Tonex RF Bootcamp
December 18, 2016 | Author: Vayudhar Mogili | Category: N/A
Short Description
RF Bootcamp...
Description
Tonex RF Bootcamp
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 1
History of RF And Early Telecommunications
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 2
How Did We Get Here? Days before radio..... • 1680 Newton first suggested concept of spectrum, but for visible light only N
LF HF VHF UHF MW IR
S
U
UV XRAY
• 1831 Faraday demonstrated that light, electricity, and magnetism are related • 1864 Maxwell’s Equations: spectrum includes more than light • 1890’s First successful demos of radio transmission
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 3
Telegraphy Samuel F.B. Morse had the idea of the telegraph on a sea cruise in the 1833. He studied physics for two years, and In 1835 demonstrated a working prototype, which he patented in 1837. Derivatives of Morse’ binary code are still in use today The US Congress funded a demonstration line from Washington to Baltimore, completed in 1844. 1844: the first commercial telegraph circuits were coming into use. The railroads soon were using them for train dispatching, and the Western Union company resold idle Samuel F. B. Morse time on railroad circuits for public telegrams, nationwide at the peak of his career 1857: first trans-Atlantic submarine cable was installed
Submarine Cable Installation news sketch from the 1850’s November, 2014
Field Telegraphy during the US Civil War, 1860’s
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 4
Telephony By the 1870’s, the telegraph was in use all over the world and largely taken for granted by the public, government, and business. In 1876, Alexander Graham Bell patented his telephone, a device for carrying actual voices over wires. Initial telephone demonstrations sparked intense public interest and by the late 1890’s, telephone service was available in most towns and cities across the USA
Alexander Graham Bell and his phone from 1876 demonstration November, 2014
Telephone Line Installation Crew 1880’s
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 5
Electromagnetic Radiation
electric field Propagation direction
Interrelated electric and magnetic fields traveling through space Electromagnetic radiation travels at about c = 3108 m/s in a vacuum – the “cosmic speed limit”! • 299792458.0 m/s, more exactly • in cables, 82-95% speed in a vacuum • In glass, about 66% speed in a vacuum
magnetic field
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 6
Radio Milestones 1888: Heinrich Hertz, German physicist, gives lab demo of existance of electromagnetic waves at radio frequencies 1895: Guglielmo Marconi demonstrates a wireless radio telegraph over a 3-km path near his home it Italy 1897: the British fund Marconi’s development of reliable radio telegraphy over ranges of 100 kM 1902: Marconi’s successful trans-Atlantic demonstration 1902: Nathan Stubblefield demonstrates voice over radio Guglielmo Marconi 1906: Lee De Forest invents “audion”, triode vacuum tube radio pioneer, 1895 • feasible now to make steady carriers, and to amplify signals
MTS, IMTS
1914: Radio became valuable military tool in World War I 1920s: Radio used for commercial broadcasting 1940s: first application of RADAR - English detection of incoming German planes during WW II 1950s: first public marriage of radio and telephony - MTS, Mobile Telephone System 1961: transistor developed: portable radio now practical 1961: IMTS - Improved Mobile Telephone Service Lee De Forest 1970s: Integrated circuit progress: MSI, LSI, VLSI, ASICs vacuum tube inventor 1979, 1983: AMPS cellular demo, commercial deployment
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 7
Prefixes for Large and Small Units
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 8
Wavelength, Frequency, and Energy Relationships
Wavelength (m)
Frequency (Hz)
Energy (J)
Radio
> 1 x 10-1
< 3 x 109
< 2 x 10-24
Microwave
1 x 10-3 - 1 x 10-1
3 x 109 - 3 x 1011
2 x 10-24- 2 x 10-22
Infrared
7 x 10-7 - 1 x 10-3
3 x 1011 - 4 x 1014
2 x 10-22 - 3 x 10-19
Optical
4 x 10-7 - 7 x 10-7
4 x 1014 - 7.5 x 1014
3 x 10-19 - 5 x 10-19
UV
1 x 10-8 - 4 x 10-7
7.5 x 1014 - 3 x 1016
5 x 10-19 - 2 x 10-17
X-ray
1 x 10-11 - 1 x 10-8
3 x 1016 - 3 x 1019
2 x 10-17 - 2 x 10-14
Gamma-ray
< 1 x 10-11
> 3 x 1019
> 2 x 10-14
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 9
Frequency vs. Wavelength
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 10
Radio Spectrum Designations Free-space Wavelengths
Designation
Abbreviation
Frequencies
Very Low Frequency
VLF
9 kHz - 30 kHz
33 km - 10 km
Low Frequency
LF
30 kHz - 300 kHz
10 km - 1 km
Medium Frequency
MF
300 kHz - 3 MHz
1 km - 100 m
High Frequency
HF
3 MHz - 30 MHz
100 m - 10 m
Very High Frequency
VHF
30 MHz - 300 MHz
10 m - 1 m
Ultra High Frequency
UHF
300 MHz - 3 GHz
1 m - 100 mm
Super High Frequency
SHF
3 GHz - 30 GHz
100 mm - 10 mm
Extremely High Frequency
EHF
30 GHz - 300 GHz
10 mm - 1 mm
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 11
Common Terms for US Frequency Bands Band
Frequency range
UHF ISM
902-928 MHz
S-Band
2-4 GHz
S-Band ISM
2.4-2.5 GHz
C-Band
4-8 GHz
C-Band satellite downlink
3.7-4.2 GHz
C-Band Radar (weather)
5.25-5.925 GHz
C-Band ISM
5.725-5.875 GHz
C-Band satellite uplink
5.925-6.425 GHz
X-Band
8-12 GHz
X-Band Radar (police/weather)
8.5-10.55 GHz
Ku-Band
12-18 GHz
Ku-Band Radar (police)
13.4-14 GHz 15.7-17.7 GHz
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 12
Microwave Bands (complete list) L band
1 to 2 GHz
S band
2 to 4 GHz
C band
4 to 8 GHz
X band
8 to 12 GHz
Ku band
12 to 18 GHz
K band
18 to 26.5 GHz
Ka band
26.5 to 40 GHz
Q band
30 to 50 GHz
U band
40 to 60 GHz
V band
50 to 75 GHz
E band
60 to 90 GHz
W band
75 to 110 GHz
F band
90 to 140 GHz
D band
110 to 170 GHz
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 13
Frequencies Used by Wireless Systems Overview of the Radio Spectrum AM
0.3
0.4
0.5
0.6
LORAN
0.7 0.8 0.9 1.0
1.2
Marine
1.4 1.6 1.8 2.0
2.4
Short Wave -- International Broadcast -- Amateur
3
4
5
6
VHF LOW Band
30
40
7
8
9
VHF TV 2-6
50
60
70
10
12
FM
80 90 100
30,000,000 i.e., 3x10 Hz
VHF VHF TV 7-13
120 140 160 180 200
0.5
3
4
5
Broadcasting November, 2014
0/6
6
300 MHz
2.4
3.0 GHz
GPS
0.7 0.8 0.9 1.0
7
240
300,000,000 i.e., 3x108 Hz DCS, PCS, AWS
UHF UHF TV 14-59
0.4
CB
14 16 18 20 22 24 26 28 30 MHz 7
700 + Cellular
0.3
3.0 MHz
3,000,000 i.e., 3x106 Hz
8
9
10
1.2
1.4 1.6 1.8 2.0
12
14 16 18 20 22 24 26 28 30 GHz 10
3,000,000,000 i.e., 3x109 Hz
30,000,000,000 i.e., 3x10
Land-Mobile Aeronautical Mobile Telephony Terrestrial Microwave Satellite RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 14
Hz
The Broadband Wireless Spectrum ISM SATELLITE WCS BCST. WCS
2300
2400
Sirius & XM
5100
800
900
1000 MHz.
ISM
EBS
BRS
U-NII
5200
2500
EBS BRS
2600 MHz. 5300
2690 5400
ISM
5700
5800
5900 MHz.
Five differently-regulated ranges of spectrum are available for broadband: ISM - the Industrial, Scientific, and Medical band. Unlicensed, already used for Wi-Fi networking, cordless phones, toys, and microwave ovens. Spread-spectrum transmission is required. In some localities this spectrum may be too cluttered to be useful for broadband. U-NII – Unlicensed National Information Infrastructure band. Unlicensed, and spread-spectrum transmission is not required. This spectrum has far fewer users at present than ISM. BRS - Broadband Radio Service. (Earlier called the Multipoint Distribution Service (MDS)/MMDS), it was used as “wireless cable” to bring video to end-users.) Links are licensed, so the potential for interference is small. Sprint and Nextel both control large blocks which are now combined. EBS – Educational Broadband Service (formerly ITFS/Instructional Television Fixed Service) instructional video and data for education. Licensed spectrum; can be used for wireless broadband. Clearwire/Craig McCaw control large blocks. WCS – Wireless Communications Service. Licensed spectrum available for broadband. Bellsouth owns large blocks. November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 15
700 MHz
800
IDEN CELL DNLNK 900
PCS Uplink
PCS DownLink
1700 1800 1900 Frequency, MegaHertz
2000
AWS DownLink
2100
SAT
AWS Uplink
AWS?
