stallings charts modified and added to1 antennas, electromagnetic propagation, fading effects, and...
TRANSCRIPT
Stallings charts modified and added to
1
Antennas, Electromagnetic Propagation, Fading Effects, and Channel Coding
Session 4
Nilesh Jha
General Frequency Ranges Microwave and Millimeter Wave frequency range
Roughly 1 GHz to 20 GHz; 20 GHz to 300 GHz The higher the frequency the higher the beam directionality (antenna gain) for
a given antenna size Used for point to point and satellite communications, but also in lower ranges
for PCS (so far up to 2GHz) and WLAN (so far up to 6 GHz)
Radio frequency range --- VHF and UHF (plus) 30 MHz to 1 GHz Easier to do omni transmission Broadcasting, radio mobile services, cellular
Infrared frequency range --- short range Roughly, 3x1011 to 2x1014 Hz Useful in local point-to-point and to multipoint applications within confined
areas
Fixed Terrestrial Microwave Description of common microwave antenna
Parabolic dish, a few feet or meters in diameter Fixed rigidly and focuses a narrow beam Achieves line-of-sight transmission to receiving antenna Located at substantial heights above ground level
Applications --- Fixed Wireless Long haul telecommunications service Short point-to-point links between buildings Wireless Local Loop --- to Homes or Businesses
Satellite Microwave Description of communication satellite
Microwave relay station Used to link two or more ground-based microwave
transmitter/receivers Receives transmissions on one frequency band (uplink),
amplifies or repeats the signal, and transmits it on another frequency (downlink)
Applications Television distribution Long-distance telephone transmission Private business networks
Broadcast Radio Description of broadcast radio antennas
Omnidirectional Antennas not required to be dish-shaped Antennas need not be rigidly mounted to a precise
alignment Receive antennas often dipoles
Applications Broadcast radio
VHF and part of the UHF band; 30 MHZ to 1GHz Covers FM radio and UHF and VHF television
Cellular, PCS and WLAN Frequencies in the 800 MHz to 1000 MHz range for
cellular --- also called First Generation or 1G PCS and DCS called 2G --- Frequencies around 1800 to
2000 MHz range WLAN around 2400 MHz, also around 5.5 GHz Cell phone antennas are short dipoles, base station
antennas longer dipoles and combinations for some gains Finding more spectrum
Some around 1700 MHz, also down at TV UHF bands Up to around 2700 MHz
Lower frequencies propagate better and penetrate buildings more, but less spectrum
Antennas -- Basic An antenna is an electrical conductor or
system of conductors Transmission - radiates electromagnetic energy
into space Reception - collects electromagnetic energy
from space In two-way communication, the same
antenna can be used for transmission and reception
Radiation Patterns Radiation pattern
Graphical representation of radiation properties of an antenna
Depicted as two-dimensional cross section Beam width (or half-power beam width)
Measure of directivity of antenna Reception pattern
Receiving antenna’s equivalent to radiation pattern
Types of Antennas Isotropic antenna (idealized)
Radiates power equally in all directions Dipole antennas
Half-wave dipole antenna (or Hertz antenna) Quarter-wave vertical antenna (or Marconi
antenna) Parabolic Reflective Antenna
Antenna Gain Antenna gain
Power output, in a particular direction, compared to that produced in any direction by a perfect omnidirectional antenna (isotropic antenna)
Effective area Related to physical size and shape of antenna
Antenna Gain Relationship between antenna gain and effective
area
G = antenna gain Ae = effective area f = carrier frequency c = speed of light (» 3 ´ 108 m/s) = carrier wavelength
2
2
2
44
c
AfAG ee
Ground Wave Propagation Follows contour of the earth Can Propagate considerable distances Frequencies up to 2 MHz Example
AM radio
Sky Wave Propagation Signal reflected from ionized layer of atmosphere
back down to earth Signal can travel a number of hops, back and forth
between ionosphere and earth’s surface Reflection effect caused by refraction Examples
Amateur radio CB radio
Line-of-Sight Propagation Transmitting and receiving antennas must be within
line of sight Satellite communication – signal above 30 MHz not reflected
by ionosphere Ground communication – antennas within effective line of
site due to refraction Refraction – bending of microwaves by the atmosphere
Velocity of electromagnetic wave is a function of the density of the medium
When wave changes medium, speed changes Wave bends at the boundary between mediums
Line-of-Sight Equations Optical line of sight
Effective, or radio, line of sight
