Principles of Configuring the FH Cell

This describes the principles of configuring the frequency hopping (FH) cell.

When configuring an FH cell, adhere to the following principles:

• The GSM900 is classified into sub frequency bands: P-GSM, E-GSM, and R-GSM. The P-GSM (900P) band provides the frequencies numbered from 1 to 124, the E-GSM (900E) provides the frequencies numbered 0 and those numbered from 975 to 1023, and the R-GSM band provides the frequencies numbered from 955 to 974.
• In initial configuration, the first channel to be configured is the BCCH by default. If the main BCCH frequency belongs to the 900P band, the frequencies from the 900P band are called compatible frequencies while those from the 900E and 1800M bands are called incompatible frequencies. If the main BCCH frequency belongs to the 900E band, the frequencies from the 900P and 900E bands are called compatible frequencies while those from the 900R and 1800M bands are called incompatible frequencies. If the main BCCH frequency belongs to the 900R band, the frequencies from the 900P, 900E, and 900R bands are called compatible frequencies while the frequencies from the 1800M band are called incompatible frequencies. For frequency hopping in non co-BCCH cells, if the main BCCH frequency belongs to the 900P band, the cells cannot contain the frequencies from the incompatible EGSM or 1800M band.
• The frequency of the TRX that carries the SDCCH can be compatible or incompatible with the main BCCH frequency. If the frequency of the TRX that carries the SDCCH and the main BCCH frequency belong to the same frequency band, the frequency band where the TRX with the SDCCH operates should not be higher than that where the TRX with the main BCCH operates. The PDCH can configured only on the TRX of compatible main BCCH frequency.
• If a cell is configured with less than two TRXs, the cell should not be configured as an FH cell.
• In a double-timeslot cell, the TRX carrying the main BCCH must be configured in the underlaid subcell.
• When a double-timeslot cell is also a concentric cell, at least one static PDCH should be configured in the overlaid subcell.
• In a double-timeslot cell, the odd-numbered channels on the TRXs in the underlaid subcell must be SDCCHs.
• If a double-timeslot cell is configured with baseband FH, the TRXs in the underlaid subcell should not be in the same FH group with other TRXs.
• If baseband FH is configured in a COBCCH cell, the frequencies in a FH group must be on the same frequency band.
• In RF FH, the TRX carrying the main BCCH must be set to No FH.
• If the baseband FH and the EDGE functionality conflict, they cannot be configured simultaneously.
• When the cell software parameter TSC Plan Enable is set to the ON state, the base station color code (BCC) of a cell must be the same as the training sequence code (TSC) in the FH data table. When the cell software parameter TSC Plan Enable is set to the OFF state, the base station color code (BCC) of a cell must be different from the training sequence code (TSC) in the FH data table.
• In the baseband FH, the FH group of non-main BCCH frequencies in timeslot 0 is exclusive to the main BCCH frequencies.
• In RF FH, the TRX carrying the main BCCH must be set to No FH.
• If a double-transceiver BTS is configured with baseband FH, the TRXs whose frequencies are in one FH group must be configured in the same cabinet. If a single-transceiver BTS is configured with baseband FH, the TRXs whose frequencies are in one FH group must be configured in the same cabinet group.
• For the FH TRXs, the same timeslots should not have the same FH group number and the same Mobile Allocation Index Offset (MAIO) simultaneously.
• In a cell, the TCHs on the carriers incompatible with the BCCH carrier can be converted into PDCHs if the MS supports the related frequency bands; the TCHs on only the carriers compatible with the BCCH carrier can be converted into PDCHs if the MS does not support the related frequency band.
• When the long-range FH switch is turned on, the number of carriers compatible with the BCCH carrier can be greater than 24 in a GPRS cell or greater than 16 in an EGPRS cell, but the following conditions must be met:
  • At least one static PDCH should be configured on the BCCH carrier.
  • The carriers compatible with the BCCH carrier and those incompatible with the BCCH carrier should not be configured in the same MA list.
  If the number of carriers compatible with the BCCH carrier in a cell is greater than 32, at least one non-FH TRX should be configured in the cell.If the number of carriers compatible with the BCCH carrier in a GPRS cell is greater than 24 but smaller than or equal to 32, or the number of carriers compatible with the BCCH carrier in an EGPRS cell is greater than 16 but smaller than or equal to 32, a maximum of one MA list in which the carriers are compatible with the BCCH carrier can be configured.
• In a concentric cell, if the BCCH carrier is located in the OL subcell, the carriers compatible with the BCCH carrier should be configured with PDCHs, and the carriers incompatible with the BCCH carrier can be configured with PDCHs or the channels on these carriers can be converted into PDCHs. If all the traffic channels in a concentric cell are configured as dynamic PDTCHs, the parameter Dynamic Channel Conversion Parameter of Concentric Cell of GPRS Attributes should be set to Convert dynamic channel in both subcells and underlaid subcell preferred.
• In a concentric cell, if the BCCH carrier is located in the UL subcell, the carrier assigned to the MS accessing the network for the first time should meet the following conditions: It should be located in the UL subcell and be compatible with the BCCH carrier, and PDCH should be configured on the carrier. Otherwise, the MS cannot access the network. The carriers incompatible with the BCCH carrier can be configured with PDCHs or the channels on these carriers can be converted into PDCHs so that the MS can be assigned these carriers through the Packet Timeslot Reconfigure procedure.