Proposed AWS-2
SAT
700 MHz.
IDEN CELL UPLINK
Current Wireless/Cellular Spectrum in the US
2200
Modern wireless began in the 800 MHz. range, when the US FCC reallocated UHF TV channels 70-83 for wireless use and AT&T’s Analog technology “AMPS” was chosen. Nextel bought many existing 800 MHz. Enhanced Specialized Mobile Radio (ESMR) systems and converted to Motorola’s “IDEN” technology The FCC allocated 1900 MHz. spectrum for Personal Communications Services, “PCS”, auctioning the frequencies for over $20 billion dollars With the end of Analog TV broadcasting in 2009, the FCC auctioned former TV channels 52-69 for wireless use, “700 MHz.” The FCC also auctioned spectrum near 1700 and 2100 MHz. for Advanced Wireless Services, “AWS”. Technically speaking, any technology can operate in any band. The choice of technology is largely a business decision. November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 16
North American Cellular Spectrum Uplink Frequencies (“Reverse Path”) 824
835
Downlink Frequencies (“Forward Path”) 845
849
Frequency, MHz
870
A
Paging, ESMR, etc. 825
846.5
Ownership and Licensing
890
880
894
B
869
891.5
Frequencies used by “A” Cellular Operator Initial ownership by Non-Wireline companies Frequencies used by “B” Cellular Operator Initial ownership by Wireline companies
In each MSA and RSA, eligibility for ownership was restricted • “A” licenses awarded to non-telephone-company applicants only • “B” licenses awarded to existing telephone companies only • subsequent sales are unrestricted after system in actual operation November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
Page 17
Development of North America PCS By 1994, US cellular systems were seriously overloaded and looking for capacity relief • The FCC allocated 120 MHz. of spectrum around 1900 MHz. for new wireless telephony known as PCS (Personal Communications Systems), and 20 MHz. for unlicensed services • allocation was divided into 6 blocks; 10-year licenses were auctioned to highest bidders PCS Licensing and Auction Details • A & B spectrum blocks licensed in 51 MTAs (Major Trading Areas ) • Revenue from auction: $7.2 billion (1995) • C, D, E, F blocks were licensed in 493 BTAs (Basic Trading Areas) • C-block auction revenue: $10.2 B, D-E-F block auction: $2+ B (1996) • Auction winners are free to choose any desired technology
51 MTAs 493 BTAs
PCS SPECTRUM ALLOCATIONS IN NORTH AMERICA
1850 MHz.
A
D
B
E F
C
15
5
15
5
15
November, 2014
5
unlic.
G data voice 1910 MHz.
1930 MHz.
A
D
B
E F
C
15
5
15
5
15
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
5
G 1990 MHz.
Page 18
Advanced Wireless Services: The AWS Spectrum
To further satisfy growing demand for wireless data services as well as traditional voice, the FCC has also allocated more spectrum for wireless in the 1700 and 2100 MHz. ranges The US AWS spectrum lines up with International wireless spectrum allocations, making “world” wireless handsets more practical than in the past Many AWS licensees will simply use their AWS spectrum to add more capacity to their existing networks; some will use it to introduce their service to new areas Page 19
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
AWS Spectrum Blocks
The AWS spectrum is divided into “blocks” Different wireless operator companies are licensed to use specific blocks in specific areas This is the same arrangement used in original 800 MHz. cellular, 1900 MHz. PCS, and the new 700 MHz. allocations
Page 20
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
The US 700 MHz. Spectrum and Its Blocks
To satisfy growing demand for wireless data services as well as traditional voice, the FCC has also taken the spectrum formerly used as TV channels 52-69 and allocated them for wireless The TV broadcasters will completely vacate these frequencies when analog television broadcasting ends in February, 2009 At that time, the winning wireless bidders may begin building and operating their networks In many cases, 700 MHz. spectrum will be used as an extension of existing operators networks. In other cases, entirely new service will be provided. Page 21
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
RF100 - 22
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Wireless Systems: Modulation and Signal Bandwidth
Q axis
Lower Sideband
fc
Upper Sideband
b a
1
0 1 0
fc
c
I axis
QPSK
1
0 1 0
fc
1
0 1 0
Q axis
b
r
a c
I axis
p v /4 shifted DQPSK
fc
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 23
Characteristics of a Radio Signal SIGNAL CHARACTERISTICS The complete, timevarying radio signal
Natural Frequency of the signal
S (t) = A cos [ c t + ] Amplitude (strength) of the signal
Phase of the signal
Compare these Signals: Different Amplitudes
Different Frequencies
The purpose of telecommunications is to send information from one place to another Our civilization exploits the transmissible nature of radio signals, using them in a sense as our “carrier pigeons” To convey information, some characteristic of the radio signal must be altered (I.e., ‘modulated’) to represent the information The sender and receiver must have a consistent understanding of what the variations mean to each other RF signal characteristics which can be varied for information transmission:
• Amplitude • Frequency • Phase
Different Phases November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 24
Modulation and Occupied Bandwidth Time-Domain
Frequency-Domain
(as viewed on an Oscilloscope)
(as viewed on a Spectrum Analyzer)
Voltage
The bandwidth occupied by a signal depends on:
Voltage
Time
0
Frequency
Lower Sideband
fc
Upper Sideband
fc
fc
• input information bandwidth • modulation method Information to be transmitted, called “input” or “baseband” • bandwidth usually is small, much lower than frequency of carrier Unmodulated carrier • the carrier itself has Zero bandwidth!! AM-modulated carrier • Notice the upper & lower sidebands • total bandwidth = 2 x baseband FM-modulated carrier • Many sidebands! bandwidth is a complex mathematical function PM-modulated carrier • Many sidebands! bandwidth is a complex mathematical function
fc
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 25
The Emergence of AM: A bit of History The early radio pioneers first used binary transmission, turning their crude transmitters on and off to form the dots and dashes of Morse code. The first successful demonstrations of radio occurred during the mid-1890’s by experimenters in Italy, England, Kentucky, and elsewhere. Amplitude modulation was the first method used to transmit voice over radio. The early experimenters couldn’t foresee other methods (FM, etc.), or today’s advanced digital devices and techniques. Commercial AM broadcasting to the public began in the early 1920’s. Despite its disadvantages and antiquity, AM is still alive: • AM broadcasting continues today in 540-1600 KHz. • AM modulation remains the international civil aviation standard, used by all commercial aircraft (108-132 MHz. band). • AM modulation is used for the visual portion of commercial television signals (sound portion carried by FM modulation) • Citizens Band (“CB”) radios use AM modulation • Special variations of AM featuring single or independent sidebands, with carrier suppressed or attenuated, are used for marine, commercial, military, and amateur communications
SSB LSB USB November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 26
Frequency Modulation (“FM”) TIME-DOMAIN VIEW
t sFM(t) =A cos c t + mm(x)dx+ t0
[
]
where: A = signal amplitude (constant) c = radian carrier frequency mfrequency deviation index m(x) = modulating signal = initial phase
Voltage
FREQUENCY-DOMAIN VIEW LOWER SIDEBANDS
0 Frequency November, 2014
UPPER SIDEBANDS
SFM(t)
Frequency Modulation (FM) is a type of angle modulation • in FM, the instantaneous frequency of the signal is varied by the modulating waveform Advantages of FM • the amplitude is constant – simple saturated amplifiers can be used – the signal is relatively immune to external noise – the signal is relatively robust; required C/I values are typically 17-18 dB. in wireless applications Disadvantages of FM • relatively complex detectors are required • a large number of sidebands are produced, requiring even larger bandwidth than AM
fc
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 27
The Digital Advantage
transmission
demodulation-remodulation
transmission
demodulation-remodulation
transmission
demodulation-remodulation
November, 2014
The modulating signals shown in previous slides were all analog. It is also possible to quantize modulating signals, restricting them to discrete values, and use such signals to perform digital modulation. Digital modulation has several advantages over analog modulation: Digital signals can be more easily regenerated than analog • in analog systems, the effects of noise and distortion are cumulative: each demodulation and remodulation introduces new noise and distortion, added to the noise and distortion from previous demodulations/remodulations. • in digital systems, each demodulation and remodulation produces a clean output signal free of past noise and distortion Digital bit streams are ideally suited to many flexible multiplexing schemes
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 28
Theory of Digital Modulation: Sampling m(t)
Sampling p(t)
m(t) Recovery
The Sampling Theorem: Two Parts •If the signal contains no frequency higher than fM Hz., it is comletely described by specifying its samples taken at instants of time spaced 1/2 fM s. •The signal can be completely recovered from its samples taken at the rate of 2 fM samples per second or higher. November, 2014
Voice and other analog signals first must be sampled (converted to digital form) for digital modulation and transmission The sampling theorem gives the criteria necessary for successful sampling, digital modulation, and demodulation • The analog signal must be bandlimited (low-pass filtered) to contain no frequencies higher than fM • Sampling must occur at least twice as fast as fM in the analog signal. This is called the Nyquist Rate Required Bandwidth for p(t) • If each sample p(t) is expressed as an n-bit binary number, the bandwidth required to convey p(t) as a digital signal is at least N*2* fM • this follows Shannon’s Theorem: at least one Hertz of bandwidth is required to convey one bit per second of data
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 29
Sampling Example: the 64 kb/s DS-0 Band-Limiting C-Message Weighting
0 dB -10dB -20dB -30dB -40dB
16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
100
300 1000 3000 Frequency, Hz
Companding
16
15
8
8 3
3
10000
4 4
t
µ-Law
y sgn(x)
ln(1 | x|) ln(1 )
(where 255)
1
A-LAW A|x| y sgn(x)
1
for 0 x A ln(1 A) 1 ln(1 A|x)| y sgn(x) for x 1 A ln(1 A) (where A 87. 6)
x = analog audio voltage y = quantized level (digital)
November, 2014
Telephony has adopted a world-wide PCM standard digital signal employing a 64 kb/s stream derived from sampled voice data Voice waveforms are band-limited • upper cutoff between 3500-4000 Hz. to avoid aliasing • rolloff below 300 Hz. to minimize vulnerability to “hum” from AC power mains Voice waveforms sampled at 8000/second rate • 8000 samples x 1 byte = 64,000 bits/second • A>D conversion is non-linear, one byte per sample, thus 256 quantized levels are possible • Levels are defined logarithmically rather than linearly to accommodate a wider range of audio levels with minimum distortion – -law companding (popular in North America & Japan) – A-law companding (used in most other countries) A>D and D>A functions are performed in a CODEC (coder-decoder) (see following figure)
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 30
Digital Modulation
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 31
Modulation by Digital Inputs Our previous modulation examples used continuously-variable analog inputs. If we quantize the inputs, restricting them to digital values, we will produce digital modulation. Voltage
Time
1
0 1 0
1
0 1 0
1
0 1 0
1
0 1 0
November, 2014
For example, modulate a signal with this digital waveform. No more continuous analog variations, now we’re “shifting” between discrete levels. We call this “shift keying”. • The user gets to decide what levels mean “0” and “1” -- there are no inherent values Steady Carrier without modulation Amplitude Shift Keying ASK applications: digital microwave Frequency Shift Keying FSK applications: control messages in AMPS cellular; TDMA cellular Phase Shift Keying PSK applications: TDMA cellular, GSM & PCS-1900
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 32
Claude Shannon:
The “Einstein” of Information Theory and Signal Science The core idea that makes CDMA possible was first explained by Claude Shannon, a Bell Labs research mathematician Shannon's work relates amount of information carried, channel bandwidth, signal-to-noise-ratio, and detection error probability • It shows the theoretical upper limit attainable In 1948 Claude Shannon published his landmark paper on information theory, A Mathematical Theory of Communication. He observed that "the fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point." His paper so clearly established the foundations of information theory that his framework and terminology are standard today. Shannon died Feb. 24, 2001, at age 84. November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 33
Modulation Techniques of 1xEV Technologies 1xEV, “1x Evolution”, is a family of alternative fast-data schemes that can be implemented on a 1x CDMA carrier. 1xEV DO means “1x Evolution, Data Only”, originally proposed by Qualcomm as “High Data Rates” (HDR). • Up to 2.4576 Mbps forward, 153.6 kbps reverse • A 1xEV DO carrier holds only packet data, and does not support circuit-switched voice • Commercially available in 2003 1xEV DV means “1x Evolution, Data and Voice”. • Max throughput of 5 Mbps forward, 307.2k reverse • Backward compatible with IS-95/1xRTT voice calls on the same carrier as the data • Not yet commercially available; work continues All versions of 1xEV use advanced modulation techniques to achieve high throughputs.
