GB_0505_E1 ZXG10 RADIO PARAMETERS

TOPICS FOR DISCUSSIONNETWORK IDENTIFICATION PARAMETERSCGI , BSIC, BCC/ NCC

CELL SELECTION PARAMETERSC1 and C2

SYSTEM CONTROL PARAMETERSRLT, CBA, CBQ and etc.

NETWORK FUNCTIONAL PARAMETERSINTAVE, LIMITn

NETWORK IDENTIFICATION PARAMETERSAs a global cellular mobile communication system, the GSM strictly numbers each GSM network in each country, or even numbers each location area, every station or every cell in every network in order that every cell around the globe has an sole corresponding number.

ROLES OF IDENTIFICATION PARAMETERSEnable the MS to correctly identify the ID of the current network so that it can correctly select the network the user (or telecom operator) wants to access to in any conditions.Enable the network to be real time informed of the correct geographical location of the MS so that the network can normally connect various service requests with the MS as the terminal.Enable the MS to report correctly the adjacent cell information during the conversation process so that the network can hand-over the calls when necessary to ensure the continuity of the conversation.

CELL GLOBAL IDENTITY (CGI)Cell Global Identity (CGI) It is used for identifying individual cells within an LA

Cell Global Identity3 Digits2-3 DigitsMax 16 BitsMax 16 bitsLAI

ROLES OF CGIThe 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. During the location updating process, the MS will report the LAI information to the network so that the network is fully aware of the cell where the MS is currently located.

SETTING OF CGI MCCMobile Country Code: consists of 3 decimal digits, and the value range is the decimal 000 999. MNCMobile Network Code: consists of 3 decimal digits, and the value range is the decimal 00 999. LACLocation Area Code: The range is 1-65535. CICell Identity: The range is 0-65535.

SETTING OF CGIMCC resource is allocated and managed by ITU. The MCC of China is 460decimal).MNC is usually allocated by the relevant telecommunication administration department of a country. The LAC encoding mode is specified correspondingly by every country. Usually, the location area should be as large as possible.Two or more cells in the same location area are not allowed to share the same CI.

BASE STATION IDENTITY CODE (BSIC) Base Station Identity Code (BSIC) It enables MSs to distinguish between neighboring base stations

3 Bits3 BitsBSICNCC Network/ National Color CodeValue Range: 0~7BCC Base Station Color CodeValue Range: 0~7

NCC and BCC ROLESNCC: In the connection mode (during conversation), the MS must measure the signals in the adjacent cells and report the result to the network. As each measurement report sent by the MS can only contain the contents of six cells, so it is necessary to control the MS so as to only report the information of cells factually related to the cell concerned. The high 3 bits (i.e. NCC) in the BSIC serve this purpose.

BCC: The BCC is used to identify different BS using the same BCCH in the same GSMPLMN.

BSIC CONFIGURATION PRINCIPLEIn general, it is required that Cells A, B, C, D, E and F use different BSIC. When the BSIC resources are not enough, the cells close to each other may take the priority to use different BSIC.

ROLES OF BSIC1. Inform the MS the TSC used by the common signaling channel of the cell.2. As the BSIC takes part in the decoding process of the random access channel (RACH), it can be used to prevent the BS from mis-decoding the RACH, sent by the MS to an adjacent cell, as the access channel of this cell.3. When the MS is in the connection mode (during conversation), it must measure the BCCH level of adjacent cells broadcasting by BCCH and report the results to the BS. In the uplink measurement report, MS must show BSIC of this carrier it has measured to every frequency point.

BA LIST (BCCH ADJACENT LIST)When a MS is turned on, it will scan from the BA (Adjacent cell BCCH table) it remembered when turned off last time. The MS will first search carriers from this table and if none is found it will turns to find any of 30 carriers with highest levels, then try to decode BCCH carriers one by one according to their level sequences.

CELL SELECTION C1 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 C1where: RXLEV_ACCESS_MIN is the minimum received level the MS is allowed to access the network MS_TXPWR_MAX_CCH is the maximum power level of the control channel (when MS sending on RACH); RXLEV is average received level; P is the maximum TX power of MS;MAXX, YX; if X Y.MAXX, YY; if Y X.C1 = RXLEV - RXLEV_ACCESS_MIN - Max(MS_TXPWR_MAX_CCH - P ,0)

C1 PATHLOSS CRITERIONAll the candidate cells for MS must meet the path loss criterion, i.e. C1>0. MS will select the cell with the maximal C1 to access and will camp on this cell unless some key conditions has changed greatly.

