Cellular network standards and generation timeline.

This is a comparison of standards of wireless networking technologies for devices such as mobile phones. A new generation of cellular standards has appeared approximately every tenth year since 1G systems were introduced in 1979 and the early to mid-1980s.

Issues

Global System for Mobile Communications (GSM, around 80–85% market share) and IS-95 (around 10–15% market share) were the two most prevalent 2G mobile communication technologies in 2007.[1] In 3G, the most prevalent technology was UMTS with CDMA-2000 in close contention.

All radio access technologies have to solve the same problems: to divide the finite RF spectrum among multiple users as efficiently as possible. GSM uses TDMA and FDMA for user and cell separation. UMTS, IS-95 and CDMA-2000 use CDMA. WiMAX and LTE use OFDM.

  • Time-division multiple access (TDMA) provides multiuser access by chopping up the channel into sequential time slices. Each user of the channel takes turns to transmit and receive signals. In reality, only one person is actually using the channel at a specific moment. This is analogous to time-sharing on a large computer server.
  • Frequency-division multiple access (FDMA) provides multiuser access by separating the used frequencies. This is used in GSM to separate cells, which then use TDMA to separate users within the cell.
  • Code-division multiple access (CDMA) This uses a digital modulation called spread spectrum which spreads the voice data over a very wide channel in pseudorandom fashion using a user or cell specific pseudorandom code. The receiver undoes the randomization to collect the bits together and produce the original data. As the codes are pseudorandom and selected in such a way as to cause minimal interference to one another, multiple users can talk at the same time and multiple cells can share the same frequency. This causes an added signal noise forcing all users to use more power, which in exchange decreases cell range and battery life.
  • Orthogonal frequency-division multiple access (OFDMA) uses bundling of multiple small frequency bands that are orthogonal to one another to provide for separation of users. The users are multiplexed in the frequency domain by allocating specific sub-bands to individual users. This is often enhanced by also performing TDMA and changing the allocation periodically so that different users get different sub-bands at different times.

In theory, CDMA, TDMA and FDMA have exactly the same spectral efficiency but practically, each has its own challenges – power control in the case of CDMA, timing in the case of TDMA, and frequency generation/filtering in the case of FDMA.

For a classic example for understanding the fundamental difference of TDMA and CDMA, imagine a cocktail party where couples are talking to each other in a single room. The room represents the available bandwidth:

TDMA: A speaker takes turns talking to a listener. The speaker talks for a short time and then stops to let another couple talk. There is never more than one speaker talking in the room, no one has to worry about two conversations mixing. The drawback is that it limits the practical number of discussions in the room (bandwidth wise).
CDMA: any speaker can talk at any time; however each uses a different language. Each listener can only understand the language of their partner. As more and more couples talk, the background noise (representing the noise floor) gets louder, but because of the difference in languages, conversations do not mix. The drawback is that at some point, one cannot talk any louder. After this if the noise still rises (more people join the party/cell) the listener cannot make out what the talker is talking about without coming closer to the talker. In effect, CDMA cell coverage decreases as the number of active users increases. This is called cell breathing.

Comparison

Generation Technology Feature Encoding Year of First Use Roaming Handset interoperability Common Interference Signal quality/coverage area Frequency utilization/Call density Handoff Voice and Data at the same time
1G FDMA NMT Analog 1981 Nordics and several other European countries None None Good coverage due to low frequencies Very low density Hard No
2G TDMA and FDMA GSM Digital 1991 Worldwide, all countries except Japan and South Korea SIM card Some electronics, e.g. amplifiers Good coverage indoors on 850/900 MHz. Repeaters possible. 35 km hard limit. Very low density Hard Yes GPRS Class A
2G CDMA IS-95 (CDMA one) Digital 1995 Limited None None Unlimited cell size, low transmitter power permits large cells Very low density Soft No
3G CDMA IS-2000 (CDMA 2000) Digital 2000 / 2002 Limited RUIM (rarely used) None Unlimited cell size, low transmitter power permits large cells Very low density Soft No EVDO / Yes SVDO[2]
3G W-CDMA UMTS (3GSM) Digital 2001 Worldwide SIM card None Smaller cells and lower indoors coverage on 2100 MHz; equivalent coverage indoors and superior range to GSM on 850/900 MHz. Very low density Soft Yes[3]
4G OFDMA LTE Digital 2009 Worldwide SIM card None Smaller cells and lower coverage on the S band. Very low density Hard No (data only)
Voice possible through VoLTE or fallback to 2G/3G
5G OFDMA NR Digital 2018 Limited SIM card None Dense cells on millimeter waves. Very low density Hard No (data only)
Voice possible through VoNR
Network compatibility and Standard
Network Compatibility Standard or Revision
GSM (TDMA, 2G) GSM (1991), GPRS (2000), EDGE (2003)
cdmaOne (CDMA, 2G) cdmaOne (1995)
CDMA2000 (CDMA/TDMA, 3G) EV-DO (1999), Rev. A (2006), Rev. B (2006), SVDO (2011)
UMTS (CDMA, 3G) UMTS (1999), HSDPA (2005), HSUPA (2007), HSPA+ (2009)
4G LTE (2009), LTE Advanced (2011), LTE Advanced Pro (2016)
5G NR (2018)

