Talk:UMTS

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Merger proposals[edit]

Formal request has been received to merge: UMTS-TDD and TD-SCDMA into Universal Mobile Telecommunications System; discuss below. GenQuest "Talk to Me" 13:27, 1 February 2016 (UTC)

Merged-in article UMTS-TDD together with some cleanup. Nightwalker-87 (talk) 21:28, 13 March 2016 (UTC)
Merged-in article TD-SCDMA together with some cleanup on 21 April 2016 (UTC). Nightwalker-87 (talk) 09:50, 21 May 2016 (UTC)

Names for various flavors of UMTS?[edit]

In Talk:UMTS (telecommunication)/Archive 1#Confusion surrounding multiple access terminology there's a long discussion of various terms used in various of the articles that were merged into the air interfaces section.

Currently, UMTS (telecommunication)#W-CDMA (UTRA-FDD) says:

W-CDMA or WCDMA (Wideband Code Division Multiple Access), along with UMTS-FDD, UTRA-FDD, or IMT-2000 CDMA Direct Spread is an air interface standard found in 3G mobile telecommunications networks. It supports conventional cellular voice, text and MMS services, but can also carry data at high speeds, allowing mobile operators to deliver higher bandwidth applications including streaming and broadband Internet access.
W-CDMA uses the DS-CDMA channel access method with a pair of 5 MHz wide channels. ...
UMTS-FDD is an acronym for Universal Mobile Telecommunications System (UMTS) - frequency-division duplexing (FDD) and a 3GPP standardized version of UMTS networks that makes use of frequency-division duplexing for duplexing over an UMTS Terrestrial Radio Access (UTRA) air interface.

So what is the relationship between "W-CDMA", "UMTS-FDD", "UTRA-FDD", and "IMT-2000 CDMA Direct Spread"? Do they all refer to the same thing? If not, which ones, if any, do refer to the same thing as some other term, and to what do they all refer?

UMTS (telecommunication)#UTRA-TDD says:

UMTS-TDD, an acronym for Universal Mobile Telecommunications System (UMTS) - time-division duplexing (TDD), is a 3GPP standardized version of UMTS networks that use UTRA-TDD. UTRA-TDD is a UTRA that uses time-division duplexing for duplexing. While a full implementation of UMTS, it is mainly used to provide Internet access in circumstances similar to those where WiMAX might be used. UMTS-TDD is not directly compatible with UMTS-FDD: a device designed to use one standard cannot, unless specifically designed to, work on the other, because of the difference in air interface technologies and frequencies used. It is more formally as IMT-2000 CDMA-TDD or IMT 2000 Time-Division (IMT-TD).
The two UMTS air interfaces (UTRAs) for UMTS-TDD are TD-CDMA and TD-SCDMA. Both air interfaces use a combination of two channel access methods, code division multiple access (CDMA) and time division multiple access (TDMA): the frequency band is divided into time slots (TDMA), which are further divided into channels using CDMA spreading codes. These air interfaces are classified as TDD, because time slots can be allocated to either uplink or downlink traffic.

The first paragraph says UTRA-TDD is a UTRA; UTRA links back to UMTS (telecommunication)#Air interfaces, which says:

UMTS combines three different air interfaces, GSM's Mobile Application Part (MAP) core, and the GSM family of speech codecs.
UMTS provides several different terrestrial air interfaces, called UMTS Terrestrial Radio Access (UTRA).

which seems to indicate that that a UTRA is an air interface.

However, the second paragraph says that UMTS-TDD has two air interfaces, which would indicate that it's not a UTRA, it's a "something else" that has two UTRAs.

