Presented at Broadband Wireless Networking and Services' class on December 6th, 2008 by Petry Purenia (9676063).
電子商務系統安全與防駭實務
2 years ago
Tuesday, December 2, 2008
Monday, October 27, 2008
3GPP Long Term Evolution
This is summary 3GPP Long Term Evolution from www.wikipedia.org
Long Term Evolution (LTE) is the next step forward in cellular 3G services. LTE is designed to meet carrier needs for high-speed data and media transport as well as high-capacity voice support well. Many methods employed in LTE are relatively new in cellular applications. These include OFDM, OFDMA, MIMO and Single Carrier Frequency Division Multiple Access (SC-FDMA). LTE employs OFDM for downlink data transmission and SC-FDMA for uplink transmission. LTE is a leading OFDMA-based, wireless mobile broadband technology supported by a new Evolved Packet Core (EPC) network. Designed from the ground up to provide interoperability and service continuity with existing UMTS networks.
- OFDMA on the DL and SC-FDMA on the UL
- Advanced antenna techniques (MIMO, SDMA, Beamforming)
Monday, October 13, 2008
History of Cellular Technology
This first-generation (1G) analog network may have been cutting edge at the time, but it soon became notorious for its iffy call quality. These are the analog cellphone standards that were introduced in the 1980s.
In the 1990s, 'second generation' (2G) mobile phone systems such as Globa System for Mobile (GSM), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA) began to be introduced. 2G phone systems were characterized by digital circuit switched transmission and the introduction of advanced and fast phone to network signaling. These second-generation (2G) networks spread voice calls across several wireless spectrums, making for more reliable connections that are much harder--though not impossible--for hackers to intercept. More importantly, CDMA and GSM networks are also capable of sending a sliver of data along with voice signals, making possible for such features as text messaging (SMS), caller ID, and conference calling.
Not long after the introduction of 2G networks, projects began to develop third generation (3G) systems. 3G is the third generation of mobile phone standards and technology. It is based on the International Telecommunication Union (ITU) family of standards under the IMT-2000. 3G networks enable network operators to offer users a wider range of more advanced services, include wide-area wireless voice telephony, video calls, and broadband wireless data, all in a mobile environment. 3G networks are wide area cellular telephone networks which evolved to incorporate high-speed internet access and video telephony.
During the development of 3g systems, 2.5G systems such as CDMA2000 1x and GPRS were developed as extensions to existing 2G networks. These provide some of the features of 3G without fulfilling the promised high data rates or full range of multimedia services. The terms "2G" and "3G" are officially defined, "2.5G" is not. It was invented for marketing purposes only.
4G is the short term for fourth-generation wireless, the stage of broadband mobile communications that will supercede the third generation (3G). While neither standards bodies nor carriers have concretely defined or agreed upon what exactly 4G will be, it is expected that end-to-end IP and high-quality streaming video will be among 4G's distinguishing features. Fourth generation networks are likely to use a combination of WiMAX and WiFi. 4G technologies are sometimes referred to by the acronym "MAGIC," which stands for Mobile multimedia, Anytime/any-where, Global mobility support, Integrated wireless and Customized personal service.
The evolution of 3G
Services and Speed
In the 1990s, 'second generation' (2G) mobile phone systems such as Globa System for Mobile (GSM), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA) began to be introduced. 2G phone systems were characterized by digital circuit switched transmission and the introduction of advanced and fast phone to network signaling. These second-generation (2G) networks spread voice calls across several wireless spectrums, making for more reliable connections that are much harder--though not impossible--for hackers to intercept. More importantly, CDMA and GSM networks are also capable of sending a sliver of data along with voice signals, making possible for such features as text messaging (SMS), caller ID, and conference calling.
Not long after the introduction of 2G networks, projects began to develop third generation (3G) systems. 3G is the third generation of mobile phone standards and technology. It is based on the International Telecommunication Union (ITU) family of standards under the IMT-2000. 3G networks enable network operators to offer users a wider range of more advanced services, include wide-area wireless voice telephony, video calls, and broadband wireless data, all in a mobile environment. 3G networks are wide area cellular telephone networks which evolved to incorporate high-speed internet access and video telephony.
During the development of 3g systems, 2.5G systems such as CDMA2000 1x and GPRS were developed as extensions to existing 2G networks. These provide some of the features of 3G without fulfilling the promised high data rates or full range of multimedia services. The terms "2G" and "3G" are officially defined, "2.5G" is not. It was invented for marketing purposes only.
4G is the short term for fourth-generation wireless, the stage of broadband mobile communications that will supercede the third generation (3G). While neither standards bodies nor carriers have concretely defined or agreed upon what exactly 4G will be, it is expected that end-to-end IP and high-quality streaming video will be among 4G's distinguishing features. Fourth generation networks are likely to use a combination of WiMAX and WiFi. 4G technologies are sometimes referred to by the acronym "MAGIC," which stands for Mobile multimedia, Anytime/any-where, Global mobility support, Integrated wireless and Customized personal service.
