uplink downlink 20 MHz 36 MHz - Angelfire · Date / Place E. Nemer - 3 • The Digital Video...

Date / Place E. Nemer - 1

BPF Pre-amp TWTABPA

LOnoise density Ns

Satellite Rx ant GSR Ts PWN

Satellite Tx ant GST

Single transponder

36 MHz

20 MHz uplink downlink

36 MHz

Freq converter AGC


Direct Video Broadcast (DVB) Systems


• The Digital Video Broadcasting (DVB) specifications cover digital

services delivered via cable, satellite and terrestrial transmitters.

• The satellite flavor is DVB-S :

It’s intended to provide Direct-To-Home(DTH) broadcast.

Provides also collective antenna systems and cable television head-

end stations.

Designed to fit different satellite transponder bandwidths and is

compatible with Moving Pictures Experts Group 2 (MPEG 2) coded TV

services.

Enables the transmission capacity to be used for a variety of TV

service

DVB-S Introduction


MPEG-2 Multiplexers

Video Coder

Audio Coder

Data Coder1

2

n

Program Multiplexer

Transport

Multiplexer

Packetizer

Packetizer

Packetizer

Packetized

Elementary

Streams

Transport

Stream


The MPEG Transport Stream

•First byte of each PES packet must be the first byte of the transport packet payload

•Each transport packet must contain data from only one PES packet


Transport Stream Role

• Transport of all programming information

– All information that a particular provider transmits (on a particular

frequency)

• Minimize processing required for:

– Retrieval of coded data from one stream

– Extraction of transport stream packets of one or more transports and

the output of a new transport stream

– Enabling the transport and recovery of a stream over a lossy

environment


Two Types of Transport Streams

• Simple Program Transport

Stream (SPTS)

– Different PES share a

common time base

– The different PES could

carry video, audio and

data

– Example would be a movie

transmitted with multiple

languages

• Multiple Program

Transport Stream (MPTS)

– Carries multiple SPTS

Multi Program TS

Carrying Single Program

TS

1. MPTS 2. MPTS 3. MPTS

1. SPTS 2. SPTS 3.SPTS

1. PES 2. PES 3.PES

ES

Network

Single Program TS

Carrying Packetized ES

Packetized ES Forming

Elementary Stream


MPEG-2 Transport Packet Header

Transport

Scrambling Control

(2 bits)

Transport Packet

Header

(4 Bytes)

Sync Byte

(8 bits)

Transport Error

Indicator

(1 bit)

Payload Unit

Start Indicator

(1 bit)

Transport

Priority

(1 bit)

PID(13 bits)

Adaptation

Field

(variable Size)

Data Bytes

(variable Size)

Adaptation Field

Control

(2 bits)

Continuity

Counter

(4bits)

MPEG-2 Systems Transport Packet (188 Bytes)

Transport Packet Header (4 Bytes)

Transport packets are 188 bytes because MPEG-2 required these packets to be carried across ATM (188 bytes = 4 ATM cells)


MPEG Program Streams

• A group of tightly coupled PES packets referenced to a

common time base

• Intended for transmission in a relatively error-free

environment

– Enable easy software processing of the received data

• Used for video playback and some network applications


Transport Layer PIDs


MPEG Signaling Tables

• PAT - Program Association Table

– Lists the PIDs of tables describing each program. The PAT is sent with the PID value of 0x000.

• CAT - Conditional Access Table

– Defines type of scrambling used and PID values of transport streams which contain the conditional access management and entitlement information (EMM). The CAT is sent with the PID value of 0x001.

• PMT - Program Map Table

– Defines the set of PIDs associated with a program, e.g. audio, video…,

• NIT - Network Information Table

– PID=10, contains details of the bearer network used to transmit the MPEG multiplex, including the carrier frequency

• DSM-CC - Digital Storage Media Command and Control

– messages to the receivers


DVB Signaling Tables

• BAT- Bouquet Association Table

– Groups services into logical groups

• SDT- Service Description Table

– Describes the name and other details of services

• TDT - Time and Date Table

– PID=14, provides present time and date

• RST - Running Status Table

– PID=13, provides status of a programmed transmission, allows

for automatic event switching

• EIT - Event Information Table

– PID=12, provides details of a programmed transmission


Transport multiplex adaptation and randomization for energy dispersal

Outer coding(i.e. Reed-Solomon)

Convolutional interleaving

Basebandshaping formodulation

Modulation.