November, 2014
QPSK
CDMA IS-95, IS-2000 1xRTT, and lower rates of 1xEV-DO, DV
16QAM 1xEV-DO at highest rates
64QAM 1xEV-DV at highest rates
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 34
Digital Modulation Systems Each symbol of a digitally modulated RF signal conveys a number of bits of information • determined by the number of degrees of modulation freedom More complex modulation schemes can carry more bits per symbol in a given bandwidth, but require better signal-to-noise ratios The actual number of bits per second which can be conveyed in a given bandwidth under given signal-to-noise conditions is described by Shannon’s equations
November, 2014
Modulation Scheme
Shannon Limit, BitsHz
BPSK QPSK 8PSK 16 QAM 32 QAM 64 QAM 256 QAM
1 b/s/hz 2 b/s/hz 3 b/s/hz 4 b/s/hz 5 b/s/hz 6 b/s/hz 8 b/s/hz
SHANNON’S CAPACITY EQUATION
C = B log2 [
1+
S N
]
B = bandwidth in Hertz C = channel capacity in bits/second S = signal power N = noise power
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 35
Digital Modulation Schemes There are many different schemes for digital modulation, each a compromise between complexity, immunity to errors in transmission, required channel bandwidth, and possible requirement for linear amplifiers Linear Modulation Techniques • BPSK Binary Phase Shift Keying • DPSK Differential Phase Shift Keying • QPSK Quadrature Phase Shift Keying IS-95 CDMA forward link – Offset QPSK IS-95 CDMA reverse link – Pi/4 DQPSK IS-54, IS-136 control and traffic channels Constant Envelope Modulation Schemes • BFSK Binary Frequency Shift Keying AMPS control channels • MSK Minimum Shift Keying • GMSK Gaussian Minimum Shift Keying GSM systems, CDPD Hybrid Combinations of Linear and Constant Envelope Modulation • MPSK M-ary Phase Shift Keying • QAM M-ary Quadrature Amplitude Modulation • MFSK M-ary Frequency Shift Keying FLEX paging protocol Spread Spectrum Multiple Access Techniques • DSSS Direct-Sequence Spread Spectrum IS-95 CDMA • FHSS Frequency-Hopping Spread Spectrum November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 36
Error Vulnerabilities of Higher-Order Modulation Schemes Higher-Order Modulation Schemes (16PSK, 32QAM, 64QAM...) are more vulnerable to transmission errors than the simpler, more rugged schemes (BPSK, QPSK) • Closely-packed constellations leave little room for vector error Non-linearities (gain compression, clipping, reflections within antenna system) “warp” the constellation Noise and long-delayed echoes cause “scatter” around constellation points Interference blurs constellation points into “rings” of error November, 2014
Q Distortion
Q Normal 64QAM
(Gain Compression)
I
I
Q Noise
Q Interference
I
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
I
RF100 - 37
Error Vector Magnitude and ρ (“Rho”) A common measurement of overall error is Error Vector Magnitude “EVM” • usually a small fraction of total vector amplitude, ~0.1 EVM is usually averaged over a large number of symbols • Root-mean-square (RMS) Commercial test equipment for BTS maintenance measures EVM Signal quality is often expressed as 1-EVM • normally called ρ (“Rho”) • typically 0.89-0.96
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 38
RF Fundamentals: Noise
RF100 - 39
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Receiving Weak Signals:
Noise, Unwelcome Guest Who Won’t Go Home! To hear a very weak signal, why can’t we just add amplifier after amplifier until we get enough gain to hear it? • Unfortunately, there’s always noise in the background – free! • The signal must be strong enough to hear despite the noise • Signal-to-Noise Ratio – SNR • Different kinds of signals have different resistance to noise The most common, ever-present kind of noise is thermal noise • Electrons in metal are always randomly moving around, propelled by free ambient heat • Electron flow is the same thing as current – noise current • Thermal noise power is distributed evenly through the radio spectrum – a certain amount per hertz of bandwidth
RF100 - 40
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
How Strong is the Thermal Noise? The strength of the noise we receive is determined by three things: • It’s proportional to absolute temperature (degrees Kelvin) • It’s proportional to the bandwidth we’re looking at (thermal noise is uniformly distributed in watts per hertz) • The exact amount of noise per degree kelvin per hertz is determined by Boltzmann’s constant In the world of radio, we usually express noise power in decibels above a milliwatt (dbm). Here’s the everyday formula for the amount of thermal noise in dbm: Where • P is the power in dbm • Delta F is the bandwidth we’re watching, in hertz the “Noise Floor”
RF100 - 41
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Thermal Noise Strength in the Bandwidths of Common Signals
RF100 - 42
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Physical Principles of Propagation
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 43
Working in Decibels GAIN and LOSS Ratio vs. dB 1,000,000 x
+60 db
100,000 x
+50 db
10,000 x
+40 db
1,000 x
+30 db
100 x
+20 db
10 x 4x 2x
1x
+10 db +6 db +3 db
0 db
.1 x
-10 db
.01 x
-20 db
.001 x
-30 db
.0001 x
-40 db
.00001 x
-50 db
.000001 x
-60 db
November, 2014
Ratio to Decibels db = 10 * Log10 (Pout/Pin) Decibels to Ratio
(Pout/Pin) = 10 (db/10) Amplifiers increase the power of electrical signals (an increase is called “gain”) Cables, attenuators, or simple radiation through space decrease signal power (called “loss”) Decibels are logarithmic units, so db values are never very big or very small db, even if the gains or losses are extremely big or small Db are always small enough to allow doing the arithmetic “in your head” without needing a calculator RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 44
Decibels can Express Relative Gains/Losses, or Absolute Amounts of Power, or Gains of Specific Antennas dB - relative gain or loss When you see just a simple value “30 dB”, this tells what happens to a signal when it passes through a certain device or system • If a device increases the signal power 1000x, that is 30 db gain. • If signal power decreases 1000x, that is -30 db gain (that’s loss). dBm - absolute power A value “30 dBm” expresses an actual amount of power. “m” stands for “milliwatts”. Example: 1000 milliwatts is +30 dBm dBi or dBd – gain of test antenna compared to a reference antenna 12.1 dbi gain means the test antenna makes signals seem 12.1 db stronger than if an isotropic antenna had been used 10 dbd gain means the test antenna makes signals seem 10 db stronger than if a dipole antenna had been used November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 45
Introduction to Propagation Propagation is a key process within every radio link. During propagation, many processes act on the radio signal. • attenuation – the signal amplitude is reduced by various natural mechanisms; if there is too much attenuation, the signal will fall below the reliable detection threshold at the receiver. Attenuation is the most important single factor in propagation. • multipath and group delay distortions – the signal diffracts and reflects off irregularly shaped objects, producing a host of components which arrive in random timings and random RF phases at the receiver. This blurs pulses and also produces intermittent signal cancellation and reinforcement. These effects are combatted through a variety of special techniques • time variability - signal strength and quality varies with time, often dramatically • space variability - signal strength and quality varies with location and distance • frequency variability - signal strength and quality differs on different frequencies Effective mastery of propagation relies on • Physics: understand the basic propagation processes • Measurement: obtain data on propagation behavior in area of interest • Statistics: characterize what is known, extrapolate to predict the unknown • Modelmaking: formalize all the above into useful models November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 46
Some Physics: Wavelength of the Signal and Its Influence on Propagation
C / F Frequency, GHz. 0.92 2.4 5.8
Radio signals in the atmosphere travel at the speed of light
Wavelength cm. in. 32.6 12.8 12.5 4.9 5.2 2.0
/2
RF100 - 47
= wavelength C = distance traveled in 1 second F = frequency, Hertz
The wavelength of a radio signal determines many of its propagation characteristics • Internal antenna elements’ size are typically in the order of 1/4 to 1/2 wavelength • Objects bigger than a wavelength can reflect or obstruct RF energy • RF energy can penetrate into a building or vehicle if it has openings the size of a wavelength, or larger
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Propagation Effects of Earth’s Atmosphere Earth’s unique atmosphere supports life (ours included) and also introduces many propagation effects -- some useful, some troublesome Skywave Propagation: reflection from Ionized Layers • LF and HF frequencies (below roughly 50 MHz.) are routinely reflected off layers of the upper atmosphere which become ionized by the sun • this phenomena produces intermittent world-wide propagation and occasional total outages • this phenomena is strongly correlated with frequency, day/night cycles, variations in earth’s magnetic field, 11year sunspot cycle • these effects are negligible for wireless systems at their much-higher frequencies
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 48
More Atmospheric Propagation Effects “Rain Fades” on MIcrowave Links
Refraction by air layers
Attenuation at Microwave Frequencies • rain droplets can substantially attenuate RF signals whose wavelengths are comparable to, or smaller than, droplet size • rain attenuations of 20 dB. or more per km. are possible • troublesome mainly above 10 GHz., and in tropical areas • must be considered in reliability calculations during path design • not major factor in wireless systems propagation
Diffraction, Wave Bending, Ducting
Ducting by air layers
• signals 50-2000 MHz. can be bent or reflected at boundaries of different air density or humidity • phenomena: very sporadic unexpected long-distance propagation beyond the horizon. May last minutes or hours • can occur in wireless systems
>100 mi.
