Mobile Communications/Characteristics of GSM - Revision history

Maintenance script: Add German interlanguage link

2026-03-16T12:28:02Z

Add German interlanguage link

Guenter at 16:41, 20 February 2023

2023-02-20T16:41:51Z

← Older revision		Revision as of 18:41, 20 February 2023
Line 55:		Line 55:
	The mapping of logical to physical channels is done using the GSM frame structure.  Here we only look to traffic channels and to the mapping in time.  In this case, each multi–frame of   $120 \ \rm ms$  duration is divided into  $26$  TDMA frames (two of them for control channels) of  $4.615\ \rm ms$  duration.  Thus, the duration of a time slot is approximately  $T_{\rm Z} = 576.9\ \rm µ s$.<br>		The mapping of logical to physical channels is done using the GSM frame structure.  Here we only look to traffic channels and to the mapping in time.  In this case, each multi–frame of   $120 \ \rm ms$  duration is divided into  $26$  TDMA frames (two of them for control channels) of  $4.615\ \rm ms$  duration.  Thus, the duration of a time slot is approximately  $T_{\rm Z} = 576.9\ \rm µ s$.<br>

	[[File:~~EN_Mob_T_3_3_S3a~~.png\|\|right\|frame\|Data and frame structure for GSM ~~'''KORREKTUR: Daten'''~~\|class=fit]]		[[File:EN_Mob_T_3_3_S2_v3.png\|\|right\|frame\|Data and frame structure for GSM\|class=fit]]

	You can see from this graphic:		You can see from this graphic:

Guenter at 13:40, 20 February 2023

2023-02-20T13:40:02Z

← Older revision		Revision as of 15:40, 20 February 2023
Line 9:		Line 9:
	<br>		<br>
	$\rm GSM$  $\rm (G$lobal  $\rm S$ystem  for  $\rm M$obile Communication$)$  is a strongly hierarchically structured system of different network components.  You can see from the graphic:		$\rm GSM$  $\rm (G$lobal  $\rm S$ystem  for  $\rm M$obile Communication$)$  is a strongly hierarchically structured system of different network components.  You can see from the graphic:
	[[File:~~P ID2203 Mob T 3 3 S1 v1~~.png\|right\|frame\|GSM system architecture ~~'''KORREKTUR: Funkschnittstelle'''~~\|class=fit]]		[[File:EN_Mob_T_3_3_S1.png\|right\|frame\|GSM system architecture\|class=fit]]
	*The mobile station  $\rm (MS)$  communicates via the radio interface with the nearest  base transceiver station  $\rm (BTS$, transmit and receive base station).<br>		*The mobile station  $\rm (MS)$  communicates via the radio interface with the nearest  base transceiver station  $\rm (BTS$, transmit and receive base station).<br>

Line 27:		Line 27:
	== Multiple access with GSM ==		== Multiple access with GSM ==
	<br>		<br>
	[[File:~~EN_Mob_T_3_3_S2~~.png\|\|right\|frame\|Realization of FDMA and TDMA with "GSM 900" ~~'''KORREKTUR: Daten'''~~\|class=fit]]		[[File:EN_Mob_T_3_3_S2_v2.png\|right\|frame\|Realization of FDMA and TDMA with "GSM 900"\|class=fit]]

	GSM uses two multiple access methods in parallel:		GSM uses two multiple access methods in parallel:

Guenter at 14:32, 7 February 2023

2023-02-07T14:32:52Z

← Older revision		Revision as of 16:32, 7 February 2023
Line 96:		Line 96:

	Regarding the topic treated here  (coherent or non-coherent demodulation of FSK)  we refer to two exercises in the book "Digital Signal Transmission":		Regarding the topic treated here  (coherent or non-coherent demodulation of FSK)  we refer to two exercises in the book "Digital Signal Transmission":
	*[[Aufgaben:Aufgabe_4.16:_Binary_Frequency_Shift_Keying\|"Excercise 4.16:   Binary Frequency Shift Keying"]],<br>		*[[Aufgaben:Aufgabe_4.16:_Binary_Frequency_Shift_Keying\|Excercise 4.16:   Binary Frequency Shift Keying]],<br>
	*[[Aufgaben:Aufgabe_4.18Z:_BER_von_kohärenter_und_nichtkohärenter_FSK\| "Excercise 4.18Z:   BER of coherent and non-coherent FSK"]].<br><br>
			*[[Aufgaben:Aufgabe_4.18Z:_BER_von_kohärenter_und_nichtkohärenter_FSK\| Excercise 4.18Z:   BER of coherent and non-coherent FSK]].<br><br>

