BTSBTSBSC TCSM MSCAterA-ifBSC ModelBSC2i248BCF/248BTS/512TRXBSC3i248BCF/248BTS/660TRXHow to select BSC capacity- 20% TRXs margin- space and futureupgrading- minimize inter BSC HO
BTSBTSBSC TCSM MSCAterA-ifUse offer traffic to calculate. Not install capacityAdd 10% traffic marginOffer 823Erl(sum fromeach BTSunder thisBSC)823+10%= 915Erl We calculate at915 Erl
BTSBTSBSC TCSM MSCAterA-ifFrom Erl-B we calculate numberof channel need at 915Erl and0.1% blocking= 985 channel (64kbps circuits)TCSM 1->4 : 1 Ater = 116 channelsTCSM 1->3 : 1 Ater = 901 A-if handle 30 channelswith TCSM can multiplex 4A-if to 1 AterBut if use TCSM 4->1 willlost 1 TSL(4channels) tosignalingActually we must have O&M link so 1 Ater = 114 channels but only 1 or 2 link/BSC so wecan ignore it. Except very small BSC have only 1 or 2 Ater.
BTSBTSBSC TCSM MSCAterA-ifAter = 985/116= 8.49= 9 Ater linksA-if =985/29= 33.9= 34 A-iflinksThis case use TCSM 1->4Ater 116 = 4 A-if with 29channels
BSC BSC BSCTCSM TCSMMSCAterA-ifTCSM racks need =Ater within same MSC / 8
When SDCCH get highcongest TCH utility becomedegradeMS terminated but noSDCCH for new callsetupTo solve congestionand utility don’tforget SDCCH!