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 49
Dominant Mechanisms of Mobile Propagation Free Space
d
A
D B
Reflection
with partial cancellation
Knife-edge Diffraction
November, 2014
Most propagation in the mobile environment is dominated by these three mechanisms: Free space • No reflections, no obstructions – first Fresnel Zone clear • Signal spreading is only mechanism • Signal decays 20 dB/decade Reflection • Reflected wave 180out of phase • Reflected wave not attenuated much • Signal decays 30-40 dB/decade Knife-edge diffraction • Direct path is blocked by obstruction • Additional loss is introduced • Formulae available for simple cases We’ll explore each of these further...
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 50
Propagation: Getting the Signal to the Customer AP
SM
“Propagation” is the name for the general process of getting a radio signal from one place to another During propagation, the signal gets weaker because of several natural processes. This weakening is called “attenuation”. Point-to-point radio links work best when there is “line-of-sight” between the two antennas. This is the condition of least attenuation • nothing along the way to block the signal In mobile systems, line-of-sight only happens near base stations or from high spots (hilltops, top floors of buildings and parking garages, etc.)
RF100 - 51
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
The First Fresnel Zone and Free-Space Propagation AP
Frequency, Path, GHz. Miles 0.92 10 2.4 10 5.8 10
Mid-Pt Fresnel R, ft 119 74 47
SM
Most of the signal power sent from one antenna to another travels in an elliptical, “football” shape called the First Fresnel zone. • the thickness of the zone depends on the signal frequency If the First Fresnel zone is free of penetration or obstruction by any objects, we say “free-space” conditions apply • this is the desirable condition providing highest received signal strength Sometimes obstructions are unavoidable, and penetrate the first fresnel zone • this attenuates the signal and reduces the signal strength received at the other end of the link • the amount of attenuation depends on the degree of penetration by the obstruction, and its absorbing characteristics RF100 - 52
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
LoS, nLoS, and NLoS Definitions
Line of Site (LoS)
Near Line of Site (nLoS)
Non Line of Site (NLoS) November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 53
Free-Space Propagation Technical Details r
Free Space “Spreading” Loss energy intercepted by receiving antenna is proportional to 1/r2
d A
The simplest propagation mode • Antenna radiates energy which spreads in space • Path Loss, db (between two isotropic antennas) = 36.58 +20*Log10(FMHZ)+20Log10(DistMILES ) • Path Loss, db (between two dipole antennas) = 32.26 +20*Log10(FMHZ)+20Log10(DistMILES ) • Notice the rate of signal decay: • 6 db per octave of distance change, which is 20 db per decade of distance change Free-Space propagation is applicable if: • there is only one signal path (no reflections) • the path is unobstructed (i.e., first Fresnel zone is not penetrated by obstacles)
1st Fresnel Zone
D B
RF100 - 54
First Fresnel Zone = {Points P where AP + PB - AB < } Fresnel Zone radius d = 1/2 (D)^(1/2)
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Path Profiles from Propagation Prediction Tools
Propagation models can also prepare automated path profiles From a path profile, you can quickly determine whether the path is line-of-sight or obstructed RF100 - 55
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Reflection With Partial Cancellation Heights Exaggerated for Clarity HTFT
HTFT
Mobile environment characteristics: • Small angles of incidence and reflection • Reflection is unattenuated (reflection coefficient =1) • Reflection causes phase shift of 180 degrees Analysis • Physics of the reflection cancellation predicts signal decay of 40 dB per decade of distance
DMILES
Path Loss [dB ]= 172 + 34 x Log (DMiles ) - 20 x Log (Base Ant. HtFeet) - 10 x Log (Mobile Ant. HtFeet) SCALE PERSPECTIVE
Comparison of Free-Space and Reflection Propagation Modes
Assumptions: Flat earth, TX ERP = 50 dBm, @ 1950 MHz. Base Ht = 200 ft, Mobile Ht = 5 ft.
DistanceMILES Received Signal in Free Space, DBM Received Signal in Reflection Mode
November, 2014
1 -52.4 -69.0
2 -58.4 -79.2
4 -64.4 -89.5
6 -67.9 -95.4
8 -70.4 -99.7
10 -72.4
15 -75.9
20 -78.4
-103.0
-109.0
-113.2
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 56
Signal Decay Rates in Various Environments Signal Level vs. Distance 0
-10
-20
-30 -40 1
2
One Octave of distance (2x)
November, 2014
3.16 5 6 7 8 Distance, Miles
One Decade
of distance (10x)
10
We’ve seen how the signal decays with distance in two basic modes of propagation: Free-Space • 20 dB per decade of distance • 6 db per octave of distance Reflection Cancellation • 40 dB per decade of distance • 12 db per octave of distance Real-life wireless propagation decay rates are typically somewhere between 30 and 40 dB per decade of distance
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 57
Obstructions and their Effects AP
SM
When an obstruction penetrates the first fresnel zone, the signal is attenuated. The degree of attenuation depends on • how much of the first fresnel zone is obstructed • the absorptive characteristics of the obstructing object(s) • whether the signal is also reflecting off of other nearby objects, possibly providing a degree of “fill-in” Depending on the length of the path, the transmitter power, and the receiver sensitivity, the link may still work despite the obstruction RF100 - 58
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Severe Obstructions AP
SM
When the path is blocked by a major obstruction (large hill, downtown building, etc.) there will be substantial signal attenuation Even under this undesirable condition, if the distance is small there may be enough signal to make the link usable • A very small amount of the signal will actually diffract (“bend”) over the obstruction • the extra attenuation caused by the obstruction can be calculated by the “knife edge diffraction” model • this “diffraction loss” can be considered in the link budget to see if the link is likely to be usable anyway RF100 - 59
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Knife-Edge Diffraction
H
R1 = -H
R2 2 ( R1 + R2) R1 R2
0 -5 atten -10 dB -15 -20 -25 -5 -4 -3 -2 -1 0 1 2 3
November, 2014
Sometimes a single well-defined obstruction blocks the path, introducing additional loss. This calculation is fairly easy and can be used as a manual tool to estimate the effects of individual obstructions. First calculate the diffraction parameter from the geometry of the path Next consult the table to obtain the obstruction loss in db Add this loss to the otherwisedetermined path loss to obtain the total path loss. Other losses such as free space and reflection cancellation still apply, but computed independently for the path as if the obstruction did not exist
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 60
Foliage and Building Penetration Considerations AP Building
SM
AP
SM
RF100 - 61
Building
At broadband wireless frequencies, the penetration loss entering a building often exceeds 35 db. • this restricts range so greatly that antennas are almost never located inside a building At broadband wireless frequencies, trees and other vegetation effectively block and absorb the signal • typical attenuation for just one mature tree can be 20 db or more Unfortunately, neither building nor vegetation loss can be predicted accurately. Measurement is the only way to know accurately what is happening.
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Combating Rayleigh Fading: Space Diversity D
Signal received by Antenna 1 Signal received by Antenna 2 Combined Signal November, 2014
Fortunately, Rayleigh fades are very short and last a small percentage of the time Two antennas separated by several wavelengths will not generally experience fades at the same time “Space Diversity” can be obtained by using two receiving antennas and switching instantby-instant to whichever is best Required separation D for good decorrelation is 10-20 • 12-24 ft. @ 800 MHz. • 5-10 ft. @ 1900 MHz.