	~~[[Diese beiden Aufgaben müssen später in DSÜ noch übersetzt werden]] '''KORREKTUR'''~~

	{{GraueBox\|TEXT=		{{GraueBox\|TEXT=
Line 142:		Line 142:
	We should also mention the  [[Mobile_Communications/General_Information_on_the_LTE_Mobile_Communications_Standard#Development_of_the_UMTS_mobile_phone_standards_towards_LTE\|$\text{EDGE Evolution}$]]  or "Evolved EDGE", i.e. the further development of the evolution of GSM in Release 7 (December 2007). For this, the developers specify data rates up to  $1 \ \rm Mbit/s$  and halved latency times  $(10 \ \rm ms$ instead of $20 \ \rm ms)$ . These values can be achieved among other things		We should also mention the  [[Mobile_Communications/General_Information_on_the_LTE_Mobile_Communications_Standard#Development_of_the_UMTS_mobile_phone_standards_towards_LTE\|$\text{EDGE Evolution}$]]  or "Evolved EDGE", i.e. the further development of the evolution of GSM in Release 7 (December 2007). For this, the developers specify data rates up to  $1 \ \rm Mbit/s$  and halved latency times  $(10 \ \rm ms$ instead of $20 \ \rm ms)$ . These values can be achieved among other things
	*by  32–QAM or  16–QAM Modulation instead of 8–PSK,		*by  32–QAM or  16–QAM Modulation instead of 8–PSK,
	* an improved error correction through the use of  [[Channel_Coding/Grundlegendes_zu_den_Turbocodes\| $\text{Turbo~~–Codes~~}$]] ~~'''KORREKTUR: Turbo codes?'''~~, and		* an improved error correction through the use of  [[Channel_Coding/Grundlegendes_zu_den_Turbocodes\| $\text{Turbo codes}$]], and
	* an increase of the symbol rate of  $20\%$  from  $270.833 \ \rm ksymbol/s$  to  $325\ \rm ksymbol/s$.<br>		* an increase of the symbol rate of  $20\%$  from  $270.833 \ \rm ksymbol/s$  to  $325\ \rm ksymbol/s$.<br>

Hwang at 15:18, 26 January 2023

2023-01-26T15:18:19Z

← Older revision		Revision as of 17:18, 26 January 2023
Line 142:		Line 142:
	We should also mention the  [[Mobile_Communications/General_Information_on_the_LTE_Mobile_Communications_Standard#Development_of_the_UMTS_mobile_phone_standards_towards_LTE\|$\text{EDGE Evolution}$]]  or "Evolved EDGE", i.e. the further development of the evolution of GSM in Release 7 (December 2007). For this, the developers specify data rates up to  $1 \ \rm Mbit/s$  and halved latency times  $(10 \ \rm ms$ instead of $20 \ \rm ms)$ . These values can be achieved among other things		We should also mention the  [[Mobile_Communications/General_Information_on_the_LTE_Mobile_Communications_Standard#Development_of_the_UMTS_mobile_phone_standards_towards_LTE\|$\text{EDGE Evolution}$]]  or "Evolved EDGE", i.e. the further development of the evolution of GSM in Release 7 (December 2007). For this, the developers specify data rates up to  $1 \ \rm Mbit/s$  and halved latency times  $(10 \ \rm ms$ instead of $20 \ \rm ms)$ . These values can be achieved among other things
	*by  32–QAM or  16–QAM Modulation instead of 8–PSK,		*by  32–QAM or  16–QAM Modulation instead of 8–PSK,
	* an improved error correction through the use of  [[Channel_Coding/Grundlegendes_zu_den_Turbocodes\| $\text{Turbo–Codes}$]], and		* an improved error correction through the use of  [[Channel_Coding/Grundlegendes_zu_den_Turbocodes\| $\text{Turbo–Codes}$]] '''KORREKTUR: Turbo codes?''', and
	* an increase of the symbol rate of  $20\%$  from  $270.833 \ \rm ksymbol/s$  to  $325\ \rm ksymbol/s$.<br>		* an increase of the symbol rate of  $20\%$  from  $270.833 \ \rm ksymbol/s$  to  $325\ \rm ksymbol/s$.<br>

