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BROADBAND WIRELESS NETWORKING

VIEWS: 4 PAGES: 89

  • pg 1
									SIGNAL MODULATION
        for
 MULTIMEDIA DATA
   TRANSMISSION


with special emphasis on wireless

          MULTIMEDIA SYSTEMS
              IREK DEFEE
•   Content:
-   SIGNAL MODULATION
    TECHNIQUES
-   RADIO WAVE PROPAGATION
-   WIRELESS SYSTEMS
-   WIRELESS DATA TRANSPORT
-   SOURCE AND CHANNEL CODING
    (WHICH WE ARE NOT COVERING)


            MULTIMEDIA SYSTEMS
                IREK DEFEE
SIGNAL MODULATION TECHNIQUES:
HOW TO OVERLAY BITS OR STREAMS OF
BITS ON A SIGNAL TO CARRY THEM?

FOR MULTIMEDIA TRANSMISSION WE
NEED TO TRANSFER A LOT OF DATA
THUS, WE NEED TO PACK THE DATA
EFFICIENTLY ON TRANSMISSION
CARRIER ( WHICH CAN BE RADIO WAVES,
ELECTRIC CURRENT, PHOTONS)

             MULTIMEDIA SYSTEMS
                 IREK DEFEE
        Let’s start from the beginning:
            Sinusoidal Waveform
• The signal at frequency around fc:
            s(t) = Acos(2pfct + q)
• To encode digital symbol of {0, 1},
  –   One can encode using the amplitude A
  –   One can encode using the phase q
  –   One can encode using the frequency fc
  –   Use some combination of amplitude, phase, or
      frequency.

                   MULTIMEDIA SYSTEMS
                       IREK DEFEE
        Let’s start from the beginning:
            Sinusoidal Waveform
• The signal at frequency around fc:
            s(t) = Acos(2pfct + q)
• To encode digital symbol of {0, 1},
  –   One can encode using the amplitude A
  –   One can encode using the phase q
  –   One can encode using the frequency fc
  –   Use some combination of amplitude, phase, or
      frequency.

                   MULTIMEDIA SYSTEMS
                       IREK DEFEE
Amplitude-Shift Keying (ASK)
   Change amplitude A




                              CARRIER


         MULTIMEDIA SYSTEMS
             IREK DEFEE
                    ASK (cont.)

• The signal is

                2 Eb
      s1 t        cos( 2pf c t )       0  t  Tb
                 Tb
      s2 t   0




                     MULTIMEDIA SYSTEMS
                         IREK DEFEE
Phase-shift Keying (PSK)
    Change phase q




       MULTIMEDIA SYSTEMS
           IREK DEFEE
                    PSK (cont.)

• Signal is

              2 Eb
    s1 t        cos( 2pf c t )         0  t  Tb
               Tb
                2 Eb
    s2 t         cos( 2pf c t )       0  t  Tb
                 Tb



                     MULTIMEDIA SYSTEMS
                         IREK DEFEE
Frequency-shift keying (FSK)




         MULTIMEDIA SYSTEMS
             IREK DEFEE
                   FSK (cont.)

• Signal is

                 2 Eb
       s1 t        cos( 2pf1t )       0  t  Tb
                  Tb
                 2 Eb
       s2 t        cos( 2pf 2t )      0  t  Tb
                  Tb



                    MULTIMEDIA SYSTEMS
                        IREK DEFEE
HOW TO PUT MORE BITS ON THE CARRIER?
1. BY USING MORE PHASE SHIFTS E.G. 8-PSK




                                                HERE WE USE
                                                8 PHASE
                                                VALUES
                    FIGURE 1/V.29
                                                EACH VALUE
           Signal space diagram at 9600 bit/s
                                                ENCODES
                MULTIMEDIA SYSTEMS
                                                3 BITS
                    IREK DEFEE
2. BY USING MORE AMPLITUDE LEVELS
AND PHASE SHIFTS – EXAMPLE 16-QAM
                                       (Im)
                                        90°

                                       4
                               11111           11000

                                D
                       01000           00101           01010
                                       2
               10010           10101           10011           10100

       00000           01111           00010           01101    C      00011
180°                                                                           0° (Re)
        –4              –2                              2               4
               11001           11110           11010           11101

                A
       00111           01001           00110           01011           00100
                                       –2
               10000           10111           10001           10110
                                                                                   HERE EACH
                       01110       00001 B 01100

                             11100
                                   –4
                                        11011
                                                                                   PHASE/AMPLITUDE
                                       270°                 T1702150-93/d03
                                                                                   VALUE ENCODES
   NOTE – The binary numbers denote Y0n Y1n Y2 n Q3n Q4n .                            5 BITS
                               FIGURE 3/V.32
32-point signal structure with trellis coding for 9600 bit/s
and states A B C and D used at 4800 bit/s and for training



                                                  MULTIMEDIA SYSTEMS
                                                      IREK DEFEE
128-QAM EXAMPLE -COMBINATION OF AMPLITUDE
AND PHASE ENCODES SPECIFIC BIT PATTERN
                                                            90°       (Im)
                                                 0110000                     0111000
                                                                  8
                                            1100000   1111001         1101000     1110001