d = distance between antenna and horizon (km) h = antenna height (m) K = adjustment factor to account for refraction,
rule of thumb K = 4/3
hd 57.3
hd 57.3
Line-of-Sight Equations Maximum distance between two antennas
for LOS propagation:
h1 = height of antenna one
h2 = height of antenna two
2157.3 hh
LOS Wireless Transmission Impairments Attenuation and attenuation distortion Free space loss Noise Atmospheric absorption Multipath Refraction Thermal noise
Attenuation Strength of signal falls off with distance over
transmission medium Attenuation factors for unguided media:
Received signal must have sufficient strength so that circuitry in the receiver can interpret the signal
Signal must maintain a level sufficiently higher than noise to be received without error
Attenuation is greater at higher frequencies, causing distortion
Free Space Loss Free space loss, ideal isotropic antenna
Pt = signal power at transmitting antenna
Pr = signal power at receiving antenna = carrier wavelength d = propagation distance between antennas c = speed of light (= 3x10^ 8 m/s)
where d and are in the same units (e.g., meters)
2
2
2
2 44
c
fdd
P
P
r
t
Free Space Loss Free space loss equation can be recast:
d
P
PL
r
tdB
4log20log10
dB 98.21log20log20 d
dB 56.147log20log204
log20
df
c
fd
Free Space Loss Free space loss accounting for gain of other
antennas
Gt = gain of transmitting antenna
Gr = gain of receiving antenna
At = effective area of transmitting antenna
Ar = effective area of receiving antenna
trtrtrr
t
AAf
cd
AA
d
GG
d
P
P2
22
2
224
Free Space Loss + Antenna Gains Free space loss accounting for gain of other
antennas can be recast as (Note: usually the antenna gains/losses are added separately)
rtdB AAdL log10log20log20
dB54.169log10log20log20 rt AAdf
)G10log(G-dB 56.147
log20log20)log(104
log20
tr
dfGG
c
fdtr
Real Distance Dependence 20xlog(d) comes from 1/d^2 propagation, spherical
propagation of wavefront
In reality propagation is through many multipath channels, with fading effects, scattering around obstacles, etc
Effective distance dependence is 10xnxlog(d)
n is propagation index, environment dependent n is usually 3-5, 4 is not too far off
Thermal Noise Thermal noise due to agitation of electrons Present in all electronic devices and
transmission media Cannot be eliminated Function of temperature Particularly significant for satellite
communication
Thermal Noise Amount of thermal noise to be found in a
bandwidth of 1Hz in any device or conductor is:
N0 = noise power density in watts per 1 Hz of bandwidth
k = Boltzmann's constant = 1.3803x10-23 J/K T = temperature, in kelvins (absolute temperature)
W/Hz k0 TN
Thermal Noise Noise is assumed to be independent of frequency Thermal noise present in a bandwidth of B Hertz
(in watts):
or, in decibel-milliwatts (dBm)
TBN k
BTN log10 log 10k log10
Blog10(NF) log 10dBm 114
Where T=NFxTsub0, and Tsub0=290 degrees KNF is effective noise figure of device
Noise Terminology Intermodulation noise – occurs if signals with
different frequencies share the same medium Interference caused by a signal produced at a frequency
that is the sum or difference of original frequencies Crosstalk – unwanted coupling between signal
paths Impulse noise – irregular pulses or noise spikes
Short duration and of relatively high amplitude Caused by external electromagnetic disturbances, or
faults and flaws in the communications system
Expression Eb/N0
Ratio of signal energy per bit to noise power density per Hertz
B=bandwidth So SNR and Eb/N0 related through B/R The bit error rate for digital data is a function of Eb/N0
Given a value for Eb/N0 to achieve a desired error rate, parameters of this formula can be selected
As bit rate R increases, transmitted signal power must increase to maintain required Eb/N0
RBSNRRBBN
S
RBN
SB
N
RS
N
Eb /*/*/
0000
Other Impairments and Effects Atmospheric absorption – water vapor and oxygen make it
worse at higher frequencies --- typically some 10-20 GHz, worse higher, some ‘windows’ around 35-40 GHz and 95 GHz
Multipath – obstacles reflect signals so that multiple copies with varying delays are received -- see fig 5.10 next
Particularly important in cellular or any path that does not have a direct line of sight, or where objects near LOS path
Diffraction -- Bending of radio waves around obstacles and corners
Refraction -- Bending by atmosphere (like lenses) due to varying index of refraction at different heights, places
Multipath Propagation Reflection - occurs when signal encounters a
surface that is large relative to the wavelength of the signal
Diffraction - occurs at the edge of an impenetrable body that is large compared to wavelength of radio wave
