09-10-2012, 02:23 PM
Third Generation Wireless Technology
1G (First Generation)
The 1G period began in the late 1970s and lasted through the 1980s. These systems featured the first true mobile phone systems, known at first as "cellular mobile radio telephone." These networks used analog voice signaling, and were little more sophisticated than the repeater networks used by amateur radio operators.
2G (Second Generation)
The 2G phase began in the 1990s and much of this technology is still in use. The 2G cell phone features digital voice encoding. Examples include CDMA and GSM. Since its inception, 2G technology has steadily improved, with increased bandwidth, packet routing, and the introduction of multimedia.
3G includes capabilities and features such as:
Enhanced multimedia (voice, data, video, and remote control ).
Usability on all popular modes (cellular telephone, e-mail, paging, fax, video conferencing, and Web browsing).
Broad bandwidth and high speed (upwards of 2 Mbps).
Roaming capability throughout Europe, Japan, and North America.
While 3G is generally considered applicable mainly to mobile wireless, it is also relevant to fixed wireless and portable wireless. A 3G system should be operational from any location on, or over, the earth's surface, including use in homes, businesses, government offices, medical establishments, the military, personal and commercial land vehicles, private and commercial watercraft and marine craft, private and commercial aircraft (except where passenger use restrictions apply), portable (pedestrians, hikers, cyclists, campers), and space stations and spacecraft.
3G offers the potential to keep people connected at all times and in all places. Researchers, engineers, and marketers are faced with the challenge of accurately predicting how much technology consumers will actually be willing to pay for. Another challenge faced by 3G services is competition from other high-speed wireless technologies, especially mobile WiMAX, and ability to roam between different kinds of wireless networks.
Speed
The ITU has not provided a clear definition of the speeds users can expect from 3G equipment or providers. Thus users sold 3G service may not be able to point to a standard and say that the speeds it specifies are not being met. While stating in commentary that "it is expected that IMT-2000 will provide higher transmission rates: a minimum speed of 2Mbit/s and maximum of 14.4Mbit/s for stationary users, and 348 kbit/s in a moving vehicle,"[3] the ITU does not actually clearly specify minimum or average speeds or what modes of the interfaces qualify as 3G, so various speeds are sold as 3G intended to meet customers expectations of broadband speed. It is often suggested by industry sources that 3G can be expected to provide 384 kbit/s at or below pedestrian speeds, but only 128 kbit/s in a moving car. While EDGE is part of the 3G standard, some phones report EDGE and 3G network availability as separate things.
Security
3G networks offer a greater degree of security than 2G predecessors. By allowing the UE to authenticate the network it is attaching to, the user can be sure the network is the intended one and not an impersonator. 3G networks use the KASUMI block crypto instead of the older A5/1 stream cipher. However, a number of serious weaknesses in the KASUMI cipher have been identified.
In addition to the 3G network infrastructure security, end to end security is offered when application frameworks such as IMS are accessed, although this is not strictly a 3G property.
3G Technology
Here is a simple introduction to some aspects of 3G radio transmission technologies (RTTs). You will find the subjects covered in this section useful if you later consider the more detailed discussions in the sections on 3G Standards and 3G Spectrum.
Simplex vs. Duplex
When people use walkie-talkie radios to communicate, only one person can talk at a time (the person doing the talking has to press a button). This is because walkie-talkie radios only use one communication frequency - a form of communication known as simplex:
Simplex: Using a walkie-talkie you have to push a button to talk one-way.
Of course, this is not how mobile phones work. Mobile phones allow simultaneous two-way transfer of data - a situation known as duplex (if more than two data streams can be transmitted, it is called multiplex):
Duplex: Allows simultaneous two-way data transfers.
The communication channel from the base station to the mobile device is called the downlink, and the communication from the mobile device back to the base station is called the uplink. How can duplex communication be achieved? Well, there are two possible methods which we will now consider: TDD and FDD.
