Mobile Communications/Technical Innovations of LTE - Revision history

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			[[de:Mobile_Kommunikation/Technische_Neuerungen_von_LTE]]

Guenter at 13:48, 20 February 2023

2023-02-20T13:48:30Z

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	$\text{Example 2:}$  The term  "MIMO"  summarizes multi-antenna techniques with different properties, each of which can be useful in certain situations.  The following description is based on the four diagrams shown here.<br>		$\text{Example 2:}$  The term  "MIMO"  summarizes multi-antenna techniques with different properties, each of which can be useful in certain situations.  The following description is based on the four diagrams shown here.<br>

	[[File:~~EN_Mob_T_4_2_S5b~~.png\|right\|frame\|Four multi-antenna procedures with different properties ~~'''KORREKTUR: multiple simultaneous'''~~\|class=fit]]		[[File:EN_Mob_T_4_2_S5b_v2.png\|right\|frame\|Four multi-antenna procedures with different properties\|class=fit]]

	*If the mostly independent channels of a MIMO system are assigned to a single user (top left diagram), one speaks of  "Single–User MIMO".  With 2×2 MIMO, the data rate is doubled compared to SISO operation and with four transmitting and receiving antennas each, the data rate can be doubled again under good channel conditions.<br>		*If the mostly independent channels of a MIMO system are assigned to a single user (top left diagram), one speaks of  "Single–User MIMO".  With 2×2 MIMO, the data rate is doubled compared to SISO operation and with four transmitting and receiving antennas each, the data rate can be doubled again under good channel conditions.<br>

Guenter at 15:54, 9 February 2023

2023-02-09T15:54:19Z

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	In the course of the introduction of LTE, the backhaul had to be redesigned.  It was important to keep an eye on future security, since the next generation  "LTE Advanced"  was already in place before the introduction.  If one believes the experts' propaganda  "Moore's Law" for mobile phone bandwidths, the most important factor for future security is the expensive new installation of better cables.<br>		In the course of the introduction of LTE, the backhaul had to be redesigned.  It was important to keep an eye on future security, since the next generation  "LTE Advanced"  was already in place before the introduction.  If one believes the experts' propaganda  "Moore's Law" for mobile phone bandwidths, the most important factor for future security is the expensive new installation of better cables.<br>

	Due to the purely packet-oriented transmission technology, the Ethernet standard, which is also IP based, is suitable for the LTE backhaul, which is realized with the help of optical fibers.  In 2009, the company Fujitsu presented in the study  [Fuj09]<ref name='Fuj09'>Fujitsu Network Communications Inc.:  4G Impacts to Mobile Backhaul.  [http://www.fujitsu.com/downloads/TEL/fnc/whitepapers/4Gimpacts.pdf ~~$\text{~~PDF Internet document}$].</ref>,  also the thesis that the current infrastructure will continue to play an important role for LTE backhaul for the next ten to fifteen years.<br>		Due to the purely packet-oriented transmission technology, the Ethernet standard, which is also IP based, is suitable for the LTE backhaul, which is realized with the help of optical fibers.  In 2009, the company Fujitsu presented in the study  [Fuj09]<ref name='Fuj09'>Fujitsu Network Communications Inc.:  4G Impacts to Mobile Backhaul.  [http://www.fujitsu.com/downloads/TEL/fnc/whitepapers/4Gimpacts.pdf "PDF Internet document"].</ref>,  also the thesis that the current infrastructure will continue to play an important role for LTE backhaul for the next ten to fifteen years.<br>

	There are two approaches for the generation change to an Ethernet based  backhaul</i> :		There are two approaches for the generation change to an Ethernet based  backhaul</i> :

Guenter at 15:53, 9 February 2023

2023-02-09T15:53:17Z

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	Unlike previous mobile phone standards, LTE only supports  »'''packet-oriented transmission'''«.  However, for speech transmission (sometimes the term "voice transmission" is used for this), a connection-oriented transmission with fixed reservation of resources would be better, since a "fragmented transmission", as is the case with the packet-oriented method, is relatively complicated.<br>		Unlike previous mobile phone standards, LTE only supports  »'''packet-oriented transmission'''«.  However, for speech transmission (sometimes the term "voice transmission" is used for this), a connection-oriented transmission with fixed reservation of resources would be better, since a "fragmented transmission", as is the case with the packet-oriented method, is relatively complicated.<br>

