bluetooth cable replacement is that if any of these devices are equipped with short-range wireless communications that have allowed them to exchange information wirelessly without user intervention. For example, keeping a laptop computer that was supposedly in the 'dream' in a folder periodically talks to cut mobile user's life and ask them to check e-mail. Your phone can send it back and

the laptop on the link shortly. The handset is able to maintain that when the computer is in "on", all the e-mails are available on your computer. If the user's actions, such as sending e-mail, talk to your computer and mobile phone application for the transfer of such data to the network.

These results conceptual special requirements and features that are often described as "ad-hoc networks.

• The short-range devices must be very cheap as it should be integrated into most of the machines. The price range up to $ 5 per chip is often discussed.

• This requirement is the same price tends to limit the devices within walking distance of one of the most expensive components in a wireless device is the RF amplifier.

• The system must make use of unlicensed spectrum and must be "self-organization" of a spectral position if there is no central control.

• Network must "self-awareness" and "self." No entity can know in advance which other devices can be nearby, so that the devices are equipped with a method to detect other devices to find out what they are and the exchange of relevant information.

With an almost infinite number of units, understanding how devices communicate information to send to others, and if you have the appropriate permissions to do so problematic.

Bluetooth is designed to operate in the unlicensed industrial, scientific and medical (ISM) approximately 2.45 GHz bandwidth of 1 MHz, 1 MHz, but the bandwidth in the bandwidth 80 MHz ISM can be selected by means of the device in relation to ' surroundings. To overcome the interference expected in the ISM band, Bluetooth uses frequency hopping as a source of error (static) only a limited impact on the quality of the transmission.

Two levels of output power is available in the Bluetooth specification, 1 mW (0 dBm) to 100 mW (20 dBm). The first allows the transmission of a maximum of about 10 meters, the last of about 100 meters. There is still some debate as to which of these skills are more appropriate. The levels of lower energy, with consequent low cost devices with minimal interference from adjacent tiles. The higher authorities are more expensive to implement, and a severe loss of battery, but can easily cover a home or other building. The

More power control devices to communicate with units of low power consumption and reduced transmission, if the authorization is not required.

A major concern of Bluetooth is to detect the presence of other users and the construction of an ad-hoc network. In addition, the general need for devices with Bluetooth Low battery consumption to have. The only way that the Bluetooth device is to find at least one periodically send However, the frequency of transfers kept low to minimize battery usage. Since the device transmits only a short time, and this in one of many different frequencies used in the receiver

should be as long as possible listening. However, it also drains batteries. Complex algorithms is to make devices aware of each other with a minimum consumption of a battery, but in a time short enough that the user waits devices.

After several failed attempts. Bluetooth market during a period of strong growth Bluetooth is standard on many phones, laptops, PDAs and computers. Bluetooth headsets have achieved great success.

3.4.6 DECT

DECT is a standard established for the wireless telephony. Telephones and DECT base stations are now commonly installed in homes and offices. DECT technology is relatively old, the voice codec with low modulation unique compression and 1880-1900 MHz

DECT is also able to process data at a speed of 500 kbit / s. So far had limited success in this role because of the higher speeds on W-LAN. In perspective, it is likely that the remains DECT wireless voice technology of choice for many years, finally overcome by what happens in the ability of the solution space.

3.4.7 Zigbee

The reason for ZigBee was created by a design decision that the Bluetooth connection. Among other Bluetooth was designed for the battery pretty quickly - devices such as Bluetooth headsets, you may need daily load. There are a wide range of applications where long battery life is desirable - for example, a wireless mouse - while high data rates and advanced options of Bluetooth is not required. This is what Zigbee

designed. The main parameters of Zigbee is:

• data rates in the range from 10 to 115 kbit / s

• 30 m

• Up to 255 nodes in a network (compared to eight Bluetooth)

• 0.5 to 2 years battery life

• 5 MHz between channels.

In 2006, he completed Zigbee standard, but the devices were not in quantity. BlueTooth producers were "struggling" with a very low power version of Bluetooth. At the moment it is still difficult to predict or Zigbee will be successful.

3.4.8 RFID

It is a broad category of equipment normally used for labeling purposes. RFID is routinely used in stores to prevent theft of luggage grants system for monitoring and so on. Increasingly used in intelligent payment systems, where the user can move a barrier to keep it open.

RFID systems can be divided into active and passive. Most solutions are passive. When a passive tag is in the presence of an electric field and radiates energy back, modified according to the information label. This makes passive tags for the price, you can not replace the battery, and very small. The limited range of up to about 30 cm, sometimes less. Active acoustic solutions to query the signal and sends

supports the right information. They may have a number of several meters, and actually more like Bluetooth or ZigBee devices.

Although a relatively large market RFID little on the periphery of the traditional wireless communication and was not further studied.