                                       0010011   0101001    0010111    0100001   0010101
                                                    D           6
                                  1011101   1000011   1011111     1000111   1011011   1000101

                         0110101       0001101   0110100    0001111    0111100    0001011    0111101
                                                                4
                    1100101       1111011   1100100    1111010    1101100   1110010    1101101    1110011

               0010001   0101011       0010010   0101010    0010110    0100010    0010100    0100011   0010000
                                                                2
                                                                                                C
        1011000     1000001       1011100   1000010    1011110    1000110   1011010    1000100    1011001   1000000

               0001000   0110111       0001100   0110110    0001110          0111110   0001010   0111111   0001001
                -8        -6            -4        -2                           2         4         6        8           (Re)

        180°        1100111       1111111   1100110    1111110        1101110    1110110    1101111   1110111         0°

               0011001   0101111       0011010   0101110    0011110    0100110   0011100   0100111    0011000
                              A                                 -2
        1010000     1001001       1010100   1001010    1010110    1001110   1010010   1001100   1010001     1001000

               0000000   0110011       0000100   0110010    0000110    0111010   0000010   0111011    0000001
                                                                -4
                    1100011       1111101   1100010    1111100    1101010   1110100   1101011   1110101

                         0101101       0011011   0101100    0011111    0100100   0011101   0100101
                                                                -6        B
                                  1010101   1001011    1010111    1001111   1010011   1001101

                                       0000101   0110001    0000111    0111001   0000011
                                                                -8
                                            1100001    1111000    1101001   1110000

                                                 0101000     270°            0100000                            T1701310-90



        Note – Binary numbers refer to Y0n , Y1n , Y2n , Q3n , Q4n , Q5n , Q6n .
        A, B, C, D refer to synchronizing signal elements.

                                                      FIGURE 2-1/V.32 bis
                           Signal space diagram and mapping for modulation at 14 400 bit/s per second



                                            MULTIMEDIA SYSTEMS
                                                IREK DEFEE
EXAMPLE OF NUMBERS ENCODING BY
SPECIFIC BIT PATTERNS
45

41
                                               408 396 394 400 414

                                398 375 349 339 329 326 335 347 359 386
                                                                                                                        These
37                    412 371 340 314 290 279 269 265 273 281 302 322 353 390                                           values of
                                                                                                                        signal are
33                401 357 318 282 257 236 224 216 212 218 228 247 270 298 337 378

29            406 350 306 266 234 206 185 173 164 162 170 181 197 220 253 288 327 379

25

21
              360 310 263 226 193 165 146 133 123 121 125 137 154 179 207 242 289 338 391

          384 324 277 229 189 156 131 110      96   87   83   92   100 117 140 172 208 254 299 354
                                                                                                                        encoded by specific
17        355 294 243 201 160 126    98   79   64   58   54   62   71   90   112 141 180 221 271 323 387                modulation
                                                                                                                        patterns
13    392 330 274 222 177 135 102    77   55   41   35   31   37   48   65   91   118 155 198 248 303 361

 9    380 316 255 203 158 119   84   60   39   24   17   15   20   30   49   72   101 138 182 230 283 348 415

 5

 1
      367 304 244 194 148 108

      362 296 238 186 142 103
                                75

                                69
                                     50

                                     43
                                          28

                                          22
                                               13

                                               9
                                                    6

                                                    1
                                                         4

                                                         0
                                                              8

                                                              5
                                                                   21

                                                                   16
                                                                        38

                                                                        32
                                                                             63

                                                                             56
                                                                                  93

                                                                                  85
                                                                                       127 171 219 275 336 402

                                                                                       122 163 213 267 328 395
                                                                                                                        on the previous
–3    365 300 240 190 144 106   73   45   25   11   3    2    7    18   36   59   88   124 166 217 272 331 397
                                                                                                                        page
–7    372 307 251 199 152 113   80   52   33   19   12   10   14   26   42   66   97   134 174 225 280 341 409

–11 388 320 261 210 167 128     94   67   47   34   27   23   29   40   57   81   111 147 187 237 291 351

–15 410 343 284 232 183 149 115      89   68   53   46   44   51   61   78   99   132 168 209 258 315 376

–19       369 311 259 214 175 139 116     95   82   74   70   76   86   104 129 157 195 235 285 342 399

–23       403 345 292 249 205 176 150 130 114 107 105 109 120 136 161 191 227 268 319 373

–27           382 332 287 250 215 184 169 153 145 143 151 159 178 202 231 264 308 358 413

–31               377 333 293 260 233 211 200 192 188 196 204 223 245 278 312 352 404

–35                   383 346 313 286 262 252 241 239 246 256 276 295 325 363 407

–39                        405 370 344 321 309 301 297 305 317 334 356 385

–43                                  411 389 374 366 364 368 381 393

      –43 –39 –35 –31 –27 –23 –19 –15 –11      –7   –3   1    5    9    13   17   21   25   29   33   37    41    45

                                                                                                      T1403000-97/d05



                     Figure 5/V.34 – One-quarter of the points in the superconstellation




                                     MULTIMEDIA SYSTEMS
                                         IREK DEFEE
• The more bits we put the better signal to
  noise must be (small phase and amplitude
  values are lost in noise)

How to put even more bits on a signal?