	The problem of integrating speech transmission methods was one of the major challenges in the development of LTE, as speech transmission remains the largest source of revenue for network operators.  There were a number of approaches, as it can be seen in the internet article   [Gut10]<ref name='Gut10'>Gutt, E.:  LTE - a new dimension of mobile broadband use.  [http://www.ltemobile.de/uploads/media/LTE_Einfuehrung_V1.pdf ~~$\text{~~PDF Internet document}$], 2010.</ref>.		The problem of integrating speech transmission methods was one of the major challenges in the development of LTE, as speech transmission remains the largest source of revenue for network operators.  There were a number of approaches, as it can be seen in the internet article   [Gut10]<ref name='Gut10'>Gutt, E.:  LTE - a new dimension of mobile broadband use.  [http://www.ltemobile.de/uploads/media/LTE_Einfuehrung_V1.pdf "PDF Internet document"], 2010.</ref>.

	'''(1)'''   A very simple and obvious method is  "Circuit Switched Fallback"  $\rm (CSFB)$.  Here a wireline transmission is used for the speech transmission.  The principle is:		'''(1)'''   A very simple and obvious method is  "Circuit Switched Fallback"  $\rm (CSFB)$.  Here a wireline transmission is used for the speech transmission.  The principle is:

Guenter at 15:52, 9 February 2023

2023-02-09T15:52:18Z

Guenter at 15:37, 9 February 2023

2023-02-09T15:37:40Z

← Older revision		Revision as of 17:37, 9 February 2023
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	== Multiple Antenna Systems==		== Multiple Antenna Systems==
	<br>		<br>
	If a radio system uses several transmitting and receiving antennas, one speaks of  ~~$\text{~~Multiple Input Multiple Output}$  $\rm (MIMO)$.  This is not an LTE specific development.  WLAN, for example, also uses this technology.		If a radio system uses several transmitting and receiving antennas, one speaks of  »'''Multiple Input Multiple Output'''»  $\rm (MIMO)$.  This is not an LTE specific development.  WLAN, for example, also uses this technology.

	{{GraueBox\|TEXT=		{{GraueBox\|TEXT=
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	*The new thing about LTE is not the actual use of  "Multiple Input Multiple Output", but the particularly intensive one, namely  2×2 MIMO  in the uplink and maximum  4×4 MIMO  in the downlink.		*The new thing about LTE is not the actual use of  "Multiple Input Multiple Output", but the particularly intensive one, namely  2×2 MIMO  in the uplink and maximum  4×4 MIMO  in the downlink.

	*In the successor  [[Mobile_Communications/LTE-Advanced - a Further Development of LTE\|~~$\text{~~LTE Advanced~~}$]]~~  the use of MIMO is even more pronounced, namely "4×4" in the uplink and "8×8" in the opposite direction.}}		*In the successor  [[Mobile_Communications/LTE-Advanced - a Further Development of LTE\|"LTE Advanced"  the use of MIMO is even more pronounced, namely "4×4" in the uplink and "8×8" in the opposite direction.}}

Guenter at 15:24, 9 February 2023

2023-02-09T15:24:32Z

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Guenter at 14:53, 9 February 2023

2023-02-09T14:53:34Z

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	[[File:EN_Mob_T_4_2_S5b.png\|right\|frame\|Four multi-antenna procedures with different properties '''KORREKTUR: multiple simultaneous'''\|class=fit]]		[[File:EN_Mob_T_4_2_S5b.png\|right\|frame\|Four multi-antenna procedures with different properties '''KORREKTUR: multiple simultaneous'''\|class=fit]]

