Customizing MAC Messaging

This example introduces new parameters that have been added to increase flexibility in configuring the information that is sent in the FCH, DL-MAP, DCD, UL-MAP, and UCD for receiver test.

  1. Select File > New from the menu or click the button in the toolbar to start a new waveform configuration.

  2. The carrier table should show one advanced carrier. If not, delete the basic carrier and add an advanced carrier. We will use the default Waveform Setup parameters shown for the advanced carrier. 

  3. Click Carrier 1 in the navigation tree on the left and look at the available parameters on this page. There are two fields, MAC CRC Order and PRBS Method. A specific setting for these fields is defined in the various reference specifications. For MAC CRC Order, MSB First and LSB First refer to whether the CRC is calculated in the order with the most significant bit first or the least significant bit. 

  4. Click Zone#1, PUSC and change the Number of Symbols to 10.

  5. Click Zone #1, PUSC and note that the advanced mode carrier allows you to add MAC messaging (FCH, DL-MAP, UL-MAP) and configure bursts.  

  6. Set Auto Allocation to off.  

  7. Click Auto DL-MAP and Auto UL-MAP and set them both to Normal. There is also now the option of creating a compressed DL-MAP or UL-MAP. These types of MAP messages require fewer bytes to send the MAC information, conserving bandwidth.

  8. Click MAC Messaging in the navigation tree. This page has many new parameters that can be controlled to customize the MAC messaging, including the following.

    1. Include DCD Message (on/off): In the N7615A, the DCD (Downlink Channel Descriptor) was always included in the DL-MAP. However, many receivers that are not fully implemented yet cannot read the DCD. Thus, the N7615C now offers a choice on whether to include the DCD in the DL-MAP.

      In version 1.9.0.0 or earlier, the N7615A/B included the DCD as part of the DL-MAP message when present. In this version, DCD is now a separate burst from the DL-MAP, following the DL-MAP and UL-MAP if present.

      If you save a settings file using the 1.9.0.0 or earlier version with DL-MAP, UL-MAP, DCD and UCD all turned on, and the Auto Allocation turned Off, when you import this settings file using this version, there will be a warning message, "DCD or UCD is out of range". This is due to the different allocation schemes. To solve this problem, just increase the Number of Symbols of the PUSC zone and properly allocate the DCD and UCD.

    2. DL-MAP Source: You can now choose to have the DL-MAP automatically generated by the Signal Studio software, or to input a user-defined DL-MAP file.

    3. DL-MAP Allocation Settings: When Auto DL-MAP is set to normal or compressed, this section is a read-only display of the allocation information. If Auto DL-MAP is turned off, the Assigned Slots can be set by the user. The purpose of this is to allow you to create specific data for the downlink frame prefix (DLFP) in the FCH (frame control header) for situations where a partially implemented receiver needs a specific DLFP, but it cannot handle a proper DL-MAP. The length of the DL-MAP is a key component of the FCH data.  

      To see this, set Auto DL-MAP to off. Go to Tools > Waveform Generation Log and generate the waveform. You will see the DLFP data displayed in the window. Now change the Assigned Slots to a different value and generate the waveform again. You will see the new DLFP data in the log window. When done, set Auto DL-MAP to Normal and continue.   

    4. DCD CID: This allows you to specify the connection ID for the DCD message. Enter any valid address from 0000 to FFFF.

    5. DIUC Generation Type (auto/manual): The DIUC code table in the DCD tells the receiver which code corresponds to what modulation and coding rate. Changing the DIUC Generation Type to Manual will enable you to edit the modulation and coding assigned to each DIUC code.

    6. Include UCD Message (on/off): As with the DCD, allows you to omit the UCD (Uplink Channel Descriptor).

      In version 1.9.0.0 or earlier, the N7615A/B included the UCD as part of the UL-MAP message when present. In this version, UCD is now a separate burst from the UL-MAP, following the DL-MAP and UL-MAP if present.

      If you save a settings file using the 1.9.0.0 or earlier version with DL-MAP, UL-MAP, DCD and UCD all turned on, and the Auto Allocation turned Off, when you import this settings file using this version, there will be a warning message, "DCD or UCD is out of range". This is due to the different allocation schemes. To solve this problem, just increase the Number of Symbols of the PUSC zone and properly allocate the DCD and UCD.

    7. Include the First Uplink Zone Switch IE (on/off): You can choose whether to include the zones switch IE in the UL-MAP.  

    8. UL-MAP Allocation Settings: When Auto Allocation for the zone is turned off, you can now manually control the location of the UL-MAP burst. In that case, you need to verify that enough slots have been allocated for the UL-MAP. An error message will be displayed if the UL-MAP burst is not big enough for the data.   

    9. Sub-DL-UL-MAP: You can choose to have up to 3 Sub-DL-UL-MAPs in the first DL-PUSC zone. These may be used with compressed MAPs, but not with normal DL-MAP or UL-MAP. Click to the left of each MAP to enable or disable the MAP and setup its parameters. Once the MAP is enabled and allocated, you will need to assign which burst IEs to be included in the Sub-DL-UL-MAP. This is done from the zone configuration page in the table of data bursts, where the last column allows you to choose whether to include the IE for that bursts in enable and allocate that MAP. Note that assigning a burst IE to a sub-DL-UL-MAP does not automatically enable and allocate that MAP; you must do both steps separately

  9. Click on Zone #1, PUSC again to turn Auto Allocation off for this zone. Add more bursts or zones to the DL and UL sections and see how the size of the DL-MAP and UL-MAP change as more bursts are added, due to the need to include descriptions for more bursts in the subframes.