Duplex signaling Comparing the MAC proposals by rageagainst

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									Duplex signaling
Comparing the MAC proposals
G. Marque-Pucheu (EADS)
TDMA TG
Denver, June 06
Duplex signaling criteria


 To assess duplex signaling, two criteria shall be applied
  – Can a transmitting unit been stopped to allow for an
    emergency call to have a channel allocated
  – On a single channel configuration, when two units are
    transmitting, can another unit send an emergency telegram
 Second dimension is the complexity required from the unit to
  do it:
  – Never (No unit can do it)
  – Frequency Duplex (only unit with a frequency duplexer)
  – Dual synthesis (unit has two frequency synthetisers to
    allow fast switching)
  – Any (no architectural requirements for the SU)

                                                                 2
Motorola MAC


                                                                               Signaling to stop a
                      Common Announcement Channel                              transmitting terminal
                                                                               implies instantaneous
Outbound                                                                       switching between
Channels      1        2       1       2       1       2       1       2       transmit and receive.
                      30 ms                                                    Frequency duplexer is
Inbound                                                                        required for proper
Channel 1              1               1               1               1       reception (switching at
                                                                               full transmit power
Inbound
                                                                               creates otherwise
Channel 2     2                2               2               2               ringing in the Rx
                                                                               filters)
           TC bit 1        0       1       0       1       0       1       0   No time available for
                                                                               emergency telegram in
                                                                               single channel
                                                                               configuration.



                                                                                                     3
     MACOM MAC


                     Superframe                                        60 msec

1         2         3         4          5         6         7         8         9
V         V         S         V          V         S         V         V         S            Outbound traffic

     1         2         3          4         5         6         7         8           9     Inbound traffic
     V         V         S          V         V         S         V         V          S
                                                                                              Outbound associated signaling

10        11        12        13         14        15        16        17        18           Inbound associated signaling
V         V         S         V          V         S         V         V         S
                                                                                              Other TDMA channel
     10        11        12         13        14        15        16        17         18
     V         V         S          V         V         S         V         V          S

                                                                                      FACCH

                    Outbound path
                                                        A transmitting unit can revert after ramping
                    Inbound path
                                                        down to receive signaling and can return
                                                        before ramping up (zero power switching),
                                                        but switching time requires dual
                                                        synthesizer (as initial EADS proposal).
                                                        Emergency can be transmitted during
                                                        inbound signaling in case on single channel
                                                        operation.                                                            4
     EADS MAC


1         2         3         4         5         6         7         8         9
     O2        O2        O2        O2        O2        O2        O2        O2 OT2           I2   Inbound traffic

     1         2         3         4         5         6         7         8         9     OT2   Outbound signaling Talker
I2        I2        I2        I2        I2        I2        I2        I2             IL2
                                                                                           IT2   Inbound signaling Talker

10        11        12        13        14        15        16        17        18         OA2 Outbound signaling All terminals
     O2        O2        O2        O2        O2        O2        O2        O2 OL2
                                                                                           O2    Outbound traffic
     10        11        12        13        14        15        16        17        18
I2        I2        I2        I2        I2        I2        I2        I2             IT2   OL2   Outbound signaling Listener

                                                                                           IL2   Inbound signaling Listener
19        20        21        22        23        24        25        26        27
     O2        O2        O2        O2        O2        O2        O2        O2 OA2                Other channel

     19        20        21        22        23        24        25        26        27
I2        I2        I2        I2        I2        I2        I2        I2             IL2   The unit transmitting during
                                                                                           I2 may take 20 ms (red lines)
28        29        30        31        32        33        34        35        36         to switch to receive OT2 and
     O2        O2        O2        O2        O2        O2        O2        O2 OL2
                                                                                           20 Outbound path
                                                                                              ms (blue lines) to switch
     28        29        30        31        32        33        34        35        36    back to transmit.
                                                                                              Inbound path
I2        I2        I2        I2        I2        I2        I2        I2             IT2
                                                                                           A unit may send emergency
                                                                                SACCH
                                                                                           telegram during IL2
                                                                                                                               5
Conclusions


 Even if offering same capabilities for duplex voice with
  staggered slots, the three different MAC structures have
  very different duplex signaling capabilities
  – For the two criteria related to emergency, EADS MAC
    performs better, but MACOM proposal may easily be
    improved by signaling slot swapping
  – Motorola proposal offers about no duplex signaling
    capabilities (only frequency duplex units may be
    shutdown)
 Differences shall be integrated in TDMA features matrix




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