UMTS (telecommunication)#TD-CDMA (UTRA-TDD 3.84 Mcps High Chip Rate (HCR)) says:

TD-CDMA, an acronym for Time-division-Code division multiple access, is a channel access method based on using spread spectrum multiple access (CDMA) across multiple time slots (TDMA). TD-CDMA is the channel access method for UTRA-TDD HCR, which is an acronym for UMTS Terrestrial Radio Access-Time Division Duplex High Chip Rate.
UMTS-TDD's air interfaces that use the TD-CDMA channel access technique are standardized as UTRA-TDD HCR, which uses increments of 5 MHz of spectrum, each slice divided into 10 ms frames containing fifteen time slots (1500 per second). The time slots (TS) are allocated in fixed percentage for downlink and uplink. TD-CDMA is used to multiplex streams from or to multiple transceivers. Unlike W-CDMA, it does not need separate frequency bands for up- and downstream, allowing deployment in tight frequency bands.
TD-CDMA is a part of IMT-2000, defined as IMT-TD Time-Division (IMT CDMA TDD), and is one of the three UMTS air interfaces (UTRAs), as standardized by the 3GPP in UTRA-TDD HCR. UTRA-TDD HCR is closely related to W-CDMA, and provides the same types of channels where possible. UMTS's HSDPA/HSUPA enhancements are also implemented under TD-CDMA.

which calls TD-CDMA both a "channel access method" and an "air interface". I get the impression that there's more to an "air interface" than a "channel access method"; is that true and, if so, which of those is TD-CDMA? Is UTRA-TDD HCR the air interface, and TD-CDMA its channel access method?

UMTS (telecommunication)#TD-SCDMA (UTRA-TDD 1.28 Mcps Low Chip Rate (LCR)) says:

Time Division Synchronous Code Division Multiple Access (TD-SCDMA) or UTRA TDD 1.28 mcps low chip rate (UTRA-TDD LCR) is an air interface found in UMTS mobile telecommunications networks in China as an alternative to W-CDMA.
TD-SCDMA uses the TDMA channel access method combined with an adaptive synchronous CDMA component on 1.6 MHz slices of spectrum, allowing deployment in even tighter frequency bands than TD-CDMA. It is standardized by the 3GPP and also referred to as "UTRA-TDD LCR" However, the main incentive for development of this Chinese-developed standard was avoiding or reducing the license fees that have to be paid to non-Chinese patent owners. Unlike the other air interfaces, TD-SCDMA was not part of UMTS from the beginning but has been added in Release 4 of the specification.
Like TD-CDMA, TD-SCDMA is known as IMT CDMA TDD within IMT-2000.
The term "TD-SCDMA" is misleading. While it suggests covering only a channel access method, it is actually the common name for the whole air interface specification.

So that's calling TD-SCDMA an air interface, not a channel access method. Is it both, unlike what might be the case with TD-CDMA? And is "UTRA TDD 1.28 mcps low chip rate" another name for the air interface?

And what's the relationship between "UTRA-XXX" and "UMTS-XXX"? Does only the first of those refer to the air interface in the case of UTRA-FDD and the two air interfaces in the case of UTRA-TDD, with the latter being "the entire UMTS stack, with one of UTRA-XXX's air interfaces as the air interface"? Or are they just two names for the same thing? And do the "IMT CDMA XXX" and "IMT XXX" names refer to the entire UMTS stack with the corresponding air interface or just to the air interface? Guy Harris (talk) 02:40, 20 May 2016 (UTC)


Hello Guy Harris. Thank you very much for opening this topic. I consider it being very important to adress this issue. Indeed this structuring and the definition of various terms is very confusing and has to be made clear. As far as I know so far the structure is as follows:

  • UMTS is the main mobile telecommunication standard.
    • The specification distinguishes two channel access methods:
      UMTS-FDD and UMTS-TDD
      • There are three existing air-interfaces:
        one for UMTS-FDD which is called W-CDMA (Wideband Code Division Multiple Access) and
        two for UMTS-TDD which are called TD-CDMA (Time Division Code Division Multiple Access) and TD-SCDMA (Time Division Synchronous Code Division Multiple Access)
        • There are 3 existing carrier bandwidths, each available for one of these air-interfaces:
          • W-CDMA uses 5 MHz wide carriers (the use of only 1,25 MHz has been specified recently as S-UMTS (Scalable UMTS), which has not seen any deployment yet and is also very unlikely to see any in the near future because of missing device compatibility, as the standard extension arrived too late.)
          • TD-CDMA uses 1,25 MHz wide carriers. Chip-rate 3,84 Mcps (= MHz)
          • TD-SCDMA uses 1,6 MHz wide carriers. Chip-rate 1,28 Mcps (= MHz)