	*If the mostly independent channels of a MIMO system are assigned to a single user (top left diagram), one speaks of  "Single–User MIMO".  With 2×2 MIMO, the data rate is doubled compared to SISO operation and with four ~~transmit '''KORREKTUR:~~ transmitting~~'''~~ and receiving antennas each, the data rate can be doubled again under good channel conditions.<br>		*If the mostly independent channels of a MIMO system are assigned to a single user (top left diagram), one speaks of  "Single–User MIMO".  With 2×2 MIMO, the data rate is doubled compared to SISO operation and with four transmitting and receiving antennas each, the data rate can be doubled again under good channel conditions.<br>

	::LTE allows maximum 4×4 MIMO but only in the downlink.  Due to the complexity of multi-antenna systems, only laptops with LTE modems can be used as receivers (end devices) for 4×4 MIMO.  For a mobile phone, the use is generally limited to 2×2 MIMO.		::LTE allows maximum 4×4 MIMO but only in the downlink.  Due to the complexity of multi-antenna systems, only laptops with LTE modems can be used as receivers (end devices) for 4×4 MIMO.  For a mobile phone, the use is generally limited to 2×2 MIMO.

Guenter at 14:52, 9 February 2023

2023-02-09T14:52:51Z

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	A MIMO system has advantages compared to  "Single Input Single Output"  (SISO, only one transmitting and one receiving antenna).  A distinction is made between several gains depending on the channel:		A MIMO system has advantages compared to  "Single Input Single Output"  (SISO, only one transmitting and one receiving antenna).  A distinction is made between several gains depending on the channel:
	*»<b>Power gain</b>«  according to the number of receiving antennas:   <br>If the radio signals arriving via several antennas are combined in a suitable way   ⇒   [https://en.wikipedia.org/wiki/Maximal-ratio_combining $\text{Maximal-ratio combining}$], the ~~reception '''KORREKTUR:~~ received~~'''~~ power is increased and the radio connection is improved.  By doubling the antennas, a power gain of maximum 3 dB is achieved.<br>		*»<b>Power gain</b>«  according to the number of receiving antennas:   <br>If the radio signals arriving via several antennas are combined in a suitable way   ⇒   [https://en.wikipedia.org/wiki/Maximal-ratio_combining $\text{Maximal-ratio combining}$], the received power is increased and the radio connection is improved.  By doubling the antennas, a power gain of maximum 3 dB is achieved.<br>

	*»<b>Diversity gain</b>« through  [https://en.wikipedia.org/wiki/Antenna_diversity $\text{Spatial Diversity}$]:  <br>If several spatially separated receiving antennas are used in an environment with strong multipath propagation, the fading at the individual antennas is mostly independent from each other and the probability that all antennas are affected by fading at the same time is very low.<br>		*»<b>Diversity gain</b>« through  [https://en.wikipedia.org/wiki/Antenna_diversity $\text{Spatial Diversity}$]:  <br>If several spatially separated receiving antennas are used in an environment with strong multipath propagation, the fading at the individual antennas is mostly independent from each other and the probability that all antennas are affected by fading at the same time is very low.<br>

Hwang at 11:14, 6 February 2023

2023-02-06T11:14:43Z

← Older revision		Revision as of 13:14, 6 February 2023
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	$\text{Example 2:}$  The term  "MIMO"  summarizes multi-antenna techniques with different properties, each of which can be useful in certain situations.  The following description is based on the four diagrams shown here.<br>		$\text{Example 2:}$  The term  "MIMO"  summarizes multi-antenna techniques with different properties, each of which can be useful in certain situations.  The following description is based on the four diagrams shown here.<br>

	[[File:EN_Mob_T_4_2_S5b.png\|right\|frame\|Four multi-antenna procedures with different properties\|class=fit]]		[[File:EN_Mob_T_4_2_S5b.png\|right\|frame\|Four multi-antenna procedures with different properties '''KORREKTUR: multiple simultaneous'''\|class=fit]]