RXLEV_ACCESS_MINIn order to avoid providing unsatisfactory communication quality and avoid the unnecessary waste of radio resources if the MS accesses to the system (the communication quality after the access often cannot ensure the normal communication process) at the very low received level, the GSM system regulates that, when a MS is to access to a network, its receiving signal level must be larger than a threshold level, i.e. the minimum receiving level the MS is allowed to access to RXLEV_ACCESS_MIN).

Default value is 0 (-110dBm).

CELL RESELECTION C2Cell 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, 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 selection.

CELL RESELECTION C2When C2 Parameter Indicator (PI) indicates YESthe 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:

C2C1CROHPTTTO, when PT 31C2C1CRO, when PT= 31

Where T is a timer. When a cell is recorded by MS as one of the six strongest cells, timer starts counting, otherwise, T is reset to zero.

PARAMETER INDICATOR (PI)PI is used to notify the MS whether to use C2 as the cell reselect parameter and whether the parameters calculating C2 exist.

PI consists of 1 bit. 1means 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 reselect; 0 means the MS should use parameter C1 as the standard for cell reselect (equivalent to C2C1.

CRO, PT AND TOThe cell reselection initiated by the radio channel quality regards C2 as the standard. C2 is a parameter based on C1 plus some artificial offset parameters. The artificial influence is to encourage the MS to take the priority in accessing to some cells or prevent it from accessing to others. These methods are often used to balance the traffic in the network.In addition to C1, there are three other factors influencing C2, namely: CELL_RESELECT_OFFSET (CRO), TEMPORARY_OFFSET (TO) and PENALTY_TIME (PT).

C2 TYPICAL APPLICATIONSIn general, its not expected that MS access the cells where the traffic is very heavy or the channel quality is very low. In this case , the PT may be set 31, making TO invalid, so C2=C1-CRO. Because the C2 is lowered deliberately, the possibility that the cell will be reselected by MS is lowered greatly. The greater the CRO, the less possibility that the cell will be reselected, and vice versa.

C2 TYPICAL APPLICATIONSIts expected that MS stay as much as possible in cells where the system utilization are very low and the traffic load is light. In this case, its recommended that CRO be ranged from 0 to 20dB. The greater the CRO, the more possible the cells will be reselected ,and vice versa. Its also suggested that TO is equal or a little higher than CRO. PT, whose main role is to avoid frequent cell reselection by MS, is generally recommended to be set at 20 seconds or 40 seconds.For cells where the traffic is moderate, the recommended value for CRO is zero and PT=31, thus causing C2=C1, i. e. no artificial impact will be imposed.

CELL RESELECTION HYSTERESISWhen 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 values 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 SELECTION HYSTERESIS (2)To minimize the influence of this issue, the GSM specifications put forward a parameter called cell reselection hysteresis (CRH), which requires that the signal level of adjacent cell (in a different location area) be larger than the local cell signal level, and their difference be larger than the value specified by the cell selection hysteresis. In this case, the MS will start the cell reselection.The cell reselection hysteresis is represented in decimal numerals, its unit is dB, its range is 014, its step length is 2dB, and its default value is 4.

CELL RESELECTION PRINCIPLEIf 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 and access to the adjacent cell. 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 cell reselection hysteresis (CRH) parameter and if it remains for 5s or longer, the MS will start the cell reselection and access to the new cell. Note that the cell reselection caused by the parameter C2 should be originated at least at the interval of 15s so as to avoid the frequent cell reselection by MS.

CELL BAR ACCESS (CBA)In the system message broadcasting in each cell, there is a bit information indicating whether to allow the MS to access to it, which is called cell bar access (CBA). The parameter CBA is to indicate whether the cell bar access is set in a cell.The parameter is represented in character string. Its value range is:

YES: the cell is barred for accessNO: the cell is not barred for access

The CBA bit is a parameter for the network operator to set. Usually all the cells are allowed to be accessed by MS , so the bit is set NO. However, in special cases, the telecom operator may want to assign a certain cells for handover service only, then the bit can be set YES.

CELL BAR ACCESS (CBA)

CELL BAR QUALIFY (CBQ)In areas where the cells overlay with each other and differ in capacity, traffic and functions, the telecom operator often hopes that the MS can have priority in selecting some cells, that is, the setting of cell priority. This function is set by way of the parameter "Cell Bar Qualify" (CBQ).