The evolution of 3G
Services and Speed
Why cellular is better than broadcast?
Cellular and Broadcast networks address different usage scenarios. Broadcast technologies will clearly address concentrated demand for the most popular content. Cellular networks provide a dedicated connection which enables carriers to offer personalized content, niche "long-tail" channels and integrated mobile-commerce.
Traditional content distribution networks can bring IP content to the edge of the cellular network. This solutions bring caching closer tot the edge of the cellular radio network need to be developed. In addition, cooperation with broadcast systems can put additional load on the uplink of cellular networks, without limiting normal mobile services; hence, revenues for cellular operators are increased.
Broadcast is a "killer application" in mobile video entertainment. Broadcast overlays are beginning to emerge. It's bring issues with cellular vs broadcast coverage disparities. Operators believe broadcast TV alone will not result in very strong average revenue per user (ARPU) growth. For increase the growth, broadcast need interactive applications over cellular network. These interactive services are recognized as the value-added service for broadcast networks that will ensure profitability in the long run. The combination of broadcast systems with a mobile return channel could enable new service models, especially if mobility is also taken into account in the broadcast system.
Traditional content distribution networks can bring IP content to the edge of the cellular network. This solutions bring caching closer tot the edge of the cellular radio network need to be developed. In addition, cooperation with broadcast systems can put additional load on the uplink of cellular networks, without limiting normal mobile services; hence, revenues for cellular operators are increased.
Broadcast is a "killer application" in mobile video entertainment. Broadcast overlays are beginning to emerge. It's bring issues with cellular vs broadcast coverage disparities. Operators believe broadcast TV alone will not result in very strong average revenue per user (ARPU) growth. For increase the growth, broadcast need interactive applications over cellular network. These interactive services are recognized as the value-added service for broadcast networks that will ensure profitability in the long run. The combination of broadcast systems with a mobile return channel could enable new service models, especially if mobility is also taken into account in the broadcast system.
Why 2G is faster than 1G?
First Generation wireless technology (1G) is the original analog, voice-only cellular telephone standard. 2G stands for the second generation of mobile wireless communication technology, which uses the digital technologies for the mobile communication. It allows slow data communications, but its primary focus is voice.
I think why 2G is faster than 1G because digital voice data can be compressed and multiplexed much more effectively than analog voice encodings through the use of various codecs, allowing more calls to be packed into the same amount of radio bandwith.
Another advantage using 2G are the digital systems were designed to emit less radio power from the handsets, the digital voice encoding allowed digital error checking which could increase sound quality by reducing dynamic and lowering the noise floor, the lower power emissions helped address health concerns, and going all-digital allowed for the introduction of digital data services, such as SMS and email.
I think why 2G is faster than 1G because digital voice data can be compressed and multiplexed much more effectively than analog voice encodings through the use of various codecs, allowing more calls to be packed into the same amount of radio bandwith.
Another advantage using 2G are the digital systems were designed to emit less radio power from the handsets, the digital voice encoding allowed digital error checking which could increase sound quality by reducing dynamic and lowering the noise floor, the lower power emissions helped address health concerns, and going all-digital allowed for the introduction of digital data services, such as SMS and email.
Homework, 10-4-2008
3. Describe a short history of development of cellular technology from 1G to 3G with a prediction of 4G and beyond.
History of cellular techonolgy
History of cellular techonolgy
Tuesday, September 30, 2008
Comment on "Serious Potential in Google’s Browser"
As the title of the article said "Serious Potential in Google’s Browser", based on my experience using Chrome there is a potential in Chrome. There are some advantages in Chrome that IE 8 (the newest edition of IE) and Firefox doesn't have, such as animation when moving the tabs or make the tab as a new window, each tab has its memory, cover its contents if there's a bug then won't infects the other tabs open at that time.
When the browser start slow, we can check which website that eats a lot of memory by using Task Manager. Because Chrome makes each tab independently. The speed of using Chrome and Firefox almost need the same time, but compare with IE 8, I think Chrome faster twice like the article said.
The interface of Chrome is simply but almost powerful like Firefox. No main menu only two buttons, about file and settings. Then only has one toolbar for bookmarks. I think this interface makes Chrome faster.
The other advantage of Chrome is when type an url, Chrome give suggestions about the url type on the address bar. This advantage makes users save time for typing urls. Chrome also save history about the pages that ever visited and when open a new tab or window, there will be nine mini boxes show what pages that usually users visit.
This Chrome sometimes not works on some website. For example, in a website which is contains movie (not Youtube), Chrome can't play the movie. The movie is using swf player, maybe Chrome doesn't have plug-in of swf. This will be correction for Chrome developer update the browser and will be become powerfull or like the title said 'Potential'.
Overall, Google's web browser, Chrome, give a good point in the earlier version. More faster and easy to use.
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