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 62
Types Of Propagation Models And Their Uses Examples of various model types
Simple Analytical models
• Used for understanding and predicting individual paths and specific obstruction cases General Area models
• Primary drivers: statistical • Used for early system dimensioning (cell counts, etc.) Point-to-Point models
• Primary drivers: analytical • Used for detailed coverage analysis and cell planning Local Variability models
• Primary drivers: statistical • Characterizes microscopic level fluctuations in a given locale, confidence-of-service probability November, 2014
Simple Analytical • Free space (Friis formula) • Reflection cancellation • Knife-edge diffraction
Area • Okumura-Hata • Euro/Cost-231 • Walfisch-Betroni/Ikegami
Point-to-Point • Ray Tracing - Lee’s Method, others • Tech-Note 101 • Longley-Rice, Biby-C
Local Variability • Rayleigh Distribution • Normal Distribution • Joint Probability Techniques
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 63
General Principles Of Area Models -50
+90
-60
+80
-70
+70
-80
+60
Field Strength, +50 dBµV/m
RSSI, -90 dBm -100
+40
-110
+30
-120 0
3
6
9 12 15 18 21 24 27 30 33
+20
Distance from Cell Site, km
Green Trace shows actual measured signal strengths on a drive test radial, as determined by real-world physics. Red Trace shows the Okumura-Hata prediction for the same radial. The smooth curve is a good “fit” for real data. However, the signal strength at a specific location on the radial may be much higher or much lower than the simple prediction. November, 2014
Area models mimic an average path in a defined area They’re based on measured data alone, with no consideration of individual path features or physical mechanisms Typical inputs used by model: • Frequency • Distance from transmitter to receiver • Actual or effective base station & mobile heights • Average terrain elevation • Morphology correction loss (Urban, Suburban, Rural, etc.) Results may be quite different than observed on individual paths in the area
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 64
The Okumura Model: General Concept 70
Urban Area
35
50
(dB) Correction factor, Garea
80 70 d, km
Median Attenuation A(f,d), dB
100
40 30 26
25 20 15
10 9 dB
5 2
5
1 10
30
850 MHz
850 100
500 Frequency f, MHz
3000
100
200
300 500 700 1000 Frequency f, (MHz)
2000
3000
The Okumura model is based on detailed analysis of exhaustive drive-test measurements made in Tokyo and its suburbs during the late 1960’s and early 1970’s. The collected date included measurements on numerous VHF, UHF, and microwave signal sources, both horizontally and vertically polarized, at a wide range of heights. The measurements were statistically processed and analyzed with respect to almost every imaginable variable. This analysis was distilled into the curves above, showing a median attenuation relative to free space loss Amu (f,d) and correlation factor Garea (f,area), for BS antenna height ht = 200 m and MS antenna height hr = 3 m. Okumura has served as the basis for high-level design of many existing wireless systems, and has spawned a number of newer models adapted from its basic concepts and numerical parameters. November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 65
Structure of the Okumura Model Path Loss [dB] = LFS + Amu(f,d) - G(Hb) - G(Hm) - Garea Free-Space Path Loss
Amu(f,d) Additional Median Loss from Okumura’s Curves
Mobile Station Height Gain = 10 x Log (Hm/3)
Morphology Gain 0 dense urban 5 urban 10 suburban 17 rural
Base Station Height Gain = 20 x Log (Hb/200)
Urban Area 100 80
50
70
d, km
Median Attenuation A(f,d), dB
70
40 30 26
Correction factor, Garea (dB)
35
30 25 20 15 10 5
5 2
850 MHz
1 10
Frequency f, MHz 100
500
100
850
200
300 500 700 1000 2000 3000 Frequency f, (MHz)
3000
The Okumura Model uses a combination of terms from basic physical mechanisms and arbitrary factors to fit 1960-1970 Tokyo drive test data Later researchers (HATA, COST231, others) have expressed Okumura’s curves as formulas and automated the computation November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 66
Examples of Morphological Zones
Suburban
Urban
Dense Urban
Suburban
Urban
Dense Urban
Suburban: Mix of residential and business communities. Structures include 1-2 story houses 50 feet apart and 2-5 story shops and offices. Urban: Urban residential and office areas (Typical structures are 5-10 story buildings, hotels, hospitals, etc.) Dense Urban: Dense business districts with skyscrapers (10-20 stories and above) and high-rise apartments
Although zone definitions are arbitrary, the examples and definitions illustrated above are typical of practice in North American PCS designs. RF100 - 67
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Example Morphological Zones Rural - Highway
Rural - Highway
Rural
Rural
Suburban
Suburban
Rural - Highway: Highways near open farm land, large open spaces, and sparsely populated residential areas. Typical structures are 1-2 story houses, barns, etc. Rural - In-town: Open farm land, large open spaces, and sparsely populated residential areas. Typical structures are 1-2 story houses, barns, etc.
Notice how different zones may abruptly adjoin one another. In the case immediately above, farm land (rural) adjoins built-up subdivisions (suburban) -- same terrain, but different land use, penetration requirements, and anticipated traffic densities. RF100 - 68
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Radio Network Planning Tools Basics
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 69
Rough Planning with Propagation Prediction Tools Access Point locations can be compared using commercial propagation prediction tools Tools include terrain databases and land-use or land-cover data to predict the signal levels between the AP and neighborhoods needing service • the AP antenna patterns can also be included in the model Actual field test measurements should be used to “tune” the model parameters for best agreement with the field data Such models are especially valuable for analyzing effects of terrain obstructions
RF100 - 70
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Typical Model Results Including Environmental Correction COST-231/Hata f =1900 MHz.
Tower Height, m
EIRP (watts)
C, dB
Range, km
Dense Urban Urban Suburban Rural
30 30 30 50
200 200 200 200
0 -5 -10 -17
2.52 3.50 4.8 10.3
f = 870 MHz.
Tower Height, m
EIRP (watts)
C, dB
Range, km
Dense Urban Urban Suburban Rural
30 30 30 50
200 200 200 200
-2 -5 -10 -26
4.0 4.9 6.7 26.8
Okumura/Hata
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 71
Propagation at 1900 MHz. vs. 800 MHz. Propagation at 1900 MHz. is similar to 800 MHz., but all effects are more pronounced. • Reflections are more effective • Shadows from obstructions are deeper • Foliage absorption is more attenuative • Penetration into buildings through openings is more effective, but absorbing materials within buildings and their walls attenuate the signal more severely than at 800 MHz. The net result of all these effects is to increase the “contrast” of hot and cold signal areas throughout a 1900 MHz. system, compared to what would have been obtained at 800 MHz. Overall, coverage radius of a 1900 MHz. BTS is approximately two-thirds the distance which would be obtained with the same ERP, same antenna height, at 800 MHz.
RF100 - 72
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Walfisch-Betroni/Walfisch-Ikegami Models Ordinary Okumura-type models do work in this environment, but the Walfisch models attempt to improve accuracy by exploiting the actual propagation mechanisms involved
Path Loss = LFS + LRT + LMS LFS = free space path loss (Friis formula) LRT = rooftop diffraction loss LMS = multiscreen reflection loss
Area View
Signal Level Legend
November, 2014
-20 dBm -30 dBm -40 dBm -50 dBm -60 dBm -70 dBm -80 dBm -90 dBm -100 dBm -110 dBm -120 dBm
Propagation in built-up portions of cities is dominated by ray diffraction over the tops of buildings and by ray “channeling” through multiple reflections down the street canyons
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 73
Elements of Propagation Measurement Systems Main Features Field strength measurement • Accurate collection in real-time • Multi-channel, averaging capability Location Data Collection Methods: • Global Positioning System (GPS) • Dead reckoning on digitized map database using on-board compass and wheel revolutions sensor • A combination of both methods is recommended for the best results Ideally, a system should be calibrated in absolute units, not just raw received power level indications • Record normalized antenna gain, measured line loss RF100 - 74
Wireless Receiver
PC or Collector
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
GPS Receiver Dead Reckoning
November, 2014
Typical Test Transmitter Operations Typical Characteristics • portable, low power needs • weatherproof or weather resistant • regulated power output • frequency-agile: synthesized Operational Concerns • spectrum coordination and proper authorization to radiate test signal • antenna unobstructed • stable AC power • SAFETY: – people/equipment falling due to wind, or tripping on obstacles – electric shock – damage to rooftop RF100 - 75
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
Statistical Techniques
Distribution Statistics Concept Signal Strength Predicted Vs. Observed
An area model predicts signal strength Vs. distance over an area • This is the “median” or most probable signal strength at every distance from the cell • The actual signal strength at any real location is determined by local physical effects, and will be higher or lower • It is feasible to measure the observed median signal strength M and standard deviation • M and can be applied to find probability of receiving an arbitrary signal level at a given distance
Signal Strength predicted by area model Observed Signal Strength
RSSI, dBm
Distance
Occurrences
Normal Distribution
RSSI Median Signal Strength
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
, dB
RF100 - 76
Statistical Techniques
Practical Application Of Distribution Statistics General Approach:
Percentage of locations where observed RSSI exceeds predicted RSSI
• Use a model to predict RSSI • Compare measurements with model – obtain median signal strength M – obtain standard deviation – now apply correction factor to obtain field RSSI, dBm strength required for desired probability of service
10% of locations exceed this RSSI 50% 90%
Applications: Given • A desired outdoor signal level (dbm) • The observed standard deviation from signal strength measurements • A desired percentage of locations which must receive that signal level • Compute a “cushion” in dB which will give us that % coverage confidence
Distance
Occurrences
Median Signal Strength
Normal Distribution
RSSI
, dB
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 77
Cell Edge
Area Availability And Probability Of Service
Statistical View of Cell Coverage
Overall probability of service is best close to the BTS, and decreases with increasing distance away from BTS For overall 90% location probability within cell coverage area, probability will be 75% at cell 75% edge
90%
Area Availability: 90% overall within area 75%at edge of area
November, 2014
• Result derived theoretically, confirmed in modeling with propagation tools, and observed from measurements • True if path loss variations are log-normally distributed around predicted median values, as in mobile environment • 90%/75% is a commonly-used wireless numerical coverage objective • Recent publications by Nortel’s Dr. Pete Bernardin describe the relationship between area and edge reliability, and the field measurement techniques necessary to demonstrate an arbitrary degree of coverage reliability
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 78
Application Of Distribution Statistics: Example Cumulative Normal Distribution
Let’s design a cell to deliver at least -95 dBm to at least 75% of the locations at the cell edge (This will provide coverage to 90% of total locations within the cell) Assume that measurements you have made show a 10 dB standard deviation On the chart:
100% 90% 80% 70%
75%
• To serve 75% of locations at the cell edge , we must deliver a median signal strength which is .675 times stronger than -95 dBm • Calculate: - 95 dBm + ( .675 x 10 dB ) = - 88 dBm • So, design for a median signal strength of -88 dBm!