YES:The cell has high priorityNO:The cell has low priority

CELL BAR QUALIFY (CBQ) 2C1 and C2 States with CBA and CBQ Configurations

Sheet1

AreaSubscriberTrafficNo. of BTSNo. of TRXNo. of BSC

ALL AREAS1,200,00030,0001,2207,3208

Region A780,00019,5007934,7585

Region B300,0007,5003051,8302

Region C120,0003,0001227321

S22224.60

Sheet2

CBQCBACell Selection PriorityCell Reselection State

NoNoNormalNormal

NoYesBarredBarred

YesNoLowNormal

YesYesLowNormal

Sheet3

EXAMPLE OF CBQ SETTING For some reasons, the traffic of Cells A and B is apparently higher than that of other adjacent cells. To balance the traffic in the whole area, you can set the priority of Cells A and B as low, and set the priority of the rest cells as normal so that the traffic in the shade area will be absorbed by adjacent cells. It must be noted that the result of this setting is that the actual coverage of Cell A and Cell B is narrowed. However, this is different from reducing the transmitting power of Cell A and Cell B, the latter may cause blind areas of the network coverage and the reduction of communication quality.

RANDOM ACCESSRandom access is the process that messages being transmitted on RACH when a MS turns from idle to specialized mode. The main parameters includes:MAXRETRANSACRE (Re-establishment Enable)

MAX RETRANSWhen starting the immediate assignment process (e.g, when MS needs location updating, originating calls or responding to paging calls), the MS will transmit the "channel request" message over the RACH to the network. As the RACH is an ALOHA channel, in order to enhance the MS access success rate, the network allows the MS to transmit multiple channel request messages before receiving the immediate assignment message. The numbers of maximum retransmission (MAX RETRANS) are determined by the network.

MAX RETRANSThe MAX RETRANS is often set in the following ways: For areas (suburbs or rural areas) where the cell radius is more than 3km and the traffic is smaller, the MAX RETRANS can be set 11 (i.e. the MAX RETRANS is 7). For areas (not bustling city blocks) where the cell radius is less than 3km and the traffic is moderate, the MAX RETRANS can be set 10i.e. the MAX RETRANS is 4). For micro-cellular, its recommend that the MAX RETRANS be set 01i.e. the MAX RETRANS is 2). For microcellular areas with very high traffic and cells with apparent congestion, its recommend that the MAX RETRANS be set 00i.e. the MAX RETRANS is 1).

ACCESS CONTROL AC In some special conditions, the telecom operator wants to bar all or part of MS from sending out the access request or paging response request in some special areas. For example, in case some areas are in emergency state or in case a GSM PLMN encounters a serious fault. For this reason, GSM Specification02.11stipulates that each GSM subscriber (ordinary subscriber) is allocated with an access level. The access level ranges from 0 to 9 and is stored in the SIM card of the subscriber. The GSM Specifications reserves 5 special access levels for some special subscribers, which range from 11 to 15. These levels usually have higher access priority. Special subscribers can have one or more access levels (11~15), and their access levels are also stored in the SIM cards.

ACCESS CONTROL ACThe access levels are distributed as follows:C 0C9: ordinary subscribers;C11: used for PLMN management;C12: used by the security department;C13: public utilities e.g. water, gas;C14: emergency service;C15: PLMN staff.

SETTING OF ACIn the BS installation and commissioning process or in the process of maintaining or testing some cells, the operator can set C0C9 as 0 to forcedly forbid the access of ordinary subscribers so as to reduce the unnecessary effects on the installation or maintenance work.

In some cells with very high traffic, the congestion will occur in busy hours. For example, the RACH conflict happens frequently, the AGCH is overloaded and the Abis interface flow is overloaded. The network operator can set proper access control parametersC0C15to control the traffic of some cells.

RE-ESTABLISHMENT ENABLE (RE)For the drop calls caused by the radio link fault, the MS can start the call reestablishment process to resume the conversation, but the network is entitled to determine whether the call reestablishment is allowed or not. 0=Yes, 1=No.In some special circumstances, the drop call may occur when the MS goes through a blind area during the conversation. If the call reestablishment is allowed, the mean drop call rate will be reduced. However, the call reestablishment process will occupy a longer period of time, most of the subscribers have hung up before the reestablishment process is over, as a result, the call reestablishment failed to achieve its purpose and wasted many radio resources. We recommend that the call reestablishment be not allowed in the network except for some individual cells.

LIMITnAccording to GSM Specification 05.08, the BTS must measure the interference levels of the upward links of all the free channels for the purpose of providing basis for managing and allocating radio resources. Moreover, the BTS should analyze its measured results, divide the interference levels into 5 grades and report them to the BSC. The division of the 5 interference grades (i.e. the so-called interference bands) is set by the operator through the man-machine interface. The parameter "Interference band border (LIMITn) determines the borders of the 5 interference bands.