Strengths and weaknesses of IS-95 and GSM

[4]

Advantages of GSM

Disadvantages of GSM

  • Interferes with some electronics, especially certain audio amplifiers.
  • Intellectual property is concentrated among a few industry participants, creating barriers to entry for new entrants and limiting competition among phone manufacturers. Situation is however worse in CDMA-based systems like IS-95, where Qualcomm is the major IP holder.
  • GSM has a fixed maximum cell site range of 120 km,[5] which is imposed by technical limitations.[6] This is expanded from the old limit of 35 km.

Advantages of IS-95

  • Capacity is IS-95's biggest asset; it can accommodate more users per MHz of bandwidth than any other technology.
  • Has no built-in limit to the number of concurrent users.
  • Uses precise clocks that do not limit the distance a tower can cover.[7]
  • Consumes less power and covers large areas so cell size in IS-95 is larger.
  • Able to produce a reasonable call with lower signal (cell phone reception) levels.
  • Uses soft handoff, reducing the likelihood of dropped calls.
  • IS-95's variable rate voice coders reduce the rate being transmitted when speaker is not talking, which allows the channel to be packed more efficiently.
  • Has a well-defined path to higher data rates.

Disadvantages of IS-95

  • Most technologies are patented and must be licensed from Qualcomm.
  • Breathing of base stations, where coverage area shrinks under load. As the number of subscribers using a particular site goes up, the range of that site goes down.
  • Because IS-95 towers interfere with each other, they are normally installed on much shorter towers. Because of this, IS-95 may not perform well in hilly terrain.
  • USSD, PTT, concatenated/E-sms are not supported by IS-95/CDMA
  • IS-95 covers a smaller portion of the world, and IS-95 phones are generally unable to roam internationally.
  • Manufacturers are often hesitant to release IS-95 devices due to the smaller market, so features are sometimes late in coming to IS-95 devices.
  • Even barring subsidy locks, CDMA phones are linked by ESN to a specific network, thus phones are typically not portable across providers.

Development of the market share of mobile standards

This graphic compares the market shares of the different mobile standards.

Cellphone subscribers by technology (left Y axis) and total number of subscribers globally (right Y axis)

In a fast-growing market, GSM/3GSM (red) grows faster than the market and is gaining market share, the CDMA family (blue) grows at about the same rate as the market, while other technologies (grey) are being phased out

Comparison of wireless Internet standards

As a reference, a comparison of mobile and non-mobile wireless Internet standards follows.

Comparison of mobile Internet access methods
Common
name		FamilyPrimary useRadio techDownstream
(Mbit/s)		Upstream
(Mbit/s)		Notes
HSPA+ 3GPPMobile InternetCDMA/TDMA/FDD
MIMO		21
42
84
672		5.8
11.5
22
168		HSPA+ is widely deployed. Revision 11 of the 3GPP states that HSPA+ is expected to have a throughput capacity of 672 Mbit/s.
LTE 3GPPMobile InternetOFDMA/TDMA/MIMO/SC-FDMA/for LTE-FDD/for LTE-TDD100 Cat3
150 Cat4
300 Cat5
25065 Cat17
1658 Cat19
(in 20 MHz FDD) [8]
50 Cat3/4
75 Cat5
2119 Cat17
13563 Cat19
(in 20 MHz FDD)[8]		LTE-Advanced Pro offers rates in excess of 3 Gbit/s to mobile users.
WiMax rel 1 802.16WirelessMANMIMO-SOFDMA37 (10 MHz TDD)17 (10 MHz TDD)With 2x2 MIMO.[9]
WiMax rel 1.5 802.16-2009WirelessMANMIMO-SOFDMA83 (20 MHz TDD)
141 (2x20 MHz FDD)		46 (20 MHz TDD)
138 (2x20 MHz FDD)		With 2x2 MIMO.Enhanced with 20 MHz channels in 802.16-2009[9]
WiMAX rel 2.0 802.16mWirelessMANMIMO-SOFDMA2x2 MIMO
110 (20 MHz TDD)
183 (2x20 MHz FDD)
4x4 MIMO
219 (20 MHz TDD)
365 (2x20 MHz FDD)		2x2 MIMO
70 (20 MHz TDD)
188 (2x20 MHz FDD)
4x4 MIMO
140 (20 MHz TDD)
376 (2x20 MHz FDD)		Also, low mobility users can aggregate multiple channels to get a download throughput of up to 1 Gbit/s[9]
Flash-OFDM Flash-OFDMMobile Internet
mobility up to 200 mph (350 km/h)		Flash-OFDM5.3
10.6
15.9		1.8
3.6
5.4		Mobile range 30 km (18 miles)
Extended range 55 km (34 miles)
HIPERMAN HIPERMANMobile InternetOFDM56.9
Wi-Fi 802.11
(11ax)		Wireless LANOFDM/OFDMA/CSMA/MIMO/MU-MIMO/Half duplex9600 Wi-Fi 6

