Chapter 8
Wireless Communications
8.1 Introduction
- LOS (line of sight) link: 40 mi = 40 ¡¿ 1.6094 km =
64 km
- Wireless Communication by Environment
Ground
fixed
Ground
mobile
Marine
Satellite
Aerospace:
deep space communication
Military
Underground:
subway, mine
IoT and sensor network
- Wireless Communication Technology Areas
Source
coding: data compression, error correction
Modulation,
waveform design, signal conditioning: spectrum efficiency, interference
rejection, robustness against channel variations
Channel
coding: multipath fading, interference
Transmitter:
circuit, digital, SoC
Antenna:
base station, handheld device, smart antenna, MIMO
Channel
and propagation
Receiver:
circuit, digital, SoC
Signal
processing
Wireless
communication network
- Link between wireless and wired communications
- Online radio coverage tool
VE2DBE, www.ve2dbe.com
Nautel,
http://support.nautel.com/login/
8.2 Friis Transmission Equation
8.3 Space Loss
8.4 Link Equation and Link
Budget
8.5 Effective Isotropic
Radiated Power and G/T Parameters
8.6 Radio/Microwave Links
1) Fading Channel Models
Small-scale fading: Rayleigh distribution, Rice
distribution
Large-scale fading: Log-normal distribution
Fast fading
Flat fading
Frequency-selective fading
Delay spread
Doppler spread
Clarke's channel model
Jakes' channel model
Nakagami distribution
2) Path Loss Model
Hata model
COST 231 model
Stanford University interim channel model
ITU path loss model
3) AWGN (Additive White
Gaussian Noise) model
- The only impairment to communication is a linear addition of wideband or white noise.
- A good model for
many satellite and deep space communication links.
- It is not a good model for most terrestrial links because of multipath, terrain blocking, interference, etc.
- For terrestrial
path modeling, AWGN is commonly used to simulate background noise of the
channel under study
8.7 Satellite
Communication Systems
1) Why SATCOM?
- In the middle of an ocean
- On Himalayan mountains
- On Sahara desert
- In Amazon jungles
- On aircrafts
- GNSS, navigation
- Scientific research
- Military communication and surveillance
2) Communication satellites
Figure: IS-34 C- and Ku-band comsat built by Space Systems/Loral for Intelsat
Figure: Satellite communication payloads. Left:
Korea's Ariragn-5, Right: Korea's Chollian
3) Communication via satellites
Figure: Global SATCOM market
share
Figure: Thuraya X5-Touch
Android mobile/satcom phone
GEO (geosynchronous orbit): 36,000 - 42,000 km
LEO (low earth orbit): 500 - 2,000 km
MEO (medium earth orbit)
C-band: downlink 3.7-4.2 GHz,
uplink 5.925-6.425 GHz
Ku-band: downlink 11.7-12.2GHz,
uplink 14.0-14.5 GHz
Multiple access methods
FDMA
TDMA
8.8 Mobile Communication
Systems
8.8.1 Cellular
Communication
Frequency allocation
Multiple access method
Duplex method
Number of channels
Channel spacing
Modulation
Bit rate
8.8.2 History
Figure: History of mobile communication technology
8.8.3 3G and 4G
Mobile
1) 3G Mobile
- 3GPP (3rd Generation Partnership Project): 1998.12 stated,
3G mobile communication standardization, ETSI (À¯·´), ARIB (ÀϺ»), TTC (ÀϺ»), CCSA (Áß±¹), ATIS (¹Ì±¹), TTA (Çѱ¹)
3GPP Release 98: pre-3G
GSM network technology (1998)
...
3GPP Release 10: LTE
Advanced (2011)
- 3GPP2: ED-DO
- Mobile Wi-Max, Wi-Bro, Flash-OFDM, IEEE 802.20
2) 4G Mobile (IMT-Advanced)
- 3GPP: LTE-A
- WiMax:
WiBro Evolution (IEEE 802.16m)
Table: LTE, LTE-A performance
Table: LTE technical parameters
8.8.4 5G Mobile
1) 5G Specifications
Figure: 5G mobile communication performance
Table: 5G specifications by ITU
2) 5G Waveforms
- OFDM (orthogonal frequency division multiplexing)
- FBMC (filter bank multi-carrier)
- UFMC (universal filtered multi-carrier modulation)
- GFDM (generalized frequency division multiplexing)
- F-OFDM (filtered OFDM)
- CP-OFDM (cyclic-prefix OFDM)
- CP-DFT-s-OFDM (cyclic-prefix discrete Fourier
transform spread OFDM)
- ZT-DFT-s-OFDM (zero-tail DFT-s-OFDM)
- UW-DFT-s-OFDM (unique word DFT-s-OFDM)
3) 5G Standards
- 3GPP: 5G, Standards to
be completed in 2020. Release 14, 15, 16
(technical reports for 5G)
- ITU: IMT-2020, 5G usage scenario
eMBB (enhanced mobile broadband)
mMTC (massive machine type
communication)
URLLC
(ultra-reliable and low latency communications)
8.9 Personal
Communication Systems
PCS
LMDS
WLAN
Satellite personal communication systems