TDD vs. FDD
Wireless duplexing has been traditionally implemented by dedicating two separate frequency bands: one band for the uplink and one band for the downlink (this arrangement of frequency bands is called paired spectrum). This technique is called Frequency Division Duplex, or FDD. The two bands are separated by a "guard band" which provides isolation of the two signals:
FDD: Uses paired spectrum - one frequency band for the uplink, one frequency band for the downlink.
Duplex communications can also be achieved in time rather than by frequency. In this approach, the uplink and the downlink operate on the same frequency, but they are switched very rapidly: one moment the channel is sending the uplink signal, the next moment the channel is sending the downlink signal. Because this switching is performed very rapidly, it does appear that one channel is acting as both an uplink and a downlink at the same time. This is called Time Division Duplex, or TDD. TDD requires a guard time instead of a guard band between transmit and receive streams.
Symmetric Transmission vs. Asymmetric Transmission
Data transmission is symmetric if the data in the downlink and the data in the uplink is transmitted at the same data rate. This will probably be the case for voice transmission - the same amount of data is sent both ways. However, for internet connections or broadcast data (e.g., streaming video), it is likely that more data will be sent from the server to the mobile device (the downlink).
FDD transmission is not so well suited for asymmetric applications as it uses equal frequency bands for the uplink and the downlink (a waste of valuable spectrum). On the other hand, TDD does not have this fixed structure, and its flexible bandwidth allocation is well-suited to asymmetric applications, e.g., the internet (see this PDF file for more details). For example, TDD can be configured to provide 384kbps for the downlink (the direction of the major data transfer), and 64kbps for the uplink (where the traffic largely comprises requests for information and acknowledgements). See this PDF file for more details.
TDMA vs. CDMA
We have considered how a mobile phone can send and receive calls at the same time (via an uplink and a downlink). Now we will examine how many users can be multiplexed into the same channel (i.e., share the channel) without getting interference from other users, a capability called multiple access. For 3G technology, there are basically two competing technologies to achieve multiple access: TDMA and CDMA.
TDMA is Time Division Multiple Access. It works by dividing a single radio frequency into many small time slots. Each caller is assigned a specific time slot for transmission. Again, because of the rapid switching, each caller has the impression of having exclusive use of the channel.
CDMA is Code Division Multiple Access. CDMA works by giving each user a unique code. The signals from all the users can then be spread over a wide frequency band. The transmitting frequency for any one user is not fixed but is allowed to vary within the limits of the band. The receiver has knowledge of the sender's unique code, and is therefore able to extract the correct signal no matter what the frequency.
This technique of spreading a signal over a wide frequency band is known as spread spectrum. The advantage of spread spectrum is that it is resistant to interference - if a source of interference blocks one frequency, the signal can still get through on another frequency. Spread spectrum signals are therefore difficult to jam, and it is not surprising that this technology was developed for military uses.
Finally, let's consider another robust technology originally developed by the military which is finding application with 3G: packet switching.
3G uses a technology protocol called HSDPA (High-Speed Downlink Packet Access) to download data fast over UMTS (Universal Mobile Telecommunications System) networks. Email attachments and web pages load twice as fast on 3G networks as on 2G EDGE networks.1 And since iPhone 3G seamlessly switches between EDGE, faster 3G, and even faster Wi-Fi, you always get the best speeds possible.
3G meets worldwide standards for cellular communications, so you can make calls and surf the web from practically anywhere on the planet. And if you’re in an area without a 3G network, iPhone connects you via GSM for calls and EDGE for data.
FDMA: Frequency Division Multiple Access (FDMA) is the most common analog system. It is a technique whereby spectrum is divided up into frequencies and then assigned to users. With FDMA, only one subscriber at any given time is assigned to a channel. The channel therefore is closed to other conversations until the initial call is finished, or until it is handed-off to a different channel. A “full-duplex” FDMA transmission requires two channels, one for transmitting and the other for receiving. FDMA has been used for first generation analog systems.
TDMA: Time Division Multiple Access (TDMA) improves spectrum capacity by splitting each frequency into time slots. TDMA allows each user to access the entire radio frequency channel for the short period of a call. Other users share this same frequency channel at different time slots. The base station continually switches from user to user on the channel. TDMA is the dominant technology for the second generation mobile cellular networks.