DVB-S Transmitter


DVB-S Transmitter


Transport Packet


Transport Stream Multiplexer


DVB Scrambler/Descrambler

p(n-14) +p(n-15)

x(n) y(n)

y(n) = x(n) + p(n-14) + p(n-15)

Self descrambling:

y(n) = x(n) + p(n-14) + p(n-15) + p(n-14) + p(n-15)

= y(n)


• It facilitates the work of a timing recovery circuit, by

eliminating long sequences consisting of '0' or '1' only.

• It eliminates the dependence of a signal's power spectrum

upon the actual transmitted data,

– Making it more dispersed to meet maximum power spectral density

requirements

– If the power is concentrated in a narrow frequency band, it can

interfere with adjacent channels caused by non-linearities of the

receiving tract).

Purposes of Scrambling


19

Randomized Transport Packets


Reed-Solomon Encoding

• The code is specified as an RS(n,k) with m-bit symbols.

– E.g. the DVB code is RS(204,188) using 8-bit symbols.

– n refers to the number of encoded symbols in a block,

– k refers to the number of original message symbols.

• The difference n-k ( called 2t) is the number of parity

symbols that have been appended to make the encoded

block.


Reed Solomon RS(204,188,t=8) error protected packet.


R-S Performance

• An RS decoder can correct up to (n-k)/2 or t symbols,

• Any t symbols can be corrupted in any way, and the original

symbols can be recovered.

• The DVB code

– splits the message into blocks 188 symbols long.

– 16 parity symbols (2t = 204-188 = 16) are then appended to produce the

full 204 symbol long code.

• Up to 8 (t = 16/2) symbol errors can then be corrected


R-S Performance

• With the DVB code, a sequence of up to 56 consecutive bits could be

corrupted affecting at most 8 symbols, and the original message could

still be recovered.

– However it does mean that RS codes are relatively sensitive to evenly spaced

errors

– i.e. in the DVB code if 9 symbols have a single bit error then no corrections

can be made.

– Therefore the RS encoded block is further encoded in a Convolutional code to

try and cope with both burst and random errors.


Framing Structure


Interleaved Frames (Interleaving depth I=12).


Convolutional Interleaver

A convolutional interleaver consists of a set of shift registers, each with afixed delay. In a typical convolutional interleaver, the delays arenonnegative integer multiples of a fixed integer (although a generalmultiplexed interleaver allows arbitrary delay values). Each new symbolfrom the input signal feeds into the next shift register and the oldestsymbol in that register becomes part of the output signal. The schematicbelow depicts the structure of a convolutional interleaver by showing theset of shift registers and their delay values D(1), D(2),...,D(N). The blocks inthis library have mask parameters that indicate the delay for each shiftregister. The delay is measured in samples.


Interleaver


Interleaving Operation

120091106810357024001

Columnsby Readout :

1296300

0118520

0010741

:

delay)Clock (2Register Third Input to

delay)Clock (1Register Second Input to

delay) (noRegister First Input to

12963

11852

10741

:

121110987654321

o

BS

B

S

Output

S

Shifting

S

Blocking

S


De-Interleaving Operation

121110987654321000000

Columnsby Readout :

1296300

1185200

1074100

:

delay)Clock (0Register Third Input to

delay)Clock (1Register Second Input to

Clock) (2Register First Input to

1296300

0118520

0010741

:

120091106810357024001

o

BS

B

o

S

Output

S

Shifting

S

Blocking

S


Convolutional Encoder

Input Bit Stream

To Q Channel

To I Channel


Convolutional Code Definition

Punctured Code Definition


Punctured Code


Puncturing Pattern & Transmission Sequence

Code Rates Puncturing patternTransmitted sequence

(after parallel-to-serial conversion)

1/2 X: 1

Y: 1 X 1Y1

2/3 X: 1 0

Y: 1 1 X1 Y1 Y2

3/4 X: 1 0 1

Y: 1 1 0 X1 Y1 Y2 X3

5/6 X: 1 0 1 0 1

Y: 1 1 0 1 0 X1 Y1 Y2 X3 Y4 X5

7/8 X: 1 0 0 0 1 0 1

Y: 1 1 1 1 0 1 0 X1 Y1 Y2 Y3 Y4 X5 Y6 X7


Punctured Convolutional Code Block Diagram


Baseband Shaping

for

for

where:

is the Nyquist frequency and = 0.35 (roll-off).


