1. Computer Communication
Dr. Yinong Chen

2. A Connected World
Source: Intel Embedded Research and Education Summit 2013

3. Communication and Networking
Host A
Host B
Application
Presentation
Session
Transport
Network
Physical
Data Link
Application
Presentation
Session
Transport
Network
Physical
Data Link CS
CSE CE EE
TCP IP
Open System Interconnection (OSI) 7-layer reference model
18 September 2018

4. Physical Layer, e.g., RS-232, X.25
Physical layer is concerned with processing signals and transmitting raw bits over a communication channel, wired or wireless
Issues to be considered:
Signal processing
frequency selection
carrier frequency
signal detection
modulation / demodulation
Analog
Telephone
Switches
RS232C
RS499
line
Modem
18 September 2018

5. Signal Processing and Transmission
Information is transmitted via varying voltage, current, or frequency in sine or cosine functions.
Fourier Function Series: Any periodic function g(t) with period T can be constructed by a number (possibly infinite) of sine and cosine functions.
18 September 2018

6. Representing Digital Signal in Analog
The bigger the n, the faster the computer need to be.
18 September 2018

7. Modem: Modulation and Demodulation
Noise control
Analog and digital conversion: voice, photo, video
Data compression
Modem
Analog
Telephone
Switches
RS232C
RS499
line
Modem
18 September 2018

8. Conversion from Analog to Digital Signals
Measure the height of the amplitude
Sender
Receiver
18 September 2018

9. NXT Brick
Main processor: 32-bit ARM7 microcontroller, with 256 Kbytes FLASH, 64 Kbytes RAM
Second processor: 8-bit AVR microcontroller, with 4 Kbytes FLASH, 512 Byte RAM
Bluetooth wireless communication
USB full speed port (12 Mbit/s)
Four input ports, 6-wire cable digital platform
Three output ports, 6-wire cable digital platform
100 x 64 pixel LCD graphical display
Loudspeaker - 8 kHz sound quality. Sound channel with 8-bit resolution and 2-16 KHz sample rate.
18 September 2018

10. Bluetooth Wi-Fi 802.11n Wireless Protocol Stack Data Rate Range
120kb – 723 kb
30ft – 300ft
Wi-Fi a
1 - 11Mb
50ft - 150ft
Wi-Fi b
1 - 54Mb
100ft - 300ft
Wi-Fi g
120ft - 350ft
Wi-Fi n
6.5 – 600 Mb
IrDA (Infra-red)
9.6kb - 115kb
< 6ft
18 September 2018

11. Establish Communication
It sends an invitation to NXT to connect.
18 September 2018

12. Add the NXT to your Connection
On the invitation, your Brick will beep.
Push the orange button to accept the invitation;
18 September 2018

13. Use the passkey and accept on NXT
18 September 2018