LIMITnDefault:LIMIT14LIMIT28LIMIT315LIMIT425The division of the interference bands should be favorable in describing the interference in the system. Generally the default values are recommended. In the ordinary situations, the free channel interference level is smaller, so the LIMIT14 value should be smaller. When apparently large interference appears in the system, you can properly increase the LIMIT1~4 values in order to know the exact interference.

Sheet1

AreaSubscriberTrafficNo. of BTSNo. of TRXNo. of BSC

ALL AREAS1,200,00030,0001,2207,3208

Region A780,00019,5007934,7585

Region B300,0007,5003051,8302

Region C120,0003,0001227321

S22224.60

Sheet2

CBQCBACell Selection PriorityCell Reselection State

NoNoNormalNormal

NoYesBarredBarred

YesNoLowNormal

YesYesLowNormal

Sheet3

Value RangeSpecified dBm Level

0

IMSI ATTACH/ DETACH (ATT)An ATT mark should be set as YES so that the network will no longer process the paging process for the called MS after the MS shuts down, thus saving the processing time of the network entities and saving lots of network resources.

Please note that the ATT in different cells but in the same location area should be set the same. Because the shutdown of the MS in cells where the ATT is YES will start the IMSI detach process, and the network will record the fact that the MS is in the non-working state and reject all the connection requests when using MS as the called. When the MS restarts and is in the same location area (so the location update process is not started) as when it shuts down but is in a different cell and the ATT of the cells is set as NO, so the MS will not start the IMSI attach process, either. In this case, the MS cannot become the called party until it starts the location updating process.

IMSI ATTACH/ DETACH (ATT) The IMSI detach process is that: the MS notifies the network that it is moving from the working state to the non-working state, or the process of the SIM card being taken from the MS. When receiving the notification from the MS, the network will indicate the IMSI subscriber to be in the non-working state, so the connection request ending the subscriber as the called party will be rejected. The corresponding IMSI attach process is that the MS notifies the network that it has been in the working state , or the SIM card is re-inserted into the MS. When the MS re-enters the working state, it will detect whether the current LAI is the same as the LAI finally recorded in the MS. If they are the same, the MS will start the IMSI attach process, otherwise the MS will start the location updating process (instead of the IMSI attach process). When receiving the location updating or IMSI attach process, the network will indicate the IMSI subscriber being in the working state.

CCCH_CONFThe CCCH can be one or more physical channels. The CCCH and SDCCH can share the same physical channel. The combination mode of the common control channel in a cell is determined by the CCCH_CONF

Sheet1

AreaSubscriberTrafficNo. of BTSNo. of TRXNo. of BSC

ALL AREAS1,200,00030,0001,2207,3208

Region A780,00019,5007934,7585

Region B300,0007,5003051,8302

Region C120,0003,0001227321

S22224.60

Sheet2

CBQCBACell Selection PriorityCell Reselection State

NoNoNormalNormal

NoYesBarredBarred

YesNoLowNormal

YesYesLowNormal

Sheet3

Value RangeSpecified dBm Level

0

CCCH_CONFThe CCCH_CONF is determined by the telecom operation department according to the traffic model of a cell. It is often decided in the system design period. The common configurations in practice are the following: If a cell has 1 or 2 TRX, we recommend that the CCCH uses one basic physical channel and shares it with the SDCCH If a cell has 3 or 4 TRX, we recommend that the CCCH uses one basic physical channel but does not share it with the SDCCH.

AGBLKSince the CCCH consists of the access grant channel (AGCH) and paging channel (PCH), it is necessary to set how many blocks of the CCCH information blocks are reserved and dedicated to the AGCH. To let the MS know about the configuration information, the system message of every cell contains a configuration parameter, that is, the access grant reserve blocks (AGBLK).AGBLK is represented in decimal numerals, and its value range is:CCCH is not combined with SDCCH: 07.CCCH is combined with SDCCH: 02.

AGBLKSETTING AND IMPACT OF AGBLK The AGBLK setting principle is: given that the AGCH is not overloaded, try to reduce the parameter as much as possible to shorten the time when the MS responds to the paging and improve the quality of service of the system.

The recommended value of AGBLK is usually 1 (when the CCCH is combined with the SDCCH), 2 or 3 (when the CCCH is not combined with the SDCCH).