QPSK and OQPSK Modulators


• The 2-dimensional QPSK modulation

is used to create 4 or 8 symbols.

• The modulated signal can be

expressed in a polar form as

)2

2cos()()(M

itftpsAtS eei

• We can use M quantized levels of , to create a variety of PSK modulation.

• M=2, makes this a BPSK, M=4 is QPSK, M=8, 8PSK and so on.

• In DVB-S the modulation required is QPSK.

• In DVB-S2 the modulation possible are QPSK, 8QPSK, 16APSK, 32 APSK

2

DVB-S Modulation


DVB-S - Bit rates versus transponder bandwidth

• The transmission symbol rate Rs can be matched to given transponder

characteristics

• Achieving the maximum transmission capacity compatible with the acceptable

signal degradation due to transponder bandwidth limitations

• The following table gives examples of the useful bit rate capacity Ru

achievable on a satellite transponder with bandwidth BW corresponding to

BW/Rs = 1,28.


BPF Pre-amp TWTABPA

LOnoise density Ns

Satellite Rx ant GSR Ts PWN

Satellite Tx ant GST

QAM modulator Earth

Station 1

BW = B1 < W

ERP P1

GT

i

iP

Other sources destined to the same transponder (TWTA)

Single transponder

Interfering sources

36 MHz

20 MHz uplink downlink

36 MHz

Freq converter

LNB

noise density Ng

Tuner

12 GHz

Demod

~1 GHz

GR

I, Q

Total path loss

AGC

Total gain gP

WNWNPPP gSTsatr

STgsat GPP

Antennadist. net


Non-linearity AM-AM and AM-PM curves are

given by TWTA specs. Distortion

is function of input backoff

(IBO), which can be as low as 0

dB.

Optus data sheet suggest

that when 2 carriers are

used per TWTA, the backoff

is > 20 dB, which makes

non-linearity very minor.

I/Q imbalance +/- 1.5 dB amplitude;

+/- 3 deg in phase

Tuner data sheets

(Broadcomm, Infineon,

Maxim).

Frequency Error - From transponder frequency

translation : +/- 25 kHz

- From LNB at user site

- From crystals at Rx (50 ppm)

Intelsat restriction for 1st

Doppler shift +/- 2kHz worst case

Tuner Phase noise -55 dBc/Hz @ 1 kHz

-75 dBc/Hz @ 10 kHz

-90 dBc/Hz @ 100 kHz

Tuner data sheets

(Broadcomm, Infineon,

Maxim).

LNB Phase noise Same order as Tuner’s LNB sheets

(CaliforniaAmplifiers,

GOSPELL).

Multipath profile -10 dBc @ 26 – 30 nsec.

-15 dBc @ 51 – 55 nsec

-20 dBc @ 76 – 80 nsec

-25 dBc @ 11 – 115 nsec

(std docs)


Maximum Power 37 dBW typical Satellite specs (eg :

OPTUS)

Output backoff [0: 20] dB depending on nb

carriers / TWTA

Satellite specs

Path loss attenuation * 206 dB free space loss;

* 0.8 dB receive antenna loss

Weather-induced

attenuation

An additional degradation of 3 to

6 dB in signal strength

An additional degradation of 3 to

15 dB in C/N

Satellite specs (eg : IESS

308)

Delay variation 175 nsec per sec Intelsat VA and VI

Adjacent satellite (Co-

chan)

40 dB Optus data sheets

Intermod noise [ 24 : 14] dB , depending on

output backoff points of TWTA

(14 dB for 1 dB OBO, and 24 dB

for 6 dB OBO)

TWTA data sheet

dBN

Eb 5.7:5.40


TWTAdistortion

Microreflections

I / Q Imbalance

Weatherattenuat

Freq Err

Timingjitter

TWTAPhase Noise

Intermodproducts

Inband QAMinterference(adj satellites)

AWGN Antenna Temperaturenoise

LNBPhase Noise

AdjacentChannelInterf

Tx Nyq

Tx(I+jQ) symbols

Rx Nyq

Rx

(I+jQ) symbols

Modeling

TunerPhase Noise


Tuner

AGCAFCNCO

I / Qbalancing

TimingRecovery

FFE

PLL

FBE

SlicerEqualizer

De-RandomizerA rsdecA

De-interleaverconv_dec

Channel De-coding

MPEG sync

SymbTo

bits

bits

bytes

1 samp/symb

2->4Samples/symbol Behavioral algorithmic

AFCestim

LPFADC

ADC

(I + j Q)