Scattering – occurs when incoming signal hits an object whose size in the order of the wavelength of the signal or less
The Effects of Multipath Propagation Multiple copies of a signal may arrive at
different phases If phases add destructively, the signal level
relative to noise declines, making detection more difficult --- Fading
Intersymbol interference (ISI) One or more delayed copies of a pulse may
arrive at the same time as the primary pulse for a subsequent bit
Types of Fading Due to multiple paths arriving at receiver and
adding constructively and destructively in a random basis
Fast fading due to small variations in path lengths as one moves or as
scatterers move -- often modeled as Rayleigh Slow fading -- shadow fading
Slower, as one moves and blockage and objects in between change -- often modeled as a log normal distribution
Error Control Process--and Error Minimization
Error control process has three components Error minimization Error detection Error correction --- FEC (Forward Error Correction)
Error minimization: modulation/coding techniques to minimize effects of noise/fading, interleaving to scramble bits (fight off effects of error ‘bursts’), equalization vs fading effects, and diversity vs fading effects
Coding done for error detection (eg, CRC) and for error correction (FEC codes: convolutional, block)
Automatic repeat request (ARQ) protocols Block of data with error is discarded, data retransmitted -- not for voice Requires error detection
Wireless Re-transmission ARQ Protocols Often inadequate for wireless applications
Error rate on wireless link can be high, results in a large number of retransmissions
Long propagation delay compared to transmission time --- lots of frames in transit
Not good for voice, possible for data if FEC is used first to have errors less often
Forward Error Correction (FEC) Required to offset channel induced errors Sometimes referred to as ‘channel coding’ Transmitter adds error-correcting code to data block
Code is a function of the data bits Receiver calculates error-correcting code from incoming data
bits If calculated code matches incoming code, no error occurred If error-correcting codes don’t match, receiver attempts to determine
bits in error and correct Codes are in fact able to correct
Channel Coding FEC used to code to offset effects of propagation -- eg
multipath fading Since fading goes in and out, when power down FEC used to
try to offset the lower SNR Involves insertion of additional FEC bits Block Codes -- similar to CRC, but are able to correct 1,
2 or more errors, depending on size of block (number of bits added) and code strength (Hamming distance)
Convolutional Codes -- combines the the bits to be corrected ---- uses Viterbi decoding
Interleaving --- used to mix bits in to minimize the effects of error bursts
Error Detection Probabilities Definitions
Pb : Probability of single bit error (BER)
P1 : Probability that a frame arrives with no bit errors
P2 : While using error detection, the probability that a frame arrives with one or more undetected errors
P3 : While using error detection, the probability that a frame arrives with one or more detected bit errors but no undetected bit errors (ie, all errors detected)
Error Detection Probabilities With no error detection
F = Number of bits per frame
0
1
1
3
12
1
P
PP
PP Fb
Error Detection Process Transmitter
For a given frame, an error-detecting code (check bits) is calculated from data bits
Check bits are appended to data bits Receiver
Separates incoming frame into data bits and check bits Calculates check bits from received data bits Compares calculated check bits against received check
bits Detected error occurs if mismatch
Parity Check Parity bit appended to a block of data Even parity
Added bit ensures an even number of 1s Odd parity
Added bit ensures an odd number of 1s Example, 7-bit character [1110001]
Even parity [11100010] Odd parity [11100011]
Cyclic Redundancy Check (CRC) Transmitter
For a k-bit block, transmitter generates an (n-k)-bit frame check sequence (FCS)
Resulting frame of n bits is exactly divisible by predetermined number
Receiver Divides incoming frame by predetermined
number If no remainder, assumes no error
CRC using Modulo 2 Arithmetic Exclusive-OR (XOR) operation Parameters:
T = n-bit frame to be transmitted D = k-bit block of data; the first k bits of T F = (n – k)-bit FCS; the last (n – k) bits of T P = pattern of n–k+1 bits; this is the predetermined
divisor Q = Quotient R = Remainder
CRC using Modulo 2 Arithmetic For T/P to have no remainder, start with
Divide 2n-kD by P gives quotient and remainder
Use remainder as FCS
FDT kn 2
P
RQ
P
Dkn
2
RDT kn 2
CRC using Modulo 2 Arithmetic Does R cause T/P have no remainder?