By using multicarrier modulation –
bits are overlayed on many carriers at the
same time.

                   MULTIMEDIA SYSTEMS
                       IREK DEFEE
• ONE USES MANY CHANNELS. EACH
  CHANNEL IS MODULATED E.G. WITH
  8 KBITS/S. WITH MANY CHANNELS
  OVERALL DATA RATE GROWS
• EACH CHANNEL CAN BE
  INDIVIDUALLY TUNED TO THE
  TRANSMISSION BANDWIDTH, E.G.
  SOME CHANNELS CAN BE SKIPPED
  COMPLETELY.

            MULTIMEDIA SYSTEMS
                IREK DEFEE
    Now we have many carriers
        s1 (t) = Acos(2pf1ct + q)
         s2 (t) = Acos(2pf2ct + q)
         s3 (t) = Acos(2pf3ct + q)
         ………………………
         sn (t) = Acos(2pfnct + q)
 The carriers are assumed to be close to each other
A
         f1c    ……………..                 fnc



                                                f
                  MULTIMEDIA SYSTEMS
                      IREK DEFEE
     How the overall modulated signal will
                    look ?
    In time domain            In frequency domain
    signals overlap            they also overlap




Example of four subcarriers       Spectra of individual subcarriers
       We have to add additional condition for
     signals in order to be able to separate them

     • This condition is orthogonality
                         1 ,   i j                                        1 , i  j
 xi  t x*  t  dt                          X i  f X *  f  df  
                                 i j                                         0 , i  j
             j                                                   j
                          0 ,

       In time domain                                   In frequency domain

     The carriers must satisfy these special conditions
     Then by summing and adding upp it will be possible
     to separate them
     This principle is called OFDM, ORTHOGONAL
     FREQUENCY DIVISION MULTIPLEX
                                        MULTIMEDIA SYSTEMS
                                            IREK DEFEE
• WHERE ARE THESE SIGNAL
MODULATION TECHNIQUES APPLIED?
1.   PSK, QPSK – GOOD FOR WEAK SIGNALS,
     APPLIED IN THE GSM MOBILE SYSTEM, ALSO IN
     DIGITAL TELEVISION FROM SATELLITES
2.   QAM – REQUIRES STRONGER SIGNALS,
     APPLIED IN DIGITAL CABLE TELEVISION
     AND IN THE EXTENSION OF GSM CALLED EDGE
3.   MULTICARRIER OFDM – APPLIED IN
     TERRESTRIAL DIGITAL TELEVISION, IN
     WIRELESS LAN, AND IN NEW 4G MOBILE
     NETWORK VERY EFFICIENT USE OF
     BANDWIDTH, CAN BE ADJUSTED FOR BAD
     SIGNAL PROPAGATION
                  MULTIMEDIA SYSTEMS
                      IREK DEFEE
          The OFDM modulation

• It uses radio bands very effectively
• Applications in wireless networks
  Digital Terrestrial Television: e.g. 8 000, 32 000
  Digital Mobile Television 4 000and 8 000 carriers
  Wireless LAN (802.11a/g): 52 carriers
  Ultra Wide Band: many carriers in many bands
  NEW 4th generation mobile system called LTE
  (Long Term Evolution)- thousands of carriers
                   MULTIMEDIA SYSTEMS
                       IREK DEFEE
      The OFDM modulation cntd.
• Applications in wired networks
ADSL – broadband networking over telephone lines

It seems OFDM is the winning signal modulation
technology for multimedia data transmission:
- it allows high data bandwidth and is robust
   against signal loss
- it is complicated but this is not a problem with
   current hardware and computer technology

                   MULTIMEDIA SYSTEMS
                       IREK DEFEE
  EXAMPLE OF APPLICATION OF
           OFDM :

               ADSL SYSTEM

      BROADBAND NETWORKING

                For the home

c@Irek Defée     MULTIMEDIA SYSTEMS
• NETWORKING FOR HOME HAS TO
   BE CHEAP AND DISTRIBUTED ON
   LARGE SCALE
• HOW TO MAKE IT?
 - LAYING NEW CABLES – NOT
   ECONOMICAL (MAYBE IN NEW
   BUILDINGS)
 - WIRELESS – BROADBAND NOT
   POSSIBLE (MAYBE IN THE
   FUTURE??)

c@Irek Defée   MULTIMEDIA SYSTEMS
• THE ONLY REALISTIC POSSIBILITY
  IS TO USE EXISTING CABLING

THERE ARE TWO TYPES OF EXTERNAL
CABLES FOR CARRYING INFORMATION
AVAILABLE IN HOMES:

TELEPHONE (ALMOST EVERYWHERE)
CABLE TV (IN MANY PLACES)


c@Irek Defée   MULTIMEDIA SYSTEMS
• TELEPHONE NETWORK IS DESIGNED AS
  NARROWBAND, CABLES ARE FOR
  SPEECH, 4kHz BAND
   BUT EVERYBODY HAS SEPARATE LINE

