• Cell Selection / Cell Reselection

The concept of Cell Seelction - C1 and Cell Reselection - C2

• Cell selection/reselection are processes, which are performed by a GSM mobile station in idle mode.
• The MS uses the cell selection algorithm to look for a cell where it can camp on  
• If the MS looses coverage of that cell, it will look for the most suitable alternative cell and it will camp on that cell. This is called cell reselection

Criteria for Cell Selection

When the MS is turned on, it will try to contact a public GSM PLMN, so the MS will select a proper cell and extract from the cell the control channel parameters and prerequisite system messages. This selection process is called cell selection. The quality of radio channels is an important factor in cell selection.  C1>0

  C1 =RX_LEV - RXLEV_ACCESS_MIN-Max[(MS_TXPWR_MAX_CCH-MS_PWR_MAX (P)),0]

1- RX_LEV :The received signal level at the MS

2- RXLEV_ACCESS_MIN :The minimum received signal level the MS is allowed to     access the network.

3- MS_PWR_MAX :The maximum power of the MS.

4- MS_TXPWR_MAX_CCH:The Maximum power level a MS may use when     accessing the system.

An MS that is switched on but is not allocated a dedicated channel is defined as an MS in idle mode. An MS in idle mode can access the network and can be reached by the network.

Criteria for Cell Reselection
Cell reselection is a process MS change its service cell in idle mode. When the MS selects a cell and if there are not major changes in the various conditions, the MS will stay in the selected cell, and the MS will begin to measure the signal levels of the BCCH TRX of its adjacent cells, record 6 adjacent cells whose signal levels are the strongest and extract from them various types of system messages and control messages of each adjacent cell. When given conditions are met, the MS will move from the current cell into another one. This process is called cell reselection.

   C2 = C1+ CRO – TO*H(PT-T)

• According to Huawei default parameter settings, TO = 0, PT = 0
• So C2= C1+ CRO
• Refer to Condition of C1 and Parameter Setting Set:
• C2 GSM = RX level GSM + 102 + CRO 
• C2 DCS = RX level DCS + 99 + CRO 

Introduction to packet service evolution & new technologies from Sokunth Che

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