Baseband I & Q


ADC

EnergyEstimate/correction

AGC

Functions : estimate and correct energy on I, Q inputs thru tuner feedback

Input is I and Q from tuner Sampling rate is [2 : 4] samples / symbolsCorrection : variable current output to the Tuner (only IF gain control)

AnalogGain

H(z)

gain

EnergyEstimate/correction

AGC

digitalGain

H(z)

ADC gain

6-8 bits 6 - 8 bits

Real System Model

Tuner


digitalGain

6 bits

5 - 10 bits

Nominal Energy

11 z

Integrator

abs

abs

S1.411

1

z

S2.7S2.7

Parameter Format Bits

Input, Output

S1.4 S2.7

6

10

Constants S0.9 10

Tuner gain fct

10 bits

Output (10 bits)

Q

I

16 bits

S2.7


AGC gain

Mag

Acquisition

Time (samples)


I / Qcorrection

2.5 to 4Samples/symbol

2.5 to 4Samples/symbol

Q’

H(z)

1

1

EstimateMag Err

Estimatephs Err

I’T_I’

T_Q’

(I + j Q)

CorrectPhase

H(z)


Equalizer out

Equalizer out

with IQ balancing

without IQ balancing

Rx Input with IQ imbalance


NCOError

Detector

12-20 taps Tsym/2

ResamplerLoopFilter

Nyquist Filter

Output symbols

error

S2.7

S2.7

10 bits

20 bits

})5.0()]1()(Re{[

)(

nxnxnx

ne

S3.16

10 bits

Timing error

Notes• N : Nyquist taps, typically 12 to 20• Resampler, Nyquist filter and error detector operate at

2*Fsym.• Loop filter operates at Fsym.• NCO operates at Fsamp, typically Fsam=2.5*Fsym


• Number of iterations to reach steady state decreases when first order loop gain increases.

• AWGN variance does not affect significantly the number of iterations to reach steady state.

Acquisition Time


FFE

PLL

FBE

Slicer

Equalizer

• CMA : • Opens the eye ; QPSK : gain control • Blind : error criteria based on preset radius

• CMA / PLL • Stops the rotating constellation (due to freq / phase offset)• Uses CMA to update the FFE filter

3 stages…enabled sequencially

(I + j Q) (I + j Q)

1 samp/symb 1 samp/symb

• LMS / PLL • Decision-directed• Uses the CMA taps as a starting FFE• Continues a locked-on phase


FFE filter

-

2S

grad

16 bits

S1.14

R

16 bits

S2.7

10 bits

S2.7

10 bits

W

16 taps

S0.20(16 effect)

Input symbols

22)( Rnyn *)()()( knxnnynGradk

)()()1( nGradnwnw kkk


AWGN : Eb/No = 7.5

FreqOff: Fs/400


FFE filerSlicer

-

2S

*je

grad

10 bits

S0.11

S2.7

10 bits

R

15 bits

16 bits

10 bits16 taps

Input symbols

LoopFilter

VCOPhase Detector

PLL

12 bits

next page


11 z

1z

Loop filter

S0.5

12 bits

VCO

gainS0.12

6 bits

LoopFilter

VCOPhase Detector

2

*

d

dr

y

yyimerr

Phase detector

slicer in

slicer out

PLL

15 bits


FFE filer

Phase Detector

Slicer

11 z

1z

*jeLoop filter

LMS

S0.5

15 bits

12 bits

S0.11

16 bits

S1.14

VCO

gainS0.12

FBE filer

LMS

Output symbols

*je

Error16 bits

Error16 bits

10 -12 bits

16 taps

6 bits

Input symbols

15 bits

12 bits

Nf

Nb


FreqOff: Fs/400

4 Reflections : @ 36, 55, 85, 155 nsec


• DVB-S2 is the second-generation specification for satellite broadcasting – developed

by the DVB (Digital Video Broadcasting) Project in 2003.

• Use a powerful FEC system based on LDPC (Low-Density Parity Check) codes

concatenated with BCH codes.

