1. UMTS definition
As a complete 3G mobile communication technology standard, UM TS is not limited to defining the air interface. In addition to WCDMA being continuously improved as the preferred air interface technology, UMTS has also introduced TD-SCDMA and HSDPA technologies in succession.
A third-generation (3G) mobile phone technology [1]. It uses WCDMA as the underlying standard and was finalized by 3GPP and represents Europe ’s response to ITU IMT-2000 ’s demand for 3G cellular radio systems. UMTS is sometimes called 3GSM, emphasizing the combination of 3G technology and the successor to the GSM standard. UMTS packet switching system is evolved from GPRS system, so the architecture of the system is quite similar.
introduction
This entry mainly discusses the technical commercial use and other aspects surrounding the UMTS standard derived from the GSM network infrastructure and W-CDMA air interface. Any issues that are only closely related to the W-CDMA interface itself are better explained in W-CDMA.
Due to the rapid changes in UMTS, the information on this page may lag behind the actual situation by two to three months. Readers are strongly recommended to publish their views and additional independent research; all letters are encouraged to be added to this page to complete this entry. Readers who are actively updating please attach appropriate modification time to help other readers establish their timeline and better understand the content of this entry.
2. UMTS features
UMTS supports a transmission rate of 1920kbps (not the 2Mbps that is often seen), but the typical highest rate in a real high-load system is only about 384Kbps. Even if the data speed is higher than the GSM error correction data channel 14.4 kbps or multiple HSCSD channels composed of 14.4 kbps, it can truly achieve affordable mobile WWW access and MMS. The premise of UMTS implementation is that the GSM mobile phone system is now widely used and belongs to 2G technology. There is also a way to evolve from 2G called GPRS. (can watch
The evolution of the 3GPP specification is 2.5G) GPRS supports better data rates (theoretically it can be up to 140.8kbps, in fact it can achieve close to 56Kbps), and data encapsulation is better than connection-oriented. GPRS has been deployed in many GSM networks.
China Unicom's UMTS network is upgraded to HSDPA, sometimes called 3.5G. It can achieve a transmission speed of downlink greater than 10Mbps.
UMTS emphasizes the possibility of mobile video teleconferencing in the market operation, although in fact there are many potential services that have not been tested and verified.
Other possible applications of UMTS are music downloads and video telephony.
3. The actual operation of UMTS
The world's first UMTS network was put into operation by Manx Telecom on the Isle of Man in 2001. The next network referred to as Mobile Operator 3 was launched in the UK in 2003. .
3 is an operator that originally grew up from a 3G network and originally belonged to Hutchison Whampoa (now a partner). It will soon launch other UMTS networks worldwide (December 2004) including Australia, Austria, Denmark, Hong Kong, Israel, Italy, Portugal, Republic of Ireland and Sweden. Most Western European GSM operators plan to upgrade to UMTS in the future because It is closer to the GSM2G standard.
In December 2003, T-Mobile launched his Austrian UMTS network, and the UK and Germany networks are also being commissioned.
In February 2004, Vodafone began the widespread deployment of UMTS in several European markets including the United Kingdom, Germany, the Netherlands and Sweden. In Portugal, UMTS already operated before Euro 2004.
The first UMTS network in Africa was put into operation in Mauritius in November 2004. China ’s Huawei provided the entire network equipment, followed by Vodacom ’s launch of 3G services in South Africa in December 2004.
Under the prior authorization of NTT DoCoMo, American AMPS / TDMA / GSM operator AT
Advanced architecture of UMTS network & T Wireless must establish and operate UMTS networks in four major cities by the end of 2004. At the CTIA 2004 annual meeting, AT & T Wireless stated that their UMTS network operates independently in the 1900MHz band, and plans to start UMTS service by the end of 2004. In July 2004, AT & T Wireless (now part of Cingular) successfully launched UMTS services in Seattle (Washington), San Francisco (California), Detroit (Michigan), Phoenix (Arizona), San Diego (California) and Dallas (Texas) .
In the first quarter of 2005, German mobile operator Vodafone D2, O2-de successively launched UMTS services.
After merging with AT & T Wireless, Cingular has announced plans to start deploying UMTS networks using HSDPA technology in 2005. Unlike UMTS developed by AT & T, Cingular has expanded the frequency range of UMTS to two frequency bands, 1900MHz and 850MHz.
T-Mobile USA plans to start deploying UMTS by 2007.
Operators began selling mobile Internet products integrating 3G and Wi-Fi services. Laptop users can buy the UMTS Modem they provide, and the client software is used to automatically detect the network status to automatically switch from the 3G network when there is a Wi-Fi signal. At first Wi-FI was considered as a competitor of 3G, but now it has to be admitted that operators must either own or rent other people's Wi-Fi networks in order to provide more competitive products than UMTS alone.
4. UMTS technology
Note: Many technical features of UMTS are common to all W-CDMA variants. For more information, please refer to the entry W-CDMA. The following discusses only some technical features unique to UMTS, which are not applicable to FOMA or other W-CDMA variants.
Simply put, UMTS combines the air interface of W-CDMA (the air communication protocol of mobile phones and base stations), the core part of mobile applications of GSM system (MAP, see en: MAP) (this protocol provides calls from or to users Routing function), as well as GSM voice coding algorithms such as adaptive multi-rate (AMR) and enhanced full rate (EFR) (they define methods for digitizing, compressing, and coding voice). In other words, W-CDMA (as defined by IMT-2000) is just an air interface, and UMTS is a complete protocol stack for 3G global mobile communications, which can be used to replace GSM. However, in fact, W-CDMA is often used as the general term for all 3G standard families that use this air interface, including UMTS, FOMA and J-Phone.