Hwang at 15:05, 26 January 2023

2023-01-26T15:05:59Z

← Older revision		Revision as of 17:05, 26 January 2023
Line 140:		Line 140:
	In practice, however, MCS–8  $(54.4 \ \rm kbit/s)$  and seven time slots are the maximum applicable.  With this, one reaches  $380.8 \ \rm kbit/s$  and thus the order of magnitude of UMTS  $(384 \ \rm kbit/s)$.<br>		In practice, however, MCS–8  $(54.4 \ \rm kbit/s)$  and seven time slots are the maximum applicable.  With this, one reaches  $380.8 \ \rm kbit/s$  and thus the order of magnitude of UMTS  $(384 \ \rm kbit/s)$.<br>

	We should also mention the  [[Mobile_Communications/~~General information on the LTE mobile communications standard~~#~~Entwicklung_der_UMTS-Mobilfunkstandards_hin_zu_LTE~~\|$\text{EDGE Evolution}$]]  or "Evolved EDGE", i.e. the further development of the evolution of GSM in Release 7 (December 2007). For this, the developers specify data rates up to  $1 \ \rm Mbit/s$  and halved latency times  $(10 \ \rm ms$ instead of $20 \ \rm ms)$ . These values can be achieved among other things		We should also mention the  [[Mobile_Communications/General_Information_on_the_LTE_Mobile_Communications_Standard#Development_of_the_UMTS_mobile_phone_standards_towards_LTE\|$\text{EDGE Evolution}$]]  or "Evolved EDGE", i.e. the further development of the evolution of GSM in Release 7 (December 2007). For this, the developers specify data rates up to  $1 \ \rm Mbit/s$  and halved latency times  $(10 \ \rm ms$ instead of $20 \ \rm ms)$ . These values can be achieved among other things
	*by  32–QAM or  16–QAM Modulation instead of 8–PSK,		*by  32–QAM or  16–QAM Modulation instead of 8–PSK,
	* an improved error correction through the use of  [[Channel_Coding/Grundlegendes_zu_den_Turbocodes\| $\text{Turbo–Codes}$]], and		* an improved error correction through the use of  [[Channel_Coding/Grundlegendes_zu_den_Turbocodes\| $\text{Turbo–Codes}$]], and

Hwang at 15:04, 26 January 2023

2023-01-26T15:04:35Z

← Older revision		Revision as of 17:04, 26 January 2023
Line 104:		Line 104:
	$\text{Example 1:}$  The following graphic is to clarify the previous statements:		$\text{Example 1:}$  The following graphic is to clarify the previous statements:

	[[File:EN_Mob_T_3_3_S4.png\|right\|frame\|~~block~~ diagram and signals with GMSK\|class=fit]]		[[File:EN_Mob_T_3_3_S4.png\|right\|frame\|Block diagram and signals with GMSK\|class=fit]]

	*Starting from a Dirac shaped source signal  $q_\delta(t)$  at point  $(1)$  you pass through a filter with the rectangular impulse response  $g_{\rm R}(t)$  to the rectangular signal  $q_{\rm R}(t)$  at point  $(2)$.		*Starting from a Dirac shaped source signal  $q_\delta(t)$  at point  $(1)$  you pass through a filter with the rectangular impulse response  $g_{\rm R}(t)$  to the rectangular signal  $q_{\rm R}(t)$  at point  $(2)$.