60% 50% 40% 30% 20%
0.675
10% 0% -3 -2.5 -2 -1.5 -1 -0.5 0
0.5
1
1.5
2
2.5
3
Standard Deviations from Median (Average) Signal Strength
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 79
Statistical Techniques:
Normal Distribution Graph & Table For Convenient Reference Cumulative Normal Distribution Standard Deviation
Cumulative Probability
-3.09
0.1%
-2.32
1%
80%
-1.65
5%
70%
-1.28
10%
60%
-0.84
20%
-0.52
30%
0
50%
0.52
70%
30%
0.675
75%
20%
0.84
80%
10%
1.28
90%
1.65
95%
2.35
99%
3.09
99.9%
3.72
99.99%
4.27
99.999%
100% 90%
50% 40%
0% -3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
Standard Deviation from Mean Signal Strength
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 80
Composite Probability Of Service
Adding Multiple Attenuating Mechanisms
Building
Outdoor Loss + Penetration Loss
COMPOSITE = ((OUTDOOR)2+( ENETRATION)2)1/2 P
LOSSCOMPOSITE = LOSSOUTDOOR+LOSSPENETRATION For an in-building user, the actual signal level includes regular outdoor path attenuation plus building penetration loss Both outdoor and penetration losses have their own variabilities with their own standard deviations The user’s overall composite probability of service must include composite median and standard deviation factors
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 81
Composite Probability of Service
Calculating Fade Margin For Link Budget Example Case: Outdoor attenuation is 8 dB., and penetration loss is 8 dB. Desired probability of service is 75% at the cell edge What is the composite ? How much fade margin is required?
COMPOSITE = ((OUTDOOR)2+(PENETRATION)2)1/2
On cumulative normal distribution curve, 75% probability is 0.675 above median. Fade Margin required =
= ((8)2+(8)2)1/2 =(64+64)1/2 =(128)1/2 = 11.31 dB
(11.31) (0.675) = 7.63 dB.
Cumulative Normal Distribution 100% 90%
Composite Probability of Service Calculating Required Fade Margin
80%
75%
70%
Environment Type (“morphology”)
60% 50%
20% 10% 0% -3 -2.5 -2 -1.5 -1 -0.5 0
.675 0.5
1
1.5
2
Standard Deviations from Median (Average) Signal Strength
November, 2014
2.5
3
OutDoor
Composite Total
Median Loss, dB
Std. Dev. , dB
Std. Dev. , dB
Area Availability Target, %
Fade Margin dB
Dense Urban Bldg.
20
8
8
90%/75% @edge
7.6
Urban Bldg.
15
8
8
90%/75% @edge
7.6
Suburban Bldg.
10
8
8
90%/75% @edge
7.6
Rural Bldg.
10
8
8
90%/75% @edge
7.6
Typical Vehicle
8
4
8
90%/75% @edge
6.0
40% 30%
Building Penetration
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 82
RF propagation
Propagation loss in non free space
For outdoor usage models have been created that include • path loss coefficient up to a measured breakpoint ( • path loss coefficient beyond measured breakpoint ( • breakpoint depend on antenna height (dbr) L(2.4GHz) = 40 +10 * * log(dbr) + 10 * * log(d/dbr) November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 83
Link Budget Analysis
Since each bit rate requires a specific receive sensitivity for a given radio, any wireless network (simply referred to as link for the purpose of this discussion) design must estimate the available link budget in dB to make sure that that the link budget is at least 0 dB for the highest bit rate desired. It is also a good practice to leave some reasonable margin (e.g., 10 dB) in the link budget to accommodate any variations in signal strength caused by interferers or reflectors and to increase the reliability of the link. • The link budget analysis can be used to estimate the range or capacity or to select an antenna. November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 84
Link Budget Calculation The first step in the calculation of the link budget is to calculate the received power at the receiver. The Received Power is given as: • Received Power = Radiated Power/EIRP – Path Loss + Receiver Gain – The radiated power (EIRP or Effective Isotropic Radiated Power is the correct technical term) in dBm is given as:
• EIRP (dBm) = Radio Transmit Power (dBm) – Cable/Connector/Switch Loss (dB) at Transmitter + Transmit Antenna Gain (dBi) • The Path Loss can be calculated using the appropriate path loss exponent, as discussed earlier, and may include attenuations caused by other objects in the path, if known. The Receiver Gain is given as: • Receiver Gain = Receive Antenna Gain (dBi) - Cable/Connector/Switch Loss (dB) at Receiver November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 85
Link Budget One important point to note here is that the antenna gain is reciprocal, i.e., the antenna gain can be added to the wireless device at either end to increase the overall link budget. For example, a wireless system with a 10 dBi antenna on the transmitter and a 2 dBi antenna on the receiver will have the same range as a system with a 4 dBi antenna the transmitter and an 8 dBi antenna on the receiver, everything else being equal. Therefore, adding a high gain antenna allows a device not only to transmit signals farther, but also to receive weaker signals. Once the received power (or signal strength) is known, the link budget can be calculated by subtracting the receive sensitivity of the receiver from the received power, i.e.,
Link Budget = Received Power – Receive Sensitivity The Noise Floor at the receiver can be subtracted from the received power to calculate the SNR. If the noise is lower than the Rx sensitivity, the link will be limited by the Rx sensitivity. Otherwise, the link will be limited by the Noise Floor.
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 86
An Example For example, with 30 dB EIRP (e.g., 23 dBm Transmit Power, 10 dBi antenna gain and 3 dB cable/connector loss) in 2.4 GHz, the signal attenuates to -50 dBm at 100 meters in free space. For a receiver with Receive Gain of 0 dB (e.g., 2 dBi Receiver antenna and 2 dB cable/connector loss), the received power is -50 dBm. If the receive sensitivity is -91 dBm for 1 Mbps, then the link margin is 41 dB. However, if the Noise Floor is -85 dBm, then the SNR is 35 dB. In either case, the signal is more than enough to decode 1 Mbps. However, as the distance increases the Noise Floor will be the limiting factor in this specific example.
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 87
Link Budgets
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 88
Link Budget Example: Usage Model and Service Assumptions Interactive Initial System Design Example
This section outlines the number of subscribers and amount of traffic by year This section shows the variability of outdoor and indoor signals, and the building penetration loss
November, 2014
v1.2
fill in GREEN fields YELLOW fields calculate automatically Step 1. Basic Business Plan Details Year Population Penetration, % #Customers BH Erl/Cust Total BH erl
Launch
1
2
3
4
5
3,886,000
3,949,350
4,012,700
4,076,050
4,139,400
4,202,750
0.05% 1,781 0.1 178.1
1.85% 72,933 0.05 3,646.7
3.72% 149,453 0.045 6,725.4
5.64% 229,941 0.05 11,497.0
7.60% 314,451 0.05 15,722.6
9.57% 402,360 0.05 20,118.0
2. Enter building penetration loss and standard deviations from measurements.
Composite Probability Of Service & Required Fade Margin Outdoor Composite Building Building Environment Std. Dev, Std. Dev, Standard Desired Reliability at Median Type dB. dB ("morphology") Loss, dB Cell Edge, % Deviation Dense Urban 20 8 8 75.0% 11.31 Urban 15 8 8 75.0% 11.31 Suburban 15 8 8 75.0% 11.31 Rural 10 8 8 75.0% 11.31 Highway 8 6 8 75.0% 10.00
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
Fade Margin, dB. 7.63 7.63 7.63 7.63 6.74
RF100 - 89
Reverse Link Budget Example 3. Construct Link Budgets
Reverse Link Budget Term or Factor MS TX Power (dbm) (+) MS antenna gain and body loss (+/-) MS EIRP (dBm) (+) Fade Margin, (dB) (-) Soft Handoff Gain (dB) (+) Receiver Interf. Margin (dB) (-) Building Penetration Loss (dB) (-) BTS RX antenna gain (dBi) (+) BTS cable loss (dB) (-) kTB (dBm/14.4 KHz.) BTS noise figure (dB) Eb/Nt (dB) BTS RX sensitivity (dBm) (-) Survivable Uplink Path Loss (dB) (+)
Dense Urb.
Given
Urban
Suburban
Rural
Highway
Formula
23 0 23.00 -7.63 4 -3 -20.00 17 -3
23.00 -7.63 4 -3 -15.00 17 -3
23.00 -7.63 4 -3 -15.00 17 -3
23.00 -7.63 4 -3 -10.00 17 -3
23.00 -6.74 4 -3 -8.00 17 -3
-120.0
-120.0
-120.0
-120.0
-120.0
-132.4 6.5 5.9
130.4
135.4
135.4
140.4
A B C D E F G H I J H+I+J
A+B+C+D+E +F+G(H+I+J) 143.3
The Reverse Link Budget describes how the energy from the phone is distributed to the base station, including the major components of loss and gain within the system
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 90
Forward Link Budget Example Forward Link Budget Term or Factor BTS TX power (dBm) (+) BTS TX power (watts) % Power for traffic channels Number of Traffic Channels in use BTS cable loss (dB) (-) BTS TX antenna gain (dBi) (+) BTS EIRP/traffic channel (dBm) (+,-) Fade margin (dB) (-) Receiver interference margin (db) (-) Building Penetration Loss (dB) (-) MS antenna gain & body loss (dB) (+,-) kTB (dBm/14.4 KHz.) Subscriber RX noise figure (dB) Eb/Nt (dB) Subscriber RX sensitivity (dBm) (-)
Given
Which link is dominant? What advantage, dB?