CDMA: Code Division Multiple Access is based on “spread” spectrum technology. Since it is suitable for encrypted transmissions, it has long been used for military purposes. CDMA increases spectrum capacity by allowing all users to occupy all channels at the same time. Transmissions are spread over the whole radio band, and each voice or data call are assigned a unique code to differentiate from the other calls carried over the same spectrum. CDMA allows for a “ soft hand-off” , which means that terminals can communicate with several base stations at the same time. The dominant radio interface for third-generation mobile, or IMT-2000, will be a wideband version of CDMA with three modes (IMT-DS, IMT-MC and IMT-TC).
3G Applications
Mobile TV
Mobile Entertainment
Gaming
Security
Java™
Mobile Connectivity: Mobile TV
TI technology supports mobile digital TV with the video processing capabilities of the OMAP™ processor. In conjunction with a mobile broadcast solution, you can watch the same TV you watch at home - but on your cell phone.
Mobile TV subscribers will have access to different types of features including:
Live television programs
Pay-per view
Interactive TV
Packaged services for sporting events
Personal Video Recording (PVR)
Digital radio services
Picture-in-picture (PIP)
and more
Today, OMAP processors play a role in today's DVB-H enabled cell phones that are being used in trials throughout Europe and the U.S. and several handsets in Korea supporting the DMB (digital media broadcast) standard.
Summary
Competitive advantage in 3G will come from the ability to recognize that mobility and location-based information are critical for success. There will be millions of users making billions of transactions every day, from real time video to checking horoscopes and weather information.
The mobile phone is already part of everyday life with penetration rates rising to 70 per cent and more in many countries, and their appeal will grow, driven by the way consumers construct their own identity. 3G products and services will facilitate and support existing lifestyles and routines, with diversity, personal choice, a balanced efficiency and enjoyment. Nokia sees the largest initial demand for 3G as a highly integrated dual-mode terminal capable of supporting the Mobile Internet, new and existing applications, advanced IP-based services, Multimedia Messaging, Multi-mode radio and open standards and is at the forefront of developing 3G technology.
1G (First Generation)
The 1G period began in the late 1970s and lasted through the 1980s. These systems featured the first true mobile phone systems, known at first as "cellular mobile radio telephone." These networks used analog voice signaling, and were little more sophisticated than the repeater networks used by amateur radio operators.
2G (Second Generation)
The 2G phase began in the 1990s and much of this technology is still in use. The 2G cell phone features digital voice encoding. Examples include CDMA and GSM. Since its inception, 2G technology has steadily improved, with increased bandwidth, packet routing, and the introduction of multimedia.
3G includes capabilities and features such as:
Enhanced multimedia (voice, data, video, and remote control ).
Usability on all popular modes (cellular telephone, e-mail, paging, fax, video conferencing, and Web browsing).
Broad bandwidth and high speed (upwards of 2 Mbps).
Roaming capability throughout Europe, Japan, and North America.
While 3G is generally considered applicable mainly to mobile wireless, it is also relevant to fixed wireless and portable wireless. A 3G system should be operational from any location on, or over, the earth's surface, including use in homes, businesses, government offices, medical establishments, the military, personal and commercial land vehicles, private and commercial watercraft and marine craft, private and commercial aircraft (except where passenger use restrictions apply), portable (pedestrians, hikers, cyclists, campers), and space stations and spacecraft.
3G offers the potential to keep people connected at all times and in all places. Researchers, engineers, and marketers are faced with the challenge of accurately predicting how much technology consumers will actually be willing to pay for. Another challenge faced by 3G services is competition from other high-speed wireless technologies, especially mobile WiMAX, and ability to roam between different kinds of wireless networks.