Previously there was only TD-CDMA available for the TDD channel access method, but this technology failed on the market as the FDD version gained much more recognition, spread, deployment and support which lead to the rapid evolution of this "part" of the UMTS telecommunication standard. In common language this resulted in UMTS-FDD (and sometimes even W-CDMA) beeing referred to as "UMTS". From the technical side this naming scheme is false, but quite many people don't got to know this background information.

Let me go ahead: At first there was only TD-CDMA available for the TDD-part which was directly standardized within the UMTS standard from the start, but as mentioned above this technology failed. Further the Chinese government and telecommunications industry wanted to introduce a 3G technology on the Chinese market. Originally the aim was to not be redundant on foreign patents related to the UMTS standard, so the Chinese telecommunications industry developed TD-SCDMA in cooperation with Siemens as an alternative to TD-CDMA. TD-SCDMA was originally not part of the UMTS standard but was later added or included as an alternative air interface to TD-CDMA on the "TDD-side". Nevertheless development and commercial introduction of TD-SCDMA to the chinese market was delayed until 2009 (compared to the introduction of UMTS with W-CDMA and TD-CDMA in 2001 in Japan). In the end this resulted in the introduction of 3G technology to the chinese mobile market in three flavours UMTS-FDD with W-CDMA (3GPP-Standard), CDMA2000 with CDMA (3GPP2-Standard) and TD-SCDMA. Each of the three main chinese mobile operators adopted one of these.

This is what I came across with so far. I hope that this helps to understand and aids existing confusion. Please let me know if there are any further questions that are worth to be discussed. I also had the intention to clear things up regarding the UMTS topic and naming. This resulted in merging various stump articles and doubled content from different articles into this one which itself was not very well written as well and lacking a lot of citations and background information. This gave the intention to concentrate everything here to clean up content, removing false information with the aim to introduce a proper structuring. Actually there is also quite a bit of of content on networking infrastructure which actually belongs into article UTRA which currently redirects to this article. To gain a better overview on everything, I have taken action and introduced an article-matrix (see here) to sort everything out. Proposals are always welcome. ;-) Nightwalker-87 (talk) 20:02, 20 May 2016 (UTC)

"UTRA" and "UTRA (telecommunication)" as separate articles?[edit]

In your reply in "Names for various flavors of UMTS?", you say "Actually there is also quite a bit of of content on networking infrastructure which actually belongs into article UTRA which currently redirects to this article." Are you saying there should be separate "UTRA" and "UTRA (telecommunication)" articles? That seems a bit confusing; perhaps they'd need more descriptive titles. What would the distinction be between the two articles? Guy Harris (talk) 22:25, 20 May 2016 (UTC)

Hi Guy Harris. No, I don't think that we need the article "UTRA (telecommunication)". The suffix together with it's plural form has only been introduced for the main articles of "UMTS" and "LTE". Actually there are the #REDIRECTS UTRA and UTRAN. Right now I'm unsure which of these to use to outsource the networking stuff (technical content on network infrastructure). This is/was also indirectly adressed by the template header, that the main article is "too technical for most readers to understand". If you are interested, you might take a look at E-UTRA, which is the counterpart for LTE. There E-UTRAN currently redirects to E-UTRA. To me it is still open, if this #REDIRECT should be reversed.
To me it would make sense to have the same structuring concerning content and redirecting for both technologies in the end. With a view on Wireless Data Standards Overview we seem to be well on the way here. Nightwalker-87 (talk) 09:42, 21 May 2016 (UTC)