CO BCCCH DOCUMENT AND STRATEGIE

7/27/2019 CO BCCCH DOCUMENT AND STRATEGIE

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this report serves to give an insight into the procedures followed , actionstaken and the resulted impact from the Co-BCCH between 900 and 1800 donein Ghardaia (MENEA all col located site) and the improvements that have beenbrought to the network implementation specially for the traffic and TCHcongestion, TCH assignement, TBF Estatablishment succes rateIn the first sections the report will explain the sites that serve it and thetriggering causes of this process , later sections will concentrate more on theimpact on KPIs and the recommended changes implemented.

final conclusion wil l summarize the recommendations and future suggestionsand further actions that should be taken into acount1. Introduction :2. Actions Trigger:The below points are the summary of the reasons behind the initiation of thefrequency tuning in the targeted area:1. huge TCH congestion Rate in BSC level specially for these sites ,although most of congestion concentrated on 900 and is caused byunbalance traffic between 900 and 1800 but we can improve it further byproviding balance between these cells

2. also many of the cells are surffed from bad KPI due to TCH Congestionlike TBF Establishment success rate and TCH assiement success rate3. moving the traffic by playing in the correct parameters to handle traffic lostdue to congestion.3EAL/O/EO Redouane BENATALLAH

ATM/O/NPOC-13:002Prepared By (also subject responsible if other)Report Number:

Approved By:checked By:

DateEAL/O/EO Mohyedeen AlkousyEAL/O/EO Samir Djebbara/ Amina Koufi1/9/2013One cell can be divided into two subcells with Co-BCCH function. The two subcellsshare one BCCH. Subcell 1 is configured with BCCH; subcell 2 is newly added. Thisis also referred as concentric circle; Subcell 1 is also referred as the outer circle, andSubcell 2, the inner circle. See Figure 1-1.3.1 Introduction to the Concept of Co-BCCH :3.2 Application Scenarios :Figure 1-1 Dual-Band Network with Co-BCCH Adopted

3 Feature Description :Dual band Co-BCCH cell refers to the situation when two TRXs of different frequencybands are configured in the same cell. Usually, the TRX with frequency band of better transmission performance is configured in Subcell1 as well as BCCH andSDCCH; the other TRX is configured in Subcell2. In this situation, the handover algorithm based on path loss/TA is often adopted.For example, it can be applied to the Co-BCCH cells (where there are both 900MTRXs and 1800M TRXs), and BCCH and SDCCH should be configured on the 900Mfrequency band. The advantage of the Co-BCCH networking is that one BCCH canbe saved. More importantly, this method makes it possible that the 1800M frequencyband can absorb the traffic of the 900M frequency band without the reselections and

handovers among the dual-band cells. Besides, when the capacity expansion is donefor the network where only GSM900M is used, it is possible to configure the 1800MTRXs in the 900M cells directly without changing the original relations of the neighbor cells.4



EAL/O/EO Redouane BENATALLAH ATM/O/NPOC-13:002Prepared By (also subject responsible if other)Report Number:

Approved By:checked By:DateEAL/O/EO Mohyedeen Alkousy

EAL/O/EO Samir Djebbara/ Amina Koufi1/9/20133.3 Handover and Channel Allocation Algorthms:There are two ways of handover between subcells in ZTE:1. Handovers based on PathLoss and TA (which can be applied in dual-bandnetwork, network expansion and concentric cells)2. Handovers based on C/I (which can be used in concentric cells)In our case we have chosen handover based on PathLoss and TA so in thisintroduction we focus to explain this algorithm in detalis3.3.1 Judgment based on PathLoss and TA :If the call happens in Subcell 1, PathLoss and TA are both small, which means

the call is nearer to BTS, therefore, it will be handed over to Subcell 2 to absorbtraffic; if the call happens in Subcell 2, PathLoss and TA are both relatively bigger,which means the call is far from the BTS, so it should be handed over to Subcell 1to prevent call drop due to failure radio link.

According to judgment formula (1)(2):• PathLoss>= PathLossMax ………… (1)• TA> SubCellTAMax ...………………(2)5EAL/O/EO Redouane BENATALLAH


Approved By:checked By:DateEAL/O/EO Mohyedeen AlkousyEAL/O/EO Samir Djebbara/ Amina Koufi1/9/2013If MS is in subcell 1 and every SubCellP out of SubCellN satisfies boththe conditions of (PATHLOSS <= PathLossMin) and (TA < SubCellTAMin), it isbelieved that a handover should be made from subcell 1 to subcell 2.

