2G/GSM

Cell Channel Description

When frequency hopping is used on the SDCCH in a cell or for cells with Immediate Assignment on traffic channel and frequency hopping, the MS needs to know which frequency band to use and which frequencies within the band it should use during frequency hopping. This information is provided in the cell channel description information.

This is one of information element being transmitted by System Information Type 1. The purpose of this paramter is to provide the reference frequency list to be used to decode the mobile allocation information element.

  +-Cell Channel Description ::= V

  | +-Octet1-16 ::= DIVISION

  |   +-Format-ID bit128-127 ::= SWITCH [bit map 0]

  |   +-(Format-ID bit128-127)=0 ::= BRANCH

  |     +-spare ::= FIX [0]

  |     +-Cell Allocation Absolute RF Channel Number bit124-121 ::= INT (0..15) [0]

  |     +-Cell Allocation Absolute RF Channel Number bit120-001 ::= OCTETARRAY SIZE(15..15)

                                                                 [000000000000000000000000000000]

The interpretation of the this information is pretty complicated. Refer to 44.018 10.5.2.1b Cell Channel Description for the details.

Encoding/Decoding Cell Channel Description is based on several complicated/confusing tables listed below (All from 44.018). I don't think/recommend you to decode/encode it manually every time you see this IE (Information Element), but it would be a good idea to try decoding/encoding by hands at least once to understand the logic.

• Figure 10.5.2.1b.1.1: Cell Channel Description information element (general format)
• Table 10.5.2.1b.1.1: Cell Channel Description information element, general format
• Figure 10.5.2.1b.2.1: Cell Channel Description information element, bit map 0 format
• Table 10.5.2.1b.2.1: Cell channel Description information element, bit map 0 format
• Figure 10.5.2.1b.3.1: Cell Channel Description information element(1024 range format)
• Table 10.5.2.1b.3.1: Cell Channel Description information element, range 1024 format
• Figure 10.5.2.1b.4.1: Cell Channel Description information element(512 range format)
• Table 10.5.2.1b.4.1: Cell Channel Description information element, range 512 format
• Figure 10.5.2.1b.5.1: Cell Channel Description information element, range 256 format
• Table 10.5.2.1b.5.1: Cell Channel Description information element, range 256 format
• Figure 10.5.2.1b.6.1: Cell Channel Description information element, range 128 format
• Table 10.5.2.1b.6.1: Cell Channel Description information element, range 128 format
• Figure 10.5.2.1b.7.1: Cell Channel Description information element, variable bit map format
• Table 10.5.2.1b.7.1: Cell Channel Description information element, variable bit map format

< Figure 10.5.2.1b.1.1: Cell Channel Description information element (general format) >

< Table 10.5.2.1b.1.1: Cell Channel Description information element, general format >

< Figure 10.5.2.1b.2.1: Cell Channel Description information element, bit map 0 format >

< Table 10.5.2.1b.2.1: Cell channel Description information element, bit map 0 format >

< Figure 10.5.2.1b.3.1: Cell Channel Description information element(1024 range format) >

< Table 10.5.2.1b.3.1: Cell Channel Description information element, range 1024 format >

< Figure 10.5.2.1b.4.1: Cell Channel Description information element(512 range format) >

< Table 10.5.2.1b.4.1: Cell Channel Description information element, range 512 format >

< Figure 10.5.2.1b.5.1: Cell Channel Description information element, range 256 format >

< Table 10.5.2.1b.5.1: Cell Channel Description information element, range 256 format >

< Figure 10.5.2.1b.6.1: Cell Channel Description information element, range 128 format >

< Table 10.5.2.1b.6.1: Cell Channel Description information element, range 128 format >

< Figure 10.5.2.1b.7.1: Cell Channel Description information element, variable bit map format >

< Table 10.5.2.1b.7.1: Cell Channel Description information element, variable bit map format >