BS-PA-MFRMS According to the GSM specifications, every mobile subscriber belongs to a paging group. In every cell, every paging group corresponds to a paging subchannel, the MS calculates the paging group to which it belongs by its own IMSI, then calculates the location of the paging subchannel belonging to the paging group.

In an actual network, the MS only "receives the contents in the paging subchannel to which it belongs but ignores the contents in other paging subchannels, or even turn off the power supply of some hardware equipment of the MS for other paging subchannels to save the MS power overhead (i.e. DRX source).

The BS-PA-MFRMS refers to how many multi-frames are used as a cycle of a paging subchannel. This parameter in fact determines how many paging sub-channels are to be divided from the paging channels of a cell.

BS-PA-MFRMS (2)BS-PA-MFRMS is represented in decimal numerals and its value range is 29, its unit is multiframe 51 frames, its default value is 2

Sheet1

BS-PA-MFRMSMultiframes of the same paging group that cycle on the paging channel

22

33

44

55

66

77

88

99

Sheet2

Sheet3

PERIODIC UPDATING TIMER (T3212) The reasons for the location update in the GSM system are of two types: one is that the MS finds its location area changed (with a different LAC), the other one is that the network requires the MS to periodically update its location. The frequency of periodic location update is controlled via the network and the period length is determined by the parameter T3212. In general, in areas with larger traffic and signaling flow, you should select the larger T3212e.g. 16 hours, 20 hours or even 25 hours, but in areas with smaller traffic and lower signaling flow, you can set the smallerT3212 (3 hours or 6 hours, etc.). In areas where traffic is far beyond the system capacity, we recommend that you set T3212 as 0.

NCCPERMIn the connection mode (during the conversation), the MS will report the measured signals of the adjacent cells to the BS, but each report may contain at most 6 adjacent cells, Therefore, let the MS only report the information of the cells that may become the hand-over target cells, do not let the MS report the information merely according to the signal level without selection (usually do not let the MS report other GSMPLMN cells).

The above functions can be fulfilled by limiting the MS to merely measure the cells whose NCC have been specified. The NCCPERM lists the NCCs of cells to be measured by the MS.

NCCPERM (2)In general, each area is allocated with one (or several) NCC. The NCCPERM of each cell in the area should contain the NCC of the area, otherwise a large number of cross-cell drop calls will occur and the cell reselection will fail. To ensure the normal roaming between different areas, the border cells of an area should contain the NCC of its adjacent areas

RADIO LINK TIMEOUT (RLT) During the MS conversation-, when the downward voice (or data) quality is degraded to be unacceptable and cannot be improved through the RF power control or handover (i.e. the so-called radio link fault), the MS will either start the call re-connection or forcedly disconnect the link. As the forced disconnection actually means a "drop call" process, the MS will regard it as a downward radio link fault when the communication quality is unacceptable (usually the user has to hang up). In this case, it is provided in the GSM specifications that the MS needs a counter S to assign an initial value--"downward radio link timeout"--. When S is counted to 0, the MS will report the downward radio link fault.

MBCR (1) In the single band GSM system, when the MS reports the adjacent cell measurement result to the network, it only needs to report the contents of the 6 adjacent cells with the strongest signals in a band. When multiple bands form a network, the telecom operator often, according to the actual situation of the network, wants the MS to access to a frequency band with priority during the handover, so the operator hopes that the MS will report the measurement result on the basis of not only signal strength but signal band as well. The parameter "multiband indication (MBCR)" is used to notify the MS that it should report the multiband adjacent cell contents. The value is 0-3

MBCR (2) 0: Based on the signal strength of adjacent cells, the MS reports the measurement results of 6 adjacent cells whose signals are the strongest, whose NCC are known and allowed no matter in which band the adjacent cells lie. The default value is 0 1: The MS should report the measurement result of an adjacent cell in each band (not including the band used by the current service area) in the adjacent table, whose signal is the strongest and whose NCC is already known and allowed. It should also report in the rest position the adjacent cells in the band used by the current service area. If there are still rest positions, it will report the information of the rest adjacent cells no matter in which band these adjacent cells lie.

MBCR (3) 2: The MS should report the measurement results of two adjacent cells in each band (not including the band used by the current service area) in the adjacent table, whose signals are the strongest and whose NCC are already known and allowed. It should also report in the rest position the adjacent cells in the band used by the current service area. If there are still rest positions, it will report the information of the rest adjacent cells no matter in which band these adjacent cells lie.3: The MS should report the measurement results of three adjacent cells in each band (not including the band used by the current service area) in the adjacent table, whose signals are the strongest and whose NCC are already known and allowed.