Examples of Communication Systems/Telecommunications Aspects of UMTS - Revision history

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	*In UMTS,  the receiver filter  $H_{\rm E}f) = H_{\rm S}(f)$  is matched to the transmitter  $($"matched filter"$)$  and the overall frequency response  $H(f) = H_{\rm S}(f) \cdot H_{\rm E}(f)$  satisfies the  [[Digital_Signal_Transmission/Properties_of_Nyquist_Systems#First_Nyquist_criterion_in_the_frequency_domain\|"first Nyquist criterion"]]:		*In UMTS,  the receiver filter  $H_{\rm E}f) = H_{\rm S}(f)$  is matched to the transmitter  $($"matched filter"$)$  and the overall frequency response  $H(f) = H_{\rm S}(f) \cdot H_{\rm E}(f)$  satisfies the  [[Digital_Signal_Transmission/Properties_of_Nyquist_Systems#First_Nyquist_criterion_in_the_frequency_domain\|"first Nyquist criterion"]]:
	:$$ H(f) = H_{\rm CRO}(f) = \left\{ \begin{array}{c} 1 \\ 0 \\ \cos^2 \left( \frac {\pi \cdot (\|f\| - f_1)}{2 \cdot (f_2 - f_1)} \right)\end{array} \right.\quad		:$$ H(f) = H_{\rm CRO}(f) = \left\{ \begin{array}{c} 1 \\ 0 \\ \cos^2 \left( \frac {\pi \cdot (\|f\| - f_1)}{2 \cdot (f_2 - f_1)} \right)\end{array} \right.\quad\begin{array}{{1}c} {\rm{for}} \\ {\rm{for}}\\ {\rm else }\hspace{0.05cm}. \end{array}\begin{array}{{20}c} \|f\| \le f_1, \\ \|f\| \ge f_2.\\ \\\end{array}$$
	\begin{array}{*{1}c} {\rm{for}} \\ {\rm{for}}\\ {\rm else }\hspace{0.05cm}. \end{array}
	\begin{array}{*{20}c} \|f\| \le f_1, \\ \|f\| \ge f_2.\\ \\\end{array}$$

	This means:   Consecutive pulses in time do not interfere with each other   ⇒   no  [[Digital_Signal_Transmission/Causes_and_Effects_of_Intersymbol_Interference\|"intersymbol interference"]]  $\rm (ISI)$  occur.  The associated time function is:		This means:   Consecutive pulses in time do not interfere with each other   ⇒   no  [[Digital_Signal_Transmission/Causes_and_Effects_of_Intersymbol_Interference\|"intersymbol interference"]]  $\rm (ISI)$  occur.  The associated time function is:
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	<br clear=all>		<br clear=all>
	If one applies a Dirac delta impulse at time  $t = 0$  to the channel input,  there will be three Dirac delta impulses at the output of the rake receiver:		If one applies a Dirac delta impulse at time  $t = 0$  to the channel input,  there will be three Dirac delta impulses at the output of the rake receiver:
	:$$ s(t) = \delta(t) \hspace{0.3cm}\Rightarrow\hspace{0.3cm}		:$$ s(t) = \delta(t) \hspace{0.3cm}\Rightarrow\hspace{0.3cm}y(t) = h_0 \cdot h_1 \cdot \delta(t - 2\tau_0) + (h_0^2 + h_1^2) \cdot \delta(t - \tau_0 - \tau_1)+h_0 \cdot h_1 \cdot \delta(t - 2\tau_1) .$$
	y(t) = h_0 \cdot h_1 \cdot \delta(t - 2\tau_0) + (h_0^2 + h_1^2) \cdot \delta(t - \tau_0 - \tau_1)+
	h_0 \cdot h_1 \cdot \delta(t - 2\tau_1) .$$

	*The signal energy is concentrated at the time  $τ_0 + τ_1$.  Of the total four paths,  two contribute  $($middle term$)$.		*The signal energy is concentrated at the time  $τ_0 + τ_1$.  Of the total four paths,  two contribute  $($middle term$)$.
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	*With rake receiver and the same weights,  the above equation is:		*With rake receiver and the same weights,  the above equation is:

