GSM Basic Radio Parameters

PowerPoint

GSM Basic Radio Parameters:: : 32-36pt:

:: : 24pt: At the end of this course, you will be able to:1.Understand the meaning of various radio parameters2.Grasp the setting of radio parameters3.State the effect to radio network performance of various kind of radio parametersObjectives> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.Network identification parametersSystem control parametersCell selection parametersContent> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.Enable the MS to correctly identify the ID of the current networkEnable the network to be real time informed of the correct geographical location of the MSEnable the MS to report correctly adjacent cell information during the conversation processRoles of identification parameters> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.Cell Global Identity(CGI)It is used for identifying individual cells within an LACGI=MCC+MNC+LAC+CICell Global Identity> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.The CGI information is sent along the system broadcasting information in every cell.When the MS receives the system information, it will extract the CGI information from it and determines whether to camp on the cell according to the MCC and MNC specified by the CGI.It judges whether the current location area is changed, then determines whether to take the location updating process.Roles of CGI> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.MCC(Mobil Country Code):The value range is the decimal 000~999MNC(Mobile Network Code):The value range is the decimal 000~999LAC(Location Area Code):The range is 1-65535CI(Cell Identity):The range is 0-65535Setting of CGI> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.Base Station Identity Code(BSIC):It enable MS to distinguish between neighboring base stationsNCC: Network Color Code Value range:0-7BCC: Base Station Color Code Value range:0-7Base Station Identity Code(BSIC)> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:


(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.The frequency of periodic location update is controlled by the network and the period length is determined by the parameter T3212.The T3212 is a decimal number, within the range of 0-255, in the unit of six minutes(1/10 hours).If the T3212 is set to 0, it means that the cell needs no periodical location update.Periodic Updating Timer(T3212)> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.GSM specification stipulates that the MS must have a timer(S), which is assigned with an initial value at the start of the conversation, that is, the radio link timeout value.Every time the MS fails to decode a correct SACCH message when it should receive the SACCH, the S is decreased by 1. On the contrary, every time the MS receive a correct SACCH message, the S is increased by 2, but the S should not exceed the radio link timeout value. When the S reaches 0, the MS will report the radio link failure.The radio link timeout is a decimal number, within the range of 4-64, at the step of 4, defaulted to 16.Radio Link Timeout(RLT)> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:


(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.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. The GSM Specifications defines the path loss rule C1. For the so-called proper cell, C1>0 must be ensured.Cell Selection C1> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.C1=RXLEV-RXLEV_ACCESS_MIN-Max(MS_TXPWR_MAX_CCH-P,0)Where:RXLEV is average received levelRXLEV_ACCESS_MIN is the minimum received level the MS is allowed to access the networkMS_TXPWR_MAX_CCH is the maximum power level of control channel(when MS sending on RACH)P is the maximum TX power of MSMAX(X,Y)=X; if XYMAX(X,Y)=Y; if X G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.The RXLEV_ACCESS_MIN is a decimal number, within the range of -110dbm~-47dbmDefault value is 0(-110dbm).

RXLEV_ACCESS_MINRXLEV_ACCESS_MINMeaning-47dBm>-48dBm(level 63)-48dBm-49~-48dBm(level 62)-108dBm-109~-108dBm(level 2)-109dBm-110~-109dBm(level 1)-110dBm G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.For a cell with traffic overload, you can appropriately increase the RXLEV_ACCESS_MINRXLEV_ACCESS_MIN value cannot be set to too high a value. Otherwise, blind area will be caused on the borders of cells.It is suggested that the RXLEV_ACCESS_MIN value should not exceed -90dBm.Setting and Influence> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.Cell Reselection(C2) is a process when MS change its service cell in idle mode.When the MS selects a cell it will begin to measure the signal levels of the BCCH TRX of its adjacent cells.When given conditions are met, the MS will move from the current cell into another one. This process is called cell reselection.Cell Reselection C2> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.When C2 Parameter Indicator(PI) indicates YES, the MS will get parameters(CRO, TO and PT), from BCCH, to be used to calculate C2(channel quality criterion), which serves as cell reselection norm. The equation is as follows:C2=C1+CRO-H(PT-T)*TO, when PT31C2=C1-CRO, when PT=31Where T is a timer, when a call is recorded by MS as one of the six strongest cells, timer starts counting , otherwise, T is reset to 0.H(X)=0, when X G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.PI is used to notify the MS whether to use C2 as the cell reselection parameter and whether the parameters calculating C2 exist.PI consists of 1 bit.1 means the MS should extract parameters from the system message broadcasting in the cell to calculate the C2 value, and use the C2 value as the standard for cell reselection;0 means the MS should use parameter C1 as the standard for cell reselection(equivalent to C2=C1).Parameter Indicator(PI)> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.For cells where the traffic is very heavy or the channel quality is very low, the PT may be set 31, making TO invalid, so C2=C1-CROFor cells where the traffic is moderate, the recommended value for CRO is 0 and PT=31, thus causing C2=C1, no artificial impact will be imposed.For cells with light traffic, its recommended that CRO be ranged from 0 to 20 dB, the greater the CRO, the more possible the cells will be reselected, and vice versa.C2 Typical Application> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.When a MS reselects a cell, if the old cell and the target cell are in different locations, then the MS must initiate a location updating process after cell reselection.Due to the fading features of the radio channel, the C2 value of two adjacent cells measured along their borders will fluctuate greatly.MS will frequently conduct the cell reselection, which will not only increase the network signaling flow and lead to low efficiency use of radio resources, but reduces the access success rate of the system, as the MS cannot respond to paging calls in the location updating process.Cell Reselection Hysteresis> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.To minimize the influence of this issue, the GSM specifications put forward a parameters called ReselHysteresis.The cell selection hysteresis is represented in decimal numerals, its unit is dB, its range is 0-14, its step length is 2dB, and its default value is 4.Cell Selection Hysteresis> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved.If the MS calculates that the C2 value of an adjacent cell(same location area)surpasses the C2 value of the serving cell and maintains for 5s or longer, the MS will start cell reselection.If the MS detects a cell that is not in the same location area with the current cell, the calculated C2 value surpasses the sum of the C2 value of the current cell and the ReselHysteresis parameter and if it remains for 5s or longer, the MS will start the cell reselection.Cell Reselection Principle> G91, B170G137, B207G174, B239G171, B189:: : 30-32pt:

(1-5):: : 28-12pt: ZTE Corporation. All rights reserved. ZTE Corporation. All rights reserved.Thanks!

Documents

GSM Basic Radio Parameters