• CABLE TV IS DESIGNED AS BROADBAND
  BUT ALL USERS SHARE
  THE SAME CABLE (FOR TV SIGNAL)
IT LOOKS IMPOSSIBLE TO USE THEM



c@Irek Defée   MULTIMEDIA SYSTEMS
• WITH THE OFDM TECHNOLOGY THIS
  CAN CHANGE. TELEPHONE CABLE
  IS NARROWBAND BUT ITS BANDWIDTH
  IS NOT 4 kHz.
      Bandwidth of typical telephone cable:




               4kHz                  1 MHz
 ABOVE THE 4kHz CABLE BANDWIDTH IS VERY
 VARIABLE. IT IS DIFFERENT FOR EACH CABLE AND
 DEPENDS ON DISTANCE


c@Irek Defée          MULTIMEDIA SYSTEMS
• UNTIL RECENTLY UNEQUALIZED
  BANDWIDTH WAS NOT USEFUL,
  TOO MUCH SIGNAL DEGRADATION
• NEW SIGNAL PROCESSING
  TECHNIQUES ENABLE ITS USE




c@Irek Defée   MULTIMEDIA SYSTEMS
                 ADSL
ASYMMETRIC DIGITAL SUBSCRIBER LOOP

THE TECHNIQUE FOR USING ”BAD” CABLE
BANDWIDTH BASED ON

OFDM MULTICARRIER SIGNAL MODULATION




 c@Irek Defée   MULTIMEDIA SYSTEMS
                   ADSL IN
               TELEPHONE NETWORK
                                       MODEM

                  D
        TELEPHONE
                  S
        EXCHANGE L
                  A                        MODEM
                  M

                                       MODEM

  BROADBAND
            LINKS TO CUSTOMERSARE FEW KM
     LINK   LONG, CABLING IS NARROWBAND
            ADSL MODEMS ENABLE TO
            USE MORE BANDWIDTH
c@Irek Defée      MULTIMEDIA SYSTEMS
 MULTICARRIER MODULATION IN ADSL




                                      f
VOICE BAND
                            HIGH BAND
      4 kHz CARRIER CHANNELS
  EACH CHANNEL IS SEPARATELY MODULATED
  WITH A SIGNAL.

  SIGNAL LEVEL OF EACH CHANNEL CAN BE
  MATCHED TO THE GAIN AT ITS FREQUENCY
  c@Irek Defée   MULTIMEDIA SYSTEMS
• IN PRACTICAL SYSTEM ONE USES
  256 CHANNELS. EACH CHANNEL IS
  MODULATED WITH E.G. 32 KBITS/S
  IN TOTAL THIS GIVES 8 Mbits/sec !!!
• EACH CHANNEL CAN BE INDIVIDUALLY
   TUNED TO THE TRANSMISSION SIGNAL
   LEVEL, E.G. SOME CHANNELS CAN BE
   SKIPPED COMPLETELY.




c@Irek Defée   MULTIMEDIA SYSTEMS
   • COMPLETE SYSTEM



                                                      f
                    4 25 160 240 .....................1200 kHz
                   TEL.    UPSTREAM      DOWNSTREAM
                            DATA            DATA
                          FROM USER        TO USER

THE SYSTEM IS ASYMMETRIC, IT SENDS MORE
DATA DOWN THE LINE THAN UP (E.G. 256 kbits/s up)
BUT FOR HOME USERS THIS IS OK

    c@Irek Defée               MULTIMEDIA SYSTEMS
• THERE ARE VERY MANY DETAILS
  IN ADSL STANDARD:
- HOW THE CARRIERS ARE MODULATED?
  (QAM MODULATION)
- HOW THE MODULATION IS REALIZED?
  (512-POINT FFT)
- HOW THE ERROR CORRECTION IS
  PERFORMED? (FEC)
- HOW THE SIGNALS ARE
  SYNCHRONIZED? (PILOT TONE)



c@Irek Defée   MULTIMEDIA SYSTEMS
• THESE DETAILS CAN BE FOUND IN THE
  ADSL STANDARD AND OVERVIEWS ON
  THE WEB.

• ADSL IS NOW OFFERED
  COMMERCIALLY ON LARGE SCALE
  PRICES (ARE IN THE RANGE OF
  FEW TENS OF €/m FOR 1-8 Mb/s
  BANDWIDTH. THE SYSTEM WORKS
  VERY RELIABLY.


c@Irek Defée   MULTIMEDIA SYSTEMS
• BUT FROM PRACTICE IT IS KNOWN
  THAT ADSL HAS A PROBLEM TOO:

- BANDWIDTH OFFERED DEPENDS ON
  DISTANCE, CABLE QUALITY AND
  MAY VARY WIDELY




c@Irek Defée   MULTIMEDIA SYSTEMS
               New ADSL standards
• These are ADSL2 and ADSL2+. They
  provide improvements by:
- using higher signal power
- bonding several phone lines
- using greater bandwidth comparing to ADSL
  (up to 2.2 MHz)
- real time channel estimation and adaptation
  of bitrate to channel conditions




c@Irek Defée       MULTIMEDIA SYSTEMS
        ANOTHER EXAMPLE:
   Proposed Ultra Wide Band Network