Substituting,
No remainder, so T is exactly divisible by P
P
R
P
D
P
RD
P
T knkn
22
QP
RRQ
P
R
P
RQ
P
T
CRC using Polynomials Widely used versions of P(X)
CRC–12 X12 + X11 + X3 + X2 + X + 1
CRC–16 X16 + X15 + X2 + 1
CRC – CCITT X16 + X12 + X5 + 1
CRC – 32 X32 + X26 + X23 + X22 + X16 + X12 + X11 + X10 + X8 + X7 + X5 + X4
+ X2 + X + 1
Block Error Correction Codes Transmitter
Forward error correction (FEC) encoder maps each k-bit block into an n-bit block codeword
Codeword is transmitted; analog for wireless transmission
Receiver Incoming signal is demodulated Block passed through an FEC decoder
FEC Decoder Outcomes No errors present
Codeword produced by decoder matches original codeword
Decoder detects and corrects bit errors Decoder detects but cannot correct bit
errors; reports uncorrectable error Decoder detects no bit errors, though errors
are present
Block Code Principles Hamming distance – for 2 n-bit binary sequences,
the number of different bits E.g., v1=011011; v2=110001; d(v1, v2)=3
Redundancy – ratio of redundant bits to data bits Code rate – ratio of data bits to total bits Coding gain – the reduction in the required Eb/N0
to achieve a specified BER of an error-correcting coded system
Hamming Code Designed to correct single bit errors Family of (n, k) block error-correcting codes with
parameters: Block length: n = 2m – 1 Number of data bits: k = 2m – m – 1 Number of check bits: n – k = m Minimum distance: dmin = 3
Single-error-correcting (SEC) code SEC double-error-detecting (SEC-DED) code
Cyclic Codes Can be encoded and decoded using linear
feedback shift registers (LFSRs) For cyclic codes, a valid codeword (c0, c1, …, cn-1),
shifted right one bit, is also a valid codeword (cn-1, c0, …, cn-2)
Takes fixed-length input (k) and produces fixed-length check code (n-k) In contrast, CRC error-detecting code accepts arbitrary
length input for fixed-length check code
BCH Codes For positive pair of integers m and t, a (n, k)
BCH code has parameters: Block length: n = 2m – 1, m greater than 2 Number of check bits: n – k mt Minimum distance:dmin 2t + 1
Can correct combinations of t or fewer errors Flexibility in choice of parameters
Block length, code rate
Reed-Solomon Codes Subclass of nonbinary BCH codes Data processed in chunks of m bits, called symbols An (n, k) RS code has parameters:
Symbol length: m bits per symbol Block length: n = 2m – 1 symbols = m(2m – 1) bits Data length: k symbols Size of check code: n – k = 2t symbols = m(2t) bits Minimum distance: dmin = 2t + 1 symbols Can correct t or fewer errors
Convolutional Codes Generates redundant bits continuously Error checking and correcting carried out
continuously (n, k, K) code
Input processes k bits at a time Output produces n bits for every k input bits K = constraint factor k and n generally very small
n-bit output of (n, k, K) code depends on: Current block of k input bits Previous K-1 blocks of k input bits
Decoding Trellis diagram – expanded encoder diagram Viterbi code – error correction algorithm
Compares received sequence with all possible transmitted sequences
Algorithm chooses path through trellis whose coded sequence differs from received sequence in the fewest number of places
Once a valid path is selected as the correct path, the decoder can recover the input data bits from the output code bits
Some Use of Codes CRC used often to detect uncorrectable errors in a frame, for
an ARQ function on data as last choice Reed-Solomon code used in CDPD Coding gain is determined by change in Eb/Nsub0 that gives
same BER -- few dB eg, 2.77 dB in Fig 8.6 Stallings at ber of 10^-5
IS-95 uses convolutional codes, as do most cellular systems, using Viterbi decoding
Bit error rates : Raw channel BER is about 10^-1 or 10^ -2 Voice needs 10^-2 or 10^-3, so coding needs to do this For data one often needs about 10^-6 --- in 3G a concatenated coding