Urban 45 31.62 74.0% 19 -3 17 44.9 -7.63 -3 -15.0 0
Suburban 45 31.62 74.0% 19 -3 17 44.9 -7.63 -3 -15.0 0
Rural
-115.9
-115.9
-115.9
-115.9
-115.9
130.2
135.2
135.2
140.2
143.1
Urban Reverse 0.2
Suburban Reverse 0.2
Rural Reverse 0.2
Highway Reverse 0.2
45 31.62 74.0% 19 -3 17 44.9 -7.63 -3 -10.0 0
Highway Formula 45 31.62 74.0% 19 -3 17 A 44.9 B -6.74 -3 C D -8.0 0 E
-132.4 10.5 6
Survivable Downlink Path Loss, dB (+) Forward/Reverse Link Balance
Dense Urb. 45 31.62 74.0% 19 -3 17 44.9 -7.63 -3 -20.0 0
Dense Urban Reverse 0.2
F A+B+C+D +E-F
This section shows the forward link power distribution, and compares the relative balance of the forward and reverse links
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 91
Link Budgets: What is the Radius of a Cell? 4. Explore propagation model to figure coverage radius of cell. Frequency, MHz. Subscriber Antenna Height, M
Base Station Antenna Height, M
Environmental Correction, dB Coverage Radius, kM Coverage Radius, Miles
870 1.5 Dense Urban 20
Urban Suburban 20 30
Rural
Dense Urban
Urban
Rural Highway -17 -17
-2
1.30 0.81
-5
Suburban -10
2.17 1.35
6.87 4.27
50
20.86 12.96
Highway 50
25.40 15.78
This section uses the Okumura-Hata/Cost-231 model to describe the frequency, antenna heights, and environmental factors, and their relationship on the cell’s coverage distance
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 92
Link Budgets: Putting It All Together Step 4 estimates the number of cells required to serve each distinct environment within the system Steps 5, 6, and 7 estimate the RF coverage from each cell, and the number of cells required November, 2014
5. Calculate number of cells required for coverage, ignoring traffic considerations.
Covered Area of this type, kM^2 One cell's coverage in this zone, kM^2 # Cells required to cover zone
Dense Urban 55 5.35 10.3
Urban Suburban 450 1700 14.73 148.46 30.6 11.5
Total Rural Highway # Cells 3400 1400 Required 1367.34 2026.72 for System 2.5 0.7 55.5
6. What is the traffic capacity (in erlangs) of your chosen BTS configuration, year-by-year? Year Erlangs which one BTS can carry
Launch 18.3
1
2 18.3
3 90
4 90
5 450
450
7, 8. What is the total busy-hour erlang traffic on your system? How many BTS are required? Year Total System Busy-Hour Erlangs Capacity of One BTS, erlangs # BTS required to handle all the traffic
Launch 178.1 18.3 9.7
1 3,646.7 18.3 199.3
2 6,725.4 90 74.7
3 11,497.0 90 127.7
4 15,722.6 450 34.9
5 20,118.0 450 44.7
9. Examine your market, #BTS required for coverage and capacity; estimate total number of BTS required. Year #BTS req'd just to achieve coverage #BTS required just to carry traffic
Launch 55.5 9.7
Estimated total #BTS required
56.3
1
2
3
4
5
55.5 199.3
55.5 74.7
55.5 127.7
55.5 34.9
55.5 44.7
206.8
206.8
206.8
206.8
206.8
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 93
Radio Link - Simplified Model
Gt
Gr Attenuator
Lt
Lp Pt Tx
November, 2014
• • • • • • • •
Lr P
r free space path obstruction atmospheric gases multipath beam spreading variation of angle of arrival and launch Precipitation (rainfall) sand and dust storms
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
Rx
RF100 - 94
Link Budget Calculations
Lr = 1.5 dB
Lt = 1.5 dB f = 18 GHz
Tx
Rx d = 12 km
Pt = 23 dBm
Gt = 38 dBi
Gr = 38 dBi
Pr = Pt - Lt + Gt - Lp + Gr - Lr
Pr = ? dBm
dBm
Lp = 92.45 + 20 log(18) + 20 log(12) = 119.11 dBm Pr = 23 - 1.5 + 38 – 119.11 + 38 - 1.5 = -23dBm
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 95
Path Loss Calculations The simplest propagation mode • Antenna radiates energy which spreads in space – Lp or Path Loss, db (between two isotropic antennas) = 36.56 +20*Log10(F MHZ)+20Log10(Dist MILES ) – Lp or Path Loss, db (between two dipole antennas) = 32.26 +20*Log10(F MHZ)+20Log10(Dist MILES ) – Lp = Path Loss, db (between two isotropic antennas) = 92.45 (30+62.45) + 20 log(FGHz) + 20 log( Distance km)
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 96
Passive Repeater Configuration
Lt = 1.5 dB
Gt = 42 dBi d = 0.8 km
Tx Pt = 23 dBm
Gt = 38 dBi
1 dB f = 18 GHz
Lr = 1.5 dB d = 12 km
Rx Pr = ? dBm
November, 2014
Gt = 42 dBi
Gr = 38 dBi
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 97
RF propagation
Simple Path Analysis Concept (alternative)
+ Antenna Gain
+ Antenna Gain
- Path Loss over link Antenna
RF Cable
distance
- LOSS Cable/connectors
Antenna
- LOSS Cable/connectors Lightning Protector
Lightning Protector
pigtail cable
pigtail cable
PC Card
WP II
RF Cable
+ Transmit Power RSL (receive signal level) or P r> sensitivity + Fade Margin
PC Card
WP II
Calculate signal in one direction if Antennas and active components are equal
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 98
RF propagation FADE MARGIN
50 ft.LMR 400 24 dBi
3.4 dB
50 ft.LMR 400
24 dBi parabolic
3.4 dB
For a Reliable link - the signal arriving at the receiver - should be greater than the Sensitivity of the Radio (-82dBm for 11 Mbit) .7 dB
This EXTRA signal strength is FADE MARGIN
.7 dB
FADE MARGIN can be equated to UPTIME 1.3 dB
Tx =15 dBm
Minimum Fade Margin = 10 dB Links subject to interference (city) = 15dB
1.3 dB
Rx = -82 dBm
Links with Adverse Weather = 20dB WP II
November, 2014
Calculate RSL > -82 + 10 = -72dBm
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
WP II
RF100 - 99
RF propagation Sample Calculation 16 Km = - 124 dB
50 ft.LMR 400 24 dBi
3.4 dB
50 ft.LMR 400
24 dBi parabolic
3.4 dB
RSL > PTx - Cable Loss + Antenna Gain - Path loss + Antenna Gain - Cable Loss
+ 15 dBm .7 dB
- 2 dB - 3.4 dB
1.3 dB
+ 24 dBi - 124 dB
Tx =15 dBm
+ 24 dBi - 3.4 dB - 2 dB
WP II
November, 2014
This lets us know that if the Fresnel zone is clear, the Link should work. If RSL < than -72 then MORE GAIN is needed, using Higher Gain Antennas or Lower loss Cables or Amplifiers (not a Agere Systems provided option)
- 71.8 dB > -72
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
.7 dB
1.3 dB
Rx = -82 dBm
WP II
RF100 - 100
RF Propagation
Antenna Height requirements Fresnel Zone Clearance = 0.6 first Fresnel distance (Clear Path for Signal at mid point) • 30 feet for 10 Km path
Clearance for Earth’s Curvature •13 feet for 10 Km path •200 feet for 40 Km path
•57 feet for 40 Km path
Midpoint clearance = 0.6F + Earth curvature + 10' when K=1 First Fresnel Distance (meters) F1= 17.3 [(d1*d2)/(f*D)]1/2 where D=path length Km, f=frequency (GHz) , d1= distance from Antenna1(Km) , d2 = distance from Antenna 2 (Km) Earth Curvature h = (d1*d2) /2 where h = change in vertical distance from Horizontal line (meters), d1&d2 distance from antennas 1&2 respectively
Fresnel Zone Clearance
Antenna Height Obstacle Clearance
Antenna Height
Earth Curvature
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 101
RF Propagation Reflections
Signals arrive 180° out of phase ( 1/2 ) from reflective surface Cancel at antenna - Try moving Antenna to change geometry of link - 6cm is the difference in-phase to out of phase
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 102
Elements of Typical Measurement Systems Main Features Field strength measurement • Accurate collection in real-time • Multi-channel, averaging capability Location Data Collection Methods: • Global Positioning System (GPS) • Dead reckoning on digitized map database using on-board compass and wheel revolutions sensor • A combination of both methods is recommended for the best results Ideally, a system should be calibrated in absolute units, not just raw received power level indications • Record normalized antenna gain, measured line loss November, 2014
Wireless Receiver
PC or Collector
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
GPS Receiver Dead Reckoning
RF100 - 103
Typical Test Transmitter Operations Typical Characteristics • portable, low power needs • weatherproof or weather resistant • regulated power output • frequency-agile: synthesized Operational Concerns • spectrum coordination and proper authorization to radiate test signal • antenna unobstructed • stable AC power • SAFETY: – people/equipment falling due to wind, or tripping on obstacles – electric shock – damage to rooftop November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 104
Antennas for Wireless Systems Dipole
Isotropic Typical Wireless Omni Antenna
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 105
Understanding Antenna Radiation The Principle Of Current Moments
An antenna is just a passive conductor carrying RF current
Zero current at each end each tiny imaginary “slice” of the antenna does its share of radiating
TX
RX Maximum current at the middle Current induced in receiving antenna is vector sum of contribution of every tiny “slice” of radiating antenna Width of band denotes current magnitude
November, 2014
• RF power causes the current flow • Current flowing radiates electromagnetic fields • Electromagnetic fields cause current in receiving antennas The effect of the total antenna is the sum of what every tiny “slice” of the antenna is doing
• Radiation of a tiny “slice” is proportional to its length times the magnitude of the current in it, at the phase of the current
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 106
Polarization of an Antenna and its Effects Antenna 1 Vertically Polarized
Antenna 2 Horizontally Polarized Electromagnetic Field
TX current
RX almost no current
RF current in a conductor causes electromagnetic fields that seek to induce current flowing in the same direction in other conductors. The orientation of the antenna is called its polarization.
To intercept significant energy, a receiving antenna must be oriented parallel to the transmitting antenna • A receiving antenna oriented at right angles to the transmitting antenna is “cross-polarized”; will have very little current induced • Vertical polarization is the default convention in wireless telephony • In the cluttered urban environment, energy becomes scattered and “depolarized” during propagation, so polarization is not as critical • Handset users hold the antennas at seemingly random angles…..
