Institute of Communications Engineering, NCTU 1

Unit 1 Introduction to Wireless Communication IC

Department of Communication Engineering, NCTU 2

Comm. IC Design Unit 1 Introduction to Filter Design

Sau-Hsuan Wu

Topics to be covered in this course Introduction to OFDM baseband system designs

Reference book: OFDM baseband receiver design for wireless communications by Tzi-Dar Chiueh and Pei-Yun Tsai

Physical layer design (PHY) 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) A simplified WiFi MAC A simply cognitive MAC

Department of Communication Engineering, NCTU 3

Comm. IC Design Unit 1 Introduction to Filter Design

Sau-Hsuan Wu

Labs are based on the OFDM reference design on Wireless Access Research Platform (WARP)

http://warp.rice.edu/trac/wiki/HardwareUsersGuides/FPGABoard_v2.2

Department of Communication Engineering, NCTU 4

Comm. IC Design Unit 1 Introduction to Filter Design

Sau-Hsuan Wu

Hardware features Xilinx Vertex-4 FPAG: XC4VFX100-FF1517-11

Logic slices: 42K DSP48 slices: 160 Block RAMs: 376 Power PC cores: 2 PC405 Tri-mode Ethernet MAC: 3

Department of Communication Engineering, NCTU 5

Comm. IC Design Unit 1 Introduction to Filter Design

Sau-Hsuan Wu

DSP slices: refer to Vertex-4 Xtreme DSP User Guide http://www.xilinx.com/support/documentation/

user_guides/ug073.pdf

Department of Communication Engineering, NCTU 6

Comm. IC Design Unit 1 Introduction to Filter Design

Sau-Hsuan Wu

An OFDM reference designhttp://warp.rice.edu/trac/wiki/OFDMReferenceDesign

Department of Communication Engineering, NCTU 7

Comm. IC Design Unit 1 Introduction to Filter Design

Sau-Hsuan Wu

Will do a basic point-to-point wireless communications 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 8

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 9

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. The rate_change_filter source model is in the repository

/ResearchApps/PHY/MIMO_OFDM/Rate Change Filters

Institute of Communications Engineering, NCTU 10

1.2 Wireless Channels

Department of Communication Engineering, NCTU 11

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 There are 6 multipaths each of which consists of 20

subpaths

Department of Communication Engineering, NCTU 12

Comm. IC Design Unit 1 Introduction to Filter Design

Sau-Hsuan Wu

Channel impulse responses For wireless channels, the baseband input-output

relationship can be expressed as

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

( ) ( ) ( ) ( )y t H t s t n t

Department of Communication Engineering, NCTU 13

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 14

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 15

Comm. IC Design Unit 1 Introduction to Filter Design

Sau-Hsuan Wu

Guard band v.s. guard interval