	:$$ y(t) = 0.48 \cdot \delta(t - 2\tau_0) + 1.0 \cdot \delta(t - \tau_0 - \tau_1)+		:$$ y(t) = 0.48 \cdot \delta(t - 2\tau_0) + 1.0 \cdot \delta(t - \tau_0 - \tau_1)+0.48 \cdot \delta(t - 2\tau_1) .$$
	0.48 \cdot \delta(t - 2\tau_1) .$$

	*The share of the main path in the total energy amounts in this simple example to  ${1^2}/{(1^2 + 0.48^2 + 0.48^2)} ≈ 68\%.$}}		*The share of the main path in the total energy amounts in this simple example to  ${1^2}/{(1^2 + 0.48^2 + 0.48^2)} ≈ 68\%.$}}

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	{{Display}}		{{Display}}
			[[de:Beispiele_von_Nachrichtensystemen/Nachrichtentechnische_Aspekte_von_UMTS]]

Guenter at 16:15, 20 April 2023

2023-04-20T16:15:42Z

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	The ratio between the signal power and the interference power is used as the controlled variable for power control in UMTS.  There are differences between the  "frequency division duplex"  $\rm (FDD)$  and the  "time division duplex"  $\rm (TDD)$  modes.		The ratio between the signal power and the interference power is used as the controlled variable for power control in UMTS.  There are differences between the  "frequency division duplex"  $\rm (FDD)$  and the  "time division duplex"  $\rm (TDD)$  modes.

	[[File:~~EN_Bei_T_4_3_S10a~~.png\|right\|frame\|Power control in the FDD mode ~~'''KORREKTUR: transmit power'''~~]]		[[File:EN_Bei_T_4_3_S10a_neu.png\|right\|frame\|Power control in the FDD mode]]
	We take a closer look at the FDD power control.  In the diagram you can see two different control loops:		We take a closer look at the FDD power control.  In the diagram you can see two different control loops:
	*The  »'''inner control loop'''«  controls the transmitter power based on time slots,  where one power command is transmitted in each time slot.		*The  »'''inner control loop'''«  controls the transmitter power based on time slots,  where one power command is transmitted in each time slot.

Guenter at 17:16, 25 March 2023

2023-03-25T17:16:34Z

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	{{GraueBox\|TEXT=		{{GraueBox\|TEXT=
	[[File:~~EN_Bei_T_4_3_S9_v2~~.png\|right\|frame\|Budget for a voice transmission channel ~~'''KORREKTUR: fault'''~~]]		[[File:EN_Bei_T_4_3_S9_v222.png\|right\|frame\|Budget for a voice transmission channel]]
	$\text{Example 7:}$		$\text{Example 7:}$
	The calculation of the link budget is illustrated using the example of a voice transmission channel in the UMTS downlink.  Regarding the exemplary numerical values,  it should be noted:		The calculation of the link budget is illustrated using the example of a voice transmission channel in the UMTS downlink.  Regarding the exemplary numerical values,  it should be noted:

