Technology Overview

1
Technology Overview

• Presented by
• Ramon Horkany
• PLM
• ramon_h_at_rad.com

2
Agenda

• Basic Wireless Communication Terminology
• Modulation techniques
• Link Budget Calculations
• 5.x GHz Band Regulation

3
Basic Wireless Communication Terminology
4
Wireless technology, Architecture Overview
5
Radio System, Modem Structure
Bit Source
Add CRC
FEC
Modulator
TX
User
Channel
FEC
Check CRC
De-Modulator
RX
Out
Sync
6
Forward Error Correction (FEC)

• FEC techniques rely on transmitting the data in
  an encoded from, such that the redundancy
  introduced by the coding allows a decoding device
  at the receiver side to detect and correct the
  errors

Eb Errored bits N0db White noise
energy Eb/N0db SNR
No FEC
FEC
SNR
7
Antenna Directivity and Gain
Isotropic Antenna (theoretical)
Energy is radiated over the whole space
17 dBm (50mW)
Non-isotropic Antenna (real)
Energy is radiated to limited area
Generator
17 dBm (50mW)
8
Equivalent Isotropic Radiated Power
Antenna Gain
Generator
17 dBm (50mW)
50 space coverage 3dBi gain

• Generated Energy (dBm) gain (dBi) dBm EIRP
• Example 21dBm 3dBi 24dBm EIRP

9
Frequency/Time Division Duplex
Frequency
Time
10
Frequency/Time Division Duplex cont.

• TDD Time Division Duplex Structure
• GB - Guard Band

11
Modulation Techniques
12
Carrier Modulation Techniques

• Bits can be modulated over a carrier using
  different methods

13
Carrier Modulation Techniques
Time Domain
Frequency Domain
A
Unmodulated Carrier
f
fc
A
Modulated Carrier (symbols)
fc
T
f

• Symbol rate is equivalent to the baud rate

14
Digital Modulation (QAM)
15
DS-SS Concept
Signal is multiplied with a code-sequence
Signal spectrum is expended
16
Direct Sequence Spread Spectrum (DSSS)
Bits
Spread sequence
Tx
Coded message
Carrier
Modulated sequence
Received message
Discover sequence
Rx
Spread sequence
Discover energy level
Discover bit
17
Direct Sequence Spread Spectrum

• Spread spectrum "spreads" a signal's power over a
  wider band of frequencies, sacrificing bandwidth
  in order to gain signal-to-noise performance
• Direct sequence spread spectrum combines a data
  signal at the sending station with a higher data
  rate bit sequence

18
OFDM

• OFDM is a wideband modulation method that divides
  the available bandwidth into multiple
  sub-channels
• Each carrier is multiplied by a modulated
  constellation generated from the input data

19
OFDM
Frequency Domain
Time Domain
20
Link Budget Calculations
21
How is The Range Calculated?

• System Characteristics
• Link Budget (Antenna Gain, Minimum Signal Level,
  Transmit Power, Noise Figure)
• Channel Characteristics
• Path Loss _at_ Free line-of-sight
• PL 32.45 20LOG(FMHzRKm)
• F frequency MHz
• R range km

22
Link Budget Calculation

• SP (TpGrGt-PL-FM) Rs
• Where
• FM - Fade Margin
• Tp - Transmitted Power
• Gr, Gt - Receiver and Transmitter antenna gain
• PL - Path Loss
• Rs - Received Power

23
5.x GHz Band Regulation
24
Frequency Spectrum

• National Resource
• Managed by the National Radio Communication
  Office
• FCC U.S, www.fcc.gov
• ERO Europe, www.ero.dk
• Some frequency slots are unlicensed and
  available for public use
• 900 MHz, 2.4 GHz, 5.8 GHz, etc.
• Other frequencies may be used based on licenses
  granted/auctioned by the regulator

25
Relative Bandwidth Available Out Door
2 GHz Spectrum
2.5
2.6
2.9
3.0
2.1
2.2
2.3
2.4
2.7
2.8
2.0
5 GHz Spectrum in U.S.
5.6
5.9
6.0
5.3
5.4
5.5
5.7
5.8
5.1
5.2
5.0
5 GHz Spectrum in Europe
5.6
6.0
5.3
5.4
5.5
5.7
5.8
5.9
5.1
5.2
5.0
5 GHz Spectrum in L. America
5.6
6.0
5.3
5.4
5.5
5.7
5.8
5.9
5.1
5.2
5.0
4.9
26
Radio Regulation

• FCC
• Regulation Part 15, Subpart E
• Spectrum 5.725-5.825GHz (UNII)
• Maximum peak transmitted power (Pt)
• Pt lt 30 dBm
• EIRP lt 53 dBm for P-P application
• ETSI
• Regulation EN 301 893
• Spectrum 5.470-5.725 GHz
• Maximum mean EIRP 30 dBm