Hwang at 15:02, 26 January 2023

2023-01-26T15:02:51Z

← Older revision		Revision as of 17:02, 26 January 2023
Line 99:		Line 99:
	*[[Aufgaben:Aufgabe_4.18Z:_BER_von_kohärenter_und_nichtkohärenter_FSK\| "Excercise 4.18Z:   BER of coherent and non-coherent FSK"]].<br><br>		*[[Aufgaben:Aufgabe_4.18Z:_BER_von_kohärenter_und_nichtkohärenter_FSK\| "Excercise 4.18Z:   BER of coherent and non-coherent FSK"]].<br><br>

	[[Diese beiden Aufgaben müssen später in DSÜ noch übersetzt werden]]		[[Diese beiden Aufgaben müssen später in DSÜ noch übersetzt werden]] '''KORREKTUR'''

	{{GraueBox\|TEXT=		{{GraueBox\|TEXT=

Hwang at 15:01, 26 January 2023

2023-01-26T15:01:47Z

← Older revision		Revision as of 17:01, 26 January 2023
Line 95:		Line 95:
	*For GSM, a low-pass filter with Gaussian characteristic is inserted before the frequency modulator   ⇒   [[Modulation_Methods/Nonlinear_Digital_Modulation#GMSK_.E2.80.93_Gaussian_Minimum_Shift_Keying\|$\text{Gaussian Minimum Shift Keying}$]]  $\rm (GMSK)$, which further reduces the bandwidth and improves bandwidth efficiency.<br><br>		*For GSM, a low-pass filter with Gaussian characteristic is inserted before the frequency modulator   ⇒   [[Modulation_Methods/Nonlinear_Digital_Modulation#GMSK_.E2.80.93_Gaussian_Minimum_Shift_Keying\|$\text{Gaussian Minimum Shift Keying}$]]  $\rm (GMSK)$, which further reduces the bandwidth and improves bandwidth efficiency.<br><br>

	Regarding the topic treated here  (coherent or non-coherent demodulation of FSK)  we refer to two ~~Exercises~~ in the book "Digital Signal Transmission":		Regarding the topic treated here  (coherent or non-coherent demodulation of FSK)  we refer to two exercises in the book "Digital Signal Transmission":
	*[[Aufgaben:Aufgabe_4.16:_Binary_Frequency_Shift_Keying\|"Excercise 4.16:   Binary Frequency Shift Keying"]],<br>		*[[Aufgaben:Aufgabe_4.16:_Binary_Frequency_Shift_Keying\|"Excercise 4.16:   Binary Frequency Shift Keying"]],<br>
	*[[Aufgaben:Aufgabe_4.18Z:_BER_von_kohärenter_und_nichtkohärenter_FSK\| "Excercise 4.18Z:   BER of coherent and non-coherent FSK"]].<br><br>		*[[Aufgaben:Aufgabe_4.18Z:_BER_von_kohärenter_und_nichtkohärenter_FSK\| "Excercise 4.18Z:   BER of coherent and non-coherent FSK"]].<br><br>

Hwang at 14:57, 26 January 2023

2023-01-26T14:57:07Z

← Older revision		Revision as of 16:57, 26 January 2023
Line 86:		Line 86:
	GSM uses the very bandwidth-efficient modulation method  [[Examples_of_Communication_Systems/Radio_Interface#Gaussian_Minimum_Shift_Keying_.28GMSK.29\| $\text{Gaussian Minimum Shift Keying}$]]  $\rm (GMSK)$.  It should again be expressly mentioned that this modulation method, just like the FDMA/TDMA multiple access, is exclusively based on the air interface between the mobile station  $\rm (MS)$  and the base transceiver station   $\rm (BTS)$, which is highlighted in yellow in the  [[Mobile_Communications/Characteristics_of_GSM#System_architecture_and_basic_units_of_GSM\|$\text{system architecture graphic}$]]  at the beginning of the chapter. <br>		GSM uses the very bandwidth-efficient modulation method  [[Examples_of_Communication_Systems/Radio_Interface#Gaussian_Minimum_Shift_Keying_.28GMSK.29\| $\text{Gaussian Minimum Shift Keying}$]]  $\rm (GMSK)$.  It should again be expressly mentioned that this modulation method, just like the FDMA/TDMA multiple access, is exclusively based on the air interface between the mobile station  $\rm (MS)$  and the base transceiver station   $\rm (BTS)$, which is highlighted in yellow in the  [[Mobile_Communications/Characteristics_of_GSM#System_architecture_and_basic_units_of_GSM\|$\text{system architecture graphic}$]]  at the beginning of the chapter. <br>

