Aufgaben:Exercise 4.3: Subcarrier Mapping - Revision history

Hwang at 12:43, 17 November 2022

2022-11-17T12:43:53Z

Javier: Text replacement - "Category:Exercises for Mobile Communications" to "Category:Mobile Communications: Exercises"

2021-03-23T12:37:21Z

Text replacement - "Category:Exercises for Mobile Communications" to "Category:Mobile Communications: Exercises"

Guenter at 12:58, 8 March 2021

2021-03-08T12:58:59Z

Guenter at 12:49, 8 March 2021

2021-03-08T12:49:21Z

Guenter at 12:48, 8 March 2021

2021-03-08T12:48:07Z

Noah at 20:33, 15 February 2021

2021-02-15T20:33:16Z

Show changes

Guenter at 15:39, 2 February 2021

2021-02-02T15:39:27Z

Guenter at 14:59, 2 February 2021

2021-02-02T14:59:30Z

Guenter at 14:58, 2 February 2021

2021-02-02T14:58:14Z

Guenter at 14:56, 2 February 2021

2021-02-02T14:56:27Z

@@ Line 37: / Line 37: @@
 <quiz display=simple>
-{What do the outlined arrangements on the information page apply to?
+{What do the outlined arrangements in the information section apply to?
 |type="()"}
 - For the LTE downlink,
 + for the LTE uplink.
-{Which units are shown on the information page?
+{Which units are shown in the information section?
 |type="[]"}
 + Arrangement  &nbsp;$\rm A$&nbsp; shows the transmitter of the LTE uplink.
@@ Line 58: / Line 58: @@
 $J \ = \ $ { 85 3% }
-{Which mapping is the graphic on the information page based on?
+{Which mapping is the graphic in the information section based on?
 |type="()"}
 - Distributed Mapping&nbsp; (DFDMA),

← Older revision		Revision as of 12:37, 23 March 2021
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−	[[Category:~~Exercises for~~ Mobile Communications\|^4.3 Use of OFDMA and SC-FDMA	+	[[Category:Mobile Communications: Exercises\|^4.3 Use of OFDMA and SC-FDMA

	^]]		^]]