scheme, with RS block coding and convolutional coding
Block Interleaving -- Time Diversity Data written to and read from memory in different orders Data bits and corresponding check bits are interspersed
with bits from other blocks At receiver, data are deinterleaved to recover original
order A burst error that may occur is spread out over a number
of blocks, making error correction possible Used in 2G and 3G systems --- speech coders produce
important bits in succession, interleaving spreads them out over time, codes can correct them
Automatic Repeat Request Mechanism used in data link control and
transport protocols Relies on use of an error detection code
(such as CRC) Flow Control Error Control
Multipath Induced Effects Causes fading (amplitude variations and deep ‘nulls’) and
ISI (copies of symbols come in delayed and overlap next symbol) -- fading is both fast (msec) and slow (seconds)
Fast is rapid variations, slow is shadowing Flat fading is for narrowband channels
BW (signal)<(Coherence) BW of channel, eg, AMPS Fast fading, ‘handled’ somewhat with coding and diversity
Frequency selective fading BW (signal)>(Coherence) BW of channel, eg, TDMA, GSM, CDMA Causes ISI, some fading but not as bad as it averages out some Fast fading ‘handled’ well with coding and diversity
Time diversity in Rake receivers for CDMA (combines multi path energies
ISI handled with equalizers in TDMA/GSM CDMA codes separate multi path returns so no mixing, can combine
Adaptive Equalization for ISI Used to combat intersymbol interference (ISI) caused by multipath Involves gathering dispersed symbol energy back into its original time interval Dispersion determined by maximum time delay spread
Represents the time over which one symbol will affect other symbols Large variation, environment dependent
Outdoors in 5-20 usecs range, maybe to 100 usec Indoors smaller, maybe to .1 to 1 usec At 30kbps one bit is 33 usec long, so if delay spread is 100 usec it causes interference with 3 bits
Even if delay spread is 10 usec it interferes with first third of next bit At 200 kbps one bit is 5 usec long so 10 usec spread interferes with 2 bits
The higher the data rate the worse the ISI effect is -- A BROADBAND EFFECT Channel coherence bandwidth Bc=(approx) 1/5x(RMS delay spread)
For delay spread = 4 usec (say), Bc=50 KHz, so AMPS at 30 KHz (so less) does NOT need equalizer but GSM at 200 KHz DOES
Equalization Techniques Need to be adaptive since channel is unknown -- at receiver
Digital signal processing algorithms, called equalizers, that estimate the channel transfer function and reverse its effects --- involves an estimate of the channel via a known symbol sequence transmitted which is then compared at receiver with stored replica
Estimate channel: training and tracking Equalizer is a time varying filter whose weights are adapted based on
channel estimate --- often implemented as adaptive transversal (FIR) filter Algorithms: weights to minimize estimated error, eg, least mean squares Linear and nonlinear -- nonlinear needed if deep nulls due to multipath NL: Decision feedback (subtracts detected symbol), maximum likelihood
(tests all possible data sequences and picks best --- lots of computation) Also possible but not as robust: blind algorithms, based on eg, keeping
envelope constant on constant envelope modulations (eg, GSM)
Diversity Techniques Diversity is based on the fact that individual channels experience independent
fading events Space diversity – techniques involving multiple physical transmission paths --
eg, multiple antennas Most base stations have two diversity receive antennas for this reason Rapaport p.327, can go from 90% prob. of not fading to 99% w/2, or 99.99% w/4 diversity