	GMSK has already been described in chapter  [[Modulation_Methods/~~Nonlinear_Digital_Modulation~~#~~Properties_of_nonlinear_modulation_methods~~\| "Properties of nonlinear modulation methods"]]  of the book "Modulation Methods".  The most important properties are briefly summarized here.		GMSK has already been described in chapter  [[Modulation_Methods/Non-Linear_Digital_Modulation#Properties_of_non-linear_modulation_methods\| "Properties of nonlinear modulation methods"]]  of the book "Modulation Methods".  The most important properties are briefly summarized here.
	*GMSK is a special form of binary  [[Modulation_Methods/~~Nichtlineare_digitale_Modulation~~#FSK_.E2.80.93_Frequency_Shift_Keying\| $\text{Frequency Shift Keying}$]]  $\rm (FSK)$.  A prerequisite for the orthogonality between the two waveforms is that the modulation index  $h$  is a multiple of  $0.5$ . For integer values of  $h$  the demodulation can also be performed non-coherently.<br>		*GMSK is a special form of binary  [[Modulation_Methods/Non-Linear_Digital_Modulation#FSK_.E2.80.93_Frequency_Shift_Keying\| $\text{Frequency Shift Keying}$]]  $\rm (FSK)$.  A prerequisite for the orthogonality between the two waveforms is that the modulation index  $h$  is a multiple of  $0.5$ . For integer values of  $h$  the demodulation can also be performed non-coherently.<br>

	*For GSM you use the smallest possible modulation index  $h = 0.5$.  A higher value would require a much larger bandwidth.  Such an FSK with  $h = 0.5$  is also called [[Modulation_Methods/~~Nichtlineare_digitale_Modulation~~#MSK_.E2.80.93_Minimum_Shift_Keying\|$\text{Minimum Shift Keying}$]]   $\rm (MSK)$.  However, a coherent demodulation is then required.<br>		*For GSM you use the smallest possible modulation index  $h = 0.5$.  A higher value would require a much larger bandwidth.  Such an FSK with  $h = 0.5$  is also called [[Modulation_Methods/Non-Linear_Digital_Modulation#MSK_.E2.80.93_Minimum_Shift_Keying\|$\text{Minimum Shift Keying}$]]   $\rm (MSK)$.  However, a coherent demodulation is then required.<br>

	*A very narrow spectrum, however, is only obtained if the phase values at the symbol boundaries are matched to each other, thus avoiding phase jumps, which is given with MSK.  Such methods are referred to as  [[Modulation_Methods/Nonlinear_Digital_Modulation#General_Description_of_Continuous_Phase_Modulation\|$\text{Continuous Phase Frequency Shift Keying}$]]  $\rm (CP–FSK)$. <br>		*A very narrow spectrum, however, is only obtained if the phase values at the symbol boundaries are matched to each other, thus avoiding phase jumps, which is given with MSK.  Such methods are referred to as  [[Modulation_Methods/Nonlinear_Digital_Modulation#General_Description_of_Continuous_Phase_Modulation\|$\text{Continuous Phase Frequency Shift Keying}$]]  $\rm (CP–FSK)$. <br>