@@ Line 77: / Line 77: @@
 '''(1)'''&nbsp; <u>Proposed solution 2</u> is correct:
-*Both arrangements show ''Single Carrier Frequency Division Multiple Access'' (SC–FDMA), recognisable by the DFT and IDFT blocks.
+*Both arrangements show "Single Carrier Frequency Division Multiple Access"&nbsp; $\text{(SC–FDMA)}$, recognisable by the DFT and IDFT blocks.
-*The advantage over ''Orthogonal Frequency Division Multiple–Access'' (OFDMA) is the more favourable ''Peak–to–Average Power–Ratio'' (PAPR).
+*The advantage over "Orthogonal Frequency Division Multiple–Access"&nbsp; $\text{(OFDMA)}$&nbsp; is the more favourable Peak–to–Average Power–Ratio&nbsp; $\text{(PAPR)}$.
 *A large PAPR means that the amplifiers must be operated below the saturation limit and thus at poorer efficiency in order to prevent excessive signal distortion.
 *A lower PAPR also means longer battery life, an extremely important criterion for smartphones.
-*This is why SC-FDMA is used in the LTE uplink. For the downlink, the aspect mentioned here is less significant.
+*This is why SC-FDMA is used in the LTE uplink.&nbsp; For the downlink, the aspect mentioned here is less significant.
@@ Line 87: / Line 87: @@
 '''(2)'''&nbsp;  <u>Proposed solutions 1 and 2 </u>are correct:
 *While in OFDMA the data symbols to be transmitted directly generate the various subcarriers, in SC-FDMA a block of data symbols is first transformed into the frequency domain using DFT.
-*To be able to transmit multiple users, $N > K$ must apply. An input block of a user thus consists of $K$ bits. It is thus obvious that arrangement&nbsp;$\rm A$&nbsp; applies to the transmitter.
+*To be able to transmit multiple users, $N > K$ must apply.&nbsp; An input block of a user thus consists of $K$ bits.&nbsp; It is thus obvious that arrangement&nbsp;$\rm A$&nbsp; applies to the transmitter.
-*Arrangement &nbsp;$\rm B$&nbsp; , on the other hand, describes the receiver of the LTE uplink and not the transmitter.
+*Arrangement &nbsp;$\rm B$,&nbsp; on the other hand, describes the receiver of the LTE uplink and not the transmitter.
 '''(3)'''&nbsp;   <u>Both statements</u> are correct:
-*The measures are necessary to be able to process a continuous bit stream at the transmitter or to ensure a continuous bit stream at the receiver as well.
+*The measures are necessary to be able to process a continuous bit stream at the transmitter,
-'''(4)'''&nbsp; The DFT also generates $K$ spectral values from $K$ input values.
+'''(4)'''&nbsp; The DFT also generates&nbsp; $K$&nbsp; spectral values from&nbsp; $K$&nbsp; input values.
-*The ''subcarrier–mapping'' does not change anything.
+*The subcarrier mapping does not change anything.
-*Further users also occupy $K$ (bits) of the total of $N$ (bits).
+*Further users also occupy&nbsp; $K$&nbsp; (bits) of the total of&nbsp; $N$&nbsp; (bits).
-*Thus $J = N/K = 1024/12 = 85.333$  &nbsp; &rArr; &nbsp;  $J \ \underline{= 85}$ users can be supplied.
+*Thus&nbsp; $J = N/K = 1024/12 = 85.333$  &nbsp; &rArr; &nbsp;  $J \ \underline{= 85}$&nbsp; users can be supplied.
 '''(5)'''&nbsp; <u>Proposed solution 3</u> is correct:
-*The graph conforms to the current 3gpp specification, which provides for ''Localized Mapping''.
+*The graph conforms to the current 3gpp specification, which provides for "Localized Mapping".
-*Here, the $K$ modulation symbols are assigned to adjacent subcarriers.
+*Here, the&nbsp; $K$&nbsp; modulation symbols are assigned to adjacent subcarriers.
-'''(6)'''&nbsp; <u>Proposed solutions 2 and 3</u> are correct:
+'''(6)'''&nbsp; <u>Solutions 2 and 3</u> are correct:
-*The realisation of DFT or IDFT as an (inverse) ''Fast Fourier Transform'' is only possible if the number of interpolation points is a power of two.
+*The realisation of DFT or IDFT as an (inverse) "Fast Fourier Transform" is only possible if the number of interpolation points is a power of two.
-*For example, for $N = 1024$, but not for $K = 12$.
+*For example, for&nbsp; $N = 1024$, but not for&nbsp; $K = 12$.
 {{ML-Fuß}}

@@ Line 20: / Line 20: @@
 For the number of interpolation points of DFT and IDFT, realistic numerical values of&nbsp; $K = 12$&nbsp; and&nbsp; $N = 1024$&nbsp; are assumed.
 *The value&nbsp; $K = 12$&nbsp; results from the fact that the symbols are "mapped" to a certain bandwidth by the&nbsp; "subcarrier mapping".&nbsp; The smallest addressable block for LTE is&nbsp; $180 \ \rm kHz$.&nbsp; With&nbsp; the subcarrier spacing of&nbsp; $15 \ \rm kHz$ &nbsp; the value&nbsp; $K = 12$&nbsp; results.
-*With the number of interpolation points&nbsp; $N$&nbsp; of the IDFT $($with arrangement&nbsp;$\rm A)$&nbsp;, up to&nbsp; $J = N/K$&nbsp; users can thus be served simultaneously.&nbsp; For subcarrier mapping, there are three different approaches with DFDMA, IFDMA and LFDMA.
+*With the number&nbsp; $N$&nbsp; of interpolation points of the IDFT $($with arrangement&nbsp;$\rm A)$&nbsp;, up to&nbsp; $J = N/K$&nbsp; users can thus be served simultaneously.&nbsp; For subcarrier mapping, there are three different approaches with DFDMA, IFDMA and LFDMA.
 *The first two users are shown in green and turquoise in the diagram.&nbsp; In subtask&nbsp; '''(5)'''&nbsp; you are to decide whether the sketch applies to DFDMA, IFDMA or LFDMA.

