字幕列表 影片播放 列印英文字幕 Has it ever struck your curious mind how 4G evolved from simple Push to talk system ? Is there any governing body which regulates the spectrum ? what kind of services we will have in next generation of communication? So friends, Lets start the journey of wireless communication. Mobile radio telephones were introduced for military communications in the early 20th century. Car-based telephones was first tested in Saint Louis in 1946. This system used a single large transmitter on top of a high rise building. A single channel was used for sending and receiving similar to a half duplex system. To talk, the user pushed a button that enabled transmission and disabled reception. Due to this, these became known as “push-to-talk” systems in the 1950s. To allow users to talk and listen at the same time, IMTS (Improved Mobile Telephone System) was introduced in the 1960s. It used two channels one for sending and one for receiving bringing telecommunication to full duplex mode. In the 1970s Private companies have started developing their own systems to evolve the existing further..Those private systems are Analogue Mobile Phone System, used in America, Total Access Communication System and Nordic Mobile Telephone, used in parts of Europe and Japanese Total Access Communication System, used in Japan and Hong Kong. Independently developed systems are called as 1st Generation communication. It was introduced in 1982 by Bell Labs and popularly known as Advanced Mobile Phone System (AMPS). The key idea here was to divide geographical areas into cells. and each cell was served by a base station so that frequency reuse can be implemented. As a result AMPS could support 5 to 10 times more users than IMTS. Major concern for the 1st generation was weak Security on air interface, full analog mode of communication. and No roaming. Now, To implement roaming. Individual organisations started working under one umbrella, European Telecommunications Standards Institute (E T S I) and developed 2nd Generation system. Second generation cellular telecom networks were commercially launched in 1991 in Finland based on GSM standards. It could deliver data at the rate of up to 9.6 Kbps. Three primary benefits of 2G networks over their predecessors were. phone conversations were now digitally encrypted. It was significantly more efficient on the spectrum and allowed far greater mobile phone penetration level. 2G introduced data services for mobile, starting with SMS text message. Further To achieve higher data rates GSM carriers started developing a service called General Packet Radio Service (GPRS). This system overlaid a packet switching network on the existing circuit switched GSM network. GPRS could transmit data at up to 160 Kbps The phase after GPRS is called Enhanced Data Rates for GSM Evolution (EDGE). It introduced 8 PSK modulation and could deliver data at up to 500 Kbps using the same GPRS infrastructure. During this time the internet was becoming popular and data services were becoming more prevalent. Post 2.5G, Multimedia services and streaming started growing and Phones now started supporting web browsing. Development of 3G, 3GPP UMTS, the Universal Mobile Telecommunications System succeeded EDGE in 1999.This system uses Wideband CDMA ( W-CDMA) to carry the radio transmissions, and often the system is referred to by the name WCDMA. Now before we go further let us understand how the governing bodies were developed. In the interests of producing truly global standards, the collaboration for both GSM and UMTS was expanded further from ETSI to encompass regional Standards Development Organizations such as ARIB and TTC from Japan, TTA from Korea, ATIS from North America and CCSA from China. The successful creation of such a large and complex system specification required a well-structured organization. This gave birth to 3GPP and which worked under the observation of ITU-R. ITU-R is one of the sector of ITU, Its role is to manage the international radio-frequency spectrum and to ensure the effective use of spectrum. ITU-R defines technology families and associates specific parts of the spectrum with these families. ITU-R also proposed requirement for radio technology. 3 organization started developing standards to meet the requirements proposed by ITU-R. 3GPP, 3GPP2, IEEE Evolution of 3gpp, started from GSM to Long term evolution Advanced. Evolution of 3GPP2, started from IS95 to CDMA Revision B. Evolution of IEEE started from 8o2.16 Fixed Wimax, to 8o2.16M Since 3GPP was dominated and widely accepted, we will only incorporated roadmap evolved by 3GPP. Now coming back to 3rd Generation. The goal of UMTS or 3G wireless systems was to provide a minimum data rate of 2 Mbit/s for stationary or walking users, and 384 kbit/s in a moving vehicle. 3GPP designated it as Release 99. The upgrades and additional facilities were introduced at successive releases of the 3GPP standard. Release 4: This release of the 3GPP standard provided for the efficient use of IP, this was a key enabler for 3G HSDPA. Release 5: This release included the core of HSDPA. It provided reduced delays for downlink packet and provided a data rate of 14 Mbps. Release 6: This included the core of HSUPA with a reduction in uplink delay it enhanced uplink raw data rate of 5.74 Mbps. This release also included MBMS for broadcasting services. Release 7: This release of the 3GPP standard included downlink MIMO operation as well as support for higher order modulation of up to 64-QAM. Either MIMO or 64-QAM could be used at a time.Evolved HSPA provides data rates up to 28 Mbit/s in the downlink and 11 Mbit/s in the uplink. This brings us to the most awaited part. Long term evolution (LTE) Initial goal of telecommunication was mobility and global connectivity, but as the technology evolved the Services started expanding. Now Services were not restricted to Voice and SMS only. For This expansion and efficient execution in LTE, whole new architecture was adopted for both non Radio part ( SAE System Architecture Evolution) and Radio part using pure IP Architecture (packet switching) To fulfill the requirement proposed by ITU-R, Study group formed and LTE standardization began in 2004. Large number of telecom companies collaborated to achieve their common vision. In June 2005 Release 8 was finally crystallized after series of refining. Some of the significant features of Release 8 were- • reduced delays, for both connection establishment and transmission latency; • increased user data throughput; • increased cell-edge bit-rate, for uniformity of service provision; • reduced cost per bit, implying improved spectral efficiency. • simplified network architecture; • seamless mobility, including between different radio-access technologies; • reasonable power consumption for the mobile terminal. These requirements were fulfilled by advancement in the underlying mobile radio technology. The three fundamental technologies that have shaped the LTE radio interface design were: multicarrier technology, multiple-antenna technology, and the application of packet-switching to the radio interface. As a result of intense activity by a larger number of organisations, the specifications for the Release 8 was completed by December 2007. The first commercial deployment took place by the end of 2009 in northern Europe. In The subsequent releases multiple services such as Multi Cell HSDPA, HETNET, Coordinate Multipoint, Carrier Aggregation, Massive MIMO and many more were targeted for a rich customer experience. Now it's time to move from services to multiservices approach, in other word from LTE Advanced to next Generation communication system which is 5th Generation. Features have been planned to be added in the 5th Generation Or next generation systems are, Pervasive networks : where a user can concurrently be connected to several wireless access technologies and seamlessly move between them. Group cooperative relay: This is a technique that is being considered to make the high data rates available over a wider area of the cell. Cognitive radio technology: it would enable the user equipment / handset to look at the radio landscape in which it is located and choose the optimum radio access network, modulation scheme and other parameters to configure itself to gain the best connection and optimum performance. Smart antennas: Another major element of any 5G cellular system will be that of smart antennas. Using these it will be possible to alter the beam direction to enable more direct communications and limit interference and increase overall cell capacity. So friends, here we have covered history of wireless communication starting from single channel based Push to Talk system to, multiple services based purely advanced digital communication system. In the future videos we will start exploring fundamental of advanced communication which will help us to understand next generation system better. Don't forget to subscribe to our channel, like our videos and comments your views, or suggestions. Thanks for watching
B1 中級 美國腔 2--從1G到4G,再到5G--通信的發展。 (2 - From 1G to 4G & Towards 5G - Evolution Of Communication) 236 20 趙浚成 發佈於 2021 年 01 月 14 日 更多分享 分享 收藏 回報 影片單字