← Older revision		Revision as of 16:57, 26 January 2023
Line 86:		Line 86:
	GSM uses the very bandwidth-efficient modulation method  [[Examples_of_Communication_Systems/Radio_Interface#Gaussian_Minimum_Shift_Keying_.28GMSK.29\| $\text{Gaussian Minimum Shift Keying}$]]  $\rm (GMSK)$.  It should again be expressly mentioned that this modulation method, just like the FDMA/TDMA multiple access, is exclusively based on the air interface between the mobile station  $\rm (MS)$  and the base transceiver station   $\rm (BTS)$, which is highlighted in yellow in the  [[Mobile_Communications/Characteristics_of_GSM#System_architecture_and_basic_units_of_GSM\|$\text{system architecture graphic}$]]  at the beginning of the chapter. <br>		GSM uses the very bandwidth-efficient modulation method  [[Examples_of_Communication_Systems/Radio_Interface#Gaussian_Minimum_Shift_Keying_.28GMSK.29\| $\text{Gaussian Minimum Shift Keying}$]]  $\rm (GMSK)$.  It should again be expressly mentioned that this modulation method, just like the FDMA/TDMA multiple access, is exclusively based on the air interface between the mobile station  $\rm (MS)$  and the base transceiver station   $\rm (BTS)$, which is highlighted in yellow in the  [[Mobile_Communications/Characteristics_of_GSM#System_architecture_and_basic_units_of_GSM\|$\text{system architecture graphic}$]]  at the beginning of the chapter. <br>

	GMSK has already been described in chapter  [[Modulation_Methods/~~Nonlinear_Digital_Modulation~~#~~Properties_of_nonlinear_modulation_methods~~\| "Properties of nonlinear modulation methods"]]  of the book "Modulation Methods".  The most important properties are briefly summarized here.		GMSK has already been described in chapter  [[Modulation_Methods/Non-Linear_Digital_Modulation#Properties_of_non-linear_modulation_methods\| "Properties of nonlinear modulation methods"]]  of the book "Modulation Methods".  The most important properties are briefly summarized here.
	*GMSK is a special form of binary  [[Modulation_Methods/~~Nichtlineare_digitale_Modulation~~#FSK_.E2.80.93_Frequency_Shift_Keying\| $\text{Frequency Shift Keying}$]]  $\rm (FSK)$.  A prerequisite for the orthogonality between the two waveforms is that the modulation index  $h$  is a multiple of  $0.5$ . For integer values of  $h$  the demodulation can also be performed non-coherently.<br>		*GMSK is a special form of binary  [[Modulation_Methods/Non-Linear_Digital_Modulation#FSK_.E2.80.93_Frequency_Shift_Keying\| $\text{Frequency Shift Keying}$]]  $\rm (FSK)$.  A prerequisite for the orthogonality between the two waveforms is that the modulation index  $h$  is a multiple of  $0.5$ . For integer values of  $h$  the demodulation can also be performed non-coherently.<br>

	*For GSM you use the smallest possible modulation index  $h = 0.5$.  A higher value would require a much larger bandwidth.  Such an FSK with  $h = 0.5$  is also called [[Modulation_Methods/~~Nichtlineare_digitale_Modulation~~#MSK_.E2.80.93_Minimum_Shift_Keying\|$\text{Minimum Shift Keying}$]]   $\rm (MSK)$.  However, a coherent demodulation is then required.<br>		*For GSM you use the smallest possible modulation index  $h = 0.5$.  A higher value would require a much larger bandwidth.  Such an FSK with  $h = 0.5$  is also called [[Modulation_Methods/Non-Linear_Digital_Modulation#MSK_.E2.80.93_Minimum_Shift_Keying\|$\text{Minimum Shift Keying}$]]   $\rm (MSK)$.  However, a coherent demodulation is then required.<br>

	*A very narrow spectrum, however, is only obtained if the phase values at the symbol boundaries are matched to each other, thus avoiding phase jumps, which is given with MSK.  Such methods are referred to as  [[Modulation_Methods/Nonlinear_Digital_Modulation#General_Description_of_Continuous_Phase_Modulation\|$\text{Continuous Phase Frequency Shift Keying}$]]  $\rm (CP–FSK)$. <br>		*A very narrow spectrum, however, is only obtained if the phase values at the symbol boundaries are matched to each other, thus avoiding phase jumps, which is given with MSK.  Such methods are referred to as  [[Modulation_Methods/Nonlinear_Digital_Modulation#General_Description_of_Continuous_Phase_Modulation\|$\text{Continuous Phase Frequency Shift Keying}$]]  $\rm (CP–FSK)$. <br>