• Ultra Wide Band is wireless network
   of very short range but with very
   high data transfer rate (600 Mb/s to
  1000 Mb/s and more)
This network can eliminate e.g. MONITOR
cable. Then mobile device can drive
the monitor directly.
              MULTIMEDIA SYSTEMS
                  IREK DEFEE
     UWB -Ultra Wideband Communication

• UWB system is proposed for high speed
  communication between devices, to
  eliminate cables:




c@Irek Defée    MULTIMEDIA SYSTEMS
                        Where is UWB?
Look around the show for various
 applications…


      Video
    Streaming                                        MP3 File Transfers


                               Print Files



                                                                Camera
                                                               Downloads
                                       Disk Backup
                  Movie                                 …and more!
                Transfers
 c@Irek Defée               MULTIMEDIA SYSTEMS
         What Problem Does UWB
                 Solve?
                        The Customer’s Frustration with Cables:
                        • Tangle of cables in our Homes and Offices
                        • Ever increasing file sizes of content to be
                          downloaded and enjoyed by Consumers
                        • Consumers don’t want to wait long for a file to
                          transfer
                        • User Models limited by the use of Cables
                        • Customers to-day prefer Wireless

           UWB is more than a Cable replacement technology

Create new User Models and product opportunities not possible today
                           with cables

                BUT…..MUST Match the Security of cables

                         MUST be easy to use
 c@Irek Defée              MULTIMEDIA SYSTEMS
                                The Vision:
             Creating new User Models and Product opportunities

          Personal
   Wireless Storage/Wallet
                                                                  Photo Printer
  Share video clips
   Music & Photos


                              SHARE and EXCHANGE
                              Create New User Models
                             not possible in the Cabled         Media Center
Photo & Video Clip                     World
     Display                  Connecting PC, CE and
                                 Mobile Segments




  In Car Media center
        & video                                           Multi Channel
                                                            Speakers


        c@Irek Defée             MULTIMEDIA SYSTEMS
        The Model that Consumers
                Expect
    Buy it           Plug it in       Use it…Easily!




• Compatible and Interoperable out of the box
• Many suppliers supporting a Common Standard at
  all levels of the ecosystem


c@Irek Defée     MULTIMEDIA SYSTEMS
            UWB opportunity

• If Ultra Wide Band networking becomes
  popular and monitors/TV’s will
  get it, then there will be no need to
  connect TV and monitor by cable
  to their signal sources. Mobile devices
  will display on them directly

               MULTIMEDIA SYSTEMS
                   IREK DEFEE
                 Imagine this
Mobile devices are more and
more capable (processors,
memory, hard discs), resembling
PC from few years ago

                                                   UWB
                                              Ultra Wide Band

                                    Mobile device has wireless
                                    links to keyboard and display

                                Bluetooth

                    MULTIMEDIA SYSTEMS
                        IREK DEFEE
               Principle of UWB

• Ultra wideband system uses very broad
  frequency band:




   There are UWB standards proposed which are based on
   several principles: One of them is MULTIBAND OFDM
   with many thousands of carriers.
c@Irek Defée      MULTIMEDIA SYSTEMS
                          UWB is Multi-band OFDM
  • Central Idea #1:
           – Divide the spectrum into bands that are 528 MHz wide.
       Band Group #1         Band Group #2             Band Group #3             Band Group #4      Band Group #5

Band      Band    Band    Band   Band   Band    Band      Band    Band    Band      Band    Band    Band   Band
 #1        #2      #3      #4     #5     #6      #7        #8      #9      #10       #11     #12     #13    #14




3432       3960    4488   5016   5544    6072    6600      7128    7656   8184       8712    9240   9768   10296
MHz        MHz     MHz    MHz    MHz     MHz     MHz       MHz     MHz    MHz        MHz     MHz    MHz     MHz
                                                                                                                    f




  • Advantages:
           – Transmitter and receiver process smaller bandwidth signals.
           – Instantaneous processing BW = 528 MHz.
                                             MULTIMEDIA SYSTEMS
                                                 IREK DEFEE
                  Exploiting the Band Plan
• Exploit range of band group’s to separate
  applications:
       Band Group #1         Band Group #2

Band      Band    Band    Band   Band   Band
 #1        #2      #3      #4     #5     #6




3432       3960    4488   5016   5544    6072
MHz        MHz     MHz    MHz    MHz     MHz
                                                             f




 Longer Range Apps
  Use BG #1 and #2
                                        MULTIMEDIA SYSTEMS
                                            IREK DEFEE
                     Exploiting the Band Plan

  • Exploit range of band group’s to separate
                                                 Band Group #3             Band Group #4
    applications:                         Band      Band    Band    Band      Band    Band
                                           #7        #8      #9      #10       #11     #12




3432   3960   4488   5016   5544   6072   6600       7128    7656   8184       8712    9240   9768   10296
MHz    MHz    MHz    MHz    MHz    MHz    MHz        MHz     MHz    MHz        MHz     MHz    MHz     MHz
                                                                                                             f




       `                                                    Shorter Range Apps
                                                             Use BG #3 and #4
                                     MULTIMEDIA SYSTEMS
                                         IREK DEFEE
           Overview of Multi-band OFDM