Like other W-CDMA variants, UMTS uses a pair of 5 MHz channels, with upstream channels around 1900 MHz and downstream channels around 2100 MHz. In contrast, CDMA2000 can use one or more 1.25 MHz channels in each direction, so UMTS is often criticized for its high bandwidth requirements.
The frequency band originally specified by UMTS is 1885-2025 MHz for uplink and 2110-2200 MHz for downlink. The current frequency band allocation can be found in [1].
For existing GSM operators, there is a simple but expensive plan to upgrade to UMTS: most of the existing infrastructure can be maintained, but the cost of obtaining frequency band authorization and completing UMTS coverage on existing base station towers can be extremely high .
A major difference between UMTS and GSM is the universal
The basic public land mobile network (PLMN) is configured with a line access network (GRAN), which can connect to different backbone networks, such as the Internet, ISDN, GSM, or UMTS networks. GRAN contains the lower three layers of the OSI model (physical layer, data link layer, network layer). The network layer (OSI 3) protocol includes the RRM protocol (RRM), which is responsible for managing the bearer channel between the mobile device and the fixed network and completing the handover function.
Interoperability and global roaming
At the air interface layer, UMTS is compatible with GSM. Although the current UMTS phones on the market are all UMTS / GSM dual-mode phones, they can all work well in a pure GSM network. If a UMTS user roams to a place without UMTS coverage, his mobile phone will automatically switch to GSM mode (to pay roaming charges). If the user roams out of UMTS coverage during the call, the phone will switch to the area covered by GSM. Ordinary GSM mobile phones cannot be used on the UMTS network.
Vodafone-Japan (formerly J-Phone) has a 3G network that uses W-CDMA and is compatible with UMTS. This makes UMTS a truly global wireless standard. The current global wireless standard, GSM is suitable for most countries except Japan and South Korea.
NTT DoCoMo's 3G network, FOMA, also uses W-CDMA, but is not compatible with UMTS. However, NTT DoCoMo owns 18 shares of AT & T Wireless Labs and originally held 3UK20 shares. These foreign capitals provide a test platform for future global roaming solutions. (By December 2004)
All UMTS / GSM dual-mode phones should be compatible with existing GSM standard SIM cards. Sometimes you are allowed to use the SIM card in the same carrier network to roam on the UMTS network.
In the United States, due to existing restrictions on frequency use, only the operator AT & T wireless network can only operate in the 1900MHz band. The UMTS mobile phone designed for the US market is different from other regions, which also reflects the current US GSM mobile phone and GSM network usage is different from other countries. Although the Federal Communications Commission (FCC) has decided to allow the addition of the 2100MHz frequency band to UMTS, most operators authorized by UMTS seem to intend to abandon their responsibility to ensure global roaming.
Although Eurasian mobile phones can achieve roaming, it is unlikely to be roaming with Eurasia in the United States in December 2004.
Spectrum allocation
More than 120 licenses have been issued to operators all over the world (as of 2004), especially GSM-based wireless access technology W-CDMA. As the technology is still being improved, politicians sell licenses too hastily, and hundreds of billions of dollars in license fees flow into the public budget. In Germany alone, license fees are as high as 50.8 billion euros. Operators are expected to start profiting from these licenses in 2005.
In North America, ITU has allocated frequency bands for UMTS. The 1900MHz range is used for 2G (PCS) services, and the 2100MHz range is used for satellite communications. Although UMTS in North America will have to share the 1900MHz band with existing 2G services, international efforts are being made to release the 2100MHz band for 3G services. Because 2G GSM service uses 900MHz and 1800MHz, it no longer shares any UMTS service frequency band.
Until new specific frequency bands are allocated for 3G, no North American manufacturer has answered those frequencies used by UMTS. At the end of 2004, AT & T Wireless has determined that the 1900 MHz band used for 2GPCS service has been enabled for UMTS services in the United States. The UMTS service initially demonstrated in Canada also uses the 1900MHz band.
Other competition standards
There are other 3G standards besides UMTS, such as CDMA2000 and proprietary systems including Arraycom's iBurst, Flarion and WCDMA-TDD (Wireless IP). However, people still expect 3GSM / UMTS to become the actual 3G that replaces the current dominant position of the GSM standard.
CDMA2000 and W-CDMA are members of the IMT-20003G standard family recognized by the ITU, in addition to EDEG and China's own 3G standard TD-SCDMA.
CDMA2000 has been improved and upgraded from CDMA1x. It does not require new frequency band allocation and can operate stably in the existing PCS frequency band.
Most existing GSM operators hold a wait-and-see attitude toward UMTS because of the high frequency bands and equipment costs.
Most North American GSM operators have accepted EDGE as a tentative 3G solution. AT & T Wireless started to operate EDGE in its own country in 2003, Cingular also operates in its own country, and T-Mobile America plans to provide EDGE nationwide. Rogers Wireless started to operate EDGE service in Canada in late 2003. The advantage of EDGE is that it effectively uses the existing GSM frequency band and is compatible with existing GSM mobile phones. EDGE provides a short-term upgrade path for GSM operators to compete with CDMA2000.
Open source UMTS projects The impact of open source on the industry is unquestionable, as is UMTS. The open source software radio GNU Radio is a free software development tool suite. It provides signal operation and processing modules, which can be used to implement software-defined radio on low-cost radio frequency (RF) hardware and general-purpose microprocessors that are easy to make. This kit is widely used by amateurs, academic institutions and commercial institutions to research and construct wireless communication systems. The application of GNU Radio is mainly written in Python programming language. But its core signal processing module is built by C ++ on a microprocessor with floating point arithmetic. Therefore, developers can easily and quickly build a real-time, high-capacity wireless communication system. Although its main function is not an emulator, GNU Radio supports the research of algorithms for signal processing of pre-stored and (signal generator) generated data without radio frequency RF hardware components.
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