← Older revision		Revision as of 14:28, 16 March 2026
Line 91:		Line 91:
	*For GSM you use the smallest possible modulation index  $h = 0.5$.  A higher value would require a much larger bandwidth.  Such an FSK with  $h = 0.5$  is also called [[Modulation_Methods/Non-Linear_Digital_Modulation#MSK_.E2.80.93_Minimum_Shift_Keying\|$\text{Minimum Shift Keying}$]]   $\rm (MSK)$.  However, a coherent demodulation is then required.<br>		*For GSM you use the smallest possible modulation index  $h = 0.5$.  A higher value would require a much larger bandwidth.  Such an FSK with  $h = 0.5$  is also called [[Modulation_Methods/Non-Linear_Digital_Modulation#MSK_.E2.80.93_Minimum_Shift_Keying\|$\text{Minimum Shift Keying}$]]   $\rm (MSK)$.  However, a coherent demodulation is then required.<br>

	*A very narrow spectrum, however, is only obtained if the phase values at the symbol boundaries are matched to each other, thus avoiding phase jumps, which is given with MSK.  Such methods are referred to as  [[Modulation_Methods/~~Nonlinear_Digital_Modulation~~#General_Description_of_Continuous_Phase_Modulation\|$\text{Continuous Phase Frequency Shift Keying}$]]  $\rm (CP–FSK)$. <br>		*A very narrow spectrum, however, is only obtained if the phase values at the symbol boundaries are matched to each other, thus avoiding phase jumps, which is given with MSK.  Such methods are referred to as  [[Modulation_Methods/Non-Linear_Digital_Modulation#General_Description_of_Continuous_Phase_Modulation\|$\text{Continuous Phase Frequency Shift Keying}$]]  $\rm (CP–FSK)$. <br>

	*For GSM, a low-pass filter with Gaussian characteristic is inserted before the frequency modulator   ⇒   [[Modulation_Methods/~~Nonlinear_Digital_Modulation~~#~~GMSK_.E2.80.93_Gaussian_Minimum_Shift_Keying~~\|$\text{Gaussian Minimum Shift Keying}$]]  $\rm (GMSK)$, which further reduces the bandwidth and improves bandwidth efficiency.<br><br>		*For GSM, a low-pass filter with Gaussian characteristic is inserted before the frequency modulator   ⇒   [[Modulation_Methods/Non-Linear_Digital_Modulation#GMSK_–_Gaussian_Minimum_Shift_Keying\|$\text{Gaussian Minimum Shift Keying}$]]  $\rm (GMSK)$, which further reduces the bandwidth and improves bandwidth efficiency.<br><br>

	Regarding the topic treated here  (coherent or non-coherent demodulation of FSK)  we refer to two exercises in the book "Digital Signal Transmission":		Regarding the topic treated here  (coherent or non-coherent demodulation of FSK)  we refer to two exercises in the book "Digital Signal Transmission":
Line 127:		Line 127:

	In the years from 1997 to 2000 new data services with higher bit rates were developed, which are attributed to the  $\text{GSM-Phase 2+}$  $($or  $\text{GSM-Phase 2.5)}$:		In the years from 1997 to 2000 new data services with higher bit rates were developed, which are attributed to the  $\text{GSM-Phase 2+}$  $($or  $\text{GSM-Phase 2.5)}$:
	*[[Examples_of_Communication_Systems/~~Weiterentwicklungen_des_GSM~~#~~High_Speed_Circuit.E2.80.93Switched_Data_.28HSCSD.29~~\| $\text{High–Speed Circuit–Switched Data}$]]  $\rm (HSCSD)$  offers a line-oriented transmission with  $14.4 \ \rm kbit/s$  $($against $9.6 \ \rm kbit/s)$, if the channel is sufficiently good due to a higher code rate  (dotting of the convolutional code).  It also enables channel bundling by combining several time slots   ⇒   "Multislot Capability".  With a bundling of four time slots, this results in a maximum transmission rate of  $57.6 \ \rm kbit/s$.<br>		*[[Examples_of_Communication_Systems/Further_Developments_of_the_GSM#High_Speed_Circuit–Switched_Data_(HSCSD)\| $\text{High–Speed Circuit–Switched Data}$]]  $\rm (HSCSD)$  offers a line-oriented transmission with  $14.4 \ \rm kbit/s$  $($against $9.6 \ \rm kbit/s)$, if the channel is sufficiently good due to a higher code rate  (dotting of the convolutional code).  It also enables channel bundling by combining several time slots   ⇒   "Multislot Capability".  With a bundling of four time slots, this results in a maximum transmission rate of  $57.6 \ \rm kbit/s$.<br>