If MS is in subcell 2 and every SubCellP out of SubCellN satisfies either thecondition (PATHLOSS >= PathLossMax) or the condition (TA > SubCellTAMax), itis believed that a handover should be made from subcell 2 to subcell 1.If SubCellTAMax = SubCellTAMin = TAMAX (the maximum TA), the prerequisitefor the handover mentioned above changes and the path loss becomes theonly criterion to be used. Similarly, if PathLossMax = PathLossMin = LMAX (themaximum path loss), the prerequisite for the handover mentioned above alsochanges and TA becomes the only criterion to be used.3.3.2 Handover based on C/IIf the call happens in Subcell 1, and C/I is large, which means radio link signal isgood, hand the call over to Subcell 2 to share traffic; if the call happens in subcell2,

C/I is small, which means radio link signal is poor, hand the call over to Subcell 1 toprevent call drop.Below algorithm show handover algorithm in case of Co-BCCH implemented6EAL/O/EO Redouane BENATALLAH




Approved By:checked By:DateEAL/O/EO Mohyedeen AlkousyEAL/O/EO Samir Djebbara/ Amina Koufi

1/9/20137EAL/O/EO Redouane BENATALLAH



1/9/20133.4 Comparisons between Co-BCCH dual-band network and traditional dual-band:1. Each of the two frequency bands in traditional dual-band network has its ownBCCH.It results in the waste of one timeslot, and it increases great amount of handover reselection of the MS and signaling load of the network.2. There is no problem of coverage overlap. MS reselection and location renewal wil lnot change due to the adding of 1800M network, therefore, handovers betweendifferent frequencies are reduced, and traffic carrying on both 900M and 1800Mfrequency bands can be bitterly controlled, and network operation will be morestable.3. In terms of project implementation, for network parameters in Co-BCCH dual-bandnetwork need not to be replanned, configure the 1800-MHz TRX as Subcell 2 in theoriginal 900-MHz cell. It is unnecessary to modify the neighbor cell relation. Theproject schedule can be greatly shortened, which is convenient for expansion of 1800-MHz network.4. However, with Co-BCCH dual-band network adopted, handovers inside the cellwillincrease dramatically, which will result in the possibility of failure assignment andhandover and affects network indicators.Co-BCCH dual-band network

Traditional dual-band network8EAL/O/EO Redouane BENATALLAH



1/9/20134. Feature Prerequisites :Our trial adopts 900/1800M dual band Co-BCCH cell over MENEA region (most congestedarea in GHARDAIA BSC) ; BCCH is configured on 900M; both the inner circle and the outer circle adopt SFH. Handover based on Pathloss and TA because and not in C/I because of



these reasons:1. the Hopping used in Mneaa area is SFH which means that the C/I values areconsiderably low due to the high TRX configuration, so we cannot balance the trafficbased on C/I only.2. this is the First time this feature is activated in ZTE vendor , so we cannot predict whatis the impact of activating the C/I algorithm.3. it's easier to tune the parameters to balance the traffic in case of path loss algorithm.4.1 Software Version Informations:

Software EnvironmentExplanationiBSCiBSC V6.20.200e p002iOMCRiOMCR V6.20.200eOMCBOMCB V4.00.200k p003SDRSDR V4.00.210e p074.2 Hardware Version Information:

Hardware EnvironmentExplanation

Antenna typeDual bandCN manufacturer ZTEThe physical link on ABISIP over ABISThe type of BSC hardware1000M platformThe type of BTS hardwareSDRNote should be taken on consideration:• BTS type must be SDR with 900M/1800M in same cabinet.• antenna type desirable to be dual band to make sure 1800&900 have sameazimuth.• Make sure that UL subcell coverage have bigger coverage than OL subcell (byanalyzing TA Measurement).• Performe Hardware optimaztion if possible like antenna tilt to leave the OL subcellhandle the most traffic nearer to the site.9

EAL/O/EO Redouane BENATALLAH ATM/O/NPOC-13:002Prepared By (also subject responsible if other)Report Number:

Approved By:checked By:DateEAL/O/EO Mohyedeen AlkousyEAL/O/EO Samir Djebbara/ Amina Koufi1/9/2013Below table shows related parameters tuned in the targeted cells the black color refer

to common parameters and red color special for handover based on Pathloss and TA All parameters shown in the table is considered as default value, after theparameters were correctly implemented, it can be changed in several time inorder to get thumps up value, as well this parameters can be defferent fromcell to other. It depends of cases.



NoParameter Suggested Value1FreqBand0 (GSM900)2SubFreqBand

2 (DCS1800)3DuleBandOffset64PathLossMax1365PathLossMin1286

SubCellTAMax27SubCellTAMin18SubCellN49SubCellP310 HoControl17path loss and TA11 HoToInnerSCYES13 PowerClass315 HoControl_11116 PSALLOCSC_0only subcell 1

4.3 Performance Analysis :Counters related to subcells are under “Subcell Statistical Measurement”. Whensubcells are configured, the measurement task measures the channels in subcellsand handovers between the subcells, and focuses on the traffic sharing in Subcell2(OL subcell). For Co-BCCH, what we shall concern about is whether the trafficsharing between the two subcells is reasonable.Currently our system cannot directly output the situation of congestion and traffic inthe two cells. We may temporarily solve the problem by setting up “Subcell StatisticalMeasurement”. From the measurement data, we may obtain the statistics of congestion and traffic in the inner circle; from performance reports, we obtain thestatistics of congestion and traffic in the cell. We may obtain data about the UL

Subcell by making subtraction between the two s

CO BCCCH DOCUMENT AND STRATEGIE

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