Guenter at 15:07, 25 March 2023

2023-03-25T15:07:01Z

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	The calculation of the link budget is illustrated using the example of a voice transmission channel in the UMTS downlink.  Regarding the exemplary numerical values,  it should be noted:		The calculation of the link budget is illustrated using the example of a voice transmission channel in the UMTS downlink.  Regarding the exemplary numerical values,  it should be noted:
	#The transmitted power is  $P_{\rm S} =19$  dBm,  which corresponds to approx.  $79$  mW.  <br>Here,  the antenna loss is considered to be  $2$  dB.		#The transmitted power is  $P_{\rm S} =19$  dBm,  which corresponds to approx.  $79$  mW.  <br>Here,  the antenna loss is considered to be  $2$  dB.
	#The noise power  $P_{\rm R} = 5 \cdot 10^{-11}$  mW   ⇒   $P_{\rm R} = -103$  dBm   <br>product of UMTS bandwidth and noise power density.		#The noise power  $P_{\rm N} = 5 \cdot 10^{-11}$  mW   ⇒   $P_{\rm N} = -103$  dBm   <br>product of UMTS bandwidth and noise power density.
	#The interference power is  $P_{\rm I} = -99$  dBm  corresponding to  $1.25 \cdot 10^{-10}$  mW.		#The interference power is  $P_{\rm I} = -99$  dBm  corresponding to  $1.25 \cdot 10^{-10}$  mW.
	#This gives the total interference power  $P_{\rm R+I} = P_{\rm R} + P_{\rm I} = 1.25 \cdot 10^{-10}$  mW   ⇒   $P_{\rm R+I} =- 97.5$  dBm.		#This gives the total interference power  $P_{\rm N+I} = P_{\rm N} + P_{\rm I} = 1.25 \cdot 10^{-10}$  mW   ⇒   $P_{\rm N+I} =- 97.5$  dBm.
	#The antenna sensitivity results in $-97.5 - 27 + 5 - 17 + 3.5 = - 133$  dBm.  <br>A large negative value here is  "good".		#The antenna sensitivity results in $-97.5 - 27 + 5 - 17 + 3.5 = - 133$  dBm.  <br>A large negative value here is  "good".
	#Maximum allowable path loss should be as large as possible.  Here  $19 - (-133) = 152$  dB.		#Maximum allowable path loss should be as large as possible.  Here  $19 - (-133) = 152$  dB.
	#The  '''link budget'''  includes the margin for fading and the handover gain,  in the example:  $140$  dB.		#The  '''link budget'''  includes the margin for fading and the handover gain,  in the example:  $140$  dB.
	#The  '''maximum cell radius'''  can be determined from the link budget using an [https://en.wikipedia.org/wiki/Path_loss "empirical formula"] of Okumura-Hata.  It holds:  $ {r}\ [{\rm km}] = 10^{({\rm LinkBudget}- 137)/35}= 10^{0.0857}\approx 1.22 . $		#The  '''maximum cell radius'''  can be determined from the link budget using an [https://en.wikipedia.org/wiki/Path_loss »empirical formula«] of Okumura-Hata.  It holds:  $ {r}\ [{\rm km}] = 10^{({\rm LinkBudget}- 137)/35}= 10^{0.0857}\approx 1.22 . $
	<br><br><br><br><br>		<br><br><br><br><br>

Guenter at 13:23, 13 March 2023

2023-03-13T13:23:04Z

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	*In UMTS,  the ~~receive '''KORREKTUR:~~ receiver~~'''~~ filter  $H_{\rm E}f) = H_{\rm S}(f)$  is matched to the transmitter  $($"matched filter"$)$  and the overall frequency response  $H(f) = H_{\rm S}(f) \cdot H_{\rm E}(f)$  satisfies the  [[Digital_Signal_Transmission/Properties_of_Nyquist_Systems#First_Nyquist_criterion_in_the_frequency_domain\|"first Nyquist criterion"]]:		*In UMTS,  the receiver filter  $H_{\rm E}f) = H_{\rm S}(f)$  is matched to the transmitter  $($"matched filter"$)$  and the overall frequency response  $H(f) = H_{\rm S}(f) \cdot H_{\rm E}(f)$  satisfies the  [[Digital_Signal_Transmission/Properties_of_Nyquist_Systems#First_Nyquist_criterion_in_the_frequency_domain\|"first Nyquist criterion"]]:
	:$$ H(f) = H_{\rm CRO}(f) = \left\{ \begin{array}{c} 1 \\ 0 \\ \cos^2 \left( \frac {\pi \cdot (\|f\| - f_1)}{2 \cdot (f_2 - f_1)} \right)\end{array} \right.\quad		:$$ H(f) = H_{\rm CRO}(f) = \left\{ \begin{array}{c} 1 \\ 0 \\ \cos^2 \left( \frac {\pi \cdot (\|f\| - f_1)}{2 \cdot (f_2 - f_1)} \right)\end{array} \right.\quad
	\begin{array}{*{1}c} {\rm{for}} \\ {\rm{for}}\\ {\rm else }\hspace{0.05cm}. \end{array}		\begin{array}{*{1}c} {\rm{for}} \\ {\rm{for}}\\ {\rm else }\hspace{0.05cm}. \end{array}
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	Thereby one receives at the correlator output the sum of		Thereby one receives at the correlator output the sum of
	[[File:EN_Bei_T_4_3_S6a_v2.png\|right\|frame\|Single-user receiver with matched filter]]		[[File:EN_Bei_T_4_3_S6a_v2.png\|right\|frame\|Single-user receiver with matched filter]]
	*the  "~~autocorrelation '''KORREKTUR:~~ auto-correlation~~'''~~ function"  of the spreading code and		*the  "auto-correlation function"  of the spreading code and

	*the  "cross-correlation function"  of all other users with their own spreading code.		*the  "cross-correlation function"  of all other users with their own spreading code.