Antenna, RF front end enhancements and minor protocol timer tweaks have helped deploy long range P2P networks compromising on radial coverage, throughput and/or spectra efficiency (310 km & 382 km)

iBurst 802.20Mobile InternetHC-SDMA/TDD/MIMO9536Cell Radius: 3–12 km
Speed: 250 km/h
Spectral Efficiency: 13 bits/s/Hz/cell
Spectrum Reuse Factor: "1"
EDGE Evolution GSMMobile InternetTDMA/FDD1.60.53GPP Release 7
UMTS W-CDMA
HSPA (HSDPA+HSUPA)		 3GPPMobile InternetCDMA/FDD

CDMA/FDD/MIMO		0.384
14.4		0.384
5.76		HSDPA is widely deployed. Typical downlink rates today 2 Mbit/s, ~200 kbit/s uplink; HSPA+ downlink up to 56 Mbit/s.
UMTS-TDD 3GPPMobile InternetCDMA/TDD16Reported speeds according to IPWireless using 16QAM modulation similar to HSDPA+HSUPA
EV-DO Rel. 0
EV-DO Rev.A
EV-DO Rev.B		 3GPP2Mobile InternetCDMA/FDD2.45
3.1
4.9xN		0.15
1.8
1.8xN		Rev B note: N is the number of 1.25 MHz carriers used. EV-DO is not designed for voice, and requires a fallback to 1xRTT when a voice call is placed or received.

Notes: All speeds are theoretical maximums and will vary by a number of factors, including the use of external antennas, distance from the tower and the ground speed (e.g. communications on a train may be poorer than when standing still). Usually the bandwidth is shared between several terminals. The performance of each technology is determined by a number of constraints, including the spectral efficiency of the technology, the cell sizes used, and the amount of spectrum available. For more information, see Comparison of wireless data standards.

For more comparison tables, see bit rate progress trends, comparison of mobile phone standards, spectral efficiency comparison table and OFDM system comparison table.

See also

References

  1. ↑ "Subscriber statistics end Q1 2007" (PDF). Archived from the original (PDF) on 27 September 2007. Retrieved 22 September 2007.
  2. ↑ "CDMA Development Group Announces 'SVDO': Handle Calls and Data at same time". Wpcentral.com. 18 August 2009. Retrieved 30 July 2018.
  3. ↑ "The Nation's Largest & Most Reliable Network – AT&T". Wireless.att.com. Archived from the original on 15 August 2018. Retrieved 30 July 2018.
  4. ↑ "IS-95 (CDMA) and GSM(TDMA)". Archived from the original on 26 February 2011. Retrieved 3 February 2011.
  5. ↑ "AllBusiness: Unexpected Error Condition". Archived from the original on 23 January 2011. Retrieved 18 January 2011.
  6. ↑ "Frequently Asked PCS Questions". Archived from the original on 9 May 2006. Retrieved 14 June 2006.
  7. ↑ "Frequently Asked PCS Questions". Archived from the original on 9 May 2006.
  8. 1 2 "LTE". 3GPP web site. 2009. Retrieved 20 August 2011.
  9. 1 2 3 "WiMAX and the IEEE 802.16m Air Interface Standard" (PDF). WiMax Forum. 4 April 2010. Retrieved 7 February 2012.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.