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Impact of MB-OFDM and DS-UWB Interference on C Band Receivers by tfs31371

VIEWS: 12 PAGES: 28

									     March 2005                                                            doc.: IEEE 802.15-05/0039r1
  Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Submission Title: [Impact of MB-OFDM and DS-UWB Interference — Part 2]
Date Submitted: []
Source: [Torbjorn Larsson] Company [Paradiddle Communications]
Address [13141 Via Canyon Drive, San Diego, CA 92129, USA]
Voice:[+1 858 538-3434], FAX: [+1 858 538-2284], E-Mail:[tlarsson@san.rr.com]
Re: [Analysis of the impact of MB-OFDM and DS-UWB interference on a DTV receiver made in earlier
contributions, in particular 802.15-04/0412r0, 802.15-04/547r0 and 04/451/r2]
Abstract: [The impact of MB-OFDM and DS-UWB interference on a C-band DTV receiver is investigated
by simulation]
Purpose: [To present an unbiased comparison of the impact of MB-OFDM and DS-UWB interference
based on a minimal set of universally accepted assumptions]
Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for
discussion and is not binding on the contributing individual(s) or organization(s). The material in this
document is subject to change in form and content after further study. The contributor(s) reserve(s) the right
to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE
and may be made publicly available by P802.15.



     Submission                                    Slide 1                                 Torbjorn Larsson
March 2005                                doc.: IEEE 802.15-05/0039r1




  Impact of MB-OFDM and DS-UWB
         Inteference — Part 2

                    Torbjorn Larsson
             Paradiddle Communications, Inc.




Submission                 Slide 2                       Torbjorn Larsson
March 2005                                              doc.: IEEE 802.15-05/0039r1



                 Motivation and Objective
 •       Motivated by the following three contributions:
       1)    04/0412r0, In-band Interference Properties of MB-OFDM, by C.
             Razell, Philips
       2)    04/547r0, Responses to “In-Band Interference Properties of MB-
             OFDM”, by C. Corral, G. Rasor and S. Emami, Freescale
             Semiconductor
       3)    04/451/r2, “Multiband OFDM Interference on In-band QPSK
             Receivers Revisited”, by C. Corral, S. Emami and G. Rasor, ,
             Freescale Semiconductor
 •       The above contributions focused on the impact of
         MB-OFDM interference on a DTV victim receiver
 •       In contrast, the objective here is to quantify the
         difference in the impact of interference from MB-
         OFDM and DS-UWB
Submission                            Slide 3                          Torbjorn Larsson
March 2005                                      doc.: IEEE 802.15-05/0039r1


              C-Band DTV Systems
 • The C-band downlink spans 3.7 – 4.2 GHz
 • C-band antennas are typically 6 – 12 feet in diameter
 • Based on the DVB-S (Digital Video Broadcasting – Satellite)
   standard (EN 300 421)
 • DVB-S was designed for MPEG-2 broadcasting in the Ku-band,
   but is also used in the C-band
 • DVB-S does not specify a unique set of data rates or symbol
   rates; However…
 • Typical transponder bandwidth is 36 MHz (33 MHz also used)
 • Typical symbol rate 27 – 29 Msps
 • DVB-S2 is the next generation with improved bandwidth
   efficiency and FEC

Submission                      Slide 4                        Torbjorn Larsson
March 2005                                                                                   doc.: IEEE 802.15-05/0039r1



                                                      DVB-S
  188               204                                    Code rates: 1/2,
 bytes             bytes                                   2/3, 3/4, 5/6, 7/8
                                              Rate-1/2                                          RRC
           RS               Inter-                                               QPSK                        Radio
                                               Conv          Puncturing                         Pulse
         Encoder           leaver                                               Modulation                    TX
                                              Encoder                                          Shaping




                    188               204
                   bytes             bytes

                             RS                  De-         Soft-Input            De-         Matched       Radio
                           Decoder           Interleaver      Viterbi           Puncturing      Filter        RX




                                                    Required BER
                                                      = 2·10-4




Submission                                                     Slide 5                                      Torbjorn Larsson
     March 2005                                                               doc.: IEEE 802.15-05/0039r1


           Typical C-Band Downlink Channelization
                                (Telesat satellite Anik F2. Footprint: North America)

                                          Horizontal Polarization             Vertical Polarization
• Total of 24 channels
                                    Channel    Center Frequency (GHZ)   Channel   Center Frequency (GHz)
• Each polarization has 12
  channels                          1A         3.720                    1B        3.740
                                    2A         3.760                    2B        3.780
• Transponder bandwidth is 36
  MHz with a 4 MHz guard band       3A         3.800                    3B        3.820