	*If the mostly independent channels of a MIMO system are assigned to a single user (top left diagram), one speaks of  "Single–User MIMO".  With 2×2 MIMO, the data rate is doubled compared to SISO operation and with four transmit '''KORREKTUR: transmitting''' and receiving antennas each, the data rate can be doubled again under good channel conditions.<br>		*If the mostly independent channels of a MIMO system are assigned to a single user (top left diagram), one speaks of  "Single–User MIMO".  With 2×2 MIMO, the data rate is doubled compared to SISO operation and with four transmit '''KORREKTUR: transmitting''' and receiving antennas each, the data rate can be doubled again under good channel conditions.<br>

← Older revision		Revision as of 17:52, 9 February 2023
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	*The new thing about LTE is not the actual use of  "Multiple Input Multiple Output", but the particularly intensive one, namely  2×2 MIMO  in the uplink and maximum  4×4 MIMO  in the downlink.		*The new thing about LTE is not the actual use of  "Multiple Input Multiple Output", but the particularly intensive one, namely  2×2 MIMO  in the uplink and maximum  4×4 MIMO  in the downlink.

	*In the successor  [[Mobile_Communications/LTE-Advanced - a Further Development of LTE\|"LTE Advanced"  the use of MIMO is even more pronounced, namely "4×4" in the uplink and "8×8" in the opposite direction.}}		*In the successor  [[Mobile_Communications/LTE-Advanced - a Further Development of LTE\|"LTE Advanced"]]  the use of MIMO is even more pronounced, namely "4×4" in the uplink and "8×8" in the opposite direction.}}


	A MIMO system has advantages compared to  "Single Input Single Output"  (SISO, only one transmitting and one receiving antenna).  A distinction is made between several gains depending on the channel:		A MIMO system has advantages compared to  "Single Input Single Output"  (SISO, only one transmitting and one receiving antenna).  A distinction is made between several gains depending on the channel:
	*»<b>Power gain</b>«  according to the number of receiving antennas:   <br>If the radio signals arriving via several antennas are combined in a suitable way   ⇒   [https://en.wikipedia.org/wiki/Maximal-ratio_combining ~~$\text{~~Maximal-ratio combining}$], the received power is increased and the radio connection is improved.  By doubling the antennas, a power gain of maximum 3 dB is achieved.<br>		*»<b>Power gain</b>«  according to the number of receiving antennas:   <br>If the radio signals arriving via several antennas are combined in a suitable way   ⇒   [https://en.wikipedia.org/wiki/Maximal-ratio_combining "Maximal-ratio combining"], the received power is increased and the radio connection is improved.  By doubling the antennas, a power gain of maximum 3 dB is achieved.<br>

	*»<b>Diversity gain</b>« through  [https://en.wikipedia.org/wiki/Antenna_diversity ~~$\text{~~Spatial Diversity}$]:  <br>If several spatially separated receiving antennas are used in an environment with strong multipath propagation, the fading at the individual antennas is mostly independent from each other and the probability that all antennas are affected by fading at the same time is very low.<br>		*»<b>Diversity gain</b>« through  [https://en.wikipedia.org/wiki/Antenna_diversity "Spatial Diversity"]:  <br>If several spatially separated receiving antennas are used in an environment with strong multipath propagation, the fading at the individual antennas is mostly independent from each other and the probability that all antennas are affected by fading at the same time is very low.<br>

	*»<b>Data rate gain</b>«:   <br> This increases the efficiency of MIMO, especially in an environment with increased multipath propagation, especially when transmitter and receiver do not have a direct line of sight and the transmission is done via reflections.  Tripling the number of antennas for the transmitter and receiver results in approximately twice the data rate.<br><br>		*»<b>Data rate gain</b>«:   <br> This increases the efficiency of MIMO, especially in an environment with increased multipath propagation, especially when transmitter and receiver do not have a direct line of sight and the transmission is done via reflections.  Tripling the number of antennas for the transmitter and receiver results in approximately twice the data rate.<br><br>
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	*The redesign of the base stations  ("eNodeB"  instead of  "NodeB")  and the interface  "X2"  are the decisive further developments from UMTS towards LTE.		*The redesign of the base stations  ("eNodeB"  instead of  "NodeB")  and the interface  "X2"  are the decisive further developments from UMTS towards LTE.

