Unit 1 Introduction to Wireless
Communication IC
Institute of Communications Engineering, NCTU
1
Comm. IC Design
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Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
Topics to be covered in this course
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Introduction to OFDM baseband system designs
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Physical layer design (PHY)
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Reference book: OFDM baseband receiver design for wireless
communications by Tzi-Dar Chiueh and Pei-Yun Tsai
Finite Impulse Response (FIR) filter design and
implementation (2 lectures + 1 lab)
Synchronization circuits (1 lecture + 1 lab)
Fast Fourier Transform (FFT) (2 lectures + 1 lab)
Channel estimation and symbol detection (1 lecture + 1 lab)
From algorithm to bit-true design (1 lecture)
Medium access control (MAC) (3 lectures + 2 labs)
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A simplified WiFi MAC
A simply cognitive MAC
Department of Communication Engineering, NCTU
2
Comm. IC Design
Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
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Labs are based on the OFDM reference design on
Wireless Access Research Platform (WARP)
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http://warp.rice.edu/trac/wiki/HardwareUsersGuides/FPGABoard_v2.2
Department of Communication Engineering, NCTU
3
Comm. IC Design

Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
Hardware features
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Xilinx Vertex-4 FPAG: XC4VFX100-FF1517-11
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Logic slices: 42K
DSP48 slices: 160
Block RAMs: 376
Power PC cores: 2 PC405
Tri-mode Ethernet MAC: 3
Department of Communication Engineering, NCTU
4
Comm. IC Design

Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
DSP slices: refer to Vertex-4 Xtreme DSP User Guide
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http://www.xilinx.com/support/documentation/user_guides/
ug073.pdf
Department of Communication Engineering, NCTU
5
Comm. IC Design

Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
An OFDM reference design
http://warp.rice.edu/trac/wiki/OFDMReferenceDesign
Department of Communication Engineering, NCTU
6
Comm. IC Design

Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
Will do a basic point-to-point wireless communications
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Virtex-4 (WARP FPGA Board v2.2):
OFDM_ReferenceDesign_FPGAv2_v16.1.zip (100MB)
Both projects were built using the latest versions of the 10.1 release of the
Xilinx tools (ISE 10.1.03 + IP3, EDK 10.1.03, Sysgen 10.1.3.1386).
Department of Communication Engineering, NCTU
7
Comm. IC Design

Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
Simulink top-level design
C:\WARP\OFDM_ReferenceDesign_FPGAv2_v16.1_public\pcores
Department of Communication Engineering, NCTU
8
Comm. IC Design


Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
The PHY circuit and system is realized with Simulink.
The entire design is in an mdl file:
(ofdm_txrx_supermimo_coded.mdl) which is used to
generate the “pcores” for Xilinx platform studie (XPS).
Because of limitations in the number of multipliers in the
Virtex-4 FPGA, the decimation filters in the
rate_change_filters pcore use non-embedded multipliers.
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The rate_change_filter source model is in the repository
/ResearchApps/PHY/MIMO_OFDM/Rate Change Filters
Department of Communication Engineering, NCTU
9
1.2 Wireless Channels
Institute of Communications Engineering, NCTU
10
Comm. IC Design

Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
A typical spatial channel model (SCM) used in IEEE
802.11n and 802.16
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There are 6 multipaths each of which consists of 20
subpaths
Department of Communication Engineering, NCTU
11
Comm. IC Design

Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
Channel impulse responses
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For wireless channels, the baseband input-output
relationship can be expressed as
y(t )  H (t ) * s(t )  n(t )
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If the signal bandwidth is sufficiently narrow such that the
channel can be treated as approximately constant over the
operating frequency (frequency flat channel), the
corresponding input-output relationship simplifies to
y (t )  H (t ) s (t )  n (t )
Department of Communication Engineering, NCTU
12
Comm. IC Design


Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
Why OFDM
What does it mean by orthogonal frequency division
multiplexing?
Department of Communication Engineering, NCTU
13
Comm. IC Design

Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
How can we suppress the multipath effects in an efficient
manner?
Department of Communication Engineering, NCTU
14
Comm. IC Design

Unit 1 Introduction to Filter Design
Sau-Hsuan Wu
Guard band v.s. guard interval
Department of Communication Engineering, NCTU
15