Hwang at 10:43, 8 March 2023

2023-03-08T10:43:22Z

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	'''Transmit power control'''<br>The  radio resource management  attempts to keep the received power and thus the carrier-to-interference ratio  $\rm (CIR)$  at the receiver constant,  or at least to prevent it from falling below a specified limit.		'''Transmit power control'''<br>The  radio resource management  attempts to keep the received power and thus the carrier-to-interference ratio  $\rm (CIR)$  at the receiver constant,  or at least to prevent it from falling below a specified limit.

	An example of the need for power control is the  [[Examples_of_Communication_Systems/Telecommunications_Aspects_of_UMTS#Near.E2.80.~~93Far.E2.80.93Effect~~\|"near-far problem"]],  which is known to cause a disconnect.		An example of the need for power control is the  [[Examples_of_Communication_Systems/Telecommunications_Aspects_of_UMTS#Near.E2.80.93far_problem\|"near-far problem"]],  which is known to cause a disconnect.

	The step size of the power control is  $1 \ \rm dB$  or  $2 \ \rm dB$,  and the frequency of the control commands is  $1500$  commands per second.		The step size of the power control is  $1 \ \rm dB$  or  $2 \ \rm dB$,  and the frequency of the control commands is  $1500$  commands per second.

Hwang at 10:42, 8 March 2023

2023-03-08T10:42:03Z

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	The ratio between the signal power and the interference power is used as the controlled variable for power control in UMTS.  There are differences between the  "frequency division duplex"  $\rm (FDD)$  and the  "time division duplex"  $\rm (TDD)$  modes.		The ratio between the signal power and the interference power is used as the controlled variable for power control in UMTS.  There are differences between the  "frequency division duplex"  $\rm (FDD)$  and the  "time division duplex"  $\rm (TDD)$  modes.

	[[File:EN_Bei_T_4_3_S10a.png\|right\|frame\|Power control in the FDD mode]]		[[File:EN_Bei_T_4_3_S10a.png\|right\|frame\|Power control in the FDD mode '''KORREKTUR: transmit power''']]
	We take a closer look at the FDD power control.  In the diagram you can see two different control loops:		We take a closer look at the FDD power control.  In the diagram you can see two different control loops:
	*The  »'''inner control loop'''«  controls the transmitter power based on time slots,  where one power command is transmitted in each time slot.		*The  »'''inner control loop'''«  controls the transmitter power based on time slots,  where one power command is transmitted in each time slot.

Hwang at 10:41, 8 March 2023

2023-03-08T10:41:37Z

← Older revision		Revision as of 12:41, 8 March 2023
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	{{GraueBox\|TEXT=		{{GraueBox\|TEXT=
	[[File:EN_Bei_T_4_3_S9_v2.png\|right\|frame\|Budget for a voice transmission channel]]		[[File:EN_Bei_T_4_3_S9_v2.png\|right\|frame\|Budget for a voice transmission channel '''KORREKTUR: fault''']]
	$\text{Example 7:}$		$\text{Example 7:}$
	The calculation of the link budget is illustrated using the example of a voice transmission channel in the UMTS downlink.  Regarding the exemplary numerical values,  it should be noted:		The calculation of the link budget is illustrated using the example of a voice transmission channel in the UMTS downlink.  Regarding the exemplary numerical values,  it should be noted:

Hwang at 10:39, 8 March 2023

2023-03-08T10:39:21Z

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	Furthermore,  this decisive criterion for UMTS also depends on the following variables:		Furthermore,  this decisive criterion for UMTS also depends on the following variables:
	#The topology and user behavior  $($number ~~ofservices~~ called up$)$,		#The topology and user behavior  $($number of services called up$)$,
	#the spreading factor  $J$  and the orthogonality of the used spreading code.		#the spreading factor  $J$  and the orthogonality of the used spreading code.