	*The graphic on the right illustrates in particular the reduction in complexity compared to UMTS that goes hand in hand with the new technology (left graphic).		*The graphic on the right illustrates in particular the reduction in complexity compared to UMTS that goes hand in hand with the new technology (left graphic).

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	The  $\text{LTE system architecture}$  can be divided into two major areas, too:		The  $\text{LTE system architecture}$  can be divided into two major areas, too:
	*the LTE core network  "Evolved Packet Core"  $\rm (EPC)$,<br>		*the LTE core network  "Evolved Packet Core"  $\rm (EPC)$,<br>
	*the air interface  "Evolved UMTS Terrestrial Radio Access Network"  $\rm (EUTRAN)$, a further development of  [[Examples_of_Communication_Systems/UMTS_Network_Architecture#Access_level_architecture\|~~$\text{~~UMTS Terrestrial Radio Access Network}$]]  $\rm (UTRAN)$.<br><br>
			*the air interface  "Evolved UMTS Terrestrial Radio Access Network"  $\rm (EUTRAN)$, a further development of  [[Examples_of_Communication_Systems/UMTS_Network_Architecture#Access_level_architecture\|"UMTS Terrestrial Radio Access Network"]]  $\rm (UTRAN)$.<br><br>

	EUTRAN transmits the data between the terminal and the LTE base station  ("eNodeB")  via the so-called  "S1"  interface with two connections, one for the transmission of user data and a second for the transmission of signalling data.  You can see from the above graphic:		EUTRAN transmits the data between the terminal and the LTE base station  ("eNodeB")  via the so-called  "S1"  interface with two connections, one for the transmission of user data and a second for the transmission of signalling data.  You can see from the above graphic:
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	*The services previously transported through the slow "E1" standard lines would have to be switched immediately to a packet-based procedure.		*The services previously transported through the slow "E1" standard lines would have to be switched immediately to a packet-based procedure.

	*Ethernet does not offer  (unlike the current standard)  any  end–to–end  synchronization, which can lead to severe delays or even service interruptions when changing radio cells, thus a huge loss of service quality.		*Ethernet does not offer  (unlike the current standard)  any  end–to–end  synchronization, which can lead to severe delays or even service interruptions when changing radio cells, thus a huge loss of service quality.
	* However, in the concept  [https://en.wikipedia.org/wiki/Synchronous_Ethernet ~~$\text{~~Synchronous Ethernet}$]  $\rm (SyncE)$, the Cisco company has already made suggestions as to how synchronization could be realized.<br>
			* However, in the concept  [https://en.wikipedia.org/wiki/Synchronous_Ethernet "Synchronous Ethernet"]  $\rm (SyncE)$, the Cisco company has already made suggestions as to how synchronization could be realized.<br>


	For conurbations, a direct conversion of the backhaul would certainly be worthwhile, as relatively few new cables would have to be laid for a comparatively high number of new users.		For conurbations, a direct conversion of the backhaul would certainly be worthwhile, as relatively few new cables would have to be laid for a comparatively high number of new users.

	In rural areas, however, major excavation work would quickly result in high costs.  However, this is exactly the area which must be covered first, according to the  [[Mobile_Communications/General Information on the LTE Mobile Communications Standard#LTE frequency band splitting\|~~$\text{~~agreement reached}$]]  between the federal government and the (German) mobile phone operators.  Here, the mostly existing microwave radio link would have to be (and probably will be) extended to high data rates.<br>		In rural areas, however, major excavation work would quickly result in high costs.  However, this is exactly the area which must be covered first, according to the  [[Mobile_Communications/General Information on the LTE Mobile Communications Standard#LTE frequency band splitting\|"agreement reached"]]  between the federal government and the (German) mobile phone operators.  Here, the mostly existing microwave radio link would have to be (and probably will be) extended to high data rates.<br>

	==Exercises for the chapter==		==Exercises for the chapter==