Conversion between Frequency and Frequency Band

1.1 Conversion between Frequency and Frequency Band

In the CDMA system, if the frequency band used by the system is known, the specific frequency can be worked out by the frequency band calculation formula. The resulting frequency is the central frequency of the band used by the system. Add or subtract 0.625MHz to or from the central frequency and the resulting value is the frequency band.

1. 450M

The currently used frequency band is Band A. The frequency is given by:

BS signal receiving (uplink): 450.00+0.025(N-1) (MHz)

BS transmitting (downlink): 460.00+0.025 (N-1) (MHz)

2. 800M

The frequency is given by:

BS signal receiving (uplink): 825.00+0.03N (MHz)

BS signal transmitting (downlink): 870.00+0.03N (MHz)

3. 1.9G

The frequency is given by:

BS signal receiving (uplink): 1850.00+0.05N (MHz)

BS signal transmitting (downlink): 1930.00+0.05N (MHz)

1.2 Definition of SID and NID

A base station is a member of a cellular system and a network, and a network is a subset of a system.

A system is identified by the SID code, and the network of a system is identified by the NID code. Therefore, a network is identified only by a pair of codes (SID, NID). SID = 0 and NID = 0 are reserved values, representing all base stations not affiliated to any specific network. NID = 65535 (2¹⁶ - 1) is also a reserved value. To the mobile station, it means the entire system identified by SID (independent of NID) is in the local (not roaming).

Fig. 2-16 shows an example of a system and a network. The subsystem with SID = i has three networks identified by t, u, and v respectively. The base station identified by NID = 0 is a member of the system i but not a member of any of the three networks.

Fig. 2-16 System and Network

The mobile station (MS) has a list that contains one or more pairs of local (non-roaming) identifiers (SID, NID). If the identifier codes (SIDs, NIDs) stored in the list (received from the system parameter information) do not match with any of the mobile station non-roaming identifier codes (SID, NID), it means the mobile station is roaming. There are two types of roaming: If the mobile station is roaming and it has some pairs of SIDs in the list that match with the SIDs of the MS non-roaming identifier codes, it means this MS is an external NID roamer. If it has no SID in the list that matches with the SIDs of the MS non-roaming identifier codes, it means the MS is an external SID roamer. The MS may have a special value NID = 65535 to indicate that it believes none of the NIDs in the SID is roaming (for example, none of all mobile stations in the base stations of the system is roaming).