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 107
Antenna Gain Antennas are passive devices: they do not produce power
• Can only receive power in one form and pass it on in another, minus incidental losses • Cannot generate power or “amplify”
Omni-directional Antenna
However, an antenna can appear to have “gain” compared against another antenna or condition. This gain can be expressed in dB or as a power ratio. It applies both to radiating and receiving A directional antenna, in its direction of maximum radiation, appears to have “gain” compared against a non-directional antenna Gain in one direction comes at the expense of less radiation in other directions Antenna Gain is RELATIVE, not ABSOLUTE
• When describing antenna “gain”, the comparison condition must be stated or implied November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
Directional Antenna RF100 - 108
Reference Antennas
Defining Gain And Effective Radiated Power Isotropic Radiator
• Truly non-directional -- in 3 dimensions • Difficult to build or approximate physically, Isotropic Antenna but mathematically very simple to describe • A popular reference: 1000 MHz and above – PCS, microwave, etc.
Dipole Antenna
• Non-directional in 2-dimensional plane only • Can be easily constructed, physically practical • A popular reference: below 1000 MHz – 800 MHz. cellular, land mobile, TV & FM Quantity Gain above Isotropic radiator Gain above Dipole reference Effective Radiated Power Vs. Isotropic Effective Radiated Power Vs. Dipole November, 2014
Units dBi dBd (watts or dBm) EIRP (watts or dBm) ERP
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
Dipole Antenna Notice that a dipole has 2.15 dB gain compared to an isotropic antenna. RF100 - 109
Radiation Patterns
Key Features And Terminology An antenna’s directivity is expressed as a series of patterns The Horizontal Plane Pattern graphs the radiation as a function of azimuth (i.e..,direction N-E-S-W) The Vertical Plane Pattern graphs the radiation as a function of elevation (i.e.., up, down, horizontal) Antennas are often compared by noting specific landmark points on their patterns:
• -3 dB (“HPBW”), -6 dB, -10 dB points • Front-to-back ratio • Angles of nulls, minor lobes, etc.
Typical Example
Horizontal Plane Pattern Notice -3 dB points 0 (N) 0 -10 -20 -30 dB 270 (W)
10 dB points Main Lobe
nulls or a Minor minima Lobe Front-to-back Ratio
180 (S)
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 110
90 (E)
How Antennas Achieve Their Gain Quasi-Optical Techniques (reflection, focusing)
• Reflectors can be used to concentrate radiation – technique works best at microwave frequencies, where reflectors are small
• Examples: – corner reflector used at cellular or higher frequencies – parabolic reflector used at microwave frequencies – grid or single pipe reflector for cellular
Array techniques (discrete elements)
• Power is fed or coupled to multiple antenna elements; each element radiates • Elements’ radiation in phase in some directions • In other directions, a phase delay for each element creates pattern lobes and nulls November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
In phase
Out of phase
RF100 - 111
Types Of Arrays Collinear vertical arrays
• Essentially omnidirectional in horizontal plane • Power gain approximately equal to the number of elements • Nulls exist in vertical pattern, unless deliberately filled Arrays in horizontal plane
• Directional in horizontal plane: useful for sectorization • Yagi
RF power
– one driven element, parasitic coupling to others
• Log-periodic – all elements driven – wide bandwidth
RF power
All of these types of antennas are used in wireless November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 112
Omni Antennas
Collinear Vertical Arrays The family of omni-directional wireless antennas: Number of elements determines
Typical Collinear Arrays Number of Elements 1 2 3 4 5 6 7 8 9 10 11 12 13 14
• Physical size • Gain • Beamwidth, first null angle Models with many elements have very narrow beamwidths
• Require stable mounting and careful alignment • Watch out: be sure nulls do not fall in important coverage areas Rod and grid reflectors are sometimes added for mild directivity Examples: 800 MHz.: dB803, PD10017, BCR10O, Kathrein 740-198 1900 MHz.: dB-910, ASPP2933 November, 2014
Power Gain 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Gain, dB 0.00 3.01 4.77 6.02 6.99 7.78 8.45 9.03 9.54 10.00 10.41 10.79 11.14 11.46
Angle n/a 26.57° 18.43° 14.04° 11.31° 9.46° 8.13° 7.13° 6.34° 5.71° 5.19° 4.76° 4.40° 4.09°
Vertical Plane Pattern beamwidth -3
d B
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
Angle of first null
RF100 - 113
Sector Antennas
Reflectors And Vertical Arrays Typical commercial sector antennas are vertical combinations of dipoles, yagis, or log-periodic elements with reflector (panel or grid) backing
• Vertical plane pattern is determined by number of vertically-separated elements – varies from 1 to 8, affecting mainly gain and vertical plane beamwidth
• Horizontal plane pattern is determined by: – number of horizontally-spaced elements – shape of reflectors (is reflector folded?)
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
Vertical Plane Pattern Up
Down Horizontal Plane Pattern N
W
E
S
RF100 - 114
Cassegrain antenna • • •
Less prone to back scatter than simple parabolic antenna Greater beam steering possibility: secondary mirror motion amplified by optical system Much more compact for a given f/D ratio
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 115
Horn antenna • Rectangular or circular waveguide flared up • Spherical wave fronts from phase centre • Flare angle and aperture determine gain
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 116
Example of Commercial Antennas
November, 2014
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 117
Model
Gain
Length
HG2401RD-MC
1 dBi
2.2 in.
2.4 GHz 1 dBi MC-Card Right Angle Plug Mini WLAN Rubber Duck Antenna
HG2401RD-MMCX
1 dBi
2.1 in.
2.4 GHz 1 dBi MMCX Right Angle Plug Mini WLAN Rubber Duck Antenna
HG2402RD-RSF
2.2 dBi
4.7 in.
2.4 GHz 2.2 dBi RP-SMA WLAN Rubber Duck Antenna with Tilt-&-Swivel Connector
HG2403RD-RSF
3 dBi
5.4 in.
2.4 GHz 3 dBi RP-SMA WLAN Rubber Duck Antenna with Tilt-&-Swivel Connector
HG2403RD-RTF
3 dBi
5.6 in.
2.4 GHz 3 dBi RP-TNC WLAN Rubber Duck Antenna with Tilt-&-Swivel Connector
HG2403RD-NM
3 dBi
5.8 in.
2.4 GHz 3 dBi N-Type Male WLAN Rubber Duck Antenna with Tilt-&-Swivel Connector
HG2405RD-RSP
5.5 dBi
8.2 in.
2.4 GHz 5.5 dBi RP-SMA WLAN Rubber Duck Antenna with Tilt-&-Swivel Connector
HG2405RD-RTP
5.5 dBi
8.4 in.
2.4 GHz 5.5 dBi RP-TNC WLAN Rubber Duck Antenna with Tilt-&-Swivel Connector
HG2405RD-NM
5.5 dBi
8.7 in.
2.4 GHz 5.5 dBi N-Type Male WLAN Rubber Duck Antenna with Tilt-&-Swivel Connector
HG2407RD-RSP
7 dBi
13 in.
2.4 GHz 7 dBi RP-SMA High Performance WLAN Rubber Duck Antenna with Tilt&-Swivel Connector
HG2407RD-RTP
7 dBi
13.2 in.
2.4 GHz 7 dBi RP-TNC High Performance WLAN Rubber Duck Antenna with Tilt&-Swivel Connector
HG2407RD-SM
7 dBi
10.6 in.
2.4 GHz 7 dBi SMA-Male High Performance WLAN Rubber Duck Antenna with Tilt-&-Swivel Connector
HG2407RD-NM
7 dBi
11 in.
2.4 GHz 7 dBi N-Male High Performance WLAN Rubber Duck Antenna with Tilt&-Swivel Connector
HG2409RD-RSP
9 dBi
15.19 in.
2.4 GHz 9 dBi RP-SMA High Performance WLAN Rubber Duck Antenna with Tilt&-Swivel Connector
HG2409RD-RTP
9 dBi
15.2 in.
2.4 GHz 9 dBi RP-TNC High Performance WLAN Rubber Duck Antenna with Tilt&-Swivel Connector
HG2409RD-NM
9 dBi
15 in.
2.4 GHz 9 dBi N-Male High Performance WLAN Rubber Duck Antenna with Tilt&-Swivel Connector
November, 2014
Description
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 118
Example of radiation patterns
Vertical (E)- Elevation
November, 2014
Horizontal (H) Azimuth
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
RF100 - 119
Example Of Antenna Catalog Specifications Electrical Data ASPP2933 1850-1990 3/5.1 GSM • Bandwidth scalable for incremental transition in existing spectrum • MBMS (Multimedia Broadcast Multicast Service) to allow about 16 TV channels simultaneously in 5 MHz. at efficiency of about 1 b/s/hz RF100 - 382
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
LTE The Evolved Packet System (EPS) is purely IP based. Both real time services and datacom services are carried by the IP protocol. • An outside IP address is allocated when the mobile is switched on and released when it has been switched off for some time. The new LTE radio signal uses OFDMA (Orthogonal Frequency Division Multiple Access) to handle high data rates and volumes. • High order modulation (up to 64QAM), large bandwidth (up to 20 MHz) and MIMO transmission on the downlink (up to 4x4) is also available. Up to 170 Mbps on uplink and 300 Mbps on the downlink! The EPC core network can inter-work with Non-3GPP access such as WiMAX, WiFi, CDMA and EV-DO. • Non 3GPP access solutions can be treated as trusted or non-trusted (using independent security) based on operator requirements. The LTE access network (“RAN”) is simply a network of base stations (eNodeBs) in a flat architecture. There is no centralized intelligent controller, and the eNBs are normally inter-connected by the X2-interface and connected towards the core network by the S1-interface. Distributing intelligence among eNodeBs speeds up connection set-up and handovers, especially critical for some types of user traffic. RF100 - 383
RF Bootcamp - Course RF100 v10.0 - (c) 2014 Tonex
November, 2014
LTE vs. LTE Advanced Characteristic Peak Data Rate Latency: Spectral Width Peak Spectral Efficiency Control-Plane User Capacity
LTE
LTE Advanced
DL: 100 Mbps UL: 50 Mbps C-Plane:
View more...
Comments