Speed
The ITU has not provided a clear definition of the speeds users can expect from 3G equipment or providers. Thus users sold 3G service may not be able to point to a standard and say that the speeds it specifies are not being met. While stating in commentary that "it is expected that IMT-2000 will provide higher transmission rates: a minimum speed of 2Mbit/s and maximum of 14.4Mbit/s for stationary users, and 348 kbit/s in a moving vehicle,"[3] the ITU does not actually clearly specify minimum or average speeds or what modes of the interfaces qualify as 3G, so various speeds are sold as 3G intended to meet customers expectations of broadband speed. It is often suggested by industry sources that 3G can be expected to provide 384 kbit/s at or below pedestrian speeds, but only 128 kbit/s in a moving car. While EDGE is part of the 3G standard, some phones report EDGE and 3G network availability as separate things.
Security
3G networks offer a greater degree of security than 2G predecessors. By allowing the UE to authenticate the network it is attaching to, the user can be sure the network is the intended one and not an impersonator. 3G networks use the KASUMI block crypto instead of the older A5/1 stream cipher. However, a number of serious weaknesses in the KASUMI cipher have been identified.
In addition to the 3G network infrastructure security, end to end security is offered when application frameworks such as IMS are accessed, although this is not strictly a 3G property.
3G Technology
Here is a simple introduction to some aspects of 3G radio transmission technologies (RTTs). You will find the subjects covered in this section useful if you later consider the more detailed discussions in the sections on 3G Standards and 3G Spectrum.
Simplex vs. Duplex
When people use walkie-talkie radios to communicate, only one person can talk at a time (the person doing the talking has to press a button). This is because walkie-talkie radios only use one communication frequency - a form of communication known as simplex:
Simplex: Using a walkie-talkie you have to push a button to talk one-way.
Of course, this is not how mobile phones work. Mobile phones allow simultaneous two-way transfer of data - a situation known as duplex (if more than two data streams can be transmitted, it is called multiplex):
Duplex: Allows simultaneous two-way data transfers.
The communication channel from the base station to the mobile device is called the downlink, and the communication from the mobile device back to the base station is called the uplink. How can duplex communication be achieved? Well, there are two possible methods which we will now consider: TDD and FDD.
TDD vs. FDD
Wireless duplexing has been traditionally implemented by dedicating two separate frequency bands: one band for the uplink and one band for the downlink (this arrangement of frequency bands is called paired spectrum). This technique is called Frequency Division Duplex, or FDD. The two bands are separated by a "guard band" which provides isolation of the two signals:
FDD: Uses paired spectrum - one frequency band for the uplink, one frequency band for the downlink.
Duplex communications can also be achieved in time rather than by frequency. In this approach, the uplink and the downlink operate on the same frequency, but they are switched very rapidly: one moment the channel is sending the uplink signal, the next moment the channel is sending the downlink signal. Because this switching is performed very rapidly, it does appear that one channel is acting as both an uplink and a downlink at the same time. This is called Time Division Duplex, or TDD. TDD requires a guard time instead of a guard band between transmit and receive streams.
Symmetric Transmission vs. Asymmetric Transmission
Data transmission is symmetric if the data in the downlink and the data in the uplink is transmitted at the same data rate. This will probably be the case for voice transmission - the same amount of data is sent both ways. However, for internet connections or broadcast data (e.g., streaming video), it is likely that more data will be sent from the server to the mobile device (the downlink).
FDD transmission is not so well suited for asymmetric applications as it uses equal frequency bands for the uplink and the downlink (a waste of valuable spectrum). On the other hand, TDD does not have this fixed structure, and its flexible bandwidth allocation is well-suited to asymmetric applications, e.g., the internet (see this PDF file for more details). For example, TDD can be configured to provide 384kbps for the downlink (the direction of the major data transfer), and 64kbps for the uplink (where the traffic largely comprises requests for information and acknowledgements). See this PDF file for more details.
TDMA vs. CDMA
We have considered how a mobile phone can send and receive calls at the same time (via an uplink and a downlink). Now we will examine how many users can be multiplexed into the same channel (i.e., share the channel) without getting interference from other users, a capability called multiple access. For 3G technology, there are basically two competing technologies to achieve multiple access: TDMA and CDMA.
TDMA is Time Division Multiple Access. It works by dividing a single radio frequency into many small time slots. Each caller is assigned a specific time slot for transmission. Again, because of the rapid switching, each caller has the impression of having exclusive use of the channel.