  • Central Idea #2:
       – Interleave OFDM symbols across all bands.
           3168
Band # 1
           3696
Band # 2
           4224
Band # 3
           4752
                                                                 Time
                  Freq (MHz)
  • Advantages:
       – Exploits frequency diversity.
       – Provide robustness against multi-path / interference.
       – Same transmit power as if the entire band is used.
                                MULTIMEDIA SYSTEMS
                                    IREK DEFEE
     IMPORTANT EXAMPLE

• EDGE – ENHANCED DATA RATE FOR
  GSM EXPANSION
TECHNIQUE FOR INCREASING THE BIT
RATE OF GSM SYSTEM BY USING
8-PSK.
IT IS ADOPTED FOR DATA TRANSFER
BUT REQUIRES MAJOR HARDWARE
UPGRADES IN THE SYSTEM
            MULTIMEDIA SYSTEMS
                IREK DEFEE
       CURRENT STATUS OF UWB

• Ultra Wide Band connections were
   demonstrated for television sets
•                        Television sets are
•                         becoming so thin
   that                   that there is no place
•                         for connectors
•                         Signal can be
transmitted by wireless UWB link.

                  MULTIMEDIA SYSTEMS
                      IREK DEFEE
         ANOTHER EXAMPLE
   Home Communication over Powerlines
• Powerlines are everywhere, in every room
  at home. There is a question if they could be used
  for data transmission. After very long development
  it looks that powerline communication will become
  available e.g. one can see products from:
              www.devolo.com



c@Irek Defée       MULTIMEDIA SYSTEMS
• The system is very simple to install:




c@Irek Defée     MULTIMEDIA SYSTEMS
• How this system operates?
It is based on a standard called Homeplug. For signal
transmission the band which is used is 2-28 MHz
with OFDM modulation. It has 917 carriers and
carriers can be independently modulated by
different modulations from PSK up to 1024 QAM
The maximum data rate can be up to 150 Mb/s,
practical rates are 40-85 Mb/s.
The standard has a lot of other details:
 www.homeplug.org

c@Irek Defée       MULTIMEDIA SYSTEMS
FURTHER EXAMPLES OF OFDM
    WIRELESS SYSTEMS

1. LTE – next generation mobile system
2. WiMax – next generation network
3. WLAN – local area network




              MULTIMEDIA SYSTEMS
                  IREK DEFEE
       LTE – Next mobile system after 3G

• LTE = Long Term Evolution
• Extension of 3G network
• Higher databandwith, uses OFDM
  modulation
• LTE is fully oriented to multimedia and
  advanced applications -> analyze next
  slide

c@Irek Defée      MULTIMEDIA SYSTEMS
c@Irek Defée   MULTIMEDIA SYSTEMS
                 LTE OFDM
• Orthogonal Frequency-Division Multiplexing




• FDM where carriers are appropriately spaced to insure
  orthogonality. Notice the overlap!!
• Spectrally efficient!!
 c@Irek Defée       MULTIMEDIA SYSTEMS
          OFDM signal in time and frequency




Please note that signals on different subcarriers (frequency axis)
carry modulation symbols (time axis). Modulation symbols
(QPSK or QAM) are separated by short breaks (guard intervals)

    c@Irek Defée          MULTIMEDIA SYSTEMS
LTE Parameters System to the User
  – How much data can be sent to the user
  – The system is very flaxible, has many parameters


                               1.25 MHz           2.5 MHz           5 MHz            10 MHz            15 MHz            20 MHz
     Transmission BW

    Sub-frame duration                                                            0.5 ms

    Sub-carrier spacing                                                           15 kHz

   Sampling frequency          1.92 MHz          3.84 MHz         7.68 MHz         15.36 MHz         23.04 MHz         30.72 MHz
                             (1/2  3.84 MHz)                    (2  3.84 MHz)    (4  3.84 MHz)    (6  3.84 MHz)    (8  3.84 MHz)

          FFT size                128                256              512              1024              1536              2048

   Number of occupied              76                151              301                601             901               1201
    sub-carriers†, ††

         Number of                                                                 7/6
      OFDM symbols
        per sub frame
      (Short/Long CP)

   CP length         Short    (4.69/9)  6,     (4.69/18)  6,   (4.69/36)  6,   (4.69/72)  6,    (4.69/108)  6,   (4.69/144)  6,
   (μs/samples)              (5.21/10)  1*     (5.21/20)  1    (5.21/40)  1    (5.21/80)  1     (5.21/120)  1     (5.21/160) 1

                     Long     (16.67/32)         (16.67/64)      (16.67/128)       (16.67/256)       (16.67/384)       (16.67/512)




 c@Irek Defée                                              MULTIMEDIA SYSTEMS
     LTE parameters User to the System
 How much data teh user can sent
                      Transmission BW                1.25        2.5 MHz      5 MHz              10 MHz      15 MHz       20 MHz
                                                     MHz

                      Timeslot duration                                               0.675 ms
                     Sub-carrier spacing                                              15 kHz