antennas, by selecting the strongest one Smart antennas can collect most of the energy from different multipaths
Frequency diversity – techniques where the signal is spread out over a larger frequency bandwidth or carried on multiple frequency carriers --- CDMA DS spreads energy over a larger BW, affects frequency diversity
Time diversity – techniques aimed at spreading the data out over time --- eg, bit repetition, interleaving, Rake processing (in CDMA)
FEC coding often thought of as a form of time diversity
LINK BUDGETS FOR WIRELESS SYSTEMS
Budget for Link: IS 95 CDMA Forward Traffic Channels
NUMBER CATEGORY BUDGET ITEM LABEL VALUE UNITS OTHER NOTES
1 Transmitter1.1 Power Transmit Power Pt 40.00 dBm 10 W1.2 Antenna Tr. Antenna Gain Gt 17.20 dBi1.3 Loss Polarization Loss Ltp 0.00 dB and Body Losses1.4 Loss Cable Loss Ltc 2.90 dB1.5 Gain Beamforming Gain Gtbf 0.00 dB1.6 Gain Other Gain Gto 0.00 dB1.7 EIRP Transmitter EIRP EIRP 54.30 dBm Effective Radiated Power
1.8 ChannelsNumber Channels per Carrier Ncc 14.00 #
Number channels allocated power at Bit Rate
1.9 Percent PowerChannel Percent Power Allocation Pac 0.64 #
Percent allocated to all channels at Bit Rate -- Traffic channels
1.10 EIRP/Channel EIRP/Channel EIRPc 40.90 dBm
2 Signal Waveform2.1 Bandwidth Carrier Bandwidth Bc 1.25 MHz2.2 Modulation Modulation Type ModT QPSK Text2.3 SNR Required Eb/No Eb/N0 7.50 dB For BER2.4 Frequency Band Frequency Band Fb 1900.00 MHz2.5 Center Frequency Center Frequency Fc 1900.00 MHz
3Propagation Loss Estimate
3.1Reference Distance Reference Distance R0 0.10 Km
3.2 Reference LossPropagation Loss Reference PL(R0) 7.00 dB
At distance R0 (change to 1m for picocells)
3.3 Frequency Factor Frequency Loss Factor PL(f) 65.58 dBFor Frequency Band, 20*log(f^2), f in MHz
3.4 Loss Index Loss Distance Index n 3.50 # For R^n Losses, from Rap.3.5 Cell Size Cell Size R 2.00 Km Planning Purposes3.6 Loss Other Loss Plo 0.00 dB
3.7 LossMean Estimated Propagation Loss Avg PL 118.11 dB Total Mean Estimated Loss
3.8 Loss Loss St. Deviation Sigma 8.00 dB From Rap.
3.9 Margin Fade Margin Mf 5.50 dB
Fade Margin for Approx. 90% Coverage (Rap. P.108)
Samplepg. 1
LINK BUDGETS FOR WIRELESS SYSTEMS
Budget for Link: IS 95 CDMA Forward Traffic Channels
NUMBER CATEGORY BUDGET ITEM LABEL VALUE UNITS OTHER NOTES4.1 Antenna Antenna Gain Gr 0.00 dBi4.2 Antenna Polarization Loss Lrp 2.00 dB and Body Losses if any4.3 Constant kTo kTo -174.00 dBm/Hz4.4 Receiver Noise Figure NF 10.00 dB Rx Design Parameter4.5 Data Rate Channel Data Rate Rc 14400.00 bps Channel Design
4.6 SNR Required Eb/N0 Eb/N0 7.50 dBMod/Demod/Coder Required Eb/N0 for FER
4.7 Error Rate Bit Error Rate BER # For FER below4.8 Error Rate Frame Error Rate FER 0.01 # For good voice quality4.9 Gain Coding Gain Gc 0.00 dB To lower further Eb/N0
4.10 GainDiversity/Beamforming Gain Grdbf 0.00 dB Beyond Gr
4.11 Loss Implementation Loss Lri 1.00 dB4.12 Loss Other Loss Lro 0.00 dB4.13 Voice Activity Voice Activity Factor VAF 0.50 # In multirate systems4.14 Receiver Receiver Sensitivity Sr -117.93 dBm
5 System5.1 Margin Fade Margin Mf 5.50 dB From 3.9
5.2 InterferenceInterference Loading Factor Lilf 1.00 dB Lib.& Rap. 2.8 in reverse
5.3 Gain Handoff Gain Gh 2.00 dB2-3 hard, 3-4 soft, often not taken
5.4 User Facility Loss User Facility Loss Luf 6.00 dB In car. 14 dB in bldg.5.5 Loss Loss Other Lo 0.00 dB5.6 System Losses Total System Losses Ls 10.50 dB
5.7Required Power at Receiver
Required Power at Receiver Req Pr -107.43 dBm Sr+Ls
5.8 Max Prop. LossMaximum Allowed Propagation Loss Max PL 148.33 dB To get Req. Pr
5.9Propagation Margin
Propagation Loss Margin PL Margin 30.22 dB
Can Be Used for More Range
5.10 Range Calc Log(Rmax/R) log(Rmax/R) 0.86 # From Prop. Loss Estimate5.11 Range Max Range Rmax 14.60 Km Possible Cell Size
Or Can Work Inside Building --- Needs 8 dB min.
Samplepg. 2