advanced wireless communications lecture notes: section 4
TRANSCRIPT
![Page 1: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/1.jpg)
Advanced Wireless Communications
lecture notes: section 4
Andrea M. Tonello
Double Master Degree in Electrical Engineering ‐ University of Udine, Italy
and Information and Communication Engineering ‐ University of Klagenfurt, Austria
Note: these lecture notes have been prepared as part of the material for the joint class “Advanced wireless communications” and “Comunicazioni Wireless” by A. Tonello. The class has been offered in the Spring 2015 term, by
means of video conferencing in time sharing between two locations.
![Page 2: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/2.jpg)
A. Tonello 2
Section content Topics
oMulticarrier modulation
oDiscrete time system representation
oOrthogonality principle: DMT and FMT
oOFDM with cyclic prefix
![Page 3: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/3.jpg)
A. Tonello 3
System model
![Page 4: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/4.jpg)
A. Tonello 4
System model
ADSL : advanced digital subscriber line
DAB : digital audio broadcast
DVB : digital video broadcast
IEEE 802.11 and Hiperlan II : wireless LAN
proposed although killed for 3rd generation cellular
Adopted in LTE
![Page 5: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/5.jpg)
A. Tonello 5
General architecture
( )t
10( )a lT
0( )ka lT
kf
0( )My nT
10( )y nT 1
0ˆ ( )a lT
0ˆ ( )Ma lT
1f
Mf
1f
0( )Ma lT
Mf
0( )ky nT 0ˆ ( )ka lT
kf
Two efficient digital implementations
DMT (Discrete Multitone): well known OFDM (orthogonal frequency division multiplexing)
scheme. Prototype filter with rectangular impulse response
FMT (Filtered Multitone): prototype pulse with frequency concentrated response
![Page 6: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/6.jpg)
A. Tonello 6
System model
![Page 7: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/7.jpg)
A. Tonello 7
System model
![Page 8: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/8.jpg)
A. Tonello 8
Discrete time realization
![Page 9: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/9.jpg)
A. Tonello 9
Discrete time realization
![Page 10: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/10.jpg)
A. Tonello 10
Discrete time realization
![Page 11: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/11.jpg)
A. Tonello 11
Receiver
![Page 12: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/12.jpg)
A. Tonello 12
Receiver
![Page 13: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/13.jpg)
A. Tonello 13
Receiver output signal
![Page 14: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/14.jpg)
A. Tonello 14
Bidimensional Nyquist criterion
![Page 15: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/15.jpg)
A. Tonello 15
Bidimensional Nyquist criterion
![Page 16: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/16.jpg)
A. Tonello 16
Orthogonal solutions
![Page 17: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/17.jpg)
A. Tonello 17
Orthogonal solutions (DMT‐OFDM‐FMT)
![Page 18: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/18.jpg)
A. Tonello 18
Comparison of SNR in SC and MRC
![Page 19: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/19.jpg)
A. Tonello 19
OFDM
![Page 20: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/20.jpg)
A. Tonello 20
OFDM
![Page 21: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/21.jpg)
A. Tonello 21
Efficient realization of an FMT system
Complexity: M/N log2M + Lg,h /N operations/sample
M point IDFT and cyclic extension to 2 1 2. . .( , )M l c m M N L M L N( )( ) ( ) 0,..., 1ig nN g i nN i N Pulses: PP components of order N, i.e.,
2L Sample with period
Synthesis
Dual operations Analysis
(Lg,h: pulse length)
![Page 22: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/22.jpg)
A. Tonello 22
OFDM with Cyclic Prefix
M tones (sub‐channels)
Rectangular sub‐channel pulse (window) of duration N > M samples
Cyclic prefix (CP) of length µ=N‐M samples (longer than the channel duration)
![Page 23: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/23.jpg)
A. Tonello 23
OFDM with cyclic prefix
![Page 24: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/24.jpg)
A. Tonello 24
OFDM with cyclic prefix
![Page 25: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/25.jpg)
A. Tonello 25
OFDM with cylic prefix
![Page 26: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/26.jpg)
A. Tonello 26
OFDM with cylic prefix
![Page 27: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/27.jpg)
A. Tonello 27
OFDM with cylic prefix
![Page 28: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/28.jpg)
A. Tonello 28
OFDM design
Knowing the channel duration NpT and the total signal bandwidth
W=1/T, we choose CP of length μ samples larger than Np
Then, we set the number of sub‐channels M so that the rate penalty
is not too high:
R = M / ((M+ μ)T)
Transmission rate in CP‐OFDM
![Page 29: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/29.jpg)
A. Tonello 29
Main advantages of multicarrire modulation
MC modulation allows to simplify the equalization task
CP‐OFDM is orthogonal is a multipath channel
The power can be optimally allocated over the sub‐channels
Spectrum notching can be easily applied
FDMA can be easily implemented to multiple in the frequency
domain multiple users
![Page 30: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/30.jpg)
A. Tonello 30
Optimal power allocation in OFDM
![Page 31: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/31.jpg)
A. Tonello 31
![Page 32: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/32.jpg)
A. Tonello 32
![Page 33: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/33.jpg)
A. Tonello 33
![Page 34: Advanced Wireless Communications lecture notes: section 4](https://reader031.vdocument.in/reader031/viewer/2022022519/6217e730d14a5e7dbb6cd86c/html5/thumbnails/34.jpg)
A. Tonello 34