                     Sampling frequency              1.92        3.84 MHz    7.68 MHz             15.36       23.04        30.72
                                                     MHz                    (2  3.84 MHz)        MHz         MHz          MHz
                                                   (1/2  3.84                                   (4  3.84    (6  3.84    (8  3.84
                                                      MHz)                                         MHz)         MHz)         MHz)

                           FFT size                   128          256          512               1024         1536         2048

                    Number of occupied                76           151          301                601          901         1201
                     sub-carriers†, ††
                         Number of                                                       9/8
                      OFDM symbols
                        per Timeslot
                      (Short/Long CP)

               CP length (μs/samples)      Short   7.29/14       7.29/28      7.29/56            7.29/112    7.29/168     7.29/224

                                           Long    16.67/32      16.67/64    16.67/128         16.67/256     16.67/384    16.67/512

          Timeslot Interval (samples)      Short      18            36           72                144          216          288

                                           Long       16            32           64                128          192          256




c@Irek Defée                               MULTIMEDIA SYSTEMS
                   LTE modulation structure




In the LTE the channel width and number of carriers is flexible
 12 carriers form one resource block, 1 slot in time is 0.5 ms
and it carries 7 OFDM symbols, 1 subframe is 2 slots
    c@Irek Defée          MULTIMEDIA SYSTEMS
      LTE DATA TRANSFER CAPACITY

• There are so many parameters in the system
  that data transfer can be very flexibly adjusted.
  One can say that practically several tens of
  megabits per second is possible. Thus, LTE will
  be the first wide area wireless network with full
  multimedia data transfer capabilities




                   MULTIMEDIA SYSTEMS
                       IREK DEFEE
               WiMax Network

• New type of networks to be deployed in the
  near future
• Two types specified:
• One type of them is a substitute for ADSL,
  with wireless modems – fixed network
• Antoher type is full mobile network


c@Irek Defée     MULTIMEDIA SYSTEMS
                            WiMAX
•        World Interoperability for Microwave Access
•        There are two main applications of WiMAX:

         1) Fixed WiMAX (IEEE 802.16-2004) - Fixed WiMAX
            applications are point-to-multipoint enabling the
            delivery of last mile wireless broadband access as an
            alternative to cable and DSL for homes and
            businesses.

         2) Mobile WiMAX (IEEE 802.16e-2005) - Mobile
            WiMAX offers the full mobility of cellular networks
            at true broadband speeds.
    c@Irek Defée          MULTIMEDIA SYSTEMS
                    WiMAX
Fixed WiMAX Architecture




c@Irek Defée      MULTIMEDIA SYSTEMS
                    WiMAX
Mobile WiMAX Architecture




c@Irek Defée      MULTIMEDIA SYSTEMS
               WiMax Basics
• WiMax allows data transport over
  multiple broad frequency ranges
• WiMax’s transmission range and data
  rate vary significantly depending on the
  frequency bands an implementation uses
• Orthogonal frequency division
  multiplexing (OFDM)
• 10 to 66 GHz range
• 75 Mbits
c@Irek Defée    MULTIMEDIA SYSTEMS
               WiMax frequency bands
• IEEE 802.16a
  Spectrum: 2 to 11GHz
  More flexible while maintaining the technology’s
  data rate and transmission range
• IEEE 802.16b
  5 and 6 GHz frequency
  provides quality of service
  priority transmission for real-time voice and video
  and to offer differentiated service levels for
  different traffic types


c@Irek Defée         MULTIMEDIA SYSTEMS
           WiMax Technical Specifications


• OFDM modulation with 256 cariers, 192 useful
• Mobile WiMax 256 to 1024 carriers
• Modulation PSK, QPSK, 16 QAM, 64 QAM




c@Irek Defée        MULTIMEDIA SYSTEMS
                WiMax Data Rates




• Note: there are several channel bandwidths,
  many modulation types and OFDM carriers

 c@Irek Defée        MULTIMEDIA SYSTEMS
           WiMax Technical Specifications

• Up to 280 Mbps per base stations
• Base station transmission range up to 50 km
• True broadband for portable users - providing
  broadband connectivity for laptops and PDAs
  with integrated WiMax technology




c@Irek Defée        MULTIMEDIA SYSTEMS
               WiMax radio frequency bands
• 2.3 GHz, 2.5 GHz, 3.4 GHz, 3.6 GHz,
• 5.4 GHz, 5.8 GHz and possibly others
• such as 700 MHz and 900 MHz or even up to 66 GHz




c@Irek Defée           MULTIMEDIA SYSTEMS
                   WLAN
               WIRELESS LOCAL
               AREA NETWORK




c@Irek Defée      MULTIMEDIA SYSTEMS
           What is Wireless LAN?




c@Irek Defée     MULTIMEDIA SYSTEMS
               Wireless LAN Solution

                           • Extends the local area network
                           • Freedom to access the corporate network
                              - high-speed rates
                              - features comparable to those of wired
                                 networks
                           • Reliable communications in network
                             access areas
                              - meeting rooms
                              - other corporate offices
                              - airports
                              - hotels
                              - remote and home offices
                           • Secure access to important information
                              - e-mail
                              - corporate data
                              - the Internet



c@Irek Defée         MULTIMEDIA SYSTEMS
        How Does Wireless LAN Solution Work?
                     Wireless LAN PC Card
                     • Each wireless station and access point has a wireless LAN card
                     • Provides an interface between an end-user device and
                       radio waves