CDMA is Code Division Multiple Access. CDMA works by giving each user a unique code. The signals from all the users can then be spread over a wide frequency band. The transmitting frequency for any one user is not fixed but is allowed to vary within the limits of the band. The receiver has knowledge of the sender's unique code, and is therefore able to extract the correct signal no matter what the frequency.
This technique of spreading a signal over a wide frequency band is known as spread spectrum. The advantage of spread spectrum is that it is resistant to interference - if a source of interference blocks one frequency, the signal can still get through on another frequency. Spread spectrum signals are therefore difficult to jam, and it is not surprising that this technology was developed for military uses.
Finally, let's consider another robust technology originally developed by the military which is finding application with 3G: packet switching.
3G uses a technology protocol called HSDPA (High-Speed Downlink Packet Access) to download data fast over UMTS (Universal Mobile Telecommunications System) networks. Email attachments and web pages load twice as fast on 3G networks as on 2G EDGE networks.1 And since iPhone 3G seamlessly switches between EDGE, faster 3G, and even faster Wi-Fi, you always get the best speeds possible.
3G meets worldwide standards for cellular communications, so you can make calls and surf the web from practically anywhere on the planet. And if you’re in an area without a 3G network, iPhone connects you via GSM for calls and EDGE for data.
FDMA: Frequency Division Multiple Access (FDMA) is the most common analog system. It is a technique whereby spectrum is divided up into frequencies and then assigned to users. With FDMA, only one subscriber at any given time is assigned to a channel. The channel therefore is closed to other conversations until the initial call is finished, or until it is handed-off to a different channel. A “full-duplex” FDMA transmission requires two channels, one for transmitting and the other for receiving. FDMA has been used for first generation analog systems.
TDMA: Time Division Multiple Access (TDMA) improves spectrum capacity by splitting each frequency into time slots. TDMA allows each user to access the entire radio frequency channel for the short period of a call. Other users share this same frequency channel at different time slots. The base station continually switches from user to user on the channel. TDMA is the dominant technology for the second generation mobile cellular networks.
CDMA: Code Division Multiple Access is based on “spread” spectrum technology. Since it is suitable for encrypted transmissions, it has long been used for military purposes. CDMA increases spectrum capacity by allowing all users to occupy all channels at the same time. Transmissions are spread over the whole radio band, and each voice or data call are assigned a unique code to differentiate from the other calls carried over the same spectrum. CDMA allows for a “ soft hand-off” , which means that terminals can communicate with several base stations at the same time. The dominant radio interface for third-generation mobile, or IMT-2000, will be a wideband version of CDMA with three modes (IMT-DS, IMT-MC and IMT-TC).
3G Applications
Mobile TV
Mobile Entertainment
Gaming
Security
Java™
Mobile Connectivity: Mobile TV
TI technology supports mobile digital TV with the video processing capabilities of the OMAP™ processor. In conjunction with a mobile broadcast solution, you can watch the same TV you watch at home - but on your cell phone.
Mobile TV subscribers will have access to different types of features including:
Live television programs
Pay-per view
Interactive TV
Packaged services for sporting events
Personal Video Recording (PVR)
Digital radio services
Picture-in-picture (PIP)
and more
Today, OMAP processors play a role in today's DVB-H enabled cell phones that are being used in trials throughout Europe and the U.S. and several handsets in Korea supporting the DMB (digital media broadcast) standard.
Summary
Competitive advantage in 3G will come from the ability to recognize that mobility and location-based information are critical for success. There will be millions of users making billions of transactions every day, from real time video to checking horoscopes and weather information.
The mobile phone is already part of everyday life with penetration rates rising to 70 per cent and more in many countries, and their appeal will grow, driven by the way consumers construct their own identity. 3G products and services will facilitate and support existing lifestyles and routines, with diversity, personal choice, a balanced efficiency and enjoyment. Nokia sees the largest initial demand for 3G as a highly integrated dual-mode terminal capable of supporting the Mobile Internet, new and existing applications, advanced IP-based services, Multimedia Messaging, Multi-mode radio and open standards and is at the forefront of developing 3G technology.