• Take advantage for combined with a variety of modulation formats (QPSK, 8PSK,

16APSK and 32APSK).

• For interactive applications, such as Internet navigation, it may implement Adaptive

Coding & Modulation (ACM), thus optimizing the transmission parameters for each

individual user.

• The DVB-S2 system has been designed for several satellite broadband applications

- Broadcast services for SDTV and HDTV

- Interactive services, including Internet access

- Digital TV contribution and News Gathering.

- Data content distribution and Internet trunking.

DVB-S2 – Overview


• Broadcast Services- digital multi-programme Television (TV) / High

Definition Television (HDTV) broadcasting services to be used for

primary and secondary distribution in Fixed Satellite Service (FSS)

and Broadcast Satellite Service (BSS) bands.

(Including compatibility to MPEG-4)

• Digital TV Contribution and Satellite News Gathering (DTVC/DSNG)

• Interactive Services- Interactive data services including Internet

access (only the forward broadband channel)

• Data content distribution/trunking and other professional

applications (only the forward broadband channel)

DVB-S2 – Overview


Performance Comparison

0

0.5

1

1.5

2

2.5

3

3.5

0 2 4 6 8 10 12

Eb / No

Bit

s/S

ec

/Hz

DVB-S and DSNG DVB-S2

2.5dB = 33% more useful data rate, or 2.5m Vs. 4.5m antenna

2.5 dB margin gain

signal-to-noise ratio

DVB-S2 – Overview


13 SDTV MPEG2

26 SDTV h.264

10 SDTV MPEG2

20 SDTV h.264

10 SDTV MPEG2

21 SDTV h.264

7 SDTV MPEG2

15 SDTV h.264

3 HD MPEG2

6 HD h.264

2 HD MPEG2

5 HD h.264

2 HD MPEG2

5 HD h.264

1 HD MPEG2

3 HD h.264

58.8 Mbps (+32%)44.4 Mbps46 Mbps (+36%)33.8 Mbps

8PSK 23QPSK 7/8QPSK 3/4QPSK 2/3

29.7 Mbauds

(ROF 0.25)

27.5 Mbauds

(ROF 0.35)

30.9 Mbauds

(ROF 0.20)

27.5 Mbauds

(ROF 0.35)

DVB-S2DVB-SDVB-S2DVB-S

SATELLITE EIRP 53.7 dBWSATELLITE EIRP 51 dBW

Typical 36MHz transponder usage with DVB-S and DVB-S2:

Number of HD channels

Number of SD channels

Bit rate

Modulation

Symbol Rate

Roll-Off factor

DVB- S - S2 – Evolution


Subject DVB-S DVB-DSNG DVB-S2

FEC Reed-Solomon &

Viterbi

Reed-Solomon &

Viterbi

LDPC

FEC rates 0.46 – 0.81 0.46 – 0.81 0.25 - 0.9

FEC Performance 2-2.5 dB better

Modulation BPSK, QPSK QPSK,8PSK,16QAM QPSK,8PSK,16APSK,32A

PSK

Max Spectral Efficiency 1.61 3.22 4.44

Block size ~ 32Kbit ~ 32Kbit 64Kbit , 16Kbit

Roll-off 0.35 0.35, 0.25 0.35, 0.25, 0.20

CCM/VCM/ACM CCM CCM VCM/ACM (for IP data)

Implementation

Complexity

Low Medium Very High

Stream adaptation MPEG MPEG MPEG & programmable

DVB- S - S2 – Evolution


• Powerful FEC system based on LDPC (Low-Density Parity Check) codes

• Wide range of code rates (from 1/4 up to 9/10)

• New Modulation schemes ranging from 2 to 5 bit/second/Hz spectrum

efficiency - QPSK, 8PSK, 16APSK, 32APSK

• Set of three spectrum shapes with roll-off factors 0.35, 0.25 and 0.20

• Flexible stream adapter, suitable to operate with single and multiple TS on

the same carrier with different modulation and FEC

• Variable & Adaptive Coding and Modulation (VCM/ACM) functionality,

allowing to optimise channel coding and modulation on a frame-by-frame

basis.