	*[[Examples_of_Communication_Systems/~~Weiterentwicklungen_des_GSM~~#General_Packet_Radio_Service_~~.28GPRS.29~~\|$\text{General Packet Radio Service}$]]  $\rm (GPRS)$  enables communication with other networks such as the Internet or company intranets.  It is packet-oriented  (instead of line-oriented)  and supports many data transfer protocols, for example the Internet Protocol (IP), X.25 and Datex–P.  The charges for GPRS are not based on the connection duration, but on the amount of data transmitted.  A GPRS user benefits from the shorter access times and the higher data rate up to  $21.4 \ \rm kbit/s$.  By the bundling of six time slots one reaches so maximally  $128.4 \ \rm kbit/s$.<br>		*[[Examples_of_Communication_Systems/Further_Developments_of_the_GSM#General_Packet_Radio_Service_(GPRS)\|$\text{General Packet Radio Service}$]]  $\rm (GPRS)$  enables communication with other networks such as the Internet or company intranets.  It is packet-oriented  (instead of line-oriented)  and supports many data transfer protocols, for example the Internet Protocol (IP), X.25 and Datex–P.  The charges for GPRS are not based on the connection duration, but on the amount of data transmitted.  A GPRS user benefits from the shorter access times and the higher data rate up to  $21.4 \ \rm kbit/s$.  By the bundling of six time slots one reaches so maximally  $128.4 \ \rm kbit/s$.<br>

	*[[Examples_of_Communication_Systems/~~Weiterentwicklungen_des_GSM~~#Enhanced_Data_Rates_for_GSM_Evolution\|$\text{Enhanced Data Rates for GSM Evolution}$]]  $\rm (EDGE)$  used in addition to GSM standard "GMSK" as a further modulation method  [[Modulation_Methods/Quadrature_Amplitude_Modulation#Other_signal_space_constellations\|$\text{8-PSK}$]], so that with each symbol three data bits are transmitted and in this way the data rate can (theoretically) be tripled. <br><br>		*[[Examples_of_Communication_Systems/Further_Developments_of_the_GSM#Enhanced_Data_Rates_for_GSM_Evolution\|$\text{Enhanced Data Rates for GSM Evolution}$]]  $\rm (EDGE)$  used in addition to GSM standard "GMSK" as a further modulation method  [[Modulation_Methods/Quadrature_Amplitude_Modulation#Other_signal_space_constellations\|$\text{8-PSK}$]], so that with each symbol three data bits are transmitted and in this way the data rate can (theoretically) be tripled. <br><br>

	With the combination of GPRS and EDGE – one speaks then of  $\text{E-GPRS}$  – there are nine different  [[Examples_of_Communication_Systems/~~Weiterentwicklungen_des_GSM~~#Enhanced_Data_Rates_for_GSM_Evolution\|$\text{Modulation and Coding Schemes}$]]  $\rm (MCS)$, between which the operator can choose:		With the combination of GPRS and EDGE – one speaks then of  $\text{E-GPRS}$  – there are nine different  [[Examples_of_Communication_Systems/Further_Developments_of_the_GSM#Enhanced_Data_Rates_for_GSM_Evolution\|$\text{Modulation and Coding Schemes}$]]  $\rm (MCS)$, between which the operator can choose:
	*with GMSK or with 8–PSK modulation,<br>		*with GMSK or with 8–PSK modulation,<br>
	*resulting code rates between  $0.37$  and  $1.00$, and<br>		*resulting code rates between  $0.37$  and  $1.00$, and<br>
Line 152:		Line 152:

	{{Display}}		{{Display}}
			[[de:Mobile_Kommunikation/Die_Charakteristika_von_GSM]]