3.4.9 The outlook for short-range devices

The history of the rules shows that only few survive, especially when interoperability is important. Of the three competing standards for video tapes, we went with VHS - less technically advanced, but after the first critical turning point. In the world of audio CD was a success, but the digital cassette and MiniDisc sent to the losers. In the world of cellular standards slowly cut with a fade now American TDMA standards, so that only GSM and CDMA. It 'hard to think of an example of an area where six standards, the current number of short range, all survived. History teaches us that the violation has been adopted before another is started, it is very difficult to move unless the new is overwhelming. In fact, some rule of thumb suggests that the new technology should be "ten times better" than the previous one, as it is for most people to convince you to believe. But if a number of competing standards all launched at the same time leading to confusion in the market and not always successful.

In a world of short-range devices, there are two standards that have been set and are on your way to success. The WLAN standard 802.11 is now incorporated in more than half of all handsets made. Likewise Bluetooth is integrated in all the high-end mobile phones and some digital devices, such as PDAs. DECT has been widely used as voice technology in the home and office, but little has been obtained in the form of usage data. With a large

LEAD Technologies, others can only be better if, or sufficiently different from W-LAN and Bluetooth or detect these technologies.

Some technologies may be relatively easy to dismiss. DECT is interesting for its ability to transfer voice and data, but data speeds are too slow to make use of this opportunity to do, and seems destined to remain a voice technology. UWB is very different from other technologies, but it is unclear if there are enough applications that require high speed data transfer and W-LAN is much better in many ways. (Although it should be noted that UWB other important applications, such as short-range radars

treated here.). This leaves us with the RFID and ZigBee as serious candidates.

Before further investigation, we must first look for any deficiencies in the current two "winners".

The 802.11 wireless LAN standard seems to have some big mistakes. There are a number of problems in terms of security, quality of service and so on, but these are done in the context of changes to the standard. W-LAN is now large enough to find a great mistake seems unlikely. Bluetooth is always better after a period in which many units were not compatible and the effort required to torque units were sometimes more than many professionals were willing to endure.

Zigbee has a great advantage over other similar models of short distance to the battery. This will be particularly important in some applications, often those that enable interoperability with existing devices. For example, the sensor in the use of ZigBee devices in the field of a farmer growing conditions no matter what standard farmer on the personal computer. Zigbee is likely to be successful in their standard niche for specific applications in which interoperability is not necessary.

That leaves RFID tags. These are usually used in various applications of short-range devices, such as luggage tags. Zigbee as if, no reason why it will not be here to be successful.

So in summary, dominates W-LAN and Bluetooth short-range devices on the market. Although not optimal for some applications, that lead on a large scale of these technologies in a variety of devices from numerous unexpected applications in the style of sneakers wireless alarm and auto-tuning. The resulting upward spiral provides a rapid growth in the market for short-range devices in the next decade, the transformation of the unit and the way we interact with them.

3.5 Basic networks

A brief analysis of the network is worth it, because almost all communications with the network path between the source and the parts fit. In the heart of a network of contacts that the call is routed through the network.

Around the switch may be many other components, such as the record position, the databases and the daughters switches. They are connected via broadband, usually dedicated interconnections. A core network, eg a cellular system, a very complicated device.

Core network is rarely binding in terms of capacity. It is much easier and cheaper to get more power at the center of the radio network. But the core network is very restrictive in terms of services and how convergence is achieved. This is the factor under examination.

Historical network integrates with special access technologies. So a mobile telephony network of the own core network-and a fixed access. The nuclei are slightly different, with different databases and small variations of the protocol, but most share the same platforms and technologies. This vertical integration of the core network with network access stems from the fact that:

• Often, the owners of the various networks are separate entities and are not willing to share the basic network

• Each system requires a little 'different and back was easier and less expensive to build separate networks and then to a more flexible core sample Implement universal.

Vertical integration also not so far seen as a big problem. The convergence is limited and the cost of the core network is typically less than 10% of the overall network such that the disadvantages observed to be minimal. Come on, it can be expected that the convergence will push the status quo on the rise.

The second drawback of the existing core network is the easy introduction of new services. Services such as call transfer three-way call is currently provided by the core network, usually the switch. Adding a new service requires an update of the switch. This can often be done by the manufacturer of the switch and is considered an important event with the potential to disrupt the entire network. This ensures that the time-consuming and expensive.

Many efforts have been made to solve this problem, including the standardization of the concept of "smart grid". This is the software you need to describe a separate service switch is in principle possible that other devices that use the software. But, for reasons different work "smart grid" was held to a limited extent.

The driver for the change is made, it is not interesting, the community working in the main network, but on the Internet. Internet from the beginning, based on the transmission of packets in which the information is encapsulated in the short packets, which are each provided with a destination tag, and is sent to the network. This is in contrast with most of the telecommunications networks, which use the circuit breaker, a special delivery path between the parties, and along which information can flow during the entire

bubbles. Advantages and disadvantages of each are well trained. Approximately packet-switched long considered unsuitable for real-time communication - calls, such as voice or video, in which the variable delays in the transmission of packets can be annoying to the user.