DVB-S2 – Overview


-3dB

35%

25%

-26dB

20%

DVB-S2 – Spectral Shape


Non-uniform 8PSK constellationHierarchical QPSK

Sending, on a single Satellite channel, two Transport Streams - Hierarchical QPSK

• HP (High Priority) DVB-S (QPSK) – modulate for DVB-S

• LP (Low Priority) DVB-S2 (BPSK) ) – modulate for DVB-S2

Example: At QPSK ¾ it can add up to 17Mbps for new programs in DVB-S2. (36Mhz TP)

DVB-S2 – Hierarchical Modulation


00

I

Q

10

11 01

Q=LSB I=MSB

000

I

Q

011

111

001

LSB

MSB

101

010

110

100

text

1100

1101 1111

1110

0000

0100

0101

0001

1001 1011

0011

0111

0110

0010

1010 1000

I

Q

= R2 / R1

LSB

MSB

R1

R2

text

10001

10011 10111

10101

00000

10000

10010

00010

00011 00111

00110

10110

10100

00100

00101 00001

I

Q

=R2 / R1

=R3 / R1

LSB

MSB

R1

R2

R3

11000

01000

11001

01001 01101

11101

01100

11100

11110

01110

11111

01111 01011

11011

01010

11010

QPSK2 bits/symbol

8PSK3 bits/symbol

16APSK4 bits/symbol

32APSK5 bits/symbol

DVB-S2 – Constellations


• The System is defined as the functional block of equipment performing the

adaptation of the baseband digital signals.

• The System is designed to support source coding MPEG delivered directly

over IP protocols.

• If the received signal is above the C/N+I threshold, the Forward Error

Correction (FEC) technique adopted in the System is designed to provide

"less than one uncorrected error-event per transmission hour at the level of

a 5 Mbit/s single TV service decoder.

DVB-S2 – System Definition


• Mode Adaptation Block

- It shall provide input stream interfacing, Input Stream Synchronization (optional), null-packet deletion (for ACM and Transport Stream input format only), CRC-8 coding for error detection at packet level in the receiver.

• Scrambler Block.

- Provide padding to complete a Base-Band Frame and Base-Band Scrambling.

• BCH Codes Block.

- In technical terms a BCH code is a multilevel cyclic variable-length digital error-correcting code used to correct multiple random error patterns.

- The principal advantage of BCH codes is the ease with which they can be decoded, via an elegant algebraic method known as syndrome decoding.

• LDPC Code Block.

- LDPC codes are a type of error-correcting code invented in the early 60's

- Low-density parity check codes are codes specified by a matrix.

DVB-S2 – Operations


• Encoding shall be carried out by the concatenation of BCH outer codes and LDPC (Low Density Parity Check) inner codes (rates 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 8/9, 9/10) .

• This sub-system shall perform outer coding (BCH), Inner Coding (LDPC) and Bit interleaving .

• Input stream shall be composed of BBFRAMEs and the output stream of FECFRAME, each BBFRAME (Kbch bits) shall be processed by the FEC coding subsystem, to generate a FECFRAME

• The parity check bits (BCHFEC) of the systematic BCH outer code shall be appendedafter the BBFRAME, and the parity check bits (LDPCFEC) of the inner LDPC encodershall be appended after the BCHFEC field

DVB-S2 – FEC, Forward Error Correction


Table Coding parameters for normal FECFRAME 64800ldpcn

Table Coding parameters (for normal FECFRAME 16200ldpcn

DVB-S2 – System Definition


CCM Constant Coding and Modulation

All frames use the same (fixed) parameters

VCM Variable Coding and Modulation

Different streams/services are coded with different (fixed)

parameters on the same carrier

ACM Adaptive Coding and Modulation

Each frame is coded with its own set of parameters. Parameters

are modified dynamically according to the reception conditions for

each receiver

DVB-S2 Operation Mode


• QPSK, 8PSK, 16APSK and 32APSK

constellations shall be applied, depending on

the application area

• Shall be applied, to shape the signal spectrum

(squared-root raised cosine, roll-off factors

0,35 or 0,25 or 0,20) and to generate the RF

signal..

• The roll-off factor, , is a measure of the excess

bandwidth of the filter.

• The graph shows the amplitude response as

is varied between 0 and 1, and the

corresponding effect on the impulse response.

uplink downlink 20 MHz 36 MHz - Angelfire · Date / Place E. Nemer - 3 • The Digital Video...

Documents

Transcript of uplink downlink 20 MHz 36 MHz - Angelfire · Date / Place E. Nemer - 3 • The Digital Video...