         +
                                                   Radio signal


                                                                                 Internet


Wireless LAN Access Point
• Connected to the wired network
• Acts as bridge between wireless
  and wired network                          E-mail       WWW        Firewall
• Enables high-performance                   server       server
  network access
      c@Irek Defée                    MULTIMEDIA SYSTEMS
                                                                   Security solution
    THE WIRELESS LAN SOLUTION
CORPORATE CAMPUS                            BRANCH OFFICES




  COMMON AREAS
                                          CONNECTIVITY TO CORP
  MEETING ROOMS
                                          FACILITIES, ACCESS FOR
 TRAINING CENTERS
                                             ROAD WARRIORS
    TEMPORARY
      OFFICES                                HOME OFFICE
    HOT SPOTS




                                          QUICK CONNECTION
 AIRPORTS, HOTELS                             PORTABLE
CONVENTION CENTERS                          EASY START-UP
  BUSINESS TOWERS
   c@Irek Defée      MULTIMEDIA SYSTEMS
• THERE ARE FOUR FAMILIES OF
   WLAN STANDARDS:

  WLAN Standard Over-the-Air            Actual rate for
                (OTA) Estimates         data transmission
                (Bitrate of signals     (Data transfer)
                transmitted)
  802.11b OLD 11 Mbps                   5 Mbps
  802.11g       54 Mbps                 25 Mbps (when
                                        .11b is not present)
  802.11a          54 Mbps              25 Mbps
  802.11n          200+ Mbps            100 Mbps

Note: 802.11n is new and not commonly available yet
c@Irek Defée       MULTIMEDIA SYSTEMS
• WLAN RADIO BANDS
IEEE 802.11g  2.4 GHz
IEEE 802.11a  5 GHz (200MHz)
IEEE 802.11n  2.4 and 5 GHz

• MODULATION:
- OFDM - (MULTICARRIER
  MODULATION) IEEE 802.11a and g



c@Irek Defée   MULTIMEDIA SYSTEMS
What is IEEE802.11b WLAN?
It is substitute for the Ethernet. All users
send and receive packets in the same band.
radio resources are allocated for them on
randomized basis.
The more users are on-line, the less bandwidth
is available. IEEE 802.11b bandwidth is:
11 Mb/s theoretically
 5 Mb/s practically – shared by all users
Range: 15-100m (bulidings, open spaces)

c@Irek Defée     MULTIMEDIA SYSTEMS
• CHANNEL BANDWIDTH

  20 MHz – 52 CARRIER FREQUENCIES
           48 USED FOR DATA

  QPSK AND QAM MODULATION IS
  USED FOR CARRIERS
  GROSS BIT RATES ARE FROM 6-54 Mb/sec
  USEFUL BIT RATES ABOUT HALF OF
  THAT



c@Irek Defée   MULTIMEDIA SYSTEMS
• THE SYSTEM DATA TRANSFER IS
  ORGANISED AS TIME DIVISION
  MULTIPLEX IN FRAMES
  EACH FRAME HAS LENGTH OF 2 ms
  AND WITHIN IT PACKETS OF DATA
  SEND (48 BYTES)




c@Irek Defée   MULTIMEDIA SYSTEMS
• PERFORMANCE CAN REACH
  PRACTICALLY 20 Mb/sec
• THE NUMBER OF USERS:

   TRANSMISSION RANGE IS 30-150 M
  (TRANSMITTER POWER 0.2-1W)
   THERE ARE MAX. 19 CHANNELS
• DEPENDING ON THE BANDWIDTH
   THERE COULD BE ABOUT 50-70(?) USERS
   FOR 1 ACCESS POINT



c@Irek Defée   MULTIMEDIA SYSTEMS
               The 802.11n standard

• This is new standard improving on the
  older ones
• The major improvements are:
- Better OFDM modulation up to 65 Mb/s
- It can use several transmission and
  receiving systems and the same time


c@Irek Defée       MULTIMEDIA SYSTEMS
       Multiple stream transmission in 802.11n




Here there is a scheme with 2 streams, in the 802.11n standard there
can be 2,3, or 4 streams, the bit rate will be 2x,3x,4x higher.
In the end we can have up to 100 Mb/s data transfer with 4 streams.
The standard has also optional modes of operation
(with wider channels)
The data rate then could be up to 300 Mb/s.

     c@Irek Defée         MULTIMEDIA SYSTEMS
 Digital Terrestrial and Mobile Television

• There are 3 standards: DVB-T, DVB-T2 and DVB-H
• OFDM modulation is used with 2000, 4000, 8000…. up
  to 32 000 carriers
• Each carrier can be modulated with PSK, 16-QAM,
  64-QAM up to 256-QAM
• Data rates are between 20-40 Mbits/sec in single TV
   channel with 8 MHz width
Digital Television is widely used in Europe



                    MULTIMEDIA SYSTEMS
                        IREK DEFEE

								
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