In reality, it is still true to a certain extent today, with VoIP calls from time to time with a lower quality than conventional calls. Switching network packet can be a single nucleus. All you need is a set of routers, packet headers and correctly analyzed. This simplicity lends itself well to another "level of service" when stored instructions more complex services, such as voice - in fact a principle identical for intelligent networks.

The growth of the Internet, and the flexibility of the Internet Protocol (IP)-based network in time, many believe that the future of the central nuclei existing vertically integrated step towards a common IP network. In this view, which is connected to some nuclei generic IP network for multiple access. Each user access information encapsulated in IP format and sends it to the plant. Specialized functions, such as mobility of mobile networks in other server sitting next to the main network. The advantages are:

• Convergence is much easier to achieve if a common core or access networks where the samples comparable, as such common services on the same server on different access networks.

• The costs should be lower because he spends less expensive than comparable routers and IP are usually more efficient use of resources in circuit switching.

• The flexibility is increased because of the services can be easily introduced.

• multimedia services is much easier to manage. For example, if a user chooses an item during a video call, a switched circuit network of a new type of connection. A network packet only generates multiple packets.

The disadvantages referred to concerns about the ability of IP networks with low delay, require low latency real-time communication. These problems are decreasing, as movements of IP protocols, such as IP version 6 (IPv6) or Multi-Protocol Label Switching (MPLS) allows both the quality of service (QoS), which are specified and the traffic is handled at ' internal network. Many mobile operators are required to put a little '

system called IMS (IP Multimedia) - the idea of ​​a central network for IP, can have a large number of different types of traffic management, and the intelligence of a number of servers are located along the edge of the core network. For the voice service is often based on a protocol called Session Initiation Protocol (SIP), which provides the necessary intelligence to route IP packets at the beginning of the call is determined.

The growing popularity of the Internet, the benefits of IP-based networks, and the gradual progress to solve problems with packet switching slowly over time, convinced that almost all major IP-based networks will be standard in the future. The balance in times of difficulty understanding.

All-IP vision is generally in the range of 5-10 years. To date, little progress towards this seemingly display. Package instead of a transition from large circuit-switched and packet switching systems, operators have chosen switched gradually, in addition to the switch.

There are a number of players such as BT, has announced major restructuring plans - in the case of BT's network for the 21st century. This should be conducted in 2010. BT is one of the major players in this space, and therefore, it will be 5-10 years before the all-IP vision becoming a reality.

3.6 Broadcasting

3.6.1 Broadcasting conventional

Broadcasting includes audio and video transmission practically - both can be treated in the same way in the context of this discussion. For as video transmission, the following mechanisms:

• terrestrial broadcasting with UHF channels for the transmission of video signals. This remains the main mode of transmission in many parts of the world.

• cable, send multiple channels over a single cable. Since this is not wireless, there is a major goal of this article.

• satellite broadcasting using a geostationary satellite multi-channel transmission to the receiver plates mounted on the side of the housing. This mechanism is currently the number of channels that are distributed and installed relatively quickly in comparison with other alternatives.

• Internet Radio is still in its infancy, but some are developing systems for the transmission of media that are end-users to access a particular site that "running" to receive broadcasts currently. Even if the end user to view the transmission from the architectural point of view, because the signal separately for each subscriber is more a mechanism multiple of one-to-one by an emission effective.

In recent years there has been a shift towards slow "personalization" in

emissions. The concept is that instead of looking at things, what is the next available channel is a channel "personal" created by each user according to their preferences. The first step to this was "home video recorder TiVo personal '(PVR) around 2000. PVRs are slowly growing in popularity and is now very successful in understanding user preferences and engaging content relevant to their hard drive.

The next step in this process would be for the research of multimedia content at home via Internet streaming content to fill the supply of personal TV channels, but this is a much more complex that the choice of broadcast content. If this approach was that the ubiquitous television, as a form of architecture to create multiple subscribers at the end cease to exist. Home media center will depend more and more material downloaded from the Internet.

The argument to customize the transmission is a bit 'weakened by cultural change is necessary to create it. People enjoy together to watch sports, or tune in every night to watch their favorite program. Cultural change of this type requires at least a generation, so even if you can change significantly over the next 20 years to see, we are probably the death of television as we know it today show.

HD transmission currently requires about 5 Mbit / s, the standard definition of definition of about 1.5 Mbit / s low and suitable for mobile screens about 200 kbit / s. These numbers will decline over time as technology improves compression. It has 1.5 Mbit / s for home using fixed networks is absolutely possible and 5 Mbit / s can be expected within a few years. With 200 kbit / s over mobile networks is also feasible, but only a subset of subscribers to the total capacity of the cell is reached.

Overall, it would be technically feasible and attractive for many to move to a world in which the transmission is personal. But just as it requires a significant cultural change in a way that is likely to be a rebirth. And no matter what happens, people still want to tune in to live a number of significant developments.