• The center frequencies are        4A         3.840                    4B        3.860
  separated by 40 MHz               5A         3.880                    5B        3.900
• The center frequencies for the    6A         3.920                    6B        3.940
  two polarizations are offset by   7A         3.960                    7B        3.980
  20 MHz
                                    8A         4.000                    8B        4.020
• The result is 24 center
                                    9A         4.040                    9B        4.060
  frequencies separated by 20
  MHz                               10A        4.080                    10B       4.100
                                    11A        4.120                    11B       4.140
                                    12A        4.160                    12B       4.180



     Submission                                        Slide 6                                 Torbjorn Larsson
March 2005                                             doc.: IEEE 802.15-05/0039r1


                  DTV Simulation Model
 • Excludes Reed-Solomon coding and interleaving
       – Impossible to simulate error rates with RS coding
 • Symbol rate: 28 Msps
 • No quantization (including input to Viterbi decoder)
 • Ideal pulse shaping/matched filters (0.35 roll-off)
 • No nonlinarity
 • No frequency offset
 • No phase noise
 • Pre-computed phase error and time offset
 • Receiver noise figure: 4 dB
 • Code rates 1/2 and 7/8

Submission                           Slide 7                          Torbjorn Larsson
 March 2005                                          doc.: IEEE 802.15-05/0039r1


              MB-OFDM Transmitter Model
• Based on the Jan. 2005 release of the MB-OFDM PHY spec

• Complete Matlab implementation of the specifications

• System operating in band-hopping mode

• Includes (5-bit) DAC and realistic filter characteristics

• Spectral pre-shaping to compensate for non-ideal filter
  characteristics (=> worst-case in this context!)

• Channel number 9 (Band group 1, TFC 1)

• Data rate “110” Mbps (106.7 Mbps)


 Submission                         Slide 8                         Torbjorn Larsson
    March 2005                                            doc.: IEEE 802.15-05/0039r1


                 DS-UWB Transmitter Model
•     Based on the January 2005 release of the DS-UWB PHY specifications
      (P802.15-04/0137r4)
•     Complete Matlab implementation of the specifications
•     No DAC
•     Ideal RRC pulse shaping filter truncated to 12 chip periods (=> worst-case)
•     Channel number 1 (chip rate: 1313 Mcps)
•     Data rate: “110” Mbps (109.417 Mbps)
•     BPSK modulation
•     Spreading code for preamble and header (PAC): -1 0 +1 -1 -1 -1 +1 +1 0 +1
      +1 +1 +1 -1 +1 -1 +1 +1 +1 +1 -1 -1 +1
•     Spreading code for frame body: +1 0 0 0 0 0

    Submission                          Slide 9                          Torbjorn Larsson
  March 2005                                                                          doc.: IEEE 802.15-05/0039r1


                             Interference Spectra
                                                     Power over 1 MHz Bandwidth
                                 -30
                                                                                         MB-OFDM
                                                                                         DS-UWB
                                                                                         FCC Mask
Resolution: 10 kHz               -40

PSD averaged over 10
packets (roughly 0.9 ms)   dBm   -50



                                 -60



                                 -70



                                 -80



                                 -90
                                       2   2.5   3      3.5      4       4.5      5       5.5       6
                                                                GHz

• Transmit power is set so as to push each spectrum as close as possible to the FCC
  limit (worst-case condition)
• MB-OFDM transmit power is -10.3 dBm
• DS-UWB transmit power is -10.8 dBm (data rate dependent)
  Submission                                         Slide 10                                           Torbjorn Larsson
 March 2005                                                                    doc.: IEEE 802.15-05/0039r1


              Interference Spectra – Close Up
                                                Power over 1 MHz Bandwidth

                                                                                     MB-OFDM
                                                                                     DS-UWB
                         -40                                                         FCC Mask
                                                     DTV center
                                                     frequencies
                         -41



                         -42
                   dBm




                         -43



                         -44



                         -45
                               3   3.2   3.4   3.6   3.8     4     4.2   4.4   4.6      4.8     5
                                                            GHz



• Both spectra exhibit substantial variations
• Solution: run simulation for multiple DTV center frequencies

 Submission                                      Slide 11                                           Torbjorn Larsson
     March 2005                                                                       doc.: IEEE 802.15-05/0039r1

          Amplitude Histogram: Wideband (without
                        Multipath)
                                        MB-OFDM                                       DS-UWB
                      0.25                                          0.25

Data rate: 110 kbps
                       0.2                                           0.2



                      0.15                                          0.15        PAR = 12.0 dB
                                  PAR = 11.9 dB


                       0.1                                           0.1



                      0.05                                          0.05



                        0                                             0
                             0   0.05     0.1     0.15      0.2            0   0.05      0.1   0.15    0.2

     Submission                                          Slide 12                                     Torbjorn Larsson
     March 2005                                                                        doc.: IEEE 802.15-05/0039r1

              Amplitude Histogram: Wideband (with
                           Multipath)
                                         MB-OFDM                                       DS-UWB
                       0.12                                          0.12
                                  PAR = 14.1 dB                                 PAR = 14.2 dB
Data rate: 110 kbps
                        0.1                                           0.1
100 multipath
channel realizations
                       0.08                                          0.08



                       0.06                                          0.06



                       0.04                                          0.04



                       0.02                                          0.02



                         0                                             0
                              0   0.05     0.1     0.15      0.2            0   0.05     0.1    0.15   0.2

     Submission                                           Slide 13                                     Torbjorn Larsson
     March 2005                                                                doc.: IEEE 802.15-05/0039r1

                  Amplitude Histogram: Output of DTV
                    Matched Filter (with Multipath)
                                       MB-OFDM                                  DS-UWB
Center frequency =     0.6                                     0.6
4 GHz

                       0.5                                     0.5
100 multipath
channel realizations
                       0.4                                     0.4



                       0.3                                     0.3



                       0.2                                     0.2



                       0.1                                     0.1



                        0                                       0
                             0   0.1   0.2   0.3   0.4               0   0.1    0.2   0.3   0.4


     Submission                                     Slide 14                                      Torbjorn Larsson
March 2005                                                                doc.: IEEE 802.15-05/0039r1



       Output of Matched Filter (Close-Up)
                            MB-OFDM                                     DS-UWB
             0.015                                       0.015




              0.01                                        0.01




             0.005                                       0.005




                0                                           0
                0.2   0.3   0.4   0.5   0.6                 0.2   0.3   0.4   0.5   0.6



Submission                                    Slide 15                                    Torbjorn Larsson
March 2005                           doc.: IEEE 802.15-05/0039r1


         Changes Since November 2004
 • All simulations carried out with center
   frequencies according to channelization
   plan on slide 6
        3.72 GHz to 4.18 GHz in steps of 20 MHz

 • Added multipath (CM3, no shadowing)

 • Increased symbol rate from 27 to 28
   Msps
Submission               Slide 16                   Torbjorn Larsson
   March 2005                                                                         doc.: IEEE 802.15-05/0039r1



                        Simulation Block Diagram
                  Center                                                          Center
                Frequency                                                       Frequency
  204 byte                                         3 dB above
  packets                                           sensitivity
                              fs = 21.6 GHz
                                                      PDTV
Random             DTV                                                            DTV              BER
 Data           Transmitter
                                         Atten 1                     +           Receiver         Counter




                MB-OFDM       PMB-OFDM
                                                                  Multi-
                                                                  path           •   Attenuation 1 is set so that the
                Transmitter                                                          received DTV power is 3 dB above
                                                                                     sensitivity
                                         Atten 2
                                                        Re-
                                                       Sample                    •   Each simulation is performed with
                                                                     fs = 21.6 GHz
                                                                                     all 24 DTV center frequencies
                 DS-UWB
                Transmitter
                              PDS-UWB
                                                                                 •   Simulation results are plotted as a
                                                                                     function of center frequency and
                                                                                     attenuation 2


   Submission                                             Slide 17                                     Torbjorn Larsson
   March 2005                                                                            doc.: IEEE 802.15-05/0039r1


                      DTV Sensitivity (NF = 4 dB)
                             0
                                                   BER After Viterbi Decoder (NF = 4 dB)
                            10
                                                                                           Code Rate 1/2
                                                                                           Code Rate 2/3
                             -1                                                            Code Rate 3/4
                            10
                                                                                           Code Rate 5/6
                                                                                           Code Rate 7/8
                             -2
                            10
                      BER




                             -3
                            10

Defines sensitivity          -4
                            10


                             -5
                            10


                             -6
                            10
                                 -96   -95   -94     -93     -92      -91    -90   -89     -88    -87      -86
                                                                   PDTV [dBm]




   Submission                                              Slide 18                                          Torbjorn Larsson
March 2005                                       doc.: IEEE 802.15-05/0039r1



             DTV Sensitivity (NF = 4 dB)
                      (Symbol rate: 28 Msps)


             Code Rate                Sensitivity [dBm]
                1/2                            -92.3
                2/3                            -90.5
                3/4                            -89.5
                5/6                            -88.5
                7/8                            -87.9

Submission                     Slide 19                         Torbjorn Larsson
   March 2005                                                                              doc.: IEEE 802.15-05/0039r1


                 BER versus Center Frequency
                                       Code Rate 1/2, without multipath
                             -2
                                         BER After Viterbi Decoder versus Center Frequency (Rate 1/2)
                            10
                                                                                                MB-OFDM
Interference                                                                                    DS-UWB

attenuation = 67 dB
                      BER




                             -3
                            10




                             -4
                            10
                                 3.7    3.75   3.8    3.85     3.9     3.95    4    4.05     4.1   4.15   4.2
                                                             Center Frequency [GHz]

   Submission                                                Slide 20                                      Torbjorn Larsson
    March 2005                                                                            doc.: IEEE 802.15-05/0039r1


                   BER versus Center Frequency
                                        Code Rate 1/2, with multipath
                              -2
                                        BER After Viterbi Decoder versus Center Frequency (Rate 1/2)
                             10
                                                                                              MB-OFDM
Interference                                                                                  DS-UWB
attenuation = 71 dB

                              -3
100 multipath                10
channel realizations
                       BER




                              -4
                             10




                                  3.7   3.75   3.8   3.85     3.9     3.95    4    4.05     4.1   4.15   4.2
                                                            Center Frequency [GHz]

    Submission                                              Slide 21                                      Torbjorn Larsson
March 2005                        doc.: IEEE 802.15-05/0039r1



             Two Performance Metrics

 1. Compute average error rate over the 24
    center frequencies

 2. Select maximum error rate from the 24
    center frequencies




Submission             Slide 22                  Torbjorn Larsson
March 2005                                                                       doc.: IEEE 802.15-05/0039r1


                                      Average BER
                              Code Rate 1/2, with multipath
                    -1
                                  Average BER After Viterbi Decoder (Code Rate 1/2)
                   10
                                                                                  MB-OFDM
                                                                                  DS-UWB


                    -2
                   10
             BER




                    -3
                   10




                    -4
                   10




                        67   68        69       70        71       72       73        74    75
                                            Interference Attenuation [dB]

Submission                                         Slide 23                                      Torbjorn Larsson
March 2005                                                                        doc.: IEEE 802.15-05/0039r1


                                      Maximum BER
                              Code Rate 1/2, with multipath
                    -1
                                  Maximum BER After Viterbi Decoder (Code Rate 1/2)
                   10
                                                                                  MB-OFDM
                                                                                  DS-UWB


                    -2
                   10
             BER




                    -3
                   10




                    -4
                   10




                        67   68         69       70        71       72       73       74    75
                                             Interference Attenuation [dB]

Submission                                            Slide 24                                   Torbjorn Larsson
    March 2005                                                                            doc.: IEEE 802.15-05/0039r1


                        BER versus Center Frequency
                                        Code Rate 7/8, with multipath
                              -1
                                        BER After Viterbi Decoder versus Center Frequency (Rate 7/8)
                             10
                                                                                             MB-OFDM
Interference                                                                                 DS-UWB
attenuation = 71 dB
                              -2
                             10

100 multipath
channel realizations
                       BER




                              -3
                             10




                              -4
                             10




                                  3.7   3.75   3.8   3.85     3.9     3.95    4    4.05   4.1    4.15   4.2
                                                            Center Frequency [GHz]

    Submission                                                Slide 25                                        Torbjorn Larsson
March 2005                                                                    doc.: IEEE 802.15-05/0039r1


                                   Average BER
                             Code Rate 7/8, with multipath
                    0
                               Average BER After Viterbi Decoder (Code Rate 7/8)
                   10
                                                                              MB-OFDM
                                                                              DS-UWB
                    -1
                   10



                    -2
                   10
             BER




                    -3
                   10



                    -4
                   10




                        64    66          68           70           72        74        76
                                         Interference Attenuation [dB]

Submission                                        Slide 26                                   Torbjorn Larsson
March 2005                                                                   doc.: IEEE 802.15-05/0039r1


                               Worst-Case BER
                             Code Rate 7/8, with multipath
                    0
                               Maximum BER After Viterbi Decoder (Code Rate 7/8)
                   10
                                                                             MB-OFDM
                                                                             DS-UWB
                    -1
                   10



                    -2
                   10
             BER




                    -3
                   10



                    -4
                   10




                        64     66          68           70           72      74        76
                                          Interference Attenuation [dB]

Submission                                         Slide 27                                 Torbjorn Larsson
March 2005                                       doc.: IEEE 802.15-05/0039r1


                        Conclusions
• For DTV code rate 1/2, there is practically no
  difference between the two interfering
  waveforms
• The difference increases with code rate
       – MB-OFDM interference is more bursty in nature and thus
         has more impact for higher code rates

• For DTV code rate 7/8, MB-OFDM is ≈ 1.3 dB
  worse than DS-UWB @ BER 2·10-4


Submission                       Slide 28                       Torbjorn Larsson

								
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