@@ Line 19: / Line 19: @@
 For the number of interpolation points of DFT and IDFT, realistic numerical values of&nbsp; $K = 12$&nbsp; and&nbsp; $N = 1024$&nbsp; are assumed.
-*The value&nbsp; $K = 12$&nbsp; results from the fact that the symbols are "mapped" to a certain bandwidth by the&nbsp; ''subcarrier mapping''&nbsp;. The smallest addressable block is&nbsp; $180 \ \rm kHz$ for LTE. With the subcarrier spacing of&nbsp; $15 \ \rm kHz$ &nbsp; $K = 12$ results.
+*The value&nbsp; $K = 12$&nbsp; results from the fact that the symbols are "mapped" to a certain bandwidth by the&nbsp; "subcarrier mapping".&nbsp; The smallest addressable block for LTE is&nbsp; $180 \ \rm kHz$.&nbsp; With&nbsp; the subcarrier spacing of&nbsp; $15 \ \rm kHz$ &nbsp; the value&nbsp; $K = 12$&nbsp; results.
-*With the number of interpolation points&nbsp; $N$&nbsp; of the IDFT $($with arrangement&nbsp;$\rm A)$&nbsp;, up to&nbsp; $J = N/K$&nbsp; users can thus be served simultaneously. For&nbsp; ''subcarrier mapping''&nbsp; , there are three different approaches with DFDMA, IFDMA and LFDMA.
+*With the number of interpolation points&nbsp; $N$&nbsp; of the IDFT $($with arrangement&nbsp;$\rm A)$&nbsp;, up to&nbsp; $J = N/K$&nbsp; users can thus be served simultaneously.&nbsp; For subcarrier mapping, there are three different approaches with DFDMA, IFDMA and LFDMA.
-*The first two users are shown in green and turquoise in the diagram. In subtask '''(5)''' you are to decide whether the sketch applies to DFDMA, IFDMA or LFDMA.
+*The first two users are shown in green and turquoise in the diagram.&nbsp; In subtask&nbsp; '''(5)'''&nbsp; you are to decide whether the sketch applies to DFDMA, IFDMA or LFDMA.

← Older revision		Revision as of 15:39, 2 February 2021
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−	''~~Hinweis~~:''	+	''Note:''
−	*~~Die Aufgabe gehört zum Kapitel~~  [[Mobile_Communications/~~Die_Anwendung_von_OFDMA_und_SC~~-FDMA_in_LTE\|~~Anwendung von~~ OFDMA ~~und~~ SC-FDMA in LTE]].	+	*The task belongs to the chapter  [[Mobile_Communications/The_Application_of_OFDMA_and_SC-FDMA_in_LTE\|The Application of OFDMA and SC-FDMA in LTE]].

@@ Line 6: / Line 6: @@
 [[File:EN_Mob_A_4_3.png|right|frame|Two SC&ndash;FDMA arrangements]]
-The diagram shows two transmission schemes that play a role in connection with&nbsp; Long Term Evolution&nbsp; $\rm (LTE)$.&nbsp; These block diagrams are referred here neutrally as&nbsp; "arrangement &nbsp;$\rm A$&"&nbsp; or&nbsp; "arrangement &nbsp;$\rm B$".
+The diagram shows two transmission schemes that play a role in connection with&nbsp; Long Term Evolution&nbsp; $\rm (LTE)$.&nbsp; These block diagrams are referred here neutrally as&nbsp; "arrangement &nbsp;$\rm A$"&nbsp; or&nbsp; "arrangement &nbsp;$\rm B$".
 * The light grey blocks represent the transition from the time to the frequency domain.
 * The dark grey blocks represent the transition from the frequency to the time domain.

@@ Line 13: / Line 13: @@
 We refer here to the following links:
-* [[Signal_Representation/Discrete_Fourier_Transform_(DFT)#Von_der_kontinuierlichen_zur_diskreten_Fouriertransformation|Diskrete Fouriertransformation]] &nbsp; &rArr; &nbsp; $\rm DFT$ ,
+* [[Signal_Representation/Discrete_Fourier_Transform_(DFT)#Von_der_kontinuierlichen_zur_diskreten_Fouriertransformation|Discrete Fourier Transform]] &nbsp; &rArr; &nbsp; $\rm DFT$,
-* [[Signal_Representation/Discrete_Fourier_Transform_(DFT)#Inverse_Diskrete_Fouriertransformation|Inverse Diskrete Fouriertransformation]] &nbsp; &rArr; &nbsp; $\rm IDFT$ .
+* [[Signal_Representation/Discrete_Fourier_Transform_(DFT)#Inverse_Discrete_Fourier_Transform|Inverse Discrete Fourier Transform]] &nbsp; &rArr; &nbsp; $\rm IDFT$.