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Cross Polarization Interference Cancellation (XPIC)

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Some carrier's transport system designers are not aware that more than one RF ... Becky Holland and Bruce Blain of NEC wrote an article for RadioResourceMagazine ... – PowerPoint PPT presentation

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Title: Cross Polarization Interference Cancellation (XPIC)


1
Cross Polarization Interference Cancellation
(XPIC)
2
Topics of Discussion
  • What is XPIC?
  • Examples
  • Design Considerations

3
General Comments
  • Some carriers transport system designers are not
    aware that more than one RF channel may be
    assigned to a path
  • Some also believe that if you do assign a second
    channel on a path that another antenna is
    required
  • And most do not know about XPIC and what it
    allows a design engineer to accomplish

4
Disclaimers
  • This presentation is not a sales pitch for NEC
    equipment
  • According to Dick Laine at Harris Corporation a
    similar capability is available for their
    Megastar Radio
  • According to Floyd Brutout, Alcatel does not at
    this time offer a similar capability

5
Disclaimers
  • The presenter only has experience with NEC XPIC
    equipment
  • Becky Holland and Bruce Blain of NEC wrote an
    article for RadioResourceMagazine
  • Information from that article is presented
    with the permission of Bruce Blaine

6
 What is XPIC?
  • Cross Polarization Interference
    Cancellation (XPIC)
  • How does microwave radio having XPIC capabilities
    effectively double the potential capacity of a
    microwave path?

7
What is XPIC?
  • It allows the assignment of the same frequency to
    both the vertical and horizontal polarization on
    a path
  • Where available frequencies are limited then it
    is possible to assign the same frequency twice on
    the same path using both polarizations

8
What is XPIC?
  • Using standard microwave equipment from any of
    the major manufacturers, if a full block of eight
    frequencies were available for a 6 GHz lower band
    path then eight frequencies could be assigned in
    each direction on the path, four per polarization
  • Using equipment with XPIC capability sixteen
    frequencies may be assigned each way on the same
    path, eight per polarization

9
What is XPIC?
  • Standard Frequency Assignments
  • 4 Frequencies Horizontal
  • 4 Frequencies Vertical
  • XPIC Frequency Assignments
  • 8 Frequencies Horizontal
  • 8 Frequencies - Vertical

10

11

12

13
Design Considerations
  • The use of XPIC requires very high cross
    polarization discrimination antennas such as
    Andrew HSX-40 dB Cross Polarization
    discrimination
  • XPIC should be considered in the initial system
    design retrofitting the equipment with the
    required intra bay cables is not easy after the
    equipment is installed, in fact NEC engineers
    told me that it cannot be retrofitted in the
    field

14
Design Considerations
  • NEC prefers to have ATPC operational on paths
    using XPIC equipment
  • ATPC must be turned ON for both directions of a
    path
  • Adjacent frequencies on a path should be
    receiving at nearly the same level in order for
    XPIC equipment to work properly

15
Design Considerations
  • For Example, if 13T requires ATPC to clear an
    interference case then 12T and 14T are also
    required to use ATPC at the same levels
  • Designers must employ XPIC for the protection
    channel and the first operational channel for the
    remaining channels 2 through 7 XPIC may be
    applied on a per channel basis

16
Design Considerations
  • For circulator coupled XPIC equipment an
    additional 7.1 dB of loss for the transmitters
    and 7.2 dB of loss for the receivers must be
    taken into account in the path calculations
  • XPIC equipment will work with one transmit
    antenna and if required a diversity antenna. The
    three-antenna configuration required by some
    